Relationships of Soil Properties and Rainfall to Effects of Subsoiling on Tobacco Yield
1987
Vepraskas, M. J. | Miner, G. S. | Peedin, G. F.
The effect of subsoiling on tobacco (Nicotiana tabacum L.) yield is variable across soils, and the reasons for this are not completely understood. As a result, it is difficult to identify soils where subsoiling will increase yields. This study evaluated relationships among relative yield increases due to subsoiling (RYI's), soil properties, and rainfall. Single-season tillage experiments were conducted at 32 locations from 1981 through 1984. Soils were Paleudults and Hapludults. Tobacco yields were measured for subsoiled and nonsubsoiled (moldboard plow/disk) tillage treatments at all sites. Rainfall was measured daily. Soil properties evaluated included bulk density, cone index, texture, water retention, exchangeable cations, pH, and base saturation. Relative yield increases due to subsoiling ranged from −9.0 to 31.8% across locations. Twelve sites had yields significantly (0.05 level) increased by subsoiling. Stepwise regression analysis showed that selected weekly rainfalls and drought duration were major factors related to RYI variations, and with water retention of Ap and E-B horizons, they accounted for 60% of the variation in RYI across all sites. Relative yield increases were greatest during dry years on sandy soils with low water retention values. Sites where relatively large RYI's (> 13%) occurred were characterized as having both bulk densities ≥ 1.63 Mg m⁻³ in the lower Ap or E-B horizon and sand contents ≥ 73% in the Ap horizon.
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