Uploaded byscholarglobeapp
PPTX, PDF64 views

SENIOR TWO SOIL presentations For Ugandan schools

The document discusses the importance, types, properties, and characteristics of soil, emphasizing its essential role as a natural resource. It details how soil supports plant life, serves as a habitat for organisms, and provides materials for construction and art. Various soil types are described based on their texture, color, and retention capabilities, along with experiments to compare properties like water retention, drainage, and capillarity.

Embed presentation

Download to read offline
1 / 111
2 / 111
3 / 111
4 / 111
5 / 111
6 / 111
7 / 111
8 / 111
9 / 111
10 / 111
11 / 111
12 / 111
13 / 111
14 / 111
15 / 111
16 / 111
17 / 111
18 / 111
19 / 111
20 / 111
21 / 111
22 / 111
23 / 111
24 / 111
25 / 111
26 / 111
27 / 111
28 / 111
29 / 111
30 / 111
31 / 111
32 / 111
33 / 111
34 / 111
35 / 111
36 / 111
37 / 111
38 / 111
39 / 111
40 / 111
41 / 111
42 / 111
43 / 111
44 / 111
45 / 111
46 / 111
47 / 111
48 / 111
49 / 111
50 / 111
51 / 111
52 / 111
53 / 111
54 / 111
55 / 111
56 / 111
57 / 111
58 / 111
59 / 111
60 / 111
61 / 111
62 / 111
63 / 111
64 / 111
65 / 111
66 / 111
67 / 111
68 / 111
69 / 111
70 / 111
71 / 111
72 / 111
73 / 111
74 / 111
75 / 111
76 / 111
77 / 111
78 / 111
79 / 111
80 / 111
81 / 111
82 / 111
83 / 111
84 / 111
85 / 111
86 / 111
87 / 111
88 / 111
89 / 111
90 / 111
91 / 111
92 / 111
93 / 111
94 / 111
95 / 111
96 / 111
97 / 111
98 / 111
99 / 111
100 / 111
101 / 111
102 / 111
103 / 111
104 / 111
105 / 111
106 / 111
107 / 111
108 / 111
109 / 111
110 / 111
111 / 111
@PETER .L. OKION 778001502/758795415 8/3/2023 @PETER .L. OKION 77800150 2/ 7587954 15
, ' t - 11, ..,·_ .' , + .. • ... ' 4 _ 4 ' · . , _- .. ~ - - . ~ - L,~ . . . . .. • . t @PETER .L. OKION 778001502/ 758795415
SOIL • • Soil is the top most layer of the earth's crust. OR The finely divided material covering the earth's surface. It is normally treated as dirt Soil is the most essential natural resource on earth, and without it, there would be no home and food for all organisms on earth. •
8/3/2023 @PETER .L. OKION 778001502/ 758795415 6
Foo r Co 8/3/2023 @PETER .L. OKION 778001502/ 758795415 7
The decaving plant and animal matter help give structure to the soil to hold the plant place. roots in "y r b ( ' -, » % ' / 4s «" ) ~ l ----- l f ! . 0 I ( r • @PETER .L. OKION 778001502/ 758795415 8/3/2023
Importance of soil • Soil provides nutrients e.g. water and minerals to plants which are the chief producers offood in the environment. Soil is a habitat (home) for many organisms such as earth worms, termites, bacteria fungi and arthropods. Soil provides a medium through which man and all other animals dispose of their wastes. Soil is an important natural resource which provides construction materials, supports agriculture, craft and art materials. • • •
TYPES OF SOIL • The appearance of soil varies from place to place. • Question: are soils from the swamps similar to those do the two soils differ? from hills?, how
ctd • Soils differ in color, texture and size of the particles. The difference in this properties determines the type of the soil. • The type of soil determines the use of the soil, which soil types are common in your area?, what are the main uses of the soil types in your community?
'peso 'oi rent o h ¢ « @P ET ER .L. OKI ON 778 8/3/2023 12
@PETER .L. OKION 778001502/ 758795415 8/3/2023
.,,, J ' t . I ' , ' ' • ' ., t ' ' ! ... 6f ~ 4 ' 4 ' . • ,. I'', , 4 I + ' .'j:, 4 J1 : I f ,. I , 6 ; e. . « d t 1 ., ·. (" 'I ~ a • i J l ' 0 - I, ~ ~ I d ... ~ .- - f t f , . 4 ., . 1 ' $ i ' 4 J t f 4 /- F .I CLAY particles are packed together tightly. It is sticky when wet and has the finest texture. 8/3/2023 LOAM Is a mixtureofsand SAND particles andclay. It contains large amountofdecaying are coarse and loose and plants animals. It has afinetexture. @PETER .L. OKION 778001502/ 758795415
Loam
ctd LOAM SOIL, this is a mixture of sand(about 40%), clay(15%) and organic matter. It is dark and has a stable crumb structure. Usually found almost everywhere especially in gardens, near compost pits and dumping areas. SANDY SOIL, it is light and has a gritty feel when wet. Found on lake shores and hilly areas. CLAY SOIL, it is heavy and has fine particles with a sticky feel when wet. found in swamps and anthills. • • •
CHARACTERISTICS OF SOIL • • • A) COLOUR Have you noticed that different soils have different colors? Do you know the color of loam soil? Why do you think it is that color?
ctd • The color of soil is usually determined by the mineral present and by the organic matter that covers the surface of the soil particles. • Black soils are generally more fertile than lighter soils because they tend to have higher organic matter content. • • • B)TEXTURE this is how rough or how smooth a particular soil sample is. The texture of sand, silt, clay analysis chart, fine-textured. a soil sample is determined by the relative proportions of and particle sizes present in the soil, e.g. using soil texture we see that sandy soils are coarse-textured and clay soils are
C l a y S Ity c l a y t o a m S a n d y lo a mn c l a y C l a y S a n d y l o a m S a n d y s i i t t o a r S i l t l o a m S a n d I n c r e a s i n g s a n d L L u t e d i u m s o il l s H e a v y s o i l s t e « i v silt . 2 o 2 3 @PETER .L. OKION 778001502/ 758795415 19
ctd • • C) PARTICLE SIZE soil particles can be categorized into 4 terms of average diameter of a particle, types based on their size in different types of soil are made up of different soil more particles particles; most soils have a combination of 3 or Particle Gravel Sand Silt Clay size Average diameter Greater than 2.0mm 0.02-2.0mm 0.002-0.02mm Less than 0. 002mm PETER .L. OKION 778001502 758795415
m Water a Organic Matter A I A 'g Water & Air in direct proportion to each other 8 3/2023 PETER L OK ON 778001502/ 758795 15
CONSTITUENTS OF SOIL • Soil constituents are materials that living and non-living things e.g ............................. ' combine to form soil. They include , ' ......................................... • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • And
soln Humus Water, Air, or organic matter Minerals Soil living organisms.
PROPERTIES OF SOIL • Different soils have different properties. The properties can be categorized into physical and chemical properties. PHYSICAL PROPERTIES, are qualities that can be perceived • by body senses like seeing, feeling and tasting E.g. water retention, drainage, color, texture and particle size. A) WATER RETENTION If plants are to obtain water from the soil, then the soil ability to retain water in its particles. • • must have the • Qn. Do all the soils have the same capacity to retain water?
ctd • Soils that retain more water are said to have a High water retention capacity while soils that retain less water are said to have • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Experiment Comparing water retention capacity of clay, loam and sandy soil Procedure a) Measure an equal volume of each soil sample. b) Fold filter papers properly and put one in each funnel. other funnel. same time pour an equal volume of water on each of the soil samples as • • c) Then place clay soil in the filter paper in one funnel and the sand in the d) Place the funnels with their contents over measuring cylinders and at the shown in the diagrams.
Setup San d Loam Clav ;J Filter funnel . 3·• 'I ··I:, ,. . . 0 0 0 0 Measuring cylinder s - - - - i i i i i •
Observation • Water passes through sandy soil faster than it does in loam and clay soils. Sandy soil gives the first drop of water and clay soil gives the last. • • So much water is water is collected collected in the cylinder with sandy soil and the least in the cylinder with clay soil. • CONCLUSION, Clay soil holds more water than loam and sandy soil
explanation • Sandy soil has large air spaces which enable water to pass through more rapidly and on the other hand , clay soil retains more water than sandy and loam soils. This is because clay soil has many small particles with small air spaces thereby retaining more water Loam soil has medium retention B) DRAINAGE • • • After rain, some places dry immediately while others remain water logged. What is the reason for this? The ability of the soil to let water move through it is called soil • • • • • • • • • • • • • • •
ctd Soil drai nage soil parti cles. to have go through it • depends on the size of the particles and air spaces between the The soil type that easily allows water to pass through it is said drainage while the soil type that does not allow water to easily is said to have drainage . • Poor soil drainage leads to water logging that destroys property and crops. • • Experiment to compare drainage of sandy, loam and clay soils. NB: For procedure and setup, refer to experiment on water retention
observation • Water passes faster through sandy soil than through loam and clay soils. Sandy soil gives the first drop of water and clay soil gives the last drop • So much water is water is collected collected in the cylinder with sandy soil and the least in the cylinder with clay soil. • CONCLUSION, sandy soil drains faster than loam and clay soil
explanation • Sandy soil has larger air spaces which enable water to drain through more more space s rapidly and on the other hand, clay soil has low because drainage and retains water than sandy and loam soil. This and small particles. Loam soil has a medium drainage is clay soil has few air • • • C) CAPILLARITY Qn. At a construction site, you have seen builders use a black polythene sheet to cover the slab after laying the foundation. Why do you think this is necessary before continuing the construction of the wall?
ctd • The rise of water from the bottom layers to the top layers through the soil particles is called It also depends on the size of the soil particles. Imagine sipping NOVIDA using a straw • •
Experiment to compare capillarity of sandy, loam and clay soils • Procedure a) Tie a muslin sheath tightly at the end of the glass tubes. b) Fill one glass tube with dry sample of sand soil and pack it ensuring that there are no spaces in the soil. c) Repeat this with clay and loam soils. well d) The sheath e) The shown glass tubes are stood vertically with the ends tied with immersed in a glass trough containing enough water. muslin glass tubes are supported upright with retort stands and clamps in the diagram below. as
Setup Sand Loam = a a - a a Clay a o m i Glass tube i I i i i i i i i i i i i I • • • i i i ii i i i II 11 1 1 II I II II 4 .a a ii i i i ii ii I • • t Ii Ii a i i i a a I Trough Cotton wool Water i i • ■l ■ i II I I I i d ii ' a ' a . " · · . . - " · + - - - m
Observation Water rises faster but to a lower level in sandy soil while in clay soil, water rises slowly but to higher levels. In loam soil water rises moderately to a moderate level. CONCLUSION; Clay soil has the highest capillarity while sandy soil has the lowest capillarity and loam soil has medium water capillarity. EXPLANATION: Water rises fastest during early stages of the experiment in sandy soil because sand has large spaces that enable water to rise rapidly Clay soil has the highest water capillarity because it is composed of tiny soil particles which present a large surface are over which water molecules cling. Water rises at a slow rate in clay soil because clay has small spaces between its particles. • • • • • •
Application • Clay mixed with water, oil and honey can be used to make clay masks that ladies apply on their faces to maintain beauty. • Basing on clay's property of being sticky when wet, it germs on the surface of the skin and deep in the pores dried up germs to the surface of the skin to be washed binds with and brings the away • Pottery, brick making .
Chemical properties of soil • SOIL PH, IS the degree of acidity or alkalinity of the soil. Most soils in the tropics are acidic. The pH of soil can be determined using universal indicator or litmus solution. a • • Qn. Why do you think it is important to know the pH of soil? SOLN. Helps one to know the crops can grow well in a given soil or land type. Qn. What would happen if you grew crops in soils with unsuitable pH? PH scale range from Oto 14. • •
ctd Soils with pH above 7 are basic or alkaline while soils with pH below 7 acidic. A soil type with a pH 7 is neither acidic nor basic, it is neutral. The pH of soil depends on its parent rock (rock from which the soil was • are • formed). pH controls which nutrients are available for plant use • • NB: PH is Potential of Hydrogen Examples of crops that grow well in acidic soils include; beans, onions, tomatoes, sweet potatoes . • Crops that grow well in alkaline soils include; pumpkin, cabbages .....
QUICK TIP cidic soils are found • • in places where the rainfall is very high poor. and drainage is Why is this s o ?
