MP Board · Class 9 · Science · Improvement in Food ResourcesSolve the numerical problem in Part A and answer the theoretical question in Part B regarding Crop Nutrient Management and Grain Storage: Part A (Numerical):\nA farmer owns an agricultural field of area $4\text{ hectares}$. The recommended dosage of fertilizers for his crop is $120\text{ kg}$ of Nitrogen (N) per hectare and $60\text{ kg}$ of Phosphorus ($P2O5$) per hectare. Calculate the total mass of Urea (containing $46\%$ Nitrogen by weight) required for the entire $4\text{-hectare}$ field. Calculate the total mass of Single Super Phosphate (SSP, containing $16\%$ $P2O5$ by weight) required for the entire $4\text{-hectare}$ field. Part B (Theoretical):\nAfter harvesting, crop grains are stored for future use or commercial sale. Categorize and explain in detail the Biotic and Abiotic factors responsible for storage losses in agricultural produce. Describe four preventive and control measures that must be strictly adopted before and during storage to protect food grains from damage.

Part A (Numerical Solution)

1. Mass of Urea required for 4 hectares:

• Field Area = $4\text{ hectares}$
• Recommended Nitrogen per hectare = $120\text{ kg}$
• Total Nitrogen requirement = $4 \times 120\text{ kg} = 480\text{ kg}$
• Percentage of N in Urea = $46%$

$$\text{Mass of Urea required} = \frac{\text{Total N Required}}{\text{Percentage of N}} \times 100$$ $$\text{Mass of Urea required} = \frac{480}{46} \times 100 = 1043.48\text{ kg}$$

2. Mass of Single Super Phosphate (SSP) required for 4 hectares:

• Recommended $P_2O_5$ per hectare = $60\text{ kg}$
• Total $P_2O_5$ requirement = $4 \times 60\text{ kg} = 240\text{ kg}$
• Percentage of $P_2O_5$ in SSP = $16%$

$$\text{Mass of SSP required} = \frac{\text{Total } P_2O_5 \text{ Required}}{\text{Percentage of } P_2O_5} \times 100$$ $$\text{Mass of SSP required} = \frac{240}{16} \times 100 = 1500\text{ kg}$$

Part B (Theoretical Solution)

1. Factors Responsible for Storage Losses\nStorage losses in harvested food grains can range up to $10\text{–}15%$ if improper methods are used. These losses are driven by two main factors:

• Biotic Factors (Living Organisms): These include living organisms that attack stored grains, such as insects, pests, rodents (rats), mites, fungi, and bacteria. Insects and rodents consume the endosperm, reducing grain mass and viability. Fungal growth leads to discoloration, toxin production (mycotoxins), and foul odor.
• Abiotic Factors (Non-living Environmental Conditions): These include unfavorable environmental parameters, mainly inappropriate moisture content in grains and high ambient temperature in storage structures. Excessive moisture promotes seed respiration, local heating, fungal infestation, and destruction of germination capacity.

2. Preventive and Control Measures Before and During Storage\nTo prevent damage to stored food grains, the following systematically managed steps must be executed:

• Strict Cleaning: Prior to storage, newly harvested grains must be thoroughly cleaned to remove foreign matter, weed seeds, chaff, broken grains, and dust, which act as points of insect infestation.
• Proper Drying: Grains should first be dried thoroughly under open sunlight to bring the internal moisture content below $12%$, followed by drying in the shade to prevent seed coat cracking.
• Fumigation: Storage structures and godowns should be treated with chemical fumigants (like aluminum phosphide tablets) to kill remnant pests and larvae without contaminating the grain for human consumption.
• Systematic Storage Structures: Utilizing modern moisture-proof and rodent-proof silos, metallic bins, or properly stacked gunny bags kept over wooden pallets elevated from the damp floor.