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Title: CONSERVATION TILLAGE IN IRRIGATED COASTAL PLAIN DOUBLE-CROP ROTATIONS.

Author
item Dowler, Clyde
item HOOK, J - UNIVERSITY OF GEORGIA
item BAKER, S - UNIVERSITY OF GEORGIA
item GASCHO, G - UNIVERSITY OF GEORGIA
item Johnson, Alva

Submitted to: Southern Conservation Tillage for Sustainable Agriculture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/30/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Various levels of conservation tillage (leaving some portion of the previous plant residue on the soil surface) are being studied and utilized for producing crops in the southeastern United States. Soil moisture is a critical factor in the sandy coastal plain soils. Supplemental irrigation is often needed to maintain consistent productivity. Research was extremely limited on studying the effects of various conservation tillage practices on crops grown under irrigation. We evaluated double cropping sequences of a small grain grown for grain and a row crop of cotton, peanut, or soybean following small grain. Irrigation application technology was utilized as much as possible. Adequate soil moisture and establishing a good crop stand are keys to good productivity. In our studies, a good crop stand was generally obtained, because good soil moisture could be maintained by irrigation. All crops yielded more in moldboard plow tillage and least in no-till tillage. In many cases, yield of cotton, soybean, or peanut under strip tillage approached that of moldboard plow tillage. Growing cotton, peanut, or soybean for 11 years of strip tillage did not result in long-term yield reduction or pest management problems. Pest management was determined by scouting, which proved effective in all rotations. Weeds, insects, and diseases were no worse in conservation tillage than in moldboard plow tillage. This was the result of continual scouting. Under irrigation, long-term conservation tillage appears feasible.

Technical Abstract: We conducted three rotation-tillage experiments involving small grain double-cropped with cotton, soybean, or peanut under irrigation. The soils were Tifton or Pelham loamy sand. The experiments utilized irrigation application technology and integrated pest management practices. Our objective was to compare strip-till, no-till, ridge plant or subsoil without seedbed preparation to moldboard tillage and to study the effects of these tillage practices on crop production. Each experiment was initiated by moldboard tillage and seeding small grain. The various tillages were established after harvesting the first small grain crop. In subsequent years, the small grain crop was seeded into the preceding crop residue. One experiment was maintained for 11 years with strip tillage for the summer row crop. The other experiments were conducted for 4 or 5 years and compared strip tillage, no-till, ridge plant, and subsoil without seedbed preparation to moldboard tillage. The initial moldboard tillage always resulted in the highest small grain yield. In general, cotton, peanut, and soybean yield did not differ significantly between strip tillage and moldboard tillage. No-till tillage generally resulted in lower yields. No insecticides were applied on any crop after 1991. No unusual disease problems occurred during the duration of the experiments, although Cylindrocladium blackrot (CBR) developed on peanuts in 1996 and 1997. Weed management relied heavily on post-emergence herbicide treatments. Yellow nutsedge was a greater problem in moldboard tillage than in any conservation tillage. Significant shifts in weed populations did not occur. Cropping sequences affected distribution of pH, calcium, and magnesium in the soil profile.