Comparative Lime Effects on Continous No-Tillage and Conventionally Tilled Corn

Because the absence of tillage precludes the mixing of lime with soil when no-tillage corn (Zea mays L.) is grown, an experiment was conducted to determine if surface application would be effective. Information on the subject is not presently available but is needed to guide growers in neutralizing soil acidity caused by high rates of nitrogen applied to corn.Because the absence of tillage precludes the mixing of lime with soil when no-tillage corn (Zea mays L.) is grown, an experiment was conducted to determine if surface application would be effective. Information on the subject is not presently available but is needed to guide growers in neutralizing soil acidity caused by high rates of nitrogen applied to corn. Field studies over an 8-year period compared continuous no-tillage corn with surface-applied lime to continuous conventionally tilled corn with lime incorporated into the soil. Comparisons of the two tillage methods were also made without lime to determine the degree of response to lime. Lime increased corn yield more than twice as much in no-tillage culture as in conventional tillage. Lime was essential for highest yields with both tillage methods but the yield increase due to surface applied lime in no-tillage culture averaged 31.3%, compared to a 13.5% yield increase due to incorporated, lime in conventional tillage culture. Associated with the larger yield increase from lime in the no-tillage culture were 1) a higher pH in the 0 to 10-cm soil layer (averaging 6.4 in no-tillage compared to 6.0 in conventional tillage) in the eighth year; and 2) larger increase in exchangeable Ca and a reduction in exchangeable AI in the 0 to 10-cm layer. The pH and exchangeable Ca and AI in the 10 to 20-cm soil layers from tilled and nontilled soil were almost identical. A highly significant correlation was found between maturity of the corn and yield increase due to lime. Thus, it appears probable that the principal mechanism for the yield reduction caused by the lack of lime was reduced growth. This was especially apparent in early growth stages but was partially overcome later. It was more noticeable in no-tillage corn than in conventionally tilled corn. At harvest, the increase in dry matter content of no-tillage corn ears which was caused by lime was larger than that in conventionally tilled corn. Water use efficiency for the increased corn grain yield due to lime in no-tillage was calculated to be almost three times that in conventional tillage.