Strip cropping is also a kind of agronomical practice in which ordinary crops are planted / grown in form of relatively narrow strips across the land slope. These strips are so arranged that the strip crops should always be separated by strips of close growing and erosion resistance crops.
Strip cropping used as a technique for erosion control is a most effective method in certain soils and topography. This method becomes more effective for erosion control, which it is followed with crop rotations in the area where terraces are not practically feasible due to the fact that the length of slope is divided into different small segments. The strip crops check the surface runoff and force them to infiltrate into the soil, thereby facilitates to the conservation of rain water. Strip cropping is more intensive practice for conserving the rain water than contouring (i.e. about twice as effective as contouring) but it does not involve greater effect on soil erosion as terracing and bunding. Generally the use of strip cropping practice for soil conservation is decided in those areas where length of slope is not too longer.
Strip – cropping to control soil erosion caused by runoff derives its effectiveness mainly from following two factors:
a) Reducing the runoff flowing through the close – growing sod strips.
b) Increasing the infiltration rate of the soil under cover condition.
The reduction of runoff velocity between the row strips is achieved by making an observation in the flow path. The observations created by row crotion are also responsible to dissipate the kinetic energy of flow checking the flow of surface water. From field studies it has been observed that the strip cropping on the contour plays a key role in conserving the soil and water, when combined with terracing. The width of these strips depends on the topographical features of the area.
Field Strip Cropping: It is modified form of contour strip cropping in which crop strips are laid parallel across the land slope but not always exactly on the contour may be changed. This type of strip cropping is frequently used only where the topography is either too imegular or undulating as it makes accurate layout of contour strip cropping, impractical. The depressed areas should be avoided from field strip cropping they may be left for establishing the grassed water ways.
Buffer Strip Cropping: In buffer strip cropping the strips of grasses or legume crops are laid between contour strip crops in regular rotation. The width of these strips may or may not be even. The buffer strips are usually 2 to 4 m wide and are placed at 10 to 20 m meters. They can also be placed on critical stops of the field (The main purpose of buffer strip cropping is to provide a protection to the land from soil croson.)
Wind Strip Cropping: In wind strip cropping system the strip crops of uniform width are laid at right angles to the direction of preventing winds without regard of the contour. The main objective of this system is to control the wind crosion father than water crosion. This cropping is recommended for level or nearly level topography where wind crosion is more effective.
A guideline for deciding the width of wind strip – cropping can be have from the values given in table 10.2
Table 10.2 Recommended strip widths for wind strip
Cropping (FAO 1965)
Strip width (m)
Layout of Contour Strip Cropping: In layout of a field for contour strip cropping the first step is to decide the width of strips at narrower points let the minimum width is assumed to be as 25 m. The next step is to establish a point for locating the contour line that will form the lower boundary of first strip. This point is located at 25 m apart from the top boundary of field by measuring along the steepest part of the stop. Now a contour line is drawn passing through this point up to the field boundary. This procedure is repeated until the entire field is laid out.
Width of Strips: It varies with the degree and length of land slope allowable soil loss soil types arrangements of crops grown in rotation and size of farm equipments used in tem aced fields the width of strip is adjusted according to the terrace interval but in untraced areas narrow width than the standard terrace interval is frequently used. In general steeper the slope narrower will be the strips of cultivated and dense growing crops both. An approximate range of trip widths based on average land slope and soil types is given in table 10.3
Table 10.3 Approximate range of strip width
Percent Trand note
Width of strips (m)
A buffer strip is more or less in a permanent contour strip usually varies in width which is normally kept between 3 to 5 m.
Crop Rotation: Crop rotations can be more effective for controlling soil crosion accompanied with strip cropping system. It can be used on the same piece of land by growing tilled crops; small grain crops hay crops or grasses either under a strip cropping system or a separate field system. In areas where perennial grasses and legumes are not feasible to grow, the row crops of small grain and annual legume crops can also be grown in strips. It is a general rule that no two cultivated strips should have the same planting or harvesting dates. The sequence of crops should be in such a manner that there could be form a dense – fibrous root system to hold the soil and retard the erosion, until the roots are croken down by tillage operations. All these activities of crop rotation also increase the organic matter in the soil thereby the physical condition of the soil become improved ultimately soil absorbs more water and also increases the capability of soil to resist the erosion.
Under use of crop rotation practices for controlling soil crosion, the simplest way to combine different crops in roa form and grow them in consecutive rotations. The frequency with which row crops should be grown depends upon the severity of crosion, taking place in the area. For example where crosion rate is very low the row crops can be grown at every alternate year but on the contrast in high erodible areas or where soil erosion is being more there may be practiced only once in five or even seven years cycle.
For erosion control by growing the crops in notation system probably the most suitable crops are legumes and grasses. The main benefits credited by these crops are mentioned as under:
* Reduction of soil erosion resulting from high degree of good ground cover.
* Help to maintain or improve the status of organic content in the soil thereby contributing the soil fertility and enable to develop more stable aggregates in the soil.
* Increase in soil nitrogen resulting from nitrogen fixation associated with legume crops.
Different crops and management practices used for growing them have different effects on soil structure. The crop affect the soil structure by the activities of their root system and the amount of organic residue contents added from the roots and top of the plants. The organic contents help in arranging and stabilizing the soil particles into granules or aggregates form. This in rum to provide greater pores in the soil mass causing rapid water take in the soil. Apart from above the soil aggregates are also developed by tillage operations wetting and drying of soil freeing and thawing of soil activities of micro organism and small animal like earth worm.
Interilled crops including vegetables and grain crops usually do not have effective root systems for improving the soil structure However most of the grain crops return a considerable amount of organic matter to the soil provided that the resides after grain movable should be covered into the soil by ploughing operations. The vegetable crops rectums very little organic matter to the soil. The dense root system of grass does much to create soil structure and also helps in binding the soil aggregates together.