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Title: FALL DEEP TILLAGE OF TUNICA AND SHARKEY CLAY: RESIDUAL EFFECTS ON SOYBEAN YIELD AND NET RETURN.

Author
item Wesley, Richard
item Smith, Lowrey
item SPURLOCK, STAN - MISSISSIPPI STATE

Submitted to: Mississippi Agricultural and Forestry Experiment Station Technical Bulletin
Publication Type: Experiment Station
Publication Acceptance Date: 4/30/2001
Publication Date: 4/1/2001
Citation: WESLEY, R.A., SMITH, L.A., SPURLOCK, S.R. FALL DEEP TILLAGE OF TUNICA AND SHARKEY CLAY: RESIDUAL EFFECTS ON SOYBEAN YIELD AND NET RETURN.. MISSISSIPPI AGRICULTURAL AND FORESTRY EXPERIMENT STATION TECHNICAL BULLETIN. Tech Bulletin #1102, pp. 12.

Interpretive Summary: On clayey soils in the midsouthern USA, Maturity Group V and VI soybean are normally planted in May and June in a conventional (disked) production system, and are often subjected to drought stress that reduce yield. In recent years, Maturity Group IV soybean have been planted in April in an early soybean production system to avoid drought stress and to improve yield. The objectives of this research were to determine 1) the residual effect of fall-applied deep tillage on yield and net return from soybean grown on Tunica and Sharkey clays, and 2) the frequency of deep tillage necessary to maximize and sustain higher yields and net returns. Over the 5-yr studies, yield from soybean grown on Tunica clay with deep tillage annually averaged 1016 kg/ha (42%) greater than the conventional production system (2436 kg/ha), whereas production systems with deep tillage once every 2 yr, or once every 3 yr, averaged 823 kg/ha (34%) greater. On Sharkey clay, production systems with deep tillage annually averaged 364 kg/ha (20%) greater than the conventional system (1865 kg/ha), whereas yield from deep tillage once every 5 yr averaged 155 kg/ha (8%) greater. On Tunica clay, net returns from the conventional system averaged $220/ha, whereas returns from production systems with deep tillage annually, once every 2 yr, or once every 3 yr, averaged from $396-436/ha, or from 80-98% greater than from the conventional system. On Sharkey clay, net returns from the conventional system averaged $166/ha, whereas returns from production systems with deep tillage annually, or once every 5 yr, averaged from $204-238/ha, or from 23-43% greater. Fall deep tillage should be applied at least once every 3 years on Tunica clay, and annually on Sharkey clay to maximize and sustain higher yields and net returns.

Technical Abstract: Nonirrigated studies were conducted on a Tunica clay (clayey over loamy, montmorrilonitic, non-acid, thermic, Vertic Haplaquept) and a Shareky clay (very-fine, montmorillonitic, non-acid, thermic, Vertic Haplaquept) to determine the effect of fall-applied deep tillage on yield and net returns from Maturity Group IV soybean grown in an early soybean production system. .Treatments included fall deep tillage applied 1) annually, 2) once every 2 yr, 3) once every 3 yr, 4) once every 4 yr, 5) once every 5 yr, 6) with a Paratill plow annually, and 7) a conventional treatment that was disked annually. On Tunica clay, yields from production systems with deep tillage annually, once every 2 yr, once every 3 yr, and with a Paratill plow annually, respectively averaged 1016 (42%), 826 (34%), 819 (34%) , and 808 kg/ha (33%) greater than the average yield from the conventional system (2436 kg/ha). On Sharkey clay, yields from production systems with deep tillage annually, once every 5 yr, and with a Paratill plow annually, respectively averaged 364 (20%), 155 (8%), and 183 kg/ha (10%) greater than the average yield from the conventional system (1865 kg/ha). On Tunica clay, net returns from the conventional system averaged $220/ha, whereas net returns from systems with deep annually, once every 2 yr, or once every 3 yr, averaged from $396-436/ha, or from 80-98% greater than returns from the conventional system. On Sharkey clay, net returns from the conventional system averaged $166/ha, whereas net returns from systems with deep tillage annually, once every 5 yr, and with a Paratill plow annually, averaged from $204-238/ha, or from 23-43% greater. Fall deep tillage should be applied at least every 3 years on Tunica clay, and annually on Sharkey clay to maximize and sustain higher yields and net returns.