Tillage effects on biomass production and moisture utilization by soybeans glycine max on coastal plain soils
Kamprath, E.J.; Cassel, D.K.; Gross, H.D.; Dibb, D.W.
Agronomy Journal 71(6): 1001-1005
ISSN/ISBN: 0002-1962 Accession: 006806965
Many coarse-textured surface soils in the southeastern Coastal Plain [USA] are prone to develop tillage pans which restrict root proliferation and moisture utilization in subsoils. The effect of tillage treatments on soybean [G. max (L.) Merr.] growth and soil moisture utilization was investigated on Norfolk sand loam (Typic Paleudult) and Wagram loamy sand (Arenic Paleudult) soils. The 3 tillage treatments used were: conventional moldboard plowing and disking only before planting; or plowing and disking, followed by either chisel-plowing; or subsoiling with bedding before planting. Measurements were made of top and root dry weight, leaf area, grain yield, soil water content and soil moisture tension. Breaking the tillage pan by chisel-plowing or subsoiling increased top growth and leaf area of soybeans at full bloom. The percentage of roots below 30 cm was increased by subsoiling and chisel-plowing when rainfall was below normal during the growth period. A higher proportion of roots was in the top 10 cm of soil with conventional tillage than with chisel-plowing or subsoiling. Chisel-plowing and subsoiling increased the amount of soil moisture utilized below a depth of 30 cm. Grain yields were increased by chisel-plowing or subsoiling in those years when rainfall was below normal during late-flowering and the beginning of pod development. Subsoiling or chisel-plowing of soils with compacted pans will increase soybean yields during years in which below-average precipitation occurs during late-flowering and the beginning of pod set. Yields increased are attributed to increased root proliferation below the pan and greater utilization of subsoil moisture.