Soil Profile Modification and Cotton Production

R.B. Campbell, W.J. Busscher, O.W. Beale, and R.E. Sojka


 
ABSTRACT

Hardpan soils of the southeastern Coastal Plains were mixed to depths up to 0.61 m in an attempt to alleviate strength problems associated with a subsurface pan. It was hypothesized-that mixing the dense, coarse-textured E Horizon with the less dense A(p) and the relatively clayey B horizon would increase the water-holding capacity of the E and decrease its strength. Mixed soil did have a higher amount of water held than the unmixed E, increasing it from 5 to 7% at -200 kPa matric potential. This would reduce its strength by approximately 0.1 mPa allowing easier root penetration whether the increased water is available for uptake or not. Although seed cotton in the deeply-mixed treatments outyielded the moldboard-plowed treatments by 233 kg/ha in one year, they were outyielded by 132 kg/ha in another year. The decrease in strength and the increases of retention as a result of the mixing were small and infiltration was unchanged. Furthermore, mixing of field samples was less homogenous than lab samples. It is doubtful that the level of improvement of cotton would warrant the effort involved in the mixing operation.

Treatments at two sites were split into fertility subplots. The only significant fertility difference was between rates of N sidedressed when plants were about 0.40 m tall. The 20 kg/ha rate outyielded the 67 kg/ha rate by up to 300 kg/ha presumably because the higher rate encouraged vegetative growth and retarded boll formation which in turn limited lint and seed production. Interactions between tillage or mixing and fertility were non-significant. Plants grew better in the deeper disturbed soils in dryer years. Other crops ma respond more favorable to the mixing.



Reprinted from 1988 Proceedings: Beltwide Cotton Production Research Conferences pp. 505 - 509
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998