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United States Department of Agriculture

Agricultural Research Service

Title: In Situ N Mineralization and N Availability in a No-Till Cotton-Cover Crop System.

Author
item Schomberg, Harry

Submitted to: World Congress of Soil Science
Publication Type: Proceedings
Publication Acceptance Date: December 15, 1997
Publication Date: N/A

Interpretive Summary: Cotton production in the southeastern U.S. has increased due to the boll weevil eradication program. Conservation tillage and cover crops can reduce soil erosion which has been a problem in conventional tillage cotton in the southern Piedmont. Nitrogen availability to cotton was compared between a cotton-crimson clover and a cotton-rye conservation tillage cropping system. More N was available to cotton following crimson clover than rye even though the cotton following rye received 30 kg N more fertilizer than cotton following clover. N mineralization rates were faster in the clover system which provided more N earlier in the season than in the rye system. A significant movement of N through the 10 cm soil columns used in the study was noted but the depth of movement was not below the rooting depth of cotton. N managment for the two systems should be different with more N appied to cotton following rye and possibly as spilt applications.

Technical Abstract: Cotton production in the southeastern U.S. has increased due to the boll weevil eradication program. Conservation tillage and cover crops can reduce soil erosion which has been a problem in conventional tillage cotton in the southern Piedmont. Nitrogen availability is affected by cover crops and conservation tillage due to changes in water and temperature availability but the rate of N mineralization is unknown. Net N mineralization was greater in a cotton-crimson clover no-till system than in a cotton-rye no-till system (0.54 kg/ha/day vs 0.33 kg/ha/day). Rates varied between measurement periods due to temperature and water availability. Significant quantities of N moved through the 10 cm soil columns but most of this N would be taken up by the cotton. Differences in N mineralization patterns between the rye and clover systems indicated more N may be needed to reach maximum production in the rye system but the timing of N application would be critical to avoid N loss later in the season. Adequate N availability was observed in the cotton-clover system which had a 30 kg N/ha N application.

Last Modified: 10/22/2014
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