Soil provides mechanical support and acts as a reservoir of nutrients for plants. Soil fertility can be maintained through various practices like applying organic and synthetic fertilizers, engaging in crop rotation, and using green manures. Nitrogen, phosphorus, and potassium are among the most important nutrients required by plants. Nitrogen fixation through symbiotic bacteria and organic matter addition helps enrich soils naturally over time.

1. Soil Fertility and
Nutrient
Management

2. What is soil
‘Soil’ is the upper layer of earth that may be dug or flowed and in which plants
grow.
Soil compost of four major components
Air
Water
Minerals
Organic matter
Soil is providing mechanical supports to plants, its serves as a
reservoir (a place where something is kept in store) of nutrients –
both the naturally occurring and those supplied by fertilizer.

3. Procedures and practices for maintaining
and sustaining the fertility of soil
•Conventional farming system.
• utilizes synthetic fertilizers as a major source of
nutrients
•Organic crop production.
• Depends on OM sources and microbial
inoculants/organism for sustaining soil health and
supplying nutrients to the plants

4. 16 ESSENTIAL PLANT ELEMENTS
MACRO-ELEMENTS
• Nitrogen
• Phosphorus
• Potassium
• Calcium
• Sulfur
• Carbon
• Hydrogen
• Oxygen
MICRO-NUTRIENTS
• Iron
• Manganese
• Copper
• Boron
• Molybdenum
• Chloride
• Zinc

5. Nitrogen
•most limiting and is required by most crops in great
amounts
•necessary in chlorophyll production
• Chlorophyll is needed to produce food for growth and
nutrient uptake
•also a component of amino acids, a building block
of proteins.

6. Nitrogen
•Nitrogen supplied by synthetic fertilizer is highly
prone to leaching or volatilization, particularly in
soils with low or negligible organic matter or low
nutrient holding capacity.
•Synthetic nitrogen sources are not allowed in
organic farming

7. Nitrogen
For efficient soil nitrogen management the following are suggested:
• incorporate farm residues 2-4 weeks before land preparation to avoid
subjecting the plant to "nitrogen hunger"
• practice intermittent flooding and draining in rice to reduce leaching
and other losses
• maintain a soil organic matter content of 2% or more to increase
nutrient holding capacity of the soil
• avoid a very dry soil condition to enhance microbial growth and
activity

8. PHOSPHORUS
• Essential in root growth and development in energy
transport in plants.
• Encourages flowering and ripening of seeds.
• Deficiency of phosphorus in plants is easily diagnosed by
the purplish coloration of the leaves, which in extreme
level leads to death.
• Among the essential nutrients, phosphorus is the most
affected by soil pH.

9. PHOSPHORUS
Ways to improve soil P availability and sequestration:
• Grow deep-rooted crops on perimeter of the farm
• Combine crops of different families in a cropping mix
• Maintain soil pH of 6-6.5
• Augment soil P availability by using rock phosphate in combination with organic
fertilizers or compost
• Employ mulching to conserve moisture and as source of organic matter.
• Improve the growing conditions for mycorzzhia by planting trees around farm.

10. POTASSIUM
• Unlike other elements, K apparently does not form an integral part of protoplasm,
fats, and cellulose.
• Its role is more of catalytic in nature such as in carbohydrate metabolism and starch
synthesis and breakdown; nitrogen metabolism and protein synthesis and in stomata
movement and water relations.
• It is also known for its ability to develop resistance to diseases in plants.
• High in clayey soils.
• Its deficiency results in a premature death of older plant parts first.

11. POTASSIUM
Ways to improve K level in soils:
• Incorporate crop residues (especially straw) and animal manures in the soil after
harvest.
• Provide permanent plant cover during rainy period (wet season) to avoid leaching
losses.
• Increase the humus content of the soil through application of compost or organic
fertilizers
• Employ mulching
• Incorporate carbonized rice hull.

13. Fertilizer
•A fertilizer is any subtance that is added to soil or to
the plant (foliar) to supply elements required in
plants.
•Ex. 14-14-14, Urea (46-0-0), 16-20-0

14. Organic Fertilizer
•This is define as any product of plant or animal origin that
has undergone substantial decomposition through biological,
chemical or any other process where the original materials
are no longer recognizable.
•Ex. Compost, vermicompost, FFJ

15. Good quality organic fertilizer
•Free from chemical fertilizers, any pathogens
•Soil like texture
•Contains not less than 20% organic matter
•Can supply nutrients to plant.

16. Synthetic or Chemical
Fertilizers

17. Synthetic or Chemical Fertilizers
• Substance that supplies one or more nutrients, which are produced
through chemical process. They usually contain high amount of
nutrients and dissolve in water.
• Synthetic fertilizers are undeniably responsible for large increases in
the yields of crops during the advent of the “Green Revolution”.
• It was contributed to the boosting of crop production that eventually
saved human from hunger.

18. Source:https://www.google.com/search?q=organic+vs+inorganic+fertilizer&hl=fil&sxsrf=ALiCzsbcI_oOw4PpdZ_Oc1VTZArwAfhn3Q:1663807057001&source=lnms&tb
m=isch&sa=X&ved=2ahUKEwikyO2klKf6AhW6qVYBHfSrB94Q_AUoAXoECAEQAw&biw=1366&bih=657&dpr=1#imgrc=L5cO8nArZaY16M

19. Soil Organic Matter
•In healthy Agricultural soils, the solid material
(approximately 95-98%) is mineral nature.
•OM consists primarily of decayed or decaying plant
and animal residues and is a very important Soil
component.
•SOM is a living component of the soil because it is
the seat of microorganisms responsible for many
biological transformations in soils.

