What is biofertilizers in Crop Production? by Shetishala

Before touching biofertilizers, some basic facts:

Fertilizers supply essential plant nutrients, mainly Nitrogen(N), Potash (K) and Phosphorous (P) as they are removed in large quantities from the soil by each successive harvest.

Increasingly high inputs of chemical fertilizers for high yield agriculture during the last 150 years has not only left our soils degraded, polluted and less productive but also posed severe health hazards.

India is the third largest producer and consumer of fertilizers in the world (after China and USA) accounting for 12% of world production of N & P nutrients and 12.6% of world consumption of NPK nutrients.

Out of the total of 329 Million Ha of India’s geographical area, about 114 Million Ha is under cultivation. With India hurtling towards overtaking China as the most populous country, meeting the increasing demand for food shall continue to be major challenge.

Further increase in food production will depend on either increasing the productivity of existing areas or by bringing additional lands, presently under fallow or wasteland categories, under cultivation.

Bio-fertilizers have the potential to play a major role in making agriculture a viable proposition here.

Declining Crop Productivity in India : 

Causes

• Imbalanced and indiscriminate use of chemical fertilizers

• Occurrence of multi-nutrients deficiency such as Zinc, boron, sulphur etc. besides NPK• 

• Rain dependent agriculture – About 2/3 area

• Inadequate irrigation facilities

• Continuous fragmentation of land, unfavorable for adoption technology

• Land holding pattern and predominance of marginal and small farmers

 

Importance of Biofertilizers

• Biofertilizers can be expected to reduce the use of chemical fertilizers and pesticides.

• The microorganisms in bio-fertilizers restore the soil’s natural nutrient cycle and build soil organic matter.

• Through the use of biofertilizers, healthy plants can be grown, while enhancing the sustainability and the health of the soil.

• They are extremely advantageous in enriching soil fertility and fulfilling plant nutrient requirements by supplying the organic nutrients.

• Biofertilizers do not contain any chemicals which are harmful to the living soil. Since they play several roles, a preferred scientific term for such beneficial bacteria is “plant-growth promoting rhizobacteria” (PGPR).

 

Concept of biofertilizer

Biofertilizer concept goes back as early as 300 BC when our ancestors realized the importance of

legume crops bearing nodules. The perspective of biofertilizer came into existence through discovery of many organisms capable of nitrogen fixation, P-solubilization, P. mobilization, potash solubilization and micronutrient transformation in the soil.

The role of biofertilizers assumes special significance due to increased cost of chemical fertilizers and their ill effects on soil health

Rhizobium inside nodule

legume root nodule

 

Biofertilizers : Organic boost

The term biofertilizer refers to preparation containing live microbes which helps in enhancing the soil fertility either by fixing atmospheric nitrogen, solubilization of phosphorus or decomposing organic wastes or by augmenting plant growth by producing growth hormones with their biological activities.

Types of biofertilizers :

 

 

biofertilizer organism’s :

Nitrogen fixing Biofertilizers

1. Rhizobium

2. A soil habitat bacterium able to colonize the legume roots

3. Fixes atmospheric elemental nitrogen symbiotically into plant usable form.

4. Fixes 50-100 kg/ha/year of nitrogen, most useful in concern with amount of N2 fixed

5. It is especially important for legumes and oilseeds.

Rhizobium

Cyanobacteria

1. Both free-living as well as symbiotic cyanobacteria (blue green algae) have been harnessed in rice cultivation.

2. The benefits due to algalization could be to the extent of 20-30 kg/ha.

3. Add growth-promoting substances & vitamin B12

4. Improve the soil’s aeration, water holding capacity and add to biomass when decomposed after life cycle

 

Azospirillium

1. Proliferates under both anaerobic and aerobic condition.

2. Nitrogen fixing ability of 20-40 kg/ha

3. PGRs production (IAA), disease resistance and drought tolerance are some the additional benefits

 

 

Azolla

1. A free-floating water fern used as Biofertilizer for wetland rice

2. Fixes atmospheric nitrogen in association with nitrogen fixing blue green algae

Anabaena azollae

3. Known to contribute 40-60 kg N/ha per rice crop

 

 

Azotobacter

1. A free living bacteria mostly found in neutral to alkaline soils.

2. Fixes the atmospheric nitrogen by converting into ammonia

3. Produces abundant slime which helps in soil aggregation.

4. Fix biologically active PGRs like IAA and gibberellins

 

Phosphate solubilizing Biofertilizer:

1. Group of beneficial bacteria capable of hydrolyzing organic and inorganic phosphorus from insoluble compounds

2. Pseudomonas, Bacillus and Rhizobium are among the most powerful

 

Phosphate mobilizing Biofertilizer (Mycorrhiza)

1. A symbiotic generally mutualistic association between a fungus and the roots of a vascular plant.

2. The fungus colonizes the host plant’s roots, either intracellularly or extracellularly 

3. This association provides the fungus with access to carbohydrates

4. In return, the plant gains the benefits of the mycelium’s higher absorptive capacity for water and mineral

5. Plant roots alone may be incapable of taking up phosphate ions that are demineralized in soils with a basic pH

6. The mycelium of the mycorrhizal fungus can make them available to the plants they colonize.

 

 

Silicate and Zinc solubilizing Biofertilizer

1. Microorganisms are capable of degrading silicates and aluminium silicates

2. Bacillus sp can be used as bio-fertilizer for zinc or aluminium silicates because these organisms solubilise the zinc present in the soil and make it available to the plants.

 

 

Plant Growth Promoting Rhizobacteria (PGPR)

1. Species of Pseudomonas and Bacillus can produce phytohormones or growth promoters.

2. They produce include indole-acetic acid, cytokinins, gibberellins and inhibitors of ethylene production

 

check my others blogs

• The Seeds Act, 1966 of India

• Sowing Methods: A Comprehensive Guide for Successful Planting

• What is biofertilizers in Crop Production ?

• Understanding Tillage & Its Types for Successful Crop Growth 

• What is Hydroponics in agriculture ?