Agricultural Practices To Reduce Non-point Source Pollution

摘要

Fanning activities such as tillage and crop harvest can leave soil exposed and susceptible to erosion by rain and wind. Tillage also opens up the land and allows carbon dioxide to escape into the atmosphere which in-turn can contribute to global warming. Removal of crop stubble after grain or fruit harvest exposes the soil to the vagaries of climate. Sediment is the leading contaminant of water. The transportation of sediments from agricultural soils can negatively affect soil productivity. Alabama A&M University scientists have developed several management practices to control soil erosion and carbon dioxide efflux from agricultural soils. Through a 10-year long field experiment, the best management practices to control the non-point source agricultural pollution were compared with farmers' practices at the Alabama Agricultural Experiment Station, Belle Mina, Alabama, USA (34~0 41 'N, 86~0 52'W) on a Decatur silt loam soil (clayey, kaolinitic thermic, Typic Paleudults). Twelve different production packages were compared in a randomised incomplete factorial design with four replications on the same plots during l996-2005. Production packages included three tillage systems (conventional, mulch till, and no-till), two cropping systems (cotton in summer and fallow in winter and cotton in summer and rye in winter), three nitrogen levels (0, 100, and 200 kg N ha~(-1)), two nitrogen sources (ammonium nitrate and poultry litter). The data indicate that conservation tillage in association with judiciously applied poultry manure and winter rye (Secale cereale L.) cover cropping has improved soil quality, conserved soil, and reduced carbon efflux in addition to maintaining or increasing cotton (Gossypium hirsutum L.) production.