20. •SOM serves as the main pool of nutrients for
crops aside from symbiotic and non symbiotic
N fixation.
•SOM contains about 5% N however, this is not
readily Available to plants because it is tied up
in organic compounds.

21. Most common sources of OM in the farm:
•Crop residues after harvest
•Animal manures
•Green manure planted in rotation either as legume
forage (Centrosema) or edible legumes (mungbean)
•Compost
•Household wastes

22. •Even in ancient agriculture, continuous
Cropping without addition of manures (animal
or green manures) fail to produce satisfactorily.

23. Practices that will Reduce Losses of SOM
•Rotate diverse crops with high biomass
•Use cover crops or close-ground growing crop
•Reduce tillage
•Practice rotational grazing
•Use manure and crop residues
•Do not burn crop residues

24. Organic approach of managing soil fertility
• Provide a more balanced and continuous supply of nutrients.
• Improve soil aeration.
• Increase water infiltration and water storage capacity.
• Improve soil tilth by enhancing soil aggregate stability.
• Decrease soil erosion losses due to better soil aggregation.
• Increase the soil nutrient holding and exchange capacity.
• Promote growth of microorganism.

25. Disadvantage
• Acidification of the soil particularly due to heavy application of N-
containing fertilizers.
• Heavy application of N- containing fertilizers pose problems of high
nitrate accumulation in plants.
• Sole use of fertilizers containing only NPK results on deficiency of
other nutrients particularly micronutrients due to continuous crop
removal without replacement.
• Inhibit proliferation of N- fixing microorganism in the soil due to
excess N supply.
• Deprive the soil of organic matter build – up, resulting in the
destruction and degradation of soil.

26. Multicropping
•as opposed to monocropping is the growing of
several crops/species in the same piece of land
at the same time or in sequence within a year.
There are several types of multicropping:
intercropping, multistorey planting, relay
cropping, and crop rotation.

27. Intercropping
•This is the growing of two or more crops in
alternate rows in the same piece of land in the
same season per year.
•The crops are of different family and are
supposed to receive benefits from their
association. Examples are corn + mungbean
intercropping, corn+ peanut intercropping.

29. Multistorey Planting
•In this system, three or more crops of
varying depths of root proliferation are
grown in storey fashion. Crops consist of
perennials and annuals.
•Smaller crops are supposed to have some
degree of tolerance to shading.

31. Multistorey Planting
•Examples are mixtures of papaya+corn+legumes+
crucifers (lowland cropping system) with botanical
plants around the perimeter of the farm;
‘lanzones’+coffee+pineapple+ginger
(upland/highland cropping system) with botanicals
in the perimeter of the farm.

32. Relay Cropping
•This is the planting of crop even before the
harvest of the main crop. The most common
of this type is the rice-mungbean relay
cropping.
•The mungbean is usually planted 3-5 days
before the rice crop is harvested and when the
soil is still moist.

33. Relay Cropping
•The objective is to take advantage of the
residual moisture and nutrients from the
soil particularly in rainfed areas.
Mungbeans are inoculated with
Rhizobium for purposes of N fixation.

35. Green Manures
• Although there is no record when man started using synthetic
fertilizers, the value of green manure in enriching the soil was
mentioned in Old testament.
• The best legumes for enriching the soil are field beans and the
most common is mungbean.
• Green manure are grown and turned under before seed maturity
• At that stage, the plants have accumulated maximum biomass and
nutrients that mineralize and become available to the plant at a
faster rate

37. Benefits from Green Manuring
•Enhance soil aggregation and granulation brought
about by root penetration. The roots serve as
channel for water infiltration
•Green manure are stablished at higher population,
three times more than the population intended for
economic product. Hence, these crops are effective
as weed control.

38. •Green manure legumes enrich the soil not only with
organic matter but with nitrogen through symbiotic
nitrogen fixation.
•Green manure can be used as fodder plants or even
to provide food for human consumption.

39. NITROGEN FIXATION

40. Nitrogen Fixation
• The conversion of free nitrogen into nitrogenous salts to
make it available for absorption of plants.
• Nitrogen Fixation in soils is also brought about by certain
free-living organisms to include blue green algae and
bacteria.
• * Clostridium, Azotobacter, and Azospirilium.

42. Types of Nitrogen Fixation
• 1. Non-Biological fixation
- The micro-organisms do not take place.
- Found in rainy seasons during lightning.
• 2. Biological fixation
- Fixation of atmospheric Nitrogen into Nitrogenous Salts with
the help of Micro-organisms.

43. Two types of Biological Fixation
• 1. Symbiotic
- Fixation of free nitrogen by micro-organisms in soil living
symbiotically inside the plant.
• 2. Non – symbiotic
- Fixation carried out by free living micro-organisms.
- Aerobic, Anaerobic and blue green algae. (Bacteria)

44. • The Exploitation of legumes as host of Rhizobium for symbiotic
nitrogen fixation has been dwindling due to the availability of
synthetic fertilizers. In Addition to symbiotic nitrogen fixation,
mycorhizzal fungi are also sources of microbrial fertilizers due to
their ability to colonize the root system and supply it with
phosphorous

45. • Many local and foreign companies recommend some
microbial inoculants such as Bio-N, Xemas, Solex, and
Bokashi. Among these microbial fertilizers, Bio- N is widely
recommended and being promoted by the government
for Rice, Corn, and Vegetables under the Tipid Abono
Program and Organic Agriculture Program.

46. Crop Rotation
•This is the growing of crops alternately in
different parts of the farm in planned fashion
to protect the soil from erosion and to build
the fertility.