Uses and care of soils

Soils are used in a great variety of ways, agriculture being the leading soil use.

There has always been great variation in the quality of soils available for agriculture. In most instances, the better soils are used for crops, and the less suitable ones are kept for pastures or timberlands.

Properties that determine the agricultural quality of soils include: 1) ability to produce high crop yields under good management and careful handling; 2) the ease with which they can be used profitably; 3) the amount and kind of care they require. Good soils respond well to proper management, which involves correct cropping practices, use of fertilizers, and effective protection against damage. Without good care all cropland deteriorates with continuous use. The loss that results from improper care of good soils is greater than from improper care of poor soils, since the former are more valu­able. A good rotation system consists of adjusting the crop arrangement to the physical nature of the land and, same time, maintaining a balanced economic farming programme. Rotation implies the growing of more than one n a farm. In other words, rotation and diversification go in hand.

Since no two crops make identical demands on the soil, one crop may require excessive amounts of a given nutrient another crop may be able to supply. For example, legumes return nitrogen to the soil, but most other crops re-more nitrogen than the soil can normally supply. Thus a rotation programme involving clovers and other legumes combined with cotton, corn, small grains, and other heavy users of nitrogen may meet most nitrogen requirements. Crop rotation and associated diversification help improve the economic status of farming in many ways. Besides maintaining the soil in a good state of productivity, rotation and diversification help reduce the risks of economic losses from low yelds. Also, the income and the labour requirements are spread through the year instead of being seasonal in nature,as in the case of a single crop, such as wheat. Some phases of a well-ordered crop rotation programme are apt to succeed, if others fail. It is not necessary for all parts of the programme to show a financial profit; it is the overall result that counts. A soil-improving crop, for example, may not be economically profitable at the time it is grown, but its benefits may be clearly realized in future years.

Land use is a continuous operation. Farmers normally do it their land aside while they are restoring their soils; repair and improve them while the land is in use. The ways that soils are used, the length of time they remain productive, and the harvests they yield depend to a marked degree upon the care they receive.

Under careful and proper use soils may continue indefini­tely to produce good yields. It is improper use and lack of care that harm soils. Thus good care is of vital importance in prolonging the useful life of soils.

Improper use may result in the deterioration of soil struc­ture; several things may contribute to this deterioration, including: plowing when soil is too wet; failure to return organic matter; unwise use or lack of lime; neglecting to ro­tate crops. An even more serious and widespread kind of soil damage is the loss of essential plant nutrients. This may re­sult from continuous growing of the same crop and from fail­ing to fertilize it properly. Still another serious cause of depletion in most soils is known to be the loss of organic matter.

Most kinds of soil damage are related to each other in many ways. For example, organic deficiency is definitely a factor in soil erosion and in structural breakdown as well as in the deficiency of plant nutrients. Consequently, under­standing these relationships and properly evaluating them in a balanced farming programme make modern agriculture truly a scientific undertaking.

Date: 2015-10-19; view: 608; Нарушение авторских прав