PERCENTAGE COMPOSITION OF SOIL CONSTITUENTS • Experiment to determine the percentage of air in the soil Apparatus: Measuring cylinders (2), dry soil sample, water, Method 1. Measure about 50 cm3 of dry soil in a measuring cylinder container to level out the soil. and glass rod. and tap the 2. 3. 4. Measure 50 cm3 of water in another measuring cylinder. Add the two together (observe carefully as you pour the water onto the soil) Allow the mixture to stand until no more bubbles appear. Read and record the final level of water plus soil in the measuring cylinder. Calculate the air content in terms of percentage.
Example • Volume of soil == 50cm3 Volume of water == 50cm3 Final volume of water+ soil after mixing== 85cm3 Volume of air in soil ( 100 - 85) = = 15cm3 air== volume of air 100 Percentage of x volume of soil air =15 x 100 50 used Percentage of Percentage of air == 30%
NB • The final volume of the mixture after stirring is lower than the initial volume of the mixture before stirring due to displacement of air around soil particles by water Expected volume == volume of water + volume of soil • • Volume of air == Expected volume - Actual volume observed
exerci• se • Bosco, a senior two student carried out an investigation to determine the percentage of air in a given soil sample and obtained values: Volume of soil used == 40cm3 Volume of water added to the soil== 50cm3 Final volume of water + soil after mixing == 80cm3 a) determine the volume of air in the soil sample. b) calculate the percentage of air in the soil sample the following • • • • •
Experiment to determine the percentage of water a soil sample Apparatus: Evaporating dish, fresh soil, weighing scale and oven or Bunsen burner. Procedure: in • a) Weigh a clean evaporating dish and record its weigh. (Let the weight be Xg). b) Fill the evaporating dish with soil and record the weight of the soil plus the evaporating dish. (Let the weight be Y g). c) d) to e) f) Dry the soil by heating it gently over a Bunsen burner flame for about 30 minutes. Heating and weighing is repeated until a constant mass is achieved. (Take care not burn the soil to produce smoke). Re-weigh the soil and the evaporating dish. (Let it be Z g). Then calculate the water content in the soil sample as shown below; Note: You should cool in a desiccator before weighing. This ensures that no fresh vapor enters the soil.
Results of the evaporating dish== X • Weight Weight Weight Weight Weight of of of of soil+ evaporating dish== Y soil+ evaporating dish after heating== soil sample== Y-X water in the soil sample == Y-Z Z • Percentage of water== amount of water amount of fresh X 100 soil Percentage of air== Y-Z Y-X • X 100
EXERCISE • 1. In an investigation, 80g of fresh soil was heated in a crucible. After repeated heating and cooling, the constant mass of the soil was found to be 65g. Calculate the percentage of water in the soil sample. • 2. which factors affect the water content of any given soil?
Experiment to determine the percentage of humus (organic matter) in the soil • Apparatus: Crucible, soil sample, tripod stand, pipe clay triangle Procedure: a) Weigh a clean empty crucible and b) Fill the crucible with soil halfway crucible on weighing scale (X g). weighing scale, heat source, wire, • • • record its weight (W g). and record the weight of soil plus • c) Dry the soil by heating it in an oven at 105 degrees C to constant weight (Y g) - the loss in weight of soil at this temperature is due to the water driven out by evaporation. d) Reweigh the soil and crucible and record the weight. e) Heat the dried soil on a crucible to redness in an oven, then weigh the soil after cooling and record its weight. Repeat this till a constant weight is achieved (Z g). • •
RESULTS • • • • • • • • • Weight of crucible == W g Weight of crucible + fresh soil == X g Constant weight of soil + crucible after heating at 1050C ==Y g Constant weight of soil + crucible after heating to redness == Z g Weight Weight Weight Weight of fresh soil == X - W of dry soil of dry soil of humus == Y - W after burning off humus == Z - W == Y - Z g Percentage of humus = @mount of humus amount of fresh X100 soil Percentage of humus == Y-Z x-w • Xl00
Exercise obtained by a student a given soil sample ; • The following data was percentage of humus in while determining the • • • Weight of the crucible Weight of the crucible = = 1 00g containing fresh soil 156g == Constant weight of the crucible containing soil after heating at 105 degrees Celsius == 143g • Constant weight 128g, calculate; of the crucible containing soil after heating to redness == • • • • a) b) c) d) weight weight weight of the of the of the fresh soil dry soil humus percentage of the humus in the soil sample
NB: • Humus bums off into carbon di oxide and water vapor causing change in color, smell and emergency of smoke
Experiment to investigate presence of living organisms in the soil • Requirements: muslin bag, soil from compost or top soil, 2 corks, lime water/bicarbonate indicator solution • Procedure: ✓Collect a handful of fresh top soil and divide it into 2 equal portions V Sterilize one portion of the soil sample by heating strongly on a crucible for 30minutes. Leave it to cool and place it in a muslin bag VPlace the remaining portion of the fresh soil sample in another muslin bag ✓Add equal amounts of lime water/ bicarbonate indicator in the conical flasks and then suspend the muslin bags with soil in the conical flasks as shown in the set up ✓Allow the conical flasks to stand for about 2days and observe the appearance of lime water/ bicarbonate indicator conical flasks, 2
Set u 52 8/3/2023
Observation • Lime water turns milky or bicarbonate indicator solution turns yellow in the conical flask A but remains clear in test conical flask B CONCLUTION Carbon dioxide was produced in conical flask A during respiration indicating the presence of living organisms Lime water remained clear in conical flask B because the living organisms in soil in conical flask B were killed by heating • • •
Sam le a stude nt. uestion set up by Study T h e a p p ar a t u s b e l o w that follow. w a s it careful ly a n d an swe r th e q u est i o n s , Sterilised soil in muslin bag F r e s h m o i s t s o i l - f ! • inmuslin bag [ ? j A _" + ' ' • ' , · e , · · . , L i e w a s . ' ? ? ' j : ? ? ? : : ? ' B L i e w a t e r capillary tube co ntainin g coloured liquid (a). W h a t w a s (i) (ii) S t at e wh a t the: aim o f th e ex peri ment . (0I mark) (0I mark) left to con tinue u s e o f th e l im e wate r in t h e setup wo ul d b e o bserv ed in each fl ask if th e (b). e x p e r i m e n t w a s for 2 4 hours. Explain your observations. Exp l ai n w h y was : (i) the soil in the flask B w a s sterilised (ii) coloured liquid level in the capillary tube dropped. (04 ma rk s) (c). ( 0 I (02 ma rk ) ma rk s) (d). S tate one ro le pl ayed b y the s oi l co mp on ent b ein g in ves t i gat ed in thi s exp erimen t? (0I marks) 8/3/2023 54
IMPORTANCE OF AIR AND WATER IN SOIL TO a)AIR LIVING ORGANISMS • VProvides oxygen for respiration of soil organisms and plant roots ✓Oxygen is also needed for the decay that produces humus VProvide nitrogen for fixation by nitrogen- fixing bacteria in the soil, the nitrogen absorbed is needed in the formation of nitrates and proteins ✓Carbon dioxide present in the air helps in increasing the soil acidity which favors proper growth of some plants ✓Carbon dioxide present in the air dissolves in water to form carbonic acid for weathering
b)WATER It moistens soil and keeps it humid/ moist, making it favorable for survival of micro organisms It dissolves mineral salts making them available for plants to take in It dissolves carbon dioxide produced by living organisms to form carbonic acid which causes chemical weathering of rocks It is a raw material for photosynthesis ►Water absorbed from the soil allows plant cells to be rigid (turgid), and this is very important for support of the plant, particularly herbaceous plant
c) Organic matter VIt is food for soil organisms Vit moderates temperature of the soil
EXERCISE • At home you have; a garden which normally gets dry has rained. The crops have even started to dry up due drainage a) which soil type makes up the highest composition your garden? shortly after to such high it • of the soil in • b) which challenge are the crops likely to face apart from lack of enough water? c) how can you improve the water drainage of your garden? •
soln • • • a) b) c) sandy soil shortage of nutrients adding humus, mulching and planting trees and cover crops
Activity of integration • Soil types in Uganda vary from place to place. The people in Kirark, activities. Some are; o Commercial farmers who cultivate crops in pots oBuilders who plaster houses in the village oPotters who make stoves a village in your neighborhood are individuals engaging in different These individuals have been using soil from a certain mining site in the loose in a very short period of time and falls off, the potters' products crack them to worry as their businesses are nearly collapsing. You have been individuals can do to sustain their businesses neighboring village. However the plaster which the builders use gets too while drying while the farmers' crops produce poor yields. This has made contacted by the village leaders who are seeking for advice on what the
Task • Using your knowledge of physical and chemical properties of soil, write a speech you will deliver to the individuals for them to understand the soil type each one needs to save his businesses
S u p p o r t M a t e r i a l A• " I I I F a r n n e r s o f 0 e a / v3a4g° f i g u r e 4 8 . A 6 8/3/2023
SOIL PROFILE • This is the vertical arrangement of the various soil layers called horizons. It represents the different layers at various stages of soil development. • as mature A soil with distinguished soil layers is known without clear profile is immature or young. The profile consists of the fallowing: i) Top soil ii) Sub soil iii) Parent or underlying rock and that • • • •
Drawing to show the soil profile Topsoil Sub soil o @PETER .L. OKION 778001502/ 758795415
Features offertile soil • Fertile soil is one which can provide adequate amounts of nutrients for plant growth, resulting into better crop yields and quality Soil fertility is the ability of the soil to sustain plant growth and optimize crop yield The healthy plants are grown in soil which has adequate water, • • humus, mineral salts and is well aerated for proper plant growth the soil with unhealthy plants might be lacking some of these constituents. while
SOIL EROSION AND CONSERVATION • • • What is soil erosion? Process of soil erosion This involves loosening of soil particles (detachment), moving of particles (movement) and placement of soil particles (deposition) soil
u h r e n t r a p w r t «l«posi ti on Theprocess soil erosion• Figure 2.7: • o
Questions: a) b) c) give the 5 types of soil erosion identify 10 causes of soil erosion what are the impacts of soil erosion?
Soln • a) ►Sheet, splash, rill, wind, gully b) VDeep slopes of land coupled with intense rainfall ✓Overgrazing of animals which removes the grass water erosion VDeforestation .Bush burning ✓Over cropping and ploughing cover and opens the soil to
c) >Nutrients and soil organisms are carried away in the top soil ►The soil left behind is unproductive ►Fields may be cut into irregular pieces by rill and gully erosion ►Floods carry away or submerge and suffocate crops and soil . organ1sms
Types of soil erosion • QN: Have you witnessed eroded fields in your community, you think could have caused that erosion? It might be the agents of erosion e.g • • • • • • • • • • • • • • • • • • • • • what do • and • When heavy winds blow away top soil, wind erosion occurs and this is referred to as when . running water carries away the top soil, • erosion is classified depending on the water carries away the top soil mechanism by which
6 6 ' c B D E 8/3/2023 Figure22R:Differenttyper~f soil erosion .l a 72 t i. • a . h . u lt d
Forms of water erosion • Sheet erosion: is the uniform removal of soil particles from an area without the development of clear water channels Rill erosion: is one that produces narrow shallow wavy channels called RILLS Gully erosion: is one that produces wide deep steep-sided channels water continues to flow down the rills deepening them • • as • Splash erosion: this is the first stage of the erosion process. It occurs when raindrops hit the bare soil. The explosive impact breaks up soil aggregates so that individual soil particles are "splashed" onto the soil surface.
Factors that lead to soil erosion • Type of surface cover: bare soils allow surface runoff carrying large volume of soil while soils covered with grass have a low rate of erosion and the speed of running water is reduced Gradient of the slope: steep slopes allow fast surface runoff carrying larger volumes of soil with it. Type of soils: more loose soils are easily carried away by water than less loose soils • •
