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Cotton Nitrogen Management in a High‐Residue Conservation System: Cover Crop Fertilization
Author(s) -
Reiter M. S.,
Reeves D. W.,
Burmester C. H.,
Torbert H. A.
Publication year - 2008
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2007.0313
Subject(s) - cover crop , agronomy , loam , lint , tillage , secale , crop residue , crop , conventional tillage , environmental science , biology , soil water , agriculture , ecology , soil science
Nitrogen is required for adequate residue production from cereal cover crops used in no‐till cotton ( Gossypium hirsutum L.) production, but residues can immobilize N needed by cotton. We conducted a 3‐yr field study on a Decatur silt loam (clayey, kaolinitic, thermic Rhodic Paleudult) in northern Alabama to test N fertilizer practices for cotton grown with a rye ( Secale cereale L.) cover crop and conservation tillage. Nitrogen rates applied to the rye cover crop were 0, 34, and 67 kg N ha −1 and cotton N rates were 0, 45, 90, and 135 kg N ha −1 Additionally, 15 N microplots were established in cover crop N treatments of 34 kg N ha −1 and in cotton treatments of 90 kg N ha −1 Data collected included cover crop aerial biomass, cover crop C/N ratios, cotton leaf N at first flower, lint yield, lint quality, and 15 N in plant and soil samples. Cotton grown in unfertilized rye treatments needed 57 to 60% (38–40 kg N ha −1 ) more N to maximize yields above median conventional tillage N recommendations (67 kg N ha −1 ). Cover crop N rates of 67 kg N ha −1 maximized cover crop biomass production for soil protection and soil organic matter aggradation. If the cover crop was fertilized, minimum cotton N applications of 70 and 76 kg N ha −1 were needed for economic optimum and maximum lint yield, respectively. We speculate that cotton N rates may be decreased in the future as new N and C pool equilibria are reached.