To Lime or Not To Lime

Nearly 20% of the samples received every year by the Soil Testing and Research Lab get a lime recommendation. Of all the crops we grow, soybean is probably the crop most affected by low soil pH as the activity of the nitrogen fixing bacteria slows down considerably and with it, the ability to form sufficient nodules to produce good yields.



The graphs show the cumulative yield response of soybean to Ag and pelletized lime. The objectives of this test were 1) to assess the yield response of soybean growing in soil with pH around 5.0, and 2) to compare the relative performance of Ag lime and pelletized lime.


Ag lime was applied at incremental rates equivalent to 700 lb/acre, while pelletized lime was applied at incremental rates equivalent to 500 lb/acre. Current lime recommendation for soybean in a silt loam is between 4,000 and 5,000 lb/acre Ag lime. At that application rate, a cumulative yield increase of more than 20 bu/acre was obtained. Pelletized lime at 500 lb/acre resulted in basically no yield gain after 2 years.


A significant yield increase was observed when pelletized lime was used, but at rates significantly higher than the 300 lb/acre commonly recommended by some fertilizer dealers. Results from this study clearly indicate that the best option to correct soil acidity is to use Ag lime.


A minimum of 1000 lb pelletized lime per acre were needed to obtain a significant yield increase, but such increase was only half of the yield gain observed when the full rate of Ag lime was applied. Lime tends to work best when applied preplant, at least 30 days before planting, and if it is incorporated.


Provided by:
Leo Espinoza, Associate Professor & Extension Soil Scientist
University of Arkansas
Division of Agriculture
lespinoza@uaex.edu - (501) 671-2168