Reducing soil fertility • Many times, farmers have complained about the reduced and they mostly attribute this to reduced soil fertility. What do you think could be the cause of the reduced soil crop harvests • fertility ? • Use the images below
c D G H I 76 8/3 20
ctd • A - soil B - misuse offertilizers through excessive application inhibiting plant growth soil compaction obstructs rain or water infiltration can alter the pH of the • leading to surface runoff or eros1• on C - soil erosion removes top soil which contains most D - mining removes top soil which exposes sand. Top supports plant growth • • nutrients soil is always rich and • • • E - poor disposal of wastes reduces soil aeration, drainage and water retention F - charcoal burning releases heat that kills soil G - flooding leaches nutrients from soil surface cannot be accessed by plant roots H - bush burning leaves the land bare exposing micro organisms to deeper layers where they • it to agents of soil erosion
Ctd • I - deforestation leaves land bare • Other activities include; ✓Over cultivation .Monocropping exposing it to agents of soil erosion ✓And other poor farming practices like clean weeding
Conserving our soil • • Soil is a valuable resource. What do you think makes soil valuable ? The great pressure on land is due to the increasing human population that has resulted to soil degradation. This is because of the various human activities carried out on land, which have resulted into soil erosion e.g. deforestation QN: what is soil degradation? This is the reduction or loss of the biological or economic productivity and complexity of land, resulting from natural or human activities • •
Activity • In your groups, discuss the steps or methods that the farmers and gardeners in your locality take to maintain the fertility of their soils (lOmarks)
Mulching- covering the soil in between crops with materials e.g. dry grass, plant leaves and • saw dust. This protects the soil from rain drops and improves water infiltration, it also suffocates weeds. Mulches release nutrients into soil after decom osition =. « ad 5 R s i ' r » •
Manuring- • organic manure is added to the soil, the humus present binds soil particles together and provides nutrients such as nitrates to the soil
Adding fertilizers - • these are rich in nitrogen, phosphorous and potassium which replace lost nutrients and improve soil fertility
Crop rotation - • this is where different crops are grown in succession on one piece of land over a number of years. Inclusion of deep rooted crops breaks up sub soil and legumes harbor rhizobium which adds nitrates to the soil
Composting - • waste materials, leaves, weeds and grass cuttings are piled and left to decay forming compost which is dug into the soil hence adding nutrients to the soil
lntercropping - • crops with poor ground cover e.g. maize are planted with beans that effectively cover the ground. This reduces the speed of water runoff and also suppresses weeds
Agroforestry - • farmers manage and integrate crops, trees and/or livestock on the same plot of land. This conserves soil through controlling water runoff and soil erosion
ctd • Wind breaks - trees are planted in rows across the direction of the prevailing wind to act as wind barriers hence reducing the effect of wind erosion • Read and make notes ►Terracing contour cultivation ►Minimum tillage ►Fallowing ►Irrigation about the following; ►Cover crops ►Soil testing, this is done soil to ascertain what nutrients are in poor supply in the
Water Balance Plants consume some of rainfall n regions, and part of the water evaporates from the soil The rest runs off the surface or recharges groundwater. Transpiration Evaporation Terracin g can change the specific hydrological path ways, increase soil roughn ess and vertical surface relief, and decrease the connectivity of overland flow. - Soil and Water conservation measures (Fanya-juu Terraces) a SOM Levels: -35% more than farms with conventional agnicfure' Crop Yields.: at least 25% more than farms with enrwantinnal arrienltre' } o 8/3/2023 - - - T r e n c h
Importance of micro organisms in Nitrogen and other cycles that keep soil fertile • Some of these organisms are large (macroscopic organisms) and can be seen with unaided eyes while others are very small (microscopic) and can only be seen under a microscope. • QN: What are the examples of soil microorganisms?
Note: • Decomposers break down compounds in dead plants environment. These are in chemical nutrients like carbon and nitrogen and animals to release them back into the tum released back into soil, there by improving soil fertility. These nutrients are then absorbed by plant roots for plant growth. Animals are able to obtain these nutrients when they eat plants. Activities of decomposers contribute to the cycling of carbon and nitrogen within the environment. □The process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts is called DECOMPOSITION
THE NITROGEN CYCLE • • • Nitrogen makes up the largest percentage ofAIR. QN: what is the percentage composition of Nitrogen in air? Surprisingly, much as nitrogen exists in abundance in air, it cannot be readily utilized by living organisms! This is because, for it to be used by living organisms it must be changed into various absorbable forms in a cycle of events called Nitrogen cycle. this describes how nitrogen circulates between plants, animals, the atmosphere and soil in the ground
script: a cloudy Monday morning, Leku a On the f a r m e r plants soy bean seeds in his feld. With little rain and sunshine, the seec germ w i t h i n a f e w For the young to continue to grow and nts Theese will enable them velop. zy need b i g g e r and stranger. A cool breeze to gr blows by, carrying nitrogen a nutrient h e i r own food. The soy bean plants cannot absorb that the soy beans need to make any of the nitrog the rhizobium mov a type t e r i a called rhizobium Deep under the soil, rithout to t h e of o f t h e bean. t h e root The rhizobiumn inhao root s y s t of the to the bean, but roots and soy bean pl Soon, t h e rhizobium attaches itself the doesn't mind. forms small nodules. flled The bax w i t h n i t r o g e izobiumn form a relationship that benefits m both As the bean plar t h e t h e bean to turn nitrogen gas into a a l i v e , the rhizobium helps usable Event nutrient N o w , t h e bean the beans to mature and grow big and produce bean pods. te their life cycle and die. T h e f a r m e r c o m e s his field of t h e plant plants coi vests a n d beans, chopping up t h e dead plants in t h e s o i l . u e o n osers break daw ts into t h e < o i l . These nut a r e absorbed by maize materials, releasing nut plants which the farmer planted in the same field. The maize n t s are fed on b y cows that s out excreta. This posed to release into reta is nitr, a - o r soil. Denitrifying bacteria convert t h e soil i n t o n i t r o g e n which g o e s t h e nitrates in back t@'the atm re. ePereR.to«ov 778001502/ 758795415 93
QUESTIONS • • • 1. 2. 3. how did the bacteria help the plant? can all plants get their nutrients from the soil, like the bean did? how did the farmer use plants to make his soil healthy? Explain how planting different crops help to replace nutrients in the soil. 4. what would happen if the farmer only grew maize in his field, year after year? •
Processes involved in the nitrogen cycle _ , · - • D E N I T R I rN 4 - A . • T O N [ w t a g e r f i x i n g 'a ] tac I V t 3 r t r i f y w r w to e ++@RETER .L. ORT N 778001502/ 7 58795415 8/3/2023
cycle T h e n i t r o g e n Nitrogen in Deniritying b a c t e r i a N i t r o g e n fixing h a t e r i air at mo sp he r ic T h u u n « e r s t ! a n d lig ht en i n g Proteins in animals D e a t h a n d P r o t e i n s plants i r I l e / i t ' t 4 t u ! w D e a d o r g a n i c n l e x c r e t a Putrefying hew' t e r i t A m m o n ium c o m p o u n d s Vitrifying bacteria m a t t e r Nitrates ( N O in t h e s o i l . . . a . Nitrites N O , 8/3/2023 @PETER .L. OKION 778001502/ 758795415 96
Nitrogen fixation can occur through: • 1) lightening: this breaks down nitrogen molecules into free nitrogen atoms that combine with oxygen, forming Nitrogen oxides. The oxides dissolve in rain and are washed into the soil where they form nitrates. 2) manufact ure of artif icial fertilizers: nit rogen and hydrogen react in an industrial chemical process, forming ammonia. The ammonia is used to make ammonium salt s and nit rat es, which are sold as fertilizers. QN: What examples of nit rogen containing fertilizers do farmers use in your area? 3) action of nitrogen fixing bacteria: these bacteria include; Rhizobium, • • • Azotobacter and spaces in the soil Clostridium. These bacteria use nitrogen gas from the air and bind it with other substances to make nitrates and other compounds. QN: Which bacteria is found in root nodules of Leguminous plants?
Ctd • Once nit rogen has eit her ammonium nit rogen by eat ing been fixed, it can be absorbed by plants in the form of salt s or nit rates used to build up proteins. Animals obtain plant s or ot her animals. • When plants and animals die, their bodies are decomposed by bacteria and fungi. Nitrogen in proteins is converted to ammonia by Putrefying bacteria before being released. Nitrifying bacteria e.g. Nitrosomonas and Nitrobacter convert Ammonia into Nitrates for plant re-absorption and re-use • • The nitrates and ammonia in goes into the atmosphere by the soil are converted into Nitrogen gas, which the action of Denitrifying bacteria e.g. Pseudomonas and thiobacillus, thus complet ing the nit rogen cycle
Sam le uestion The figure below shows the nitrogen nitrogen cycle. in atmosphere B plants soil nitrates ammonium salts in soil (05 marks) (02 marks) (0I mark) (02 marks) 99 (a). (b). Name the processes taking place at A, B, C, D and E. (i). (ii). State How is the process at B useful to plants? What organisms are responsible for the process the imporlance of the process at A in the cycle. at C. (c). 8/3/2023
Sam le uestion T h e n i t r o g e n c y c l e . f i g u r e b e l o w s h o w s t h e i n a t m o s p h e r e F r e e n i t r o g e n P r o d u c t 3 N i t r o g e n d i o x i d e 1 A i v P r o d u c t 2 Nitric acid - N i t r i t e s P r o d u c t 1 (03 '% m a r k s) ( 0 1 m a r k s ) (02 m a r k s ) ( a ) ( b ) ( e ) ( d ) s / 6 9 ) N a m e N a m e t h e t h e p r o c e s s e s t a k i n g p l a c e a t A t o G . a n d 3 . o f t h e b a c t e r i a r e p r e s e n t e d b y i t o i v . p r o d u c t s 1, 2 G i v e t h e g e n e r a l n a m e s L i s t 4 d i f f e r e n t w a y s i n w h i c h n i t ro g e n m a y b e lo s t f r o m th e s o i l . (02 m a r k s) (02 m a r k s ) E x p l a i n w h y w a t e r l o g g e d s o i l s a r e u s u a l l y d e f i c i e n t i n n i t r a t e s . 100
Microorganisms in the root nodules Root nodule P Figure 2.8: Root nodules on roots of a leguminous.plant.. 8/3/2023 0
Ctd • When you uproot a bean or soya bean plant, you notice round swellings on the roots . QN: what are they called ? Are the swellings on these roots important to the plant? What do the above features contain? • •
Exercise 7 g c r o p s . . . - t r o w c e r t 8/3/2023 103
Ctd • a) which activities are likely to improve on the nitrogen content of the soil? How? b) which activities are/is likely to reduce on the nitrogen content of the soil? How? 2) how can each of the following activities affect the nitrogen content of the soil; • • a) use of chemicals to spray fields b) rearing a cattle on a piece of land c) burning of bushes to prepare land for planting crops
Activity of integration At the beginning of each growing season, the farmers prepare their seed gardens by; in your area • • • Collecting and burning the plant remains Gathering plant remains and using them to make boundaries Planting crops while with plant remains are still in the garden
Support material B Fi g ur e 2. C A
Task • Design a poster you will use to advise the people in your home area, on the potential risks or benefits of their activities towards maintaining soil fertility and conservation
TEST YOURSELF indicators of a fertile soil each of the following is involved in soil erosion • • 1. mention four 2. a) 3. describe how Detachment b) Transport c) Deposition • Suggest how the following conditions are likely to affect the rate of soil er0s1• on a) area with light soils 4. state how soil fertility Uganda; a) Lake Victoria basin c) Kigezi highlands b) hilly areas c) soil with much vegetation • can be conserved in the following regions of b) Karamoja region
The figure below represents the Nitrogen cycle Ni• trogen • in• air b ' + ] Plants Animals ·« Nitrates e f l Ammonium compounds Figure 2.11: Nitrites The nitrogen cycle @PETER .L. OKION 778001502/ 758795415 8/3/2023
QNS. • • • a) b) c) name the processes a to f how do the processes a and b affect fertility of soil identify the microorganisms involved in processes a, b, d and f
SENIOR TWO SOIL presentations For Ugandan schools

