Soil pH and Crop Response to Lime Source and Tillage.

Pelletized lime is often marketed as a liming agent that can increase soil pH at application rates much lower than recommended aglime rates; but is often five times more expensive. A study was initiated in a notill field in 2009 to evaluate the effectiveness of pelletized lime to change soil pH compared to aglime (80-89 grade) in notill and chisel systems. The experimental design was a split-split plot with tillage as the main plot, lime source as the sub-plot and lime rate as the sub-sub-plot (0, 2.25, 5.61, and 11.23 Mg ha^-1) with four replications. Soil samples were collected from each plot at 0 to 5.1, 5.1 to 10.6, 10.6 to 15.2, 15.2 to 20.3, and 0 to 20.3 cm depths prior to lime application in the spring of 2009 and in spring 2012. The crop sequence was soybean-alfalfa-alfalfa-alfalfa. Soil pH prior to lime application was 5.7, 5.8, 6.2, and 6.3 at 0 to 5.1, 5.1 to 10.6, 10.6 to 15.2, and 15.2 to 20.3 cm depths. Three years after application, there was no significant difference in the increase in soil pH between lime sources regardless of the rate of lime applied. For chisel plow, there was no clear advantage to using pelletized lime instead of aglime with regard to increasing soil pH. The effectiveness of either lime source was related to the rate of lime applied. In no-till, there may be a slight advantage to using pelletized lime if a pH changed is desired through an 8 inch-depth, though individual depth increments did not show this advantage. If smaller pH changes are desired, then pelletized lime applied at a 2.25 to 5.61 Mg ha^-1 rate could be as effective as aglime at 11.23 Mg ha^-1. Aglime is a more cost effective lime source, regardless of tillage system.