Nitrogen supplied to corn by legumes in a Central Amazon Oxisol
1991
Smyth, T.J. (North Carolina State University, North Carolina (USA). Department of Soil Science) | Cravo, M.S. | Melgar, R.J.
Two field studies with legume crop residues were conducted during three consecutive years in a Central Amazon Oxisol to determine their fertilizer-N substitution value and the influence of legume residue management on succeeding corn crops. Incorporated legume residues from two legume cover crops, mucuna and indigofera and from cowpea were compared each year with five different urea-N rates with regard to their effect on yield and N accumulation by a succeeding corn crop. Also legume residue management treatments, evaluated only with mucuna were (1) incorporation; or (2) mulch of aboveground biomass produced in situ; (3) removal of aboveground biomass; and (4) incorporation of imported aboveground biomass to a bare plot. Mean fertilizer-N substitution value, during three consecutive years, was 74 kg/ha for mucuna and 26kg/ha for indigofera and cowpea. Corn yields with incorporation of aboveground mucuna biomass exceeded the yields of the mulch treatment in only one of the three years.
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