SOIL COMPACTION AND TILLAGE EFFECTS ON DRY BEAN YIELDS

Excessive soil compaction causes yield losses in dry beans (Phaseolus vulgaris L.) when field operations are conducted on wet soils in the spring. Few studies have investigated the alleviation of compacted soil during planting. The treatments used were: compaction with no planting time ripping (C-NPTR); compaction with planting time ripping (C-PTR); no compaction, no planting time ripping (NC-NPTR); and no compaction with planting time ripping (NC-PTR). Planting time ripping (PTR) consisted of chisels set 6 in. to the side and 8 in. below the soil surface. Compaction reduced dry bean yields 26% during the 3-yr. When PTR was used on compacted plots, only 78% of the yield loss from compaction was restored. Noncompacted and ripped treatments had the highest total plant biomass after a hailstorm in 1988. These same treatments had the highest incidence of white mold [Sclerotinia sclerotiorum (Lib.) deBary] in 1989. Compacted soils, caused by early spring field operations, reduced dry beam yields. When this occurs, PTR on compated areas will improve yields.