2. LAND PREPARATION
Major purposes of land preparation
1) Levelling the land
2) Incorporate crop residues, green manure, crops cover
3) Prepare and maintain a good seed bed
4) Help to control weeds, diseases and insects
5) Improve the physical condition of the soil
6) Control erosion
“Tillage” – mechanical manipulation of soil to provide a favorable
environment for crop growth.
Done – variety of equipment and various purposes
factor – soil moisture, to dry, too wet,
Eg. – seedbed – soil loose, mix , air, water
5. MOLDBOARD PLOUGH
Moldboard plough are used when – soil is
sufficiently moist to allow the plow o pass
through easily.
Not too wet or to dry – stick to the surface
of moldboard.
Used on – bare fields, small grain stubble,
corn stubble, hay crop fields.
6. DISC PLOUGH
The disc plough bears little resemblance to the common mouldboardplough.
A large, revolving, concave steel disc replaces the share and the mouldboard.
The disc turns the furrow slice to one side with a scooping action.
The usual size of the disc is 60 cm in diameter and this turns a 35 to 30 cm furrow
slice.
The disc plough is more suitable for land in which there is much fibrous growth of
weeds as the disc cuts and incorporates the weeds. The disc plough works well in
soils free from stones. No harrowing is necessary to break the clods of the
upturned soil as in a mouldboard plough.
7. DISC HARROWS
A disc harrow is a farm implement that is used to cultivate the soil
where crops are to be planted. It is also used to chop up unwanted weeds or
crop remainders.
It consists of many iron or steel discs which have slight concavity and are
arranged into two or four sections. When viewed from above, the four
sections would appear to form an "X" which has been flattened to be wider
than it is tall.
This is so they slice the ground they cut over a little bit to optimize the result.
The concavity of the discs as well as their being offset causes them to loosen
8. HARROWING
Function – Further reduce the size of soil clods left after disking, to smooth the soil
surface and to do small scale levelling.
• Destroy small weeds
• Final touch of seedbed preparation.
• Follows disking. Do both operation simultaneously
Harrows used
Priciples – 1)spike tooth
2) spring tooth
3) chain or drags
4) cultipackers, packers, mulchers and corrugated rollers.
9. CULTIVATION
Is the tillage between seedling emergence and crop harvest.
Function – to control weeds, improve water filtration, soil aeration, loosening
compacted soil
11. LAND LEVELLING
• Land is leveled to permit water to flow and spread evenly over the soil surface
without causing erosion.
• Types of land levelling depend on the land suitability, production capacity and
irrigation methods.
12. SOIL FUMIGATION
“Pasteurizes the soil” – make sure the soil is clean from disease, weed, harmfull
bacteria and fungi.
Soil fumigation can yield vastly improve seedlings and crop performance.
Common used – methyl bromide CH3Br
By decreasing weed competition and eliminating parasitic attack by
nematodes. The fumigation cost is more than offset by increased production.
Plant bed fumigation with a mixture of methyl bromide and chloropicrin has
proven considerably more effective and uniform than steam sterilization or
burning.
13. IRRIGATION
Irrigation is the artificial application of water to the land or soil.
Function of irrigation:
• In the growing of agricultural crops,
• maintenance of landscapes, and
• Revegetation of disturbed soils in dry areas and during periods of
inadequate rainfall.
• Protecting plants against frost
• Suppressing weed growth in grain fields
• Preventing soil consolidation.
In contrast, agriculture that relies only on direct rainfall is referred to as rain-fed
or dryland farming.
14. Factors
• Climate
• Type of crop
• Cost of water
• Slope of field
• Physical properties of
soil
• Water quality
• Water availability
• Drainage capability
• Salinity or other
problems
METHODS OF APPLICATION
15. TYPE OF IRRIGATION
Center-Pivot: Automated sprinkler irrigation achieved by automatically rotating
the sprinkler pipe or boom, supplying water to the sprinkler heads or nozzles,
as a radius from the center of the field to be irrigated. Water is delivered to
the center or pivot point of the system. The pipe is supported above the crop
by towers at fixed spacings and propelled by pneumatic, mechanical,
hydraulic, or electric power on wheels or skids in fixed circular paths at
uniform angular speeds.
Drip: A planned irrigation system in which water is applied directly to the Root
Zone of plants by means of applicators (orifices, emitters, porous tubing,
perforated pipe, etc.) operated under low pressure with the applicators being
placed either on or below the surface of the ground.