More Related Content

PPTX
GRADE 4: DIFFERENT TYPES OF SOIL
byAngelicaATuringan
 
PPTX
Soil properties Gr. 6
byRuba Salah
 
PDF
S2 SOIL BY TR. OKION.pdf based on the new lower secondary curriculum
byJAKI68
 
PPTX
Properties of soils (teach)
byMoira Whitehouse
 
PPTX
Propertiesofsoilsteach 111021040220-phpapp02
bysrikar adivi
 
PDF
Class 7 Soil
byAreyoustupid
 
PPTX
power point presentation for grade 4 science
bymeshirleyday08
 
PDF
Identifying Your Soil for Rain Gardens
bySotirakou964
 
GRADE 4: DIFFERENT TYPES OF SOIL
byAngelicaATuringan
 
Soil properties Gr. 6
byRuba Salah
 
S2 SOIL BY TR. OKION.pdf based on the new lower secondary curriculum
byJAKI68
 
Properties of soils (teach)
byMoira Whitehouse
 
Propertiesofsoilsteach 111021040220-phpapp02
bysrikar adivi
 
Class 7 Soil
byAreyoustupid
 
power point presentation for grade 4 science
bymeshirleyday08
 
Identifying Your Soil for Rain Gardens
bySotirakou964
 

Similar to SENIOR TWO SOIL presentations For Ugandan schools

PDF
Grade 4 School Garden Lesson Plan - Soils Lesson; Make Your Own Soil ~ Massac...
bySchool Vegetable Gardening - Victory Gardens
 
PPT
Soil
byRichardParsons50
 
DOCX
Soil
byMussaOmary3
 
PPTX
exploring the types of Soil-Science grade 4.p Q4pt
byElmy48Akramen
 
PPTX
The Different Types of Soil.pptx grade 4 /q1
byLeahAlo
 
PPTX
Types Of Soil.. Grade eight and grade nine
bymanasikaushal15152
 
PPTX
Ppt presentation onthe concept ofthe.pptx
bysrikanth744666
 
PPTX
soil.pptx
byrogercabarlesiii2
 
PPT
457143972-soil-ppt-level-one.pptjbcjdbjdni
byAhKi3
 
PPTX
PPT for Science 4 Quarter 4 - WEEK 1.pptx
byvirginiagayo0
 
PPTX
Soil
bySHANTANU TYAGI
 
PDF
3rd u5 l3_soil
byBISD
 
PDF
Soil
byJoni Merquita Cruz
 
PPTX
Soil
byRaja_khan1
 
PPTX
HEGUYTGYUDIFY YGUYFHIDUH 2.3 SOIL TYPE.pptx
byluiisennghiimbwasha
 
PDF
Soils Overview is very educational and helpful
byngoloasavela23
 
PPTX
SOIL TEXTURE LECTURE.pptx..............................
byrcbulayog
 
PPTX
Layers of soil
byshielapadilla_
 
PPT
Grow Your Own, Nevada! Fall 2012: Gardening in Nevada's Soils
byUniversity of Nevada Cooperative Extension
 
PDF
Unit 7 Soils.pdf
byHope Haven Rwanda
 
Grade 4 School Garden Lesson Plan - Soils Lesson; Make Your Own Soil ~ Massac...
bySchool Vegetable Gardening - Victory Gardens
 
Soil
byRichardParsons50
 
Soil
byMussaOmary3
 
exploring the types of Soil-Science grade 4.p Q4pt
byElmy48Akramen
 
The Different Types of Soil.pptx grade 4 /q1
byLeahAlo
 
Types Of Soil.. Grade eight and grade nine
bymanasikaushal15152
 
Ppt presentation onthe concept ofthe.pptx
bysrikanth744666
 
soil.pptx
byrogercabarlesiii2
 
457143972-soil-ppt-level-one.pptjbcjdbjdni
byAhKi3
 
PPT for Science 4 Quarter 4 - WEEK 1.pptx
byvirginiagayo0
 
Soil
bySHANTANU TYAGI
 
3rd u5 l3_soil
byBISD
 
Soil
byJoni Merquita Cruz
 
Soil
byRaja_khan1
 
HEGUYTGYUDIFY YGUYFHIDUH 2.3 SOIL TYPE.pptx
byluiisennghiimbwasha
 
Soils Overview is very educational and helpful
byngoloasavela23
 
SOIL TEXTURE LECTURE.pptx..............................
byrcbulayog
 
Layers of soil
byshielapadilla_
 
Grow Your Own, Nevada! Fall 2012: Gardening in Nevada's Soils
byUniversity of Nevada Cooperative Extension
 
