Improving fertility

Crop plants use the nutrients in the soil for their growth and development. Since they are harvested and not allowed to die and decompose in the soil, the minerals absorbed by them are not returned to the soil. So nutrients have to be added to the soil to maintain its fertility. This can be done in the following ways.

Using organic manure

Organic manure consist decomposed organic waste, like agriculture residue, weeds, the sludge that remains after sewage is treated, and dung. The decomposition can take place in the or in covered pits. In the latter case, the manure is called compost.

Sometimes, plant is frown specially to be ploughed into the soil to increase its fertility. This type of manure is called green manure. Clover, black gram, cowpea, cluster bean and sunn hemp are some plants grown for this purpose.

Adding organic manure has for long been considered the best way of improving soil fertility. Organic manure not only provides most o the nutrients required by plants, but also improves the texture of the soil by adding humus. Besides, it encourages the activity of soil organisms, which is essential for the maintenance of soil fertility. The disadvantages of organic manure are that it is bulky and difficult to transport, and that it does not provide all the nutrients required by crop plants in the right proportions.

Using bio fertilizers

Bio fertilizers are microorganisms which enrich the soil by fixing atmosphere nitrogen and dissolving minerals present in the soil. These microorganisms are cultivated and supplied to farmers in packets. Farmers mix them with the seeds they sow.

Rotation of crops

All crops do not utilize the same mineral at the same rate. That is to say, each crop has its own special rate. That is to say, each crop has its own special requirement of minerals. So, f a particular crop is grown on the same piece of land year after year, the soil may become deficient in a particular set of minerals. To prevent this, one crop is grown in one season and another in the next season. The practice of growing different crop in succession on the same piece of land is called crop rotation. Crop rotation also helps discourage pests, since pests are selective about the plants they attack. If one crop is grown in one season and another the next, it is likely that the first will not thrive on the second.

Generally, cereal crops use up nitrogen, so they are alternated with groundnut and pulses, which have nitrogen- fixing bacteria in their roots. Three of four crops can also be in rotation. Some crop rotation patterns practiced in India are maize –mustard, rice-pulses- jute, sugar cane- peas and rice –wheat pulses –mustard.

Mixed crop

This involves cultivating two or more crops simultaneously. The crops are selected in such a way that they do not complete with each other for nutrients, space and light. In fact, they help each other. The taller crop many provide shade, while the other may save moisture, the secretions from the roots of one may serve as nutrition for the other, and so on.

Fallow field

`Leaving the land allow’ means no cultivating it for a year or more. This helps the soil regain fertility by natural process.

Chemical fertilizers

These are inorganic compounds with specific compositions. They are mixed with the soil to provide plants with nutrients they need. Unlike manures, fertilizers provide the nutrients required by crops in the right proportions. They also have advantages of being soluble, and easy to store, transport and handle because they are compact. However, they harm the texture of the soil, making it prone to erosion. They can also turn soil acidic or alkaline.