Furrow/Flood: A partial surface flooding method of irrigation normally used with
clean-tilled crops where water is applied in furrows or rows of sufficient
capacity to contain the designed irrigation system.
16. Rotation: A system by which irrigators receive an allotted quantity of water, not a
continuous rate, but at stated intervals.
Sprinkler: A planned irrigation system in which water is applied by means of
perforated pipes or nozzles operated under pressure so as to form a spray
pattern.
Surface: Irrigation where the soil surface is used as a conduit, as in furrow and
border irrigation as opposed to sprinkler irrigation or subirrigation.
21. Element Abbreviation Form absorbed
Nitrogen N NH4
+ (ammonium) and NO3
-
(nitrate)
Phosphorus P H2PO4
- and HPO4
-
2 (orthophosphate)
Potassium K K+
Sulfur S SO4
-2(sulfate)
Calcium Ca Ca+2
Magnesium Mg Mg+2
Iron Fe Fe+2 (ferrous) and
Fe+3 (ferric)
Zinc Zn Zn+2
Manganese Mn Mn+2
Molybdenum Mo MoO4
-2 (molybdate)
Copper Cu Cu+2
Boron B H3BO3 (boric acid) and
H2BO3
- (borate)
22. NITROGEN
Of all the essential nutrients, nitrogen is required by plants in the largest quantity and is
most frequently the limiting factor in crop productivity.
In plant tissue, the nitrogen content ranges from 1 and 6%.
Proper management of nitrogen is important because it is often the most limiting nutrient in
crop production and easily lost from the soil system.
Nitrogen Forms and Function
Forms of nitrogen available for plant uptake : Ammonium and Nitrate
Functions of nitrogen in plants
Nitrogen is an essential element of all amino acids. Amino acids are the building blocks of
proteins.
Nitrogen is also a component of nucleic acids, which form the DNA of all living things and
holds the genetic code.
Nitrogen is a component of chlorophyll, which is the site of carbohydrate formation
(photosynthesis). Chlorophyll is also the substance that gives plants their green color.
Photosynthesis occurs at high rates when there is sufficient nitrogen.
A plant receiving sufficient nitrogen will typically exhibit vigorous plant growth. Leaves will
also develop a dark green color.
23. Mineralization: Conversion of organic nitrogen to ammonium
Nitrification: Conversion of ammonium to nitrate
Losses of Nitrogen from the Soil
Denitrification: Conversion of nitrate to atmospheric forms of
nitrogen
Volatilization: Loss of gaseous ammonia to the atmosphere
Run-off
Leaching
Consumption by plants and other organisms
24. CONDITIONS AFFECTING N MINERALIZATION
The amount of ammonium that is released to the soil through mineralization
depends on several factors:
• Quantity of Organic Nitrogen: The amount of organic nitrogen originally
present in the organic matter determines the amount of N that can ultimately
be mineralized.
• Temperature: The optimal range for mineralization to occur is between 77-95
degrees Fahrenheit.
• Oxygen: Microorganisms need oxygen and since microorganisms mediate
mineralization, sufficient oxygen must be available in the soil.
• Moisture content: Ideally, water should fill 15 – 70 % of pore space for
maximum mineralization. This roughly corresponds to field capacity.
• Ratio of carbon to nitrogen (C:N): The C:N ratio is a term used to describe
the relative amount of total carbon in comparison the amount of total nitrogen
present in the soil and/or organic matter.
This ratio is very important in determining the rate of mineralization that should
occur for a given type of organic matter.
25. After mineralization of N occurs, ammonium can be:
• Taken up by the plants
• Consumed by other organisms
• Nitrified
• Volatilized
26. NITRIFICATION
In most aerobic soils under optimal soil conditions, ammonium is rapidly converted to
nitrate by soil bacteria through a process known as nitrification.
Nitrification involves two steps:
First, ammonium is converted to nitrite
Then, nitrite is converted to nitrate.
The process of nitrification
produces hydrogen ions.
When large quantities of
ammonium-containing fertilizers
are applied to soil over time, this
process can acidify the soil. See
figure below for a simplified
presentation of the nitrification
process.
27. Phosphorus (P)
• Absorbed mainly as orthophosphate ions (H2PO4-, HPO4
2-)
•Like nitrogen, phosphorus (P) is an essential part of the process of
photosynthesis.
•Key element for formation of ADP, ATP and AMD- photosynthesis and
respiration
•Involved in the formation of all oils, sugars, starches, etc.
•Helps with the transformation of solar energy into chemical energy;
proper plant maturation; withstanding stress.
