i. Crop rotation
ii. Multiple cropping
i. Crop Rotation:
Crop rotation is a method of plantation that is planned over two to three years. As part of this method, different crops are grown on the same field in different years. If the same crop is grown year after year, the same nutrients get absorbed by the crop every year and the fertility of the soil declines.
This causes lower yield of the crop. Succeeding crops in different years belong to different families. For example, the application of alternate cropping pattern with leguminous and non-leguminous crops helps to improve the soil fertility. The roots of leguminous crops such as beans and peas possess nodules that contain nitrogen-fixing bacteria.
These enrich the soil with nitrogen. Such techniques avoid growth of organisms that are host specific. If the same crop is repeated over years, it will lead to rise in problems of pests. Other advantages of crop rotation are:
a. Maintains soil fertility and curbs soil erosion
b. Controls threat of pests and therefore reduces the need for pesticides
c. Prevents diseases
d. Controls growth of weeds
ii. Multiple Cropping:
Multiple cropping involves growing a variety of crops on the same field simultaneously. One crop is of short duration and the other crop of longer duration, so that they do not ripen at the same time. This form of farming is particularly popular with small-scale farmers. Not only does this make the land more productive, it also makes possible production of a variety of crops. Multiple cropping provides advantages like:
a. Reducing risk to crops from pests, climate and diseases because at least one crop is able to fight back.
b. Multiple cropping fixes nitrogen in the soil, enabling soil to retain its fertility.
c. Since a number of crops are grown, there is little space for weeds to grow.
d. A mix of vegetation is healthier, particularly for small-scale farmers who also consume their own produce.
2. Agricultural inputs and their appropriate use:
Fresh Water for Irrigation:
Almost 70 per cent of the available fresh water is used for irrigation. This makes water an indispensible part of agriculture. But there are methods by which water can be used productively and judiciously for agriculture.
i. Using sprinklers and drip irrigation, the amount of water that is fed to the crops can be controlled. While it saves unnecessary water from being used for irrigation, it also protects the soil cover.
ii. Fields should be watered only when required to avoid use of water at wrong times. This requires planning and knowledge.
iii. The crops grown on a field should be suitable for the environment of the region. This way, the crops will require less extra water because their demands will be met by the environment.
iv. If the soil and the crop are compatible, less water will be required to irrigate the land.
v. Mulching of crops with vegetative cover helps to reduce water loss by transpiration.
Use of Chemical Fertilizers:
With modern agricultural practices, the use of chemical fertilizers is increasing. Chemical fertilizers are made from inorganic materials and contain phosphorus, potassium and nitrogen. But they may also contain acids that harm microorganisms like the nitrogen-fixing bacteria present in the soil. This spoils the health of soil and causes stunting of the crop as well.
The advantage of fertilizers is that they contain all three nutrients and can be used as and when the need arises. Unfortunately, fertilizers are often used excessively. Due to this, other nutrients of the soil are not used and it becomes deficient in important nutrients, like zinc, cobalt and nickel. Excess of nitrogen in fertilizers also decreases plants’ resistance to diseases.
To ensure that fertilizers are used appropriately, they should be used in accordance with the requirement of the crop and should be used in the recommended quantity. Farmers should also make sure that they compensate for the lack of certain nutrients in the soil.
Use of Pesticides:
Pesticides are useful in preventing, destroying and repelling pests that cause harm to a crop. With the increase in high yielding varieties being grown, pesticides become more important because these crops are more prone to attack from pests.
Pesticides spread fast in a crop. There is a stipulated time frame between when the pesticides are applied to the crops and when they are harvested. Many farmers are not aware of this ‘waiting period’. Due to this, the pesticides are washed off into the soil and into the water they are washed in. This contaminates the soil as well as the water, thus harming the health of all living organisms. Like fertilizers, pesticides also harm the microorganisms found in the soil.
Disadvantages of Using Pesticides:
There are many disadvantages of using pesticides.
i. Many pesticides are broad spectrum and kill many useful microorganisms, earthworms, bees and butterflies.
ii. Pesticides are non-biodegradable and even reach human bodies through the food chain.
iii. Pesticides when used in excess pollute the groundwater, soil and other water bodies like lakes, rivers and seas.
3. Use of organic fertilizers or manures:
Manures are organic materials which are added to the soil to increase crop production. These manures are rich in phosphorous, potassium and nitrogen which are necessary for the growth of crops. Organic fertilizers are easily absorbed into the soil because they are biodegradable.
They also improve soil quality because with organic manures, soil is able to absorb moisture better. Organic manures provide food for soil organisms like earthworms that are responsible for improving soil quality. Organic manures include
ii. Farmyard manure
iv. Green manure
Compost consists of a variety of farm wastes such as farm weeds, sugar cane waste, straw, vegetables, kitchen wastes, and groundnut and rice husk. The organic matter is decomposed by aerobic and anaerobic microorganisms through biological process. Compost increases microbial population of the soil.
ii. Farmyard Manure:
Farmyard manure is formed by the decomposition of farm wastes like straw, litter and crop residue mixed with dung and urine of farm animals like cow, horse, goat and sheep. They are readymade manures and contain nitrogen, phosphorus and potassium.
Vermiculture is the artificial rearing or cultivation of earthworms. Earthworms eat cow dung as well as farm wastes, which when passed from their bodies are converted into vermicompost. These earthworm excreta is rich in humus. Vermicompost has become a popular form of organic manure in the country.
Like Gujarat, Maharashtra and Karnataka are extensively making use of vermicompost to improve soil quality, to help increase the crop yield, and to improve crop quality. It is produced by vermiculture technology, which aids in sustainable improvement of soil fertility and helps in minimizing the use of chemical fertilizers by 50 per cent. It increases crop yield by almost 20 per cent because of increased supply of all essential elements.
iv. Green Manure:
Green manuring is the practice of growing and then ploughing in the green crops into the soil.
It is a cost effective method to increase the soil fertility as it can supplement farmyard and other organic manures. Green manures add nitrogen and organic matter to the soil. They also improve aeration and drainage of the soil. Both leguminous and non- leguminous plants are grown for making green manure.