• The fresh crop has more moisture. Hence, they should be dried in the sun to reduce moisture before storage because if freshly harvested grains are stored they may get spoilt or attacked by organisms.

• Insects in stored grain can cause much damage. The farmer may lose up to a third of the stored grain. 
• Large scale storage of grains is done in silos and granaries to protect them from pests like rats and insects.

• Drip irrigation is an irrigation method that saves water and fertilizer by allowing water to drip slowly to the roots of plants, either onto the soil surface or directly onto the root zone, through a network of valves, pipes, tubing, and emitters. 

• The supply of water to the crops at different intervals is called irrigation. Lakes, rivers, dams, canals, etc. are the sources of water for irrigation.
•  Various traditional ways of irrigation are pulley system, chain pump, dhekli, and Rahat. 
• Traditional methods are cheaper but they are less efficient as compared to modern methods. The modern methods of irrigation include sprinkler systems, drip systems, etc. 
• In the sprinkler system, water is sprinkled on the crop by using a pipe and nozzle system. It resembles raining. In the drip system, waterfalls drop by drop just at the position of the root.

• The storage of food crops is an important step of agricultural practices. If the crop grains are to be kept for a longer time, they should be prevented from moisture, insects, rats, and microorganisms. 

• Storage of food crops is an important step of agricultural practices as harvesting because if the grains are not stored properly it may get spoilt or attacked by insects or rats or microorganisms. 
• Large scale storage of grains is done in granaries or silo. Farmers store their dried grains in jute bags or metallic bins. 

Heating of stored grains results due to the high moisture content in the grains. The grains heat up the water content present in the grain due to thier pre existing temperature which attracts more moisture leading to the growth of microbes in the grains or germinate the seeds thus destroying the yield. 

Most important aspect of agriculture is proper storage of harvested grains and other agricultural produce. Proper storage is necessary to get seasonal foods regularly throughout the year. The godowns and stores should be properly clean, storage bags should be fumigated or treated with insecticides or pesticides. In India, the loss due to improper storage of grains is about 9% annually. So, the correct answer is 'All of the above'.

Food can be spoiled when temperatures are not controlled because high temperature give way for the growth of bacteria and excessive heat increases the rate of enzyme reactions. Exposing food to clod temperature also damages the food.

Neem oil is mainly used to prevent the pests at home. Neem leaves help in stopping the growth of pests. It kills larvae and locusts at homes. Mosquitos die when neem extract is sprayed.

The grains are stored in huge stores and warehouses. These stores and warehouses should be regularly and strictly cleaned, disinfected and kept dry to avoid ants, insects, worms or rodents infestations and keep the grains safe and hygienic for consumption at any time. There should be proper space or be disjoining between the grain sacks for fumigation and regular inspection of the grains The grains are stored in mass scale in huge chambers called silos. the silos have a proper outlet to withdraw the desired quantity of grains.The silos have built-in arrangements for aeration, fumigation, protection from rodents, insects and bird etc. Thus all three options strict cleaning, proper disjoining and fumigation is equally important for the storage of grains.

If the freshly harvested grains are not dried, it might contain moisture and moisture provide growth media for various organisms like molds. Drying will delay the spoilage of the grains.
Thus, the correct answer is option A.

Aspergillus consists of several hundred mould species found in various climates worldwide. Aspergillus is highly aerobic and are found in almost all oxygen rich environments. The storage grain produces aflatoxin due to growth of Aspergillus which can cause acute liver damage and cancer.

Fertilizer burn can occur when too much fertilizer is applied resulting in drying out of the leaves, damage or even death of the plant.

Nitrogenous fertilizers leach away from the soil easily due to their high solubility in water and pollute the water bodies. Nitrogen leaching is a naturally occurring process, it occurs when nitrogen leaves the soil in drainage water. Nitrate is soluble and mobile. It is no problem when it is within the root-zone, but once it gets into the groundwater and other freshwater bodies it is an environmental pollutant.

Nitrogen has to be converted to nitrate, in order to be used by plants. Hence, using nitrate fertilizers directly would be the quickest way to provide nitrogen to the plants. Ammonium nitrate is an important fertilizer with the NPK-rating 34-0-0 (34% nitrogen). It is less concentrated than urea (46-0-0), giving ammonium nitrate a slight transportation disadvantage. Ammonium nitrate's advantage over urea is that it is more stable and does not rapidly lose nitrogen to the atmosphere. During warm weather it is best to apply urea soon before rain is expected or to cover it with soil to minimize nitrogen loss. 

All plants require sufficient supplies of macronutrients for healthy growth, and nitrogen (N) is a nutrient that is commonly in limited supply. Nitrogen deficiency in plants can occur when organic matter with high carbon content, such as sawdust, is added to soil. Soil organisms use any nitrogen to break down carbon sources, making N unavailable to plants. This is known as "robbing" the soil of nitrogen. All vegetables apart from nitrogen fixing legumes are prone to this disorder.

Some symptoms of nitrogen deficiency (in absence or low supply) are given below:

1. The chlorophyll content of the plant leaves is reduced which results in pale yellow colour. Older leaves turn completely yellow.
2. Flowering, fruitings, protein and starch contents are reduced. Reduction in protein results in stunted growth and dormant lateral buds

NPK $:$ The elemental shorthand for the three major nutrients in fertilizers. “N” stands for Nitrogen, “P” stands for Phosphate (${ P } _{ 2 }{ O } _{ 2 }$) and “K” stands for Potash ($\\ { K } _{ 2 }O$). These are the chemical forms of nitrogen, phosphorus and potassium that are present in fertilizers.

