Agrimly: Notes on Role of Manures and Fertilizers in Crop Production

Notes on Role of Manures and Fertilizers in Crop Production

References: www.eagri.org or https://ecourses.icar.gov.in/

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Manures:

Manures are plant and animal wastes used as a source of plant nutrients.
They release nutrients after decomposition.
Manures are categorized as bulky organic manures and concentrated organic manures.
Examples of bulky organic manures include FYM, compost, night soil, sludge, sewage, and green manures.
Concentrated organic manures include oilcakes, blood meal, fishmeal, and bone meal.
Fertilizers are industrially manufactured chemicals containing plant nutrients.
Fertilizers have higher nutrient content compared to organic manures and release nutrients almost immediately.
Three groups of fertilizers: Straight fertilizers (single nutrient), Complex fertilizers (two or more nutrients), Mixed fertilizers (two or more nutrients).

Role of Manures and Fertilizers:

Organic manures improve water holding capacity in sandy soil.
They enhance aeration and root growth in clayey soil.
Organic manures add plant nutrients, including micronutrients, essential for plant growth.
Increase microbial activity, aiding in nutrient release.
Organic manures require incorporation before sowing due to slow nutrient release.
Fertilizers supply essential nutrients in large quantities to crops.
They are readily utilized by plants directly or after rapid transformation.
Fertilizer dose can be adjusted based on soil testing.
Balanced nutrient application is possible by mixing appropriate fertilizers.

Agronomic Interventions for Enhancing Fertilizer Use Efficiency (FUE):

Using the best fertilizer source depends on crop, variety, climate, soil condition, and availability.
Examples of fertilizer sources for different nutrients are provided:

Nitrogen: Ammoniacal or Nitrate
Phosphorus: Water soluble or Citrate soluble
Potassium: Muriate of potash
Sulphur: Sulphate or Elemental S
Multinutrient fertilizers: MAP, DAP, SSP, Nitrophosphates
Multi-nutrient mixtures: Various NPK combinations
Fortified fertilizers: Neem-coated urea, Zincated urea, Boronated SSP, NPKS mix.

Balanced Fertilization:

Balanced fertilization involves adequate supply of essential nutrients, proper application methods, timing, and nutrient interrelationships.
Adequate supply of all essential nutrients is essential to avoid deficiencies in secondary and micro-nutrients.
Experimental results show that adding minor quantities of micro-nutrients (about 20-25 kg or two foliar sprays) can increase crop yields by up to 20%.
Proper methods for applying nutrients include broadcasting, band placement, and foliar sprays, depending on the nutrient and soil type.
Timing of nutrient application varies according to the crop's physiological needs.
Upland crops typically require two splits of fertilization (seeding and 3-5 weeks after the first dose).
Flooded rice usually requires three splits (transplanting, 3 and 6 weeks after the first dose).
Nutrient interrelationships should be considered to avoid antagonistic effects.
Excessive application of certain fertilizers, like 120 kg P ha-1, can lead to imbalances and reduced crop yields and quality.

Integrated Nutrient Management:

Integrated nutrient management involves blending organic sources (manures, crop residues, green manures, bio-fertilizers) with inorganic fertilizers to meet crop demands.
Efficient use of available organic sources reduces the need for inorganic fertilizers.

Utilization of Residual Nutrients:

Efficient utilization of crop residues involves understanding climatic conditions and carry-over effects.
Proper blending of residues in cereal-legume rotations is important.
Mixing shallow-deep rooted crop rotations helps utilize residual nutrients effectively.

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