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BeneficialEffectsofProperRotation
Proper crop rotation is one of the essential factors of good farm management.Continuous growing of a crop is likely to produce good effect for a few years, but well – planned rotations are best over a long period of time because they conserve and improve the soil.
The physical condition of the soil is known to be unfavorably affected by growing cultivated crops for many years. However, if grasses and legumes are included in the rotation, the tilth is considerably improved. Legumes are also valuable because they add organic matter to the soil. Besides, they are able to fix nitrogen from the air and convert it into a form that can be used by all growing crops.
Various crops differ in the kind and amount of nutrients they take from the soil, that is why crop rotation helps to maintain the proper nutritional balance in the soil. Most weeds and pests are believed to be controlled by crop rotation. Diseases and insect usually attack certain crops, and they cannot develop during the periods when resistant crops are grown.
With crop rotation labour is distributed more uniformly, as peak work periods on farms growing different crops come not at the same time. Many grain growers have suffered losses because temporary labour was not available at harvest time. Finally, the risk of poor production is usually greater with one crop than when several crops are grown.
The advantages of crop rotation.Many advantages may be given for the use of a properly planned crop rotation scheme. Among these are the following.Different crops require different amounts of plant nutrients. A diversity of crops is of value in the maintenance of fertility, since the drain is not so great on any nutrients.
The use of a cultivated crop in the rotation aids in weed, insect, and disease control. Without a rotation, weedy plants, insects and diseases tend to become more numerous, since there is less check to their continued increase in population. The growing of legumes in the rotation helps to increase the nitrogen content of the soil, as properly inoculated legumes take nitrogen from the air.
Rotations that include sod crops aid in the control of erosion. The sod greatly slows the movement of water and may be interspersed with cultivated areas to prevent erosion. Crop residues may be returned to the soil to aid in the maintenance of organic matter. It is desirable that straw produced on the farm be returned in the manures. Stubble and other crop residues may be plowed under to advantage on most farms.
18. In which paragraphs of the text there is an information:
a) about the aim of using tilled crops in crop rotation;
b) why many grain manufactures suffer losses during harvesting;
c) about the role of stubble and plant residues.
Comment on the role of legumes in crop rotation.
Enumerate in Russian the advantages of crop rotation in growing farm crops.