Crop Response to Deep Tillage with Lime and Fertilizer1, 2

Investigations over a 5-year period on deep plowing, subsoiling, and deep incorporation of lime and fertilizer were conducted on Almena silt loam (strongly acid and tight subsoil). Subsoil treatments included tillage only, tillage with liming, and tillage with liming and fertilizing. The plow-layer of all subsoiled plots was limed to pH 6.5 and fertilized uniformly. Plots not subsoiled received varying amounts of fertilizer, equal in several cases to the total applied to both the plow-layer and subsoil of the subsoiled plots. Deeper root penetration of alfalfa was promoted by subsoil liming and fertilizing, but not by subsoiling alone. Subsoil liming and fertilizing helped materially in establishing alfalfa during a dry year. Second-year and especially third- and fourth-year hay yields appeared to be increased (up to one-half ton per acre in dry years) by subsoil liming and fertilizing, but were not increased by subsoil treatment where the fertilizer was omitted. The potassium content of the alfalfa from subsoil fertilized plots was as much as 1% higher during dry years. Corn and oats did not appear to respond to these subsoil treatments even in the dry years, and when they followed the alfalfa-brome grown with subsoil treatments. In the case of deep plowing with liming and fertilizing, first-year alfalfa-brome gave a consistent but small response to this deep treatment; however, second-year hay yields were increased appreciably when plowing was to a 12-inch depth. Where the depth of plowing was 9 inches, the response was somewhat less, but still greater than where plowing, liming, and fertilizing was to a 6-inch depth only. In no year were the yields of corn and oats increased by deeper plowing, liming, and fertilizing, although increased vigor was noted in some years.