Management of soil acidity in no-till production systems through surface application of lime

Increasing acreage of no-till (NT) cropping systems with surface applications of N fertilizer brings forth the important issue of management of acidic soils in these systems. Our objectives were to determine the vertical movement of surface-applied lime, and to determine if frequency or type of lime applied affects the rate of movement; to evaluate the effect of surface application of lime on soil chemical properties; and to determine the correct application rate of lime for acidic NT soils. Three NT field sites were identified that had below-optimal soil pH (<6.0) in the surface 15 cm. Various time treatments were established in 2000 or 2002, consisting of differing rates [as kg effective calcium carbonate (ECC) ha(-1)] of either limestone (commercially available) or pelletized limestone, plus an unlimed control. In the spring of 2005, soil samples were taken to a depth of 30 cm; the surface 15 cm was separated into 2.5-cm increments and the lower 15 cm was separated into 7.5-cm increments. Evidence of lime movement was limited to 7.5 cm or less at all three NT sites, as indicated by significant increases in pH compared with the control. Type of liming material or frequency of limestone application seemed to have no effect on any variables measured. Significant yield increases were not observed for crops as a result of limestone applications. Limestone recommendations for NT production systems need to be based on correcting pH in the surface 7.5 cm for production systems receiving 800 to 1000 nun of annual precipitation.