Unit 7 Soils.pdf
byHope Haven Rwanda
 

Recently uploaded

PDF
AAC2026_Richter_Why Agile Alone Isn't Enough - From Agile Methods to Goal-Dir...
byAgile Austria Conference
 
PDF
Robbee Minicola PhD Oral Defense Presentation
byMicrosoft
 
PDF
AAC2026_Keynote_Horx Strathern_Megatrends Countertrends.pdf
byAgile Austria Conference
 
PDF
AAC2026_Liebisch_It Starts With You - How Personal Growth Builds the Foundati...
byAgile Austria Conference
 
PPTX
Overview-Swine-Production-and-Breeds-of-Swine.pptx
bypanangcadjhonemart2
 
PDF
French Revolution { Class 9 } Presentation .pdf
bymanjusuhag88
 
PDF
Fix Your LSA Reputation Score: 7 Signals That Improve LSA Rankings
byDigital Harvest
 
PDF
AAC2026_Lister_Understand your 'Scrum DNA' !pdf
byAgile Austria Conference
 
PDF
When to Use Google Ads Instead of Local Service Ads: 4 Clear Scenarios
byDigital Harvest
 
PDF
AAC2026_Tanzer_Grown Organically Software and Bonsai.pdf
byAgile Austria Conference
 
PDF
Reasons LSA Ranking Dropped: 3 Causes That Push You Into “See More”
byDigital Harvest
 
PDF
AAC2026_Durcevic_Seeing the System: Making Relationships Visible to Unlock th...
byAgile Austria Conference
 
PDF
🇮🇳🇮🇳🇮🇳 Welcome to India 🇮🇳🇮🇳🇮🇳.pdf
bymanjusuhag88
 
PPTX
Bob Stewart Greater 02 08 2026.pptx
byFamilyWorshipCenterD
 
PDF
AAC2026_Batusek_Beyond the Bus Factor: Build your teams for for the future.pdf
byAgile Austria Conference
 
PPTX
Kitui County SRA 2025 Debrief_29_01 _2026_WE (002).pptx
byWilliam Waithaka
 
PDF
AAC2026_Lavrova_ The Second Spear of Agility Why We Need Meaning, Not Metrics...
byAgile Austria Conference
 
AAC2026_Richter_Why Agile Alone Isn't Enough - From Agile Methods to Goal-Dir...
byAgile Austria Conference
 
Robbee Minicola PhD Oral Defense Presentation
byMicrosoft
 
AAC2026_Keynote_Horx Strathern_Megatrends Countertrends.pdf
byAgile Austria Conference
 
AAC2026_Liebisch_It Starts With You - How Personal Growth Builds the Foundati...
byAgile Austria Conference
 
Overview-Swine-Production-and-Breeds-of-Swine.pptx
bypanangcadjhonemart2
 
French Revolution { Class 9 } Presentation .pdf
bymanjusuhag88
 
Fix Your LSA Reputation Score: 7 Signals That Improve LSA Rankings
byDigital Harvest
 
AAC2026_Lister_Understand your 'Scrum DNA' !pdf
byAgile Austria Conference
 
When to Use Google Ads Instead of Local Service Ads: 4 Clear Scenarios
byDigital Harvest
 
AAC2026_Tanzer_Grown Organically Software and Bonsai.pdf
byAgile Austria Conference
 
Reasons LSA Ranking Dropped: 3 Causes That Push You Into “See More”
byDigital Harvest
 
AAC2026_Durcevic_Seeing the System: Making Relationships Visible to Unlock th...
byAgile Austria Conference
 
🇮🇳🇮🇳🇮🇳 Welcome to India 🇮🇳🇮🇳🇮🇳.pdf
bymanjusuhag88
 
Bob Stewart Greater 02 08 2026.pptx
byFamilyWorshipCenterD
 
AAC2026_Batusek_Beyond the Bus Factor: Build your teams for for the future.pdf
byAgile Austria Conference
 
Kitui County SRA 2025 Debrief_29_01 _2026_WE (002).pptx
byWilliam Waithaka
 
AAC2026_Lavrova_ The Second Spear of Agility Why We Need Meaning, Not Metrics...
byAgile Austria Conference
 