•Effects rapid growth.
•Encourages blooming and root growth.
•Phosphorus often comes from fertilizer, bone meal, and
superphosphate.
•Ferilizer – Rock phosphate
28. POTASSIUM(K+)
· Carbohydrate metabolism and the break down and translocation of starches
· Increases photosynthesis – opening and closing of stomata
· Increases water-use efficiency – water retention
· Essential to protein synthesis
· Important in fruit formation
· Activates enzymes and controls their reaction rates
· Improves quality of seeds and fruit
· Improves winter hardiness
· Increases disease resistance
Fertilizer : Potasium chloride (KCL)(MOP),
potassium sulphate (K2SO4) (sulfate of potash), and
potassium nitrate (KNO3)(saltpeter)
29. CALCIUM (Ca2+)
· Source – dolomite, calcite, apatite and feldspar
· Involved in nitrogen metabolism
· Reduces plant respiration
· Aids translocation of photosynthesis from leaves to fruiting organs
· Increases fruit set
· Essential for nut development in peanuts
· Stimulates microbial activity
In soil – reclaim sodic soil (soil structure) and agregation in saline soil.
Correct Ca deficiency - lime stone (CaCO3) and gypsum (CaSO4)
MAGNESIUM (Mg2+)
· Key element of chlorophyll production
· Improves utilization and mobility of phosphorus
· Activator and component of many plant enzymes
· Directly related to grass tetany
· Increases iron utilization in plants
· Influences earliness and uniformity of maturity
Source : dolomitic limestone (CaCo3. MgCo3), potassium magnesium sulfate (k2SO4. 2MgSo4)
30. CHLORINE
· Not much information about its functions
· Interferes with P uptake
· Enhances maturity of small grains on some soils
COPPER
· Major function in photosynthesis
· Major function in reproductive stages
· Indirect role in chlorophyll production
· Increases sugar content
· Intensifies color
· Improves flavor of fruits and vegetables
IRON
· Promotes formation of chlorophyll
· Acts as an oxygen carrier
· Reactions involving cell division and growth
31. MANGANESE
· Functions as a part of certain enzyme systems
· Aids in chlorophyll synthesis
· Increases the availability of P and Ca
MOLYBDENUM
· Required to form the enzyme "nitrate reductas" which reduces nitrates to ammonium in plant
· Aids in the formation of legume nodules
· Needed to convert inorganic phosphates to organic forms in the plant
ZINC
· Aids plant growth hormones and enzyme system
· Necessary for chlorophyll production
· Necessary for carbohydrate formation
· Necessary for starch formation
· Aids in seed formation
BORON
· Essential of germination of pollon grains and growth of pollen tubes
· Essential for seed and cell wall formation
· Promotes maturity
· Necessary for sugar translocation
· Affects nitrogen and carbohydrate
34. PHYSICAL PROPERTIES OF FERTILIZER
Straight Fertilizers
These are products where a nitrogen, phosphate or potassium
fertilizer has a declared content of only one of the primary plant nutrients, N, P or
K.
N. Examples of straight N. Urea, Calcium Ammonium Nitrate, Triple Super,
Muriate of
Potash.
Compound Fertilizer:
Fertilizer is having a declared content of at least two of the nutrients, nitrogen,
phosphorus and potassium, obtained chemically or by blending, or both.
Complex Fertilizer:
Fertilizer having a declared content of at least two of the nutrients nitrogen,
phosphorus and potassium, obtained by chemical reaction.
36. SOIL CONSERVATION
Definition – is the preservation and extension of the life of soil by using land wisely,
keeping it in it most productive state for the present and future generations. It is
also about solving the problems of land degradation, particularly accelerated soil
erosion.
Erosion – caused by human interference – physical forces of wind and water on soil
Factors – Natural vs. Human induced
Plant cover – tree losses
Rain
Topography – leveled or sloping
Soil physical properties
37. METHODS OF CONSERVATION
• Deforestation
• Fuelwood
• Overgrazing
• Agriculture
• Industrialization
Terraces
• How it helps??
39. Strip cropping - is a very effective and inexpensive method for controlling soil
erosion
40. Grass waterways
Grass waterways are a type of conservation buffer; they downhill grassed
channels, generally broad and shallow, designed to prevent soil erosion while
draining runoff water from adjacent cropland. As water travels down the
waterway, the grass vegetation prevents erosion that would otherwise result
from concentrated flows. Grass waterways also help prevent gully erosion in
areas of concentrated flow.
