The Effects of Tillage and Legume N on No-Till Cotton Stands and Soil Organisms

D.H. Rickerl, W.B. Gordon, and J.T. Touchton


 
ABSTRACT

Field studies were conducted at two locations in Alabama during 1985 to identify cultural practices that would improve cotton stands when planted no-till into winter legumes. The soils were a Decatur silt loam (DSL) and Norfolk sandy loam (NSL). Treatment variables at cotton planting included tillage, starter fertilizers, N source and fungicide split plots within winter annual legume and fallow soil whole plots. Soil samples were collected for population studies of Collembola species (Proisotoma and Onychiurus) and their interaction with cotton disease fungi (Rhizoctonia solani). Disease infestation in the DSL was 10% higher in legume than fallow soils and 18% higher in legume than fallow soils at the NSL site. Collembola, which feed on Rhizoctonia solani, were more populous in legume soils, but insufficient at both locations to expect disease control. Cotton seedling survival was consistently greater in fallow than legume soils. In the NSL cotton, populations without in-furrow fungicides were 70% less with legume soils and 21% less with fallow soils than populations with Terraclor in-furrow. In the DSL, populations were 64 and 7% less without than with fungicide in legume and fallow soils, respectively. Tillage and/or bedding improved stands in legume areas in both soil types. Nitrogen source did not affect cotton stands in the DSL, however, in the NSL, urea with DCD and calcium nitrate treatments resulted in stand reductions in legume mulches. Yields in DSL were consistently high (2300 kg/ha). At the Norfolk site, tillage and starter fertilizer brought cotton yields in legume plots up to those in no-till fallow plots.



Reprinted from 1986 Proceedings: Beltwide Cotton Production Research Conferences pp. 455 - 456
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998