SENIOR TWO SOIL presentations For Ugandan schools

  • 1.
  • 3.
    , ' t - 11, ..,·_ .' , + ..• ... ' 4 _ 4 ' · . , _- .. ~ - - . ~ - L,~ . . . . .. • . t @PETER .L. OKION 778001502/ 758795415
  • 4.
    SOIL • • Soil is thetop most layer of the earth's crust. OR The finely divided material covering the earth's surface. It is normally treated as dirt Soil is the most essential natural resource on earth, and without it, there would be no home and food for all organisms on earth. •
  • 6.
    8/3/2023 @PETER .L.OKION 778001502/ 758795415 6
  • 7.
    Foo r Co 8/3/2023 @PETER .L.OKION 778001502/ 758795415 7
  • 8.
    The decaving plant and animalmatter help give structure to the soil to hold the plant place. roots in "y r b ( ' -, » % ' / 4s «" ) ~ l ----- l f ! . 0 I ( r • @PETER .L. OKION 778001502/ 758795415 8/3/2023
  • 9.
    Importance of soil •Soil provides nutrients e.g. water and minerals to plants which are the chief producers offood in the environment. Soil is a habitat (home) for many organisms such as earth worms, termites, bacteria fungi and arthropods. Soil provides a medium through which man and all other animals dispose of their wastes. Soil is an important natural resource which provides construction materials, supports agriculture, craft and art materials. • • •
  • 10.
    TYPES OF SOIL •The appearance of soil varies from place to place. • Question: are soils from the swamps similar to those do the two soils differ? from hills?, how
  • 11.
    ctd • Soils differin color, texture and size of the particles. The difference in this properties determines the type of the soil. • The type of soil determines the use of the soil, which soil types are common in your area?, what are the main uses of the soil types in your community?
  • 12.
  • 13.
    @PETER .L. OKION778001502/ 758795415 8/3/2023
  • 14.
    .,,, J ' t . I ' , '' • ' ., t ' ' ! ... 6f ~ 4 ' 4 ' . • ,. I'', , 4 I + ' .'j:, 4 J1 : I f ,. I , 6 ; e. . « d t 1 ., ·. (" 'I ~ a • i J l ' 0 - I, ~ ~ I d ... ~ .- - f t f , . 4 ., . 1 ' $ i ' 4 J t f 4 /- F .I CLAY particles are packed together tightly. It is sticky when wet and has the finest texture. 8/3/2023 LOAM Is a mixtureofsand SAND particles andclay. It contains large amountofdecaying are coarse and loose and plants animals. It has afinetexture. @PETER .L. OKION 778001502/ 758795415
  • 15.
  • 16.
    ctd LOAM SOIL, thisis a mixture of sand(about 40%), clay(15%) and organic matter. It is dark and has a stable crumb structure. Usually found almost everywhere especially in gardens, near compost pits and dumping areas. SANDY SOIL, it is light and has a gritty feel when wet. Found on lake shores and hilly areas. CLAY SOIL, it is heavy and has fine particles with a sticky feel when wet. found in swamps and anthills. • • •
  • 17.
    CHARACTERISTICS OF SOIL • • • A)COLOUR Have you noticed that different soils have different colors? Do you know the color of loam soil? Why do you think it is that color?
  • 18.
    ctd • The colorof soil is usually determined by the mineral present and by the organic matter that covers the surface of the soil particles. • Black soils are generally more fertile than lighter soils because they tend to have higher organic matter content. • • • B)TEXTURE this is how rough or how smooth a particular soil sample is. The texture of sand, silt, clay analysis chart, fine-textured. a soil sample is determined by the relative proportions of and particle sizes present in the soil, e.g. using soil texture we see that sandy soils are coarse-textured and clay soils are
  • 19.
    C l ay S Ity c l a y t o a m S a n d y lo a mn c l a y C l a y S a n d y l o a m S a n d y s i i t t o a r S i l t l o a m S a n d I n c r e a s i n g s a n d L L u t e d i u m s o il l s H e a v y s o i l s t e « i v silt . 2 o 2 3 @PETER .L. OKION 778001502/ 758795415 19
  • 20.
    ctd • • C) PARTICLE SIZE soilparticles can be categorized into 4 terms of average diameter of a particle, types based on their size in different types of soil are made up of different soil more particles particles; most soils have a combination of 3 or Particle Gravel Sand Silt Clay size Average diameter Greater than 2.0mm 0.02-2.0mm 0.002-0.02mm Less than 0. 002mm PETER .L. OKION 778001502 758795415
  • 21.
    m Water a OrganicMatter A I A 'g Water & Air in direct proportion to each other 8 3/2023 PETER L OK ON 778001502/ 758795 15
  • 22.
    CONSTITUENTS OF SOIL •Soil constituents are materials that living and non-living things e.g ............................. ' combine to form soil. They include , ' ......................................... • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • And
  • 23.
  • 24.
    PROPERTIES OF SOIL •Different soils have different properties. The properties can be categorized into physical and chemical properties. PHYSICAL PROPERTIES, are qualities that can be perceived • by body senses like seeing, feeling and tasting E.g. water retention, drainage, color, texture and particle size. A) WATER RETENTION If plants are to obtain water from the soil, then the soil ability to retain water in its particles. • • must have the • Qn. Do all the soils have the same capacity to retain water?
  • 25.
    ctd • Soils thatretain more water are said to have a High water retention capacity while soils that retain less water are said to have • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Experiment Comparing water retention capacity of clay, loam and sandy soil Procedure a) Measure an equal volume of each soil sample. b) Fold filter papers properly and put one in each funnel. other funnel. same time pour an equal volume of water on each of the soil samples as • • c) Then place clay soil in the filter paper in one funnel and the sand in the d) Place the funnels with their contents over measuring cylinders and at the shown in the diagrams.
  • 26.
    Setup San d Loam Clav ;J Filterfunnel . 3·• 'I ··I:, ,. . . 0 0 0 0 Measuring cylinder s - - - - i i i i i •
  • 27.
    Observation • Water passesthrough sandy soil faster than it does in loam and clay soils. Sandy soil gives the first drop of water and clay soil gives the last. • • So much water is water is collected collected in the cylinder with sandy soil and the least in the cylinder with clay soil. • CONCLUSION, Clay soil holds more water than loam and sandy soil
  • 28.
    explanation • Sandy soilhas large air spaces which enable water to pass through more rapidly and on the other hand , clay soil retains more water than sandy and loam soils. This is because clay soil has many small particles with small air spaces thereby retaining more water Loam soil has medium retention B) DRAINAGE • • • After rain, some places dry immediately while others remain water logged. What is the reason for this? The ability of the soil to let water move through it is called soil • • • • • • • • • • • • • • •
  • 29.
    ctd Soil drai nage soil parti cles. to have go through it •depends on the size of the particles and air spaces between the The soil type that easily allows water to pass through it is said drainage while the soil type that does not allow water to easily is said to have drainage . • Poor soil drainage leads to water logging that destroys property and crops. • • Experiment to compare drainage of sandy, loam and clay soils. NB: For procedure and setup, refer to experiment on water retention
  • 30.
    observation • Water passesfaster through sandy soil than through loam and clay soils. Sandy soil gives the first drop of water and clay soil gives the last drop • So much water is water is collected collected in the cylinder with sandy soil and the least in the cylinder with clay soil. • CONCLUSION, sandy soil drains faster than loam and clay soil
  • 31.
    explanation • Sandy soilhas larger air spaces which enable water to drain through more more space s rapidly and on the other hand, clay soil has low because drainage and retains water than sandy and loam soil. This and small particles. Loam soil has a medium drainage is clay soil has few air • • • C) CAPILLARITY Qn. At a construction site, you have seen builders use a black polythene sheet to cover the slab after laying the foundation. Why do you think this is necessary before continuing the construction of the wall?
  • 32.
    ctd • The riseof water from the bottom layers to the top layers through the soil particles is called It also depends on the size of the soil particles. Imagine sipping NOVIDA using a straw • •
  • 33.
    Experiment to comparecapillarity of sandy, loam and clay soils • Procedure a) Tie a muslin sheath tightly at the end of the glass tubes. b) Fill one glass tube with dry sample of sand soil and pack it ensuring that there are no spaces in the soil. c) Repeat this with clay and loam soils. well d) The sheath e) The shown glass tubes are stood vertically with the ends tied with immersed in a glass trough containing enough water. muslin glass tubes are supported upright with retort stands and clamps in the diagram below. as
  • 34.
    Setup Sand Loam = a a -a a Clay a o m i Glass tube i I i i i i i i i i i i i I • • • i i i ii i i i II 11 1 1 II I II II 4 .a a ii i i i ii ii I • • t Ii Ii a i i i a a I Trough Cotton wool Water i i • ■l ■ i II I I I i d ii ' a ' a . " · · . . - " · + - - - m
  • 35.
    Observation Water rises fasterbut to a lower level in sandy soil while in clay soil, water rises slowly but to higher levels. In loam soil water rises moderately to a moderate level. CONCLUSION; Clay soil has the highest capillarity while sandy soil has the lowest capillarity and loam soil has medium water capillarity. EXPLANATION: Water rises fastest during early stages of the experiment in sandy soil because sand has large spaces that enable water to rise rapidly Clay soil has the highest water capillarity because it is composed of tiny soil particles which present a large surface are over which water molecules cling. Water rises at a slow rate in clay soil because clay has small spaces between its particles. • • • • • •
  • 36.
    Application • Clay mixedwith water, oil and honey can be used to make clay masks that ladies apply on their faces to maintain beauty. • Basing on clay's property of being sticky when wet, it germs on the surface of the skin and deep in the pores dried up germs to the surface of the skin to be washed binds with and brings the away • Pottery, brick making .
  • 37.
    Chemical properties ofsoil • SOIL PH, IS the degree of acidity or alkalinity of the soil. Most soils in the tropics are acidic. The pH of soil can be determined using universal indicator or litmus solution. a • • Qn. Why do you think it is important to know the pH of soil? SOLN. Helps one to know the crops can grow well in a given soil or land type. Qn. What would happen if you grew crops in soils with unsuitable pH? PH scale range from Oto 14. • •
  • 38.
    ctd Soils with pHabove 7 are basic or alkaline while soils with pH below 7 acidic. A soil type with a pH 7 is neither acidic nor basic, it is neutral. The pH of soil depends on its parent rock (rock from which the soil was • are • formed). pH controls which nutrients are available for plant use • • NB: PH is Potential of Hydrogen Examples of crops that grow well in acidic soils include; beans, onions, tomatoes, sweet potatoes . • Crops that grow well in alkaline soils include; pumpkin, cabbages .....
  • 39.
    QUICK TIP cidic soilsare found • • in places where the rainfall is very high poor. and drainage is Why is this s o ?
  • 40.
    PERCENTAGE COMPOSITION OF SOILCONSTITUENTS • Experiment to determine the percentage of air in the soil Apparatus: Measuring cylinders (2), dry soil sample, water, Method 1. Measure about 50 cm3 of dry soil in a measuring cylinder container to level out the soil. and glass rod. and tap the 2. 3. 4. Measure 50 cm3 of water in another measuring cylinder. Add the two together (observe carefully as you pour the water onto the soil) Allow the mixture to stand until no more bubbles appear. Read and record the final level of water plus soil in the measuring cylinder. Calculate the air content in terms of percentage.
  • 41.
    Example • Volume ofsoil == 50cm3 Volume of water == 50cm3 Final volume of water+ soil after mixing== 85cm3 Volume of air in soil ( 100 - 85) = = 15cm3 air== volume of air 100 Percentage of x volume of soil air =15 x 100 50 used Percentage of Percentage of air == 30%
  • 42.
    NB • The finalvolume of the mixture after stirring is lower than the initial volume of the mixture before stirring due to displacement of air around soil particles by water Expected volume == volume of water + volume of soil • • Volume of air == Expected volume - Actual volume observed
