Increased fuels costs have prompted many producers to consider conservation tillage techniques and single pass applications of nitrogen (N) fertilizer and herbicide to reduce fuel expenses. The objective of this study was to determine the impacts of tillage and nitrogen application methodology on corn grain yield. The experiment was conducted from 2002-2005 at the Northwest Research Station of the Ohio Agricultural Research and Development Center (OARDC) near Hoytville, OH. Six different tillage regimes were established as main plots: no-till, fall disc-field cultivator, Aerway tool tillage, early planted strip-till, late planted strip-till, and zone deep-till. Subplots consisted of either a single-pass application of broadcast, surface applied urea-ammonoium nitrate (UAN) representing a weed 'n' feed application, a split application of nitrogen between planter applied and sidedress N (subsurface injected N), or an unfertilized control. The rate of N for the different application methodologies was 168 kg ha −1 . Dry conditions during the 2002 growing season resulted in very poor corn yield and thus little response to tillage or N application. In 2003, the split treatment maximized corn yield likely due to minimized ammonia volatilization independent of tillage regime. Surface broadcast applications of UAN resulted in lower grain yields in conservation tillage treatments compared to split nitrogen applications in 2004. No statistical differences were noted between the two application methods in the conventional tillage treatments. In 2005, no yield differences could be attributed to N application methodology across tillage treatments. From this study it was concluded that surface broadcast application of UAN can result in yield loss, especially in conservation tillage systems.

Lime is used as a soil amendment to achieve the optimum pH suitable for good crop growth. Buffer pH (BpH) measurements have been calibrated to relate the linear drop in pH of the soil-buffer system to the amount of lime needed to neutralize soil to a certain pH level. The amount of lime required to neutralize soil acidity, called the lime requirement (LR), is obtained from soil-limestone (CaCO 3 ) incubations. In this study, 13 soils from Ohio were incubated with CaCO 3 for a period of 1 month to determine the LR to achieve different target pHs. This LR was then regressed with the different BpHs of four buffer solutions [(1) Shoemaker, McLean, and Pratt (SMP), (2) Sikora, (3) Mehlich, and (4) modified Mehlich] to obtain calibration equations. The Sikora and modified Mehlich buffers are variations of the SMP and Mehlich buffers, respectively, but they are designed to promote buffering without use of any hazardous constituents [i.e., chromium(VI) in SMP buffer and barium in the Mehlich buffer]. This study was done to verify the applicability of the buffers that do not contain any hazardous constituents and to calibrate these buffers for predicting lime requirement needs for Ohio soils. Comparing the calibrated equations of the SMP and Sikora buffers with CaCO 3 -incubation LR recommendations revealed that the SMP and Sikora buffer solutions were not significantly different, and a single calibrated equation can be used for these two buffers to determine LR predictions in Ohio. The Mehlich and modified Mehlich calibration equations differed significantly from the SMP calibration equations and were not as highly correlated with CaCO 3 -incubation LR recommendations using a linear model (r 2 , 0.54). Thus, it is possible to use the Mehlich and modified Mehlich for determining lime recommendations, but they require a correction factor such as inclusion of the initial soil pH to improve the precision of the LR prediction. We also found the various buffers tested in this study were better able to predict LR rates for greater LR soils than low LR soils. In conclusion, successful laboratory tests to predict LR for Ohio soils are possible using alternative buffers that do not contain hazardous constituents.