SOIL AND NUTRIENT LOSSES IN SURFACE RUNOFF FROM CONVENTIONAL AND NO-TILL CORN SYSTEMS

Abstract

A natural-rainfall erosion plot study was conducted during three consecutive growing seasons (May to September) on a tile-drained sandy loam with a 9% slope to evaluate differences in soil and nutrient losses (NO3-N, P, K) from conventional (C-T) and no-till (N-T) silage corn systems. For the N-T system, corn was seeded directly into an alfalfa-timothy sod that had been treated with atrazine at 4.5 kg ha−1 a few days prior to seeding to kill the sod. The conventional system involving continuous cultivation consisted of fall moldboard plowing, spring disking with a 2.2 kg ha−1 of atrazine applied to control weeds, and seeding. When compared with the C-T system, the N-T system reduced rainfall loss as runoff by 63.6% and soil losses by 92.4%. The 3-yr total soil losses amounted to 3.87 t ha−1 for N-T and 50.68 t ha−1 for C-T. The N-T system reduced K losses by 72.6% and P losses by 93.5% with respect to C-T. NO3-N losses were significantly lower for the C-T treatment as compared to the N-T treatment. Lower percentage nutrient loss occurred in solution from C-T corn because of better incorporation of the fertilizer into the soil. Yield and percent ear were not significantly different between the two systems. Key words: No-till corn, nitrogen, phosphorus, potassium, soil erosion, surface runoff