  • 43.
    exerci• se • Bosco, asenior two student carried out an investigation to determine the percentage of air in a given soil sample and obtained values: Volume of soil used == 40cm3 Volume of water added to the soil== 50cm3 Final volume of water + soil after mixing == 80cm3 a) determine the volume of air in the soil sample. b) calculate the percentage of air in the soil sample the following • • • • •
  • 44.
    Experiment to determinethe percentage of water a soil sample Apparatus: Evaporating dish, fresh soil, weighing scale and oven or Bunsen burner. Procedure: in • a) Weigh a clean evaporating dish and record its weigh. (Let the weight be Xg). b) Fill the evaporating dish with soil and record the weight of the soil plus the evaporating dish. (Let the weight be Y g). c) d) to e) f) Dry the soil by heating it gently over a Bunsen burner flame for about 30 minutes. Heating and weighing is repeated until a constant mass is achieved. (Take care not burn the soil to produce smoke). Re-weigh the soil and the evaporating dish. (Let it be Z g). Then calculate the water content in the soil sample as shown below; Note: You should cool in a desiccator before weighing. This ensures that no fresh vapor enters the soil.
  • 45.
    Results of the evaporatingdish== X • Weight Weight Weight Weight Weight of of of of soil+ evaporating dish== Y soil+ evaporating dish after heating== soil sample== Y-X water in the soil sample == Y-Z Z • Percentage of water== amount of water amount of fresh X 100 soil Percentage of air== Y-Z Y-X • X 100
  • 46.
    EXERCISE • 1. Inan investigation, 80g of fresh soil was heated in a crucible. After repeated heating and cooling, the constant mass of the soil was found to be 65g. Calculate the percentage of water in the soil sample. • 2. which factors affect the water content of any given soil?
  • 47.
    Experiment to determinethe percentage of humus (organic matter) in the soil • Apparatus: Crucible, soil sample, tripod stand, pipe clay triangle Procedure: a) Weigh a clean empty crucible and b) Fill the crucible with soil halfway crucible on weighing scale (X g). weighing scale, heat source, wire, • • • record its weight (W g). and record the weight of soil plus • c) Dry the soil by heating it in an oven at 105 degrees C to constant weight (Y g) - the loss in weight of soil at this temperature is due to the water driven out by evaporation. d) Reweigh the soil and crucible and record the weight. e) Heat the dried soil on a crucible to redness in an oven, then weigh the soil after cooling and record its weight. Repeat this till a constant weight is achieved (Z g). • •
  • 48.
    RESULTS • • • • • • • • • Weight of crucible== W g Weight of crucible + fresh soil == X g Constant weight of soil + crucible after heating at 1050C ==Y g Constant weight of soil + crucible after heating to redness == Z g Weight Weight Weight Weight of fresh soil == X - W of dry soil of dry soil of humus == Y - W after burning off humus == Z - W == Y - Z g Percentage of humus = @mount of humus amount of fresh X100 soil Percentage of humus == Y-Z x-w • Xl00
  • 49.
    Exercise obtained by a studenta given soil sample ; • The following data was percentage of humus in while determining the • • • Weight of the crucible Weight of the crucible = = 1 00g containing fresh soil 156g == Constant weight of the crucible containing soil after heating at 105 degrees Celsius == 143g • Constant weight 128g, calculate; of the crucible containing soil after heating to redness == • • • • a) b) c) d) weight weight weight of the of the of the fresh soil dry soil humus percentage of the humus in the soil sample
  • 50.
    NB: • Humus bumsoff into carbon di oxide and water vapor causing change in color, smell and emergency of smoke
  • 51.
    Experiment to investigatepresence of living organisms in the soil • Requirements: muslin bag, soil from compost or top soil, 2 corks, lime water/bicarbonate indicator solution • Procedure: ✓Collect a handful of fresh top soil and divide it into 2 equal portions V Sterilize one portion of the soil sample by heating strongly on a crucible for 30minutes. Leave it to cool and place it in a muslin bag VPlace the remaining portion of the fresh soil sample in another muslin bag ✓Add equal amounts of lime water/ bicarbonate indicator in the conical flasks and then suspend the muslin bags with soil in the conical flasks as shown in the set up ✓Allow the conical flasks to stand for about 2days and observe the appearance of lime water/ bicarbonate indicator conical flasks, 2
  • 52.
  • 53.
    Observation • Lime waterturns milky or bicarbonate indicator solution turns yellow in the conical flask A but remains clear in test conical flask B CONCLUTION Carbon dioxide was produced in conical flask A during respiration indicating the presence of living organisms Lime water remained clear in conical flask B because the living organisms in soil in conical flask B were killed by heating • • •
  • 54.
    Sam le a stude nt. uestion set upby Study T h e a p p ar a t u s b e l o w that follow. w a s it careful ly a n d an swe r th e q u est i o n s , Sterilised soil in muslin bag F r e s h m o i s t s o i l - f ! • inmuslin bag [ ? j A _" + ' ' • ' , · e , · · . , L i e w a s . ' ? ? ' j : ? ? ? : : ? ' B L i e w a t e r capillary tube co ntainin g coloured liquid (a). W h a t w a s (i) (ii) S t at e wh a t the: aim o f th e ex peri ment . (0I mark) (0I mark) left to con tinue u s e o f th e l im e wate r in t h e setup wo ul d b e o bserv ed in each fl ask if th e (b). e x p e r i m e n t w a s for 2 4 hours. Explain your observations. Exp l ai n w h y was : (i) the soil in the flask B w a s sterilised (ii) coloured liquid level in the capillary tube dropped. (04 ma rk s) (c). ( 0 I (02 ma rk ) ma rk s) (d). S tate one ro le pl ayed b y the s oi l co mp on ent b ein g in ves t i gat ed in thi s exp erimen t? (0I marks) 8/3/2023 54
  • 55.
    IMPORTANCE OF AIRAND WATER IN SOIL TO a)AIR LIVING ORGANISMS • VProvides oxygen for respiration of soil organisms and plant roots ✓Oxygen is also needed for the decay that produces humus VProvide nitrogen for fixation by nitrogen- fixing bacteria in the soil, the nitrogen absorbed is needed in the formation of nitrates and proteins ✓Carbon dioxide present in the air helps in increasing the soil acidity which favors proper growth of some plants ✓Carbon dioxide present in the air dissolves in water to form carbonic acid for weathering
  • 56.
    b)WATER It moistens soiland keeps it humid/ moist, making it favorable for survival of micro organisms It dissolves mineral salts making them available for plants to take in It dissolves carbon dioxide produced by living organisms to form carbonic acid which causes chemical weathering of rocks It is a raw material for photosynthesis ►Water absorbed from the soil allows plant cells to be rigid (turgid), and this is very important for support of the plant, particularly herbaceous plant
  • 57.
    c) Organic matter VItis food for soil organisms Vit moderates temperature of the soil
  • 58.
    EXERCISE • At homeyou have; a garden which normally gets dry has rained. The crops have even started to dry up due drainage a) which soil type makes up the highest composition your garden? shortly after to such high it • of the soil in • b) which challenge are the crops likely to face apart from lack of enough water? c) how can you improve the water drainage of your garden? •
  • 59.
    soln • • • a) b) c) sandy soil shortage ofnutrients adding humus, mulching and planting trees and cover crops
  • 60.
    Activity of integration •Soil types in Uganda vary from place to place. The people in Kirark, activities. Some are; o Commercial farmers who cultivate crops in pots oBuilders who plaster houses in the village oPotters who make stoves a village in your neighborhood are individuals engaging in different These individuals have been using soil from a certain mining site in the loose in a very short period of time and falls off, the potters' products crack them to worry as their businesses are nearly collapsing. You have been individuals can do to sustain their businesses neighboring village. However the plaster which the builders use gets too while drying while the farmers' crops produce poor yields. This has made contacted by the village leaders who are seeking for advice on what the
  • 61.
    Task • Using yourknowledge of physical and chemical properties of soil, write a speech you will deliver to the individuals for them to understand the soil type each one needs to save his businesses
  • 62.
    S u pp o r t M a t e r i a l A• " I I I F a r n n e r s o f 0 e a / v3a4g° f i g u r e 4 8 . A 6 8/3/2023
  • 63.
    SOIL PROFILE • Thisis the vertical arrangement of the various soil layers called horizons. It represents the different layers at various stages of soil development. • as mature A soil with distinguished soil layers is known without clear profile is immature or young. The profile consists of the fallowing: i) Top soil ii) Sub soil iii) Parent or underlying rock and that • • • •
  • 64.
    Drawing to showthe soil profile Topsoil Sub soil o @PETER .L. OKION 778001502/ 758795415
  • 65.
    Features offertile soil •Fertile soil is one which can provide adequate amounts of nutrients for plant growth, resulting into better crop yields and quality Soil fertility is the ability of the soil to sustain plant growth and optimize crop yield The healthy plants are grown in soil which has adequate water, • • humus, mineral salts and is well aerated for proper plant growth the soil with unhealthy plants might be lacking some of these constituents. while
  • 66.
    SOIL EROSION ANDCONSERVATION • • • What is soil erosion? Process of soil erosion This involves loosening of soil particles (detachment), moving of particles (movement) and placement of soil particles (deposition) soil
  • 67.
    u h re n t r a p w r t «l«posi ti on Theprocess soil erosion• Figure 2.7: • o
  • 68.
    Questions: a) b) c) give the 5types of soil erosion identify 10 causes of soil erosion what are the impacts of soil erosion?
  • 69.
    Soln • a) ►Sheet, splash,rill, wind, gully b) VDeep slopes of land coupled with intense rainfall ✓Overgrazing of animals which removes the grass water erosion VDeforestation .Bush burning ✓Over cropping and ploughing cover and opens the soil to
  • 70.
    c) >Nutrients and soilorganisms are carried away in the top soil ►The soil left behind is unproductive ►Fields may be cut into irregular pieces by rill and gully erosion ►Floods carry away or submerge and suffocate crops and soil . organ1sms
  • 71.
    Types of soilerosion • QN: Have you witnessed eroded fields in your community, you think could have caused that erosion? It might be the agents of erosion e.g • • • • • • • • • • • • • • • • • • • • • what do • and • When heavy winds blow away top soil, wind erosion occurs and this is referred to as when . running water carries away the top soil, • erosion is classified depending on the water carries away the top soil mechanism by which
  • 72.
  • 73.
    Forms of watererosion • Sheet erosion: is the uniform removal of soil particles from an area without the development of clear water channels Rill erosion: is one that produces narrow shallow wavy channels called RILLS Gully erosion: is one that produces wide deep steep-sided channels water continues to flow down the rills deepening them • • as • Splash erosion: this is the first stage of the erosion process. It occurs when raindrops hit the bare soil. The explosive impact breaks up soil aggregates so that individual soil particles are "splashed" onto the soil surface.
  • 74.
    Factors that leadto soil erosion • Type of surface cover: bare soils allow surface runoff carrying large volume of soil while soils covered with grass have a low rate of erosion and the speed of running water is reduced Gradient of the slope: steep slopes allow fast surface runoff carrying larger volumes of soil with it. Type of soils: more loose soils are easily carried away by water than less loose soils • •
  • 75.
    Reducing soil fertility •Many times, farmers have complained about the reduced and they mostly attribute this to reduced soil fertility. What do you think could be the cause of the reduced soil crop harvests • fertility ? • Use the images below
  • 76.
    c D G H I76 8/3 20
  • 77.
