Management of nutrients on agricultural land for improved water quality

A rainfall simulator was utilized to determine the effects of 2-, 10-, and 20-year storm frequencies on losses of water, soil and nutrients from plots subjected to different crop rotations, fertilizer schemes and manure applications. Crop rotations, rates of fertilizer and manure were compared. Simulations were made on freshly tilled soil. Comparative erosion losses were as follows: continuous sod - corn - alfalfa rotations continuous corn. Fertilizer alone tended to increase runoff, but this effect was overcome when fertilizer was used with manure. Continuous recording of surface and subsurface flow and subsequent losses of nutrients to the environment was conducted on larger plots. Rate and time of fertilization determined the plant nutrients lost. Returning crop residues to the soil improved water infiltration, increasing deep seepage losses. Phosphorous inputs into cultural media as it related to algal growth was studied. Sustained concentration determined the biomass of phosphorous.