Soil and Environmental Benefits of Cover Crops In the Semiarid Central Great Plains.

Replacement of fallow in crop-fallow systems with cover crops may improve soil properties and enhance soil productivity. We studied whether replacing fallow in no-till winter wheat (Triticum aestivum L.)-fallow with cover crops for five years reduced wind and water erosion, sequestered soil organic carbon (SOC), and improved soil physical properties in the semiarid central Great Plains. Winter cover crops [triticale (×Triticosecale Wittm.) and lentil (Lens culinaris Medik.)], spring cover crops [lentil, pea (Pisum sativum L. ssp.), and triticale], and fallow and continuous winter wheat as control were selected for this study from a larger experiment. Winter and spring triticale designed in split plot with half the cover crop plot hayed was selected to study haying effects. Winter and spring triticale sequestered 0.56 and spring lentil sequestered 0.44 Mg ha^-1 of SOC per year in the 0- to 7.5-cm depth relative to fallow. Spring triticale and spring lentil increased geometric mean diameter of dry aggregates, while spring lentil reduced wind erodible fraction (<0.84 mm aggregates) by 1.7 times compared with fallow, indicating that cover crops reduced soil’s susceptibility to wind erosion. Winter triticale and spring pea reduced loss of sediment, total P, and NO₃-N in runoff. Cover crops also increased amount of water-stable aggregates. Wet and dry aggregate stability increased while erodible fraction decreased with cover crop-induced increase in SOC concentration. Haying of winter and spring triticale appears to have little or no effects on SOC storage, soil erosion, and soil properties after five years. Cover crops were no better than continuous wheat for improving soil properties, and their effects eight months after termination were not significant. Overall, replacing fallow with cover crops, particularly with triticale, increases SOC pool, reduces soil erosion, and improves soil properties in this climate.