    ctd • A - soil B- misuse offertilizers through excessive application inhibiting plant growth soil compaction obstructs rain or water infiltration can alter the pH of the • leading to surface runoff or eros1• on C - soil erosion removes top soil which contains most D - mining removes top soil which exposes sand. Top supports plant growth • • nutrients soil is always rich and • • • E - poor disposal of wastes reduces soil aeration, drainage and water retention F - charcoal burning releases heat that kills soil G - flooding leaches nutrients from soil surface cannot be accessed by plant roots H - bush burning leaves the land bare exposing micro organisms to deeper layers where they • it to agents of soil erosion
  • 78.
    Ctd • I -deforestation leaves land bare • Other activities include; ✓Over cultivation .Monocropping exposing it to agents of soil erosion ✓And other poor farming practices like clean weeding
  • 79.
    Conserving our soil • • Soilis a valuable resource. What do you think makes soil valuable ? The great pressure on land is due to the increasing human population that has resulted to soil degradation. This is because of the various human activities carried out on land, which have resulted into soil erosion e.g. deforestation QN: what is soil degradation? This is the reduction or loss of the biological or economic productivity and complexity of land, resulting from natural or human activities • •
  • 80.
    Activity • In yourgroups, discuss the steps or methods that the farmers and gardeners in your locality take to maintain the fertility of their soils (lOmarks)
  • 81.
    Mulching- covering the soilin between crops with materials e.g. dry grass, plant leaves and • saw dust. This protects the soil from rain drops and improves water infiltration, it also suffocates weeds. Mulches release nutrients into soil after decom osition =. « ad 5 R s i ' r » •
  • 82.
    Manuring- • organic manureis added to the soil, the humus present binds soil particles together and provides nutrients such as nitrates to the soil
  • 83.
    Adding fertilizers - •these are rich in nitrogen, phosphorous and potassium which replace lost nutrients and improve soil fertility
  • 84.
    Crop rotation - •this is where different crops are grown in succession on one piece of land over a number of years. Inclusion of deep rooted crops breaks up sub soil and legumes harbor rhizobium which adds nitrates to the soil
  • 85.
    Composting - • wastematerials, leaves, weeds and grass cuttings are piled and left to decay forming compost which is dug into the soil hence adding nutrients to the soil
  • 86.
    lntercropping - • cropswith poor ground cover e.g. maize are planted with beans that effectively cover the ground. This reduces the speed of water runoff and also suppresses weeds
  • 87.
    Agroforestry - • farmersmanage and integrate crops, trees and/or livestock on the same plot of land. This conserves soil through controlling water runoff and soil erosion
  • 88.
    ctd • Wind breaks- trees are planted in rows across the direction of the prevailing wind to act as wind barriers hence reducing the effect of wind erosion • Read and make notes ►Terracing contour cultivation ►Minimum tillage ►Fallowing ►Irrigation about the following; ►Cover crops ►Soil testing, this is done soil to ascertain what nutrients are in poor supply in the
  • 89.
    Water Balance Plants consumesome of rainfall n regions, and part of the water evaporates from the soil The rest runs off the surface or recharges groundwater. Transpiration Evaporation Terracin g can change the specific hydrological path ways, increase soil roughn ess and vertical surface relief, and decrease the connectivity of overland flow. - Soil and Water conservation measures (Fanya-juu Terraces) a SOM Levels: -35% more than farms with conventional agnicfure' Crop Yields.: at least 25% more than farms with enrwantinnal arrienltre' } o 8/3/2023 - - - T r e n c h
  • 90.
    Importance of microorganisms in Nitrogen and other cycles that keep soil fertile • Some of these organisms are large (macroscopic organisms) and can be seen with unaided eyes while others are very small (microscopic) and can only be seen under a microscope. • QN: What are the examples of soil microorganisms?
  • 91.
    Note: • Decomposers breakdown compounds in dead plants environment. These are in chemical nutrients like carbon and nitrogen and animals to release them back into the tum released back into soil, there by improving soil fertility. These nutrients are then absorbed by plant roots for plant growth. Animals are able to obtain these nutrients when they eat plants. Activities of decomposers contribute to the cycling of carbon and nitrogen within the environment. □The process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts is called DECOMPOSITION
  • 92.
    THE NITROGEN CYCLE • • • Nitrogenmakes up the largest percentage ofAIR. QN: what is the percentage composition of Nitrogen in air? Surprisingly, much as nitrogen exists in abundance in air, it cannot be readily utilized by living organisms! This is because, for it to be used by living organisms it must be changed into various absorbable forms in a cycle of events called Nitrogen cycle. this describes how nitrogen circulates between plants, animals, the atmosphere and soil in the ground
  • 93.
    script: a cloudy Mondaymorning, Leku a On the f a r m e r plants soy bean seeds in his feld. With little rain and sunshine, the seec germ w i t h i n a f e w For the young to continue to grow and nts Theese will enable them velop. zy need b i g g e r and stranger. A cool breeze to gr blows by, carrying nitrogen a nutrient h e i r own food. The soy bean plants cannot absorb that the soy beans need to make any of the nitrog the rhizobium mov a type t e r i a called rhizobium Deep under the soil, rithout to t h e of o f t h e bean. t h e root The rhizobiumn inhao root s y s t of the to the bean, but roots and soy bean pl Soon, t h e rhizobium attaches itself the doesn't mind. forms small nodules. flled The bax w i t h n i t r o g e izobiumn form a relationship that benefits m both As the bean plar t h e t h e bean to turn nitrogen gas into a a l i v e , the rhizobium helps usable Event nutrient N o w , t h e bean the beans to mature and grow big and produce bean pods. te their life cycle and die. T h e f a r m e r c o m e s his field of t h e plant plants coi vests a n d beans, chopping up t h e dead plants in t h e s o i l . u e o n osers break daw ts into t h e < o i l . These nut a r e absorbed by maize materials, releasing nut plants which the farmer planted in the same field. The maize n t s are fed on b y cows that s out excreta. This posed to release into reta is nitr, a - o r soil. Denitrifying bacteria convert t h e soil i n t o n i t r o g e n which g o e s t h e nitrates in back t@'the atm re. ePereR.to«ov 778001502/ 758795415 93
  • 94.
    QUESTIONS • • • 1. 2. 3. how did thebacteria help the plant? can all plants get their nutrients from the soil, like the bean did? how did the farmer use plants to make his soil healthy? Explain how planting different crops help to replace nutrients in the soil. 4. what would happen if the farmer only grew maize in his field, year after year? •
  • 95.
    Processes involved inthe nitrogen cycle _ , · - • D E N I T R I rN 4 - A . • T O N [ w t a g e r f i x i n g 'a ] tac I V t 3 r t r i f y w r w to e ++@RETER .L. ORT N 778001502/ 7 58795415 8/3/2023
  • 96.
    cycle T h en i t r o g e n Nitrogen in Deniritying b a c t e r i a N i t r o g e n fixing h a t e r i air at mo sp he r ic T h u u n « e r s t ! a n d lig ht en i n g Proteins in animals D e a t h a n d P r o t e i n s plants i r I l e / i t ' t 4 t u ! w D e a d o r g a n i c n l e x c r e t a Putrefying hew' t e r i t A m m o n ium c o m p o u n d s Vitrifying bacteria m a t t e r Nitrates ( N O in t h e s o i l . . . a . Nitrites N O , 8/3/2023 @PETER .L. OKION 778001502/ 758795415 96
  • 97.
    Nitrogen fixation canoccur through: • 1) lightening: this breaks down nitrogen molecules into free nitrogen atoms that combine with oxygen, forming Nitrogen oxides. The oxides dissolve in rain and are washed into the soil where they form nitrates. 2) manufact ure of artif icial fertilizers: nit rogen and hydrogen react in an industrial chemical process, forming ammonia. The ammonia is used to make ammonium salt s and nit rat es, which are sold as fertilizers. QN: What examples of nit rogen containing fertilizers do farmers use in your area? 3) action of nitrogen fixing bacteria: these bacteria include; Rhizobium, • • • Azotobacter and spaces in the soil Clostridium. These bacteria use nitrogen gas from the air and bind it with other substances to make nitrates and other compounds. QN: Which bacteria is found in root nodules of Leguminous plants?
  • 98.
    Ctd • Once nitrogen has eit her ammonium nit rogen by eat ing been fixed, it can be absorbed by plants in the form of salt s or nit rates used to build up proteins. Animals obtain plant s or ot her animals. • When plants and animals die, their bodies are decomposed by bacteria and fungi. Nitrogen in proteins is converted to ammonia by Putrefying bacteria before being released. Nitrifying bacteria e.g. Nitrosomonas and Nitrobacter convert Ammonia into Nitrates for plant re-absorption and re-use • • The nitrates and ammonia in goes into the atmosphere by the soil are converted into Nitrogen gas, which the action of Denitrifying bacteria e.g. Pseudomonas and thiobacillus, thus complet ing the nit rogen cycle
  • 99.
    Sam le uestion Thefigure below shows the nitrogen nitrogen cycle. in atmosphere B plants soil nitrates ammonium salts in soil (05 marks) (02 marks) (0I mark) (02 marks) 99 (a). (b). Name the processes taking place at A, B, C, D and E. (i). (ii). State How is the process at B useful to plants? What organisms are responsible for the process the imporlance of the process at A in the cycle. at C. (c). 8/3/2023
  • 100.
    Sam le uestion Th e n i t r o g e n c y c l e . f i g u r e b e l o w s h o w s t h e i n a t m o s p h e r e F r e e n i t r o g e n P r o d u c t 3 N i t r o g e n d i o x i d e 1 A i v P r o d u c t 2 Nitric acid - N i t r i t e s P r o d u c t 1 (03 '% m a r k s) ( 0 1 m a r k s ) (02 m a r k s ) ( a ) ( b ) ( e ) ( d ) s / 6 9 ) N a m e N a m e t h e t h e p r o c e s s e s t a k i n g p l a c e a t A t o G . a n d 3 . o f t h e b a c t e r i a r e p r e s e n t e d b y i t o i v . p r o d u c t s 1, 2 G i v e t h e g e n e r a l n a m e s L i s t 4 d i f f e r e n t w a y s i n w h i c h n i t ro g e n m a y b e lo s t f r o m th e s o i l . (02 m a r k s) (02 m a r k s ) E x p l a i n w h y w a t e r l o g g e d s o i l s a r e u s u a l l y d e f i c i e n t i n n i t r a t e s . 100
  • 101.
    Microorganisms in theroot nodules Root nodule P Figure 2.8: Root nodules on roots of a leguminous.plant.. 8/3/2023 0
  • 102.
    Ctd • When youuproot a bean or soya bean plant, you notice round swellings on the roots . QN: what are they called ? Are the swellings on these roots important to the plant? What do the above features contain? • •
  • 103.
    Exercise 7 g c ro p s . . . - t r o w c e r t 8/3/2023 103
  • 104.
    Ctd • a) whichactivities are likely to improve on the nitrogen content of the soil? How? b) which activities are/is likely to reduce on the nitrogen content of the soil? How? 2) how can each of the following activities affect the nitrogen content of the soil; • • a) use of chemicals to spray fields b) rearing a cattle on a piece of land c) burning of bushes to prepare land for planting crops
  • 105.
    Activity of integration Atthe beginning of each growing season, the farmers prepare their seed gardens by; in your area • • • Collecting and burning the plant remains Gathering plant remains and using them to make boundaries Planting crops while with plant remains are still in the garden
  • 106.
  • 107.
    Task • Design aposter you will use to advise the people in your home area, on the potential risks or benefits of their activities towards maintaining soil fertility and conservation
  • 108.
    TEST YOURSELF indicators ofa fertile soil each of the following is involved in soil erosion • • 1. mention four 2. a) 3. describe how Detachment b) Transport c) Deposition • Suggest how the following conditions are likely to affect the rate of soil er0s1• on a) area with light soils 4. state how soil fertility Uganda; a) Lake Victoria basin c) Kigezi highlands b) hilly areas c) soil with much vegetation • can be conserved in the following regions of b) Karamoja region
  • 109.
    The figure belowrepresents the Nitrogen cycle Ni• trogen • in• air b ' + ] Plants Animals ·« Nitrates e f l Ammonium compounds Figure 2.11: Nitrites The nitrogen cycle @PETER .L. OKION 778001502/ 758795415 8/3/2023
  • 110.
    QNS. • • • a) b) c) name the processesa to f how do the processes a and b affect fertility of soil identify the microorganisms involved in processes a, b, d and f