Tillage and Fertilizer Management Effects on Soybean Growth and Yield on Three Mississippi Soils

Abstract

Soybeans [ Glycine max (L.) Merr.] have not responded favorably to no‐till culture on some Mississippi soils. Positional unavailability of surface‐applied fertilizers may be one reason for the poor response. A 2 X 2 X 3 factorial field experiment with five replications in a randomized complete block split‐split plot design was used to measure effects of tillage (conventional vs. no‐tillage), P and K placement (broadcast vs. injected), and P and K rates (0 and 0, 13 and 37, 40 and 112 lb/acre P and K, respectively) on soybean growth and yield from 1983 to 1985 on three soils. The soils were Okolona silty clay (fine, mont‐morillonitic, thermic Typic Chromudert) at Brooksville, Memphis silt loam (fine‐silty, siliceous, thermic Typic Hapludalf) at Raymond, and Prentiss very fine sandy loam (coarse‐loamy, siliceous, thermic Glossic Fragiudult) at Newton. All soils were initially low in P and K. Seed yields in general were lowest at Brooksville, and ranged from 16.4 to 22.4 bu/acre with a 3‐yr average of 19.4 bu/acre. Yields were much better at the two other sites, except Raymond in 1983 when seed yield averaged 16.9 bu/acre. The Raymond site had the best overall average yield of 29.2 bu/acre, while the 2‐yr average at Newton was 28.2 bu/acre. No‐tillage reduced growth and yields on the Okolona and Memphis soils. On the Prentiss soil, only growth was reduced by no‐tillage. Under no‐till conditions,injection of P and K produced greater yields than broadcast on the Okolona and Memphis soils but not on the Prentiss soil. There was little response to rate of P and K rates on either soil. The low yields on Okolona silty clay appeared to be related to variables not considered in this study.