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Title: FALL DEEP TILLAGE OF SHARKEY CLAY: EFFECT ON SOYBEAN YIELD AND NET RETURN

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

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/1999
Publication Date: 1/1/2001
Citation: WESLEY, R.A., SMITH, L.A., SPURLOCK, S.R. FALL DEEP TILLAGE OF SHARKEY CLAY: EFFECT ON SOYBEAN YIELD AND NET RETURN. AGRONOMY JOURNAL. 93(1):170-178

Interpretive Summary: On the clay soils of the midsouthern USA, Maturity Group V and VI soybean are normally planted in a conventional (disked) production system in May and June. Soybean grown in this system are often subjected to drought stress that reduce yield. During the 1970-1991 period, soybean yields from this system of production averaged 1500 kg/ha and were marginally profitable. In recent years, Maturity Group IV soybean have been planted in an early soybean production system in April to avoid drought stress and to improve yield. The objective of this research was to determine the effect of fall-applied deep tillage on yield and net return from nonirrigated, Maturity Group IV soybean grown on Sharkey clay. Over the 5-yr study, yield from soybean grown in a production system with fall deep tillage annually averaged 364 kg/ha (20%) greater than the average yield from a production system with fall conventional (disked) tillage (1865 kg/ha), whereas yield from a production system with fall deep tillage applied once every 5-yr averaged 155 kg/ha (8%) greater. Net returns from the conventional production system averaged $166/ha and was the lowest, whereas net returns from production systems with fall deep tillage annually or once every 5-yr ranged from $204 to $238/ha, or from 23 to 43% greater. Fall deep tillage applied annually on Sharkey clay significantly increased yields and net returns above that produced from fall conventional (disked) tillage.

Technical Abstract: A 5-yr study was conducted on a nonirrigated Sharkey clay (very- fine, montmorillonitic, non-acid, thermic, Vertic Haplaquept) to determine the effect of fall-applied deep tillage on yields and net returns from Maturity Group IV soybean planted in April in an early soybean production system. The treatments included fall deep tillage applied 1) annually, 2) once every 5 yr, 3) with a Paratill plow annually, and 4) a conventionally-tilled treatment that was disked annually. Yields from soybean grown in production systems with fall deep tillage applied annually, once every 5 yr, and with a Paratill plow annually averaged 364 (20%), 155 (8%), and 183 kg/ha (10%) greater, respectively than the average yield from the conventional (disked) production system (1865 kg/ha). Net returns from the conventional system averaged lowest ($166/ha), whereas net returns from production systems with fall deep tillage annually, once every 5 yr, and with a Paratill plow annually averaged $72 (43%), $52 (31%), and $38/ha (23%) greater, respectively than net returns from the conventional production system. Fall deep tillage applied annually significantly increased yield and net returns from Maturity Group IV soybean grown in an early soybean production system on nonirrigated Sharkey clay.