Biomagnification stands for Biological Magnification, which means the increase of contaminated substances or toxic chemicals that take place in the food chains. These substances often arise from intoxicated or contaminated environments. The contaminants include heavy metals namely mercury, arsenic, fertilizers&pesticides such as DDT, and polychlorinated biphenyls (PCBs) compounds which are then taken up by organisms because of the food they consume or the intoxication of their environment.

The uses of fertilizer are :

1. They boost crop yields.
2. Increases the protein content of the plants.
3. Imparts dark green colour to the leaves.
4. Improves overall quality of the plants.
5. Help in blooming and seed formation.
6. Increases vigour, resistance to frost and insects, pests and diseases.
7. Helps in the development of healthy root system.
8. Makes the stalks stronger.
9. Helps in ripening of cereals and fruits.
10. Increases vigour and diseases resistance in the plants.
11. Enhances the synthesis of carbohydrates.

Soil pH is considered a master variable in soils as it affects many chemical processes. It specifically affects plant nutrient availability by controlling the chemical forms of the different nutrients and influencing the chemical reactions they undergo. 

Growers apply ammonium sulfate primarily where they need supplemental N and S to meet the nutritional requirement of growing plants. Since, ammonium sulfate contains only 21 percent N, other fertilizer sources are more concentrated and economical to transport, often making them a better choice for N-deficient fields. However, ammonium sulfate provides an excellent source of S, which supports or drives numerous essential plant functions, including protein synthesis.

Disadvantages of fertilizers are:

1. Constant application is needed.
2. Cause soil pollution, water pollution.
3. Cause plant toxicity.
4. Lead to biomagnifications.

To produce fertilizer in the most usable form, each of the different compounds, ammonium nitrate, potassium chloride, ammonium phosphate, and triple superphosphate are granulated and blended together. So, commercial fertilisers are available mostly in the form of granules.

The characteristic of good fertilizer are:

1. It should be soluble in water so that it can penetrate the soil and thus it may be easily assimilated by the plants.
2. It must have essential elements in the form of a compound, which can be easily assimilated by plants.
3. It should not alter the acidity or alkalinity of soil.
4. It should not be fairly stable i.e it not decompose rapidly in soil and lose its essential element.
5. It storage properties must be good with little or no tendency to setting or deliquescence.

Foliar fertilizers are applied directly to leaves. The method is almost invariably used to apply water-soluble straight nitrogen fertilizers and used especially for high value crops such as fruits.

The addition of fertilizer to irrigation water is called "fertigation".

There are actually only two classes of fertilisers: liquid and solid, but the majority of fertilisers used in agriculture are in solid state.

Liquid fertilizer is inorganic substance produced industrially and introduced into the soil in a liquid state. Liquid fertilizers include nitrogenous fertilizers,, anhydrous liquid ammonia, aqueous ammonia, ammoniates, concentrated solutions of ammonium nitrate and urea, and complex fertilizers containing two or three basic plant food elements(nitrogen, phosphorous, and potassium) in various proportions.

The nitrophosphate process (also known as the Odda process) was a method for the industrial production of nitrogen fertilizers, invented by Erling Johnson in the municipality of Odda, Norway, around 1927.

Superphosphate of lime dissolved with water converts in phosphorous which can be added into soil that can be absorbed by plants.

Fertilizers are materials which supply essential elements to the plants through soil.

The key element required for plants in the soil is nitrogen, phosphorous and potassium. So, it is delivered in form of fertilizers.

Trace elements:-

Examples of nitrogenous fertilizers:-

The most essential elements required for the development of all plants are:-

Because of the nitrogen deficiency following things happens:-

 The most important elements that plants need, without which they won't thrive, are the three macronutrients: potassium, nitrogen, and phosphorus. Because they are basic building blocks of every plant are ATP, cell membranes and amino acids. Nitrogen is an element in every amino acid; ATP, which is the primary source of energy for all cells, contains phosphorus. Potassium is essential to a plant's ability to metabolize. This element also comprises up to two percent of a plant's weight.

Superphosphate is the chief material supplying phosphoric acid in fertilizer and may be considered the basis of the modern fertilizer industry. 

Most nitrogen fertilizers contain nitrates which decompose slowly, in the presence of oxygen, to give harmful gases like nitrous oxide. 

1) Nitrogen fertilizers does not lead to pest problem but it leads to other bad causes to environment.

2) Excess nitrogen in the air can impair our ability to breathe, limit visibility and alter plant growth.  

3) Nutrient pollution is one of America's most widespread, costly and challenging environmental problems, and is caused by excess nitrogen and phosphorus in the air and water.

There are biotic and abiotic factors that damage the food materials. Moisture is the abiotic factor that damages the food material if it is raised to undesirable amount.

(c) Biological control methods include using natural predators of pests, using resistant varieties, crop rotation, etc.

Indiscriminate eradication of pests is undesirable because without them the beneficial predatory and parasitic organisms which depend upon them for food would also be eliminated. The biocontrol method of pest and pathogen control involves use of viruses, bacteria and other insects (which are their natural predators and pests).

There are two methods used for controlling the insects and pests on crops viz. chemical methods and biological methods.