Nutrient Losses in Runoff from Conventional and No‐Till Corn Watersheds

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Abstract
A study was initiated to determine the quantity of nutrients and sediment in runoff from conventional and no‐till corn (Zea mays L.) watersheds. Runoff was collected with H‐type flumes and Coshocton wheels. Parameters measured in runoff included NH4+‐N, NO3−‐N, total N, ortho‐PO4, total soluble P, total P, suspended sediment, and soluble solids.There was a significant difference in total runoff between the conventional and no‐till watersheds. Over nine times more runoff originated from the conventional‐till watershed when compared with the no‐till watershed in 1982. A large difference between the two watersheds in suspended sediment content was also observed. Yearly sediment losses of 370 and 9 kg ha−1 from the conventional and no‐till watersheds, respectively, were found for 1982. There was also a significant difference in the loss of soluble solids between the two watersheds. For 1982, there was over a 29‐fold greater loss of soluble solids from the conventional‐till watershed than from the no‐till watershed.Losses of NH4+‐N, NO3−‐N, and total N from each watershed were very low, although large differences were observed between the two watersheds. In 1980, 271, 638, and 1199 g ha−1 of NH4+‐N, NO3−‐N, and total N, respectively, were lost from the conventional‐till watershed, while 2, 47, and 87 g ha−1, respectively, of the above parameters were lost from the no‐till watershed.The loss of all forms of P from each watershed was also very small. During 1982, 161 g ha−1 of total P were lost from the conventional‐till watershed while only 8 g ha−1 were lost from the no‐till watershed. The loss of ortho‐PO4 and total soluble P was not significantly different between the two tillage treatments.