Strip cropping is a sustainable agricultural practice that involves planting a field with alternating, narrow strips of different crops. This method is a form of conservation farming designed to protect the soil from wind and water erosion. By systematically arranging various plant types, strip cropping creates a natural barrier against environmental forces. This technique improves the stability of farmland while supporting continued crop production.
Physical Arrangement and Design Principles
The fundamental design of strip cropping requires alternating two distinct types of crops: one that is close-growing and erosion-resistant, and another that is a cultivated row crop. Close-growing crops, such as small grains like wheat or forage plants like hay and legumes, provide dense ground cover that holds the soil in place. These strips are rotated with row crops, like corn, cotton, or soybeans, which expose more soil to the elements during their growth cycle.
Determining the precise width of each strip is a mechanical consideration influenced by the slope of the land and the type of farming equipment used. Strips must be wide enough to accommodate multiple full-width passes of machinery for tilling, planting, and harvesting efficiently. Strip widths often range between 25 and 75 feet, with a minimum width of around 50 feet being practical for most modern farm implements. The alternating strips are arranged across the field, usually following the land’s contour to maximize their protective effect.
Soil Conservation and Environmental Functions
The physical arrangement of alternating crop strips provides significant outcomes for soil conservation, primarily by disrupting the flow of water and wind. When rain falls, the close-growing strips act as miniature dams, substantially reducing the velocity of water runoff across the field surface. Slowing the water allows more time for the moisture to soak into the ground, which improves water infiltration and retention in the soil profile.
This reduction in runoff velocity is also responsible for trapping soil particles and nutrients detached from the row crop strips. The dense vegetation acts as a filter, preventing sediment, minerals, and farm chemicals from being carried off the field into waterways. This technique maintains the fertile topsoil needed for future harvests by reducing soil erosion. Additionally, the alternating heights and densities of the crops mitigate wind erosion by reducing the speed and impact of air currents near the ground.
Major Implementation Styles
The application of strip cropping is adapted to the specific topography and erosion concerns of a field, leading to several distinct implementation styles.
Contour Strip Cropping
Contour strip cropping is employed on sloping land where water erosion is the primary concern. In this system, the strips are planted along the contour lines of the terrain, running perpendicular to the direction of the slope. This orientation ensures that each strip acts as a barrier to slow down and catch runoff water before it can gain momentum.
Field Strip Cropping
Field strip cropping is used on fields that are relatively level or have a gentle, uniform slope. This style involves planting straight, parallel strips laid out perpendicular to the direction of the prevailing winds. The straight alignment makes this type easier to manage with farm machinery and is primarily used to control wind erosion. Alternating tall and short crops helps create a windbreak effect across the entire field.
Buffer Strip Cropping
Buffer strip cropping involves planting permanent, un-harvested strips of vegetation, such as perennial grasses or legumes. These buffer strips are established along the edges of fields, near streams, or adjacent to ditches vulnerable to erosion. Their purpose is to provide a stable barrier that filters out sediment and excess nutrients. This prevents them from entering local water bodies and preserves the ecosystem.