Grass Component Effect On Soil Physical Properties in An Organic Crop Rotation.

Soil quality and environmental health are dependent upon agricultural practices. It is believed that organic production systems are capable of reducing problems caused by traditional chemical‑dependent agriculture, notably those related to poor soil quality. However, more research is needed.

Crop rotation is an essential component of organic crop production systems. An added temporary grass component could be important in organic crop rotations for maintaining soil structure, controlling pests and weeds, and enhancing nutrient cycling. Existing research focuses on conventionally managed rotations. Therefore, implications for organic systems must be inferred.

The objective of this research was to measure changes in soil physical quality indicator variables in the first and last crop components, before and after three years of grass and two manure application rates, and in the first and last crop components of an organic rotation without grass component and with two manure application rates. Some soil quality indicator variables measured were bulk density, wet and dry aggregate stability, and saturated hydraulic conductivity (Ksat).

The research was conducted on an existing rotation experiment on the West Virginia University Organic Farm in Morgantown, WV. Soils in the study area are classified as Culleoka‑Westmoreland, Dormont and Guernsey, or Tilst silt loams. A four and a seven year rotation were studied to fulfill our experimental objective. Both rotations were manured at two different rates, tilled conventionally, and the same crops and crop sequences were used: corn, soy, wheat, and kale. Three years of orchardgrass and red clover were planted and grazed by sheep in the seven year rotation.

Higher soil organic matter was measured when higher rates of manure were added. Differences in bulk density were related to soil management (tillage) and the crop/grass component present. This research has the potential to increase the understanding of soil quality changes in organic crop rotations.