ISSN:
1573-5036
Keywords:
neem
;
N fertilizer
;
nitrate
;
Oryza sativa L.
;
Vigna unguiculata (L.) Walp.
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Cowpea, Vigna unguiculata (L.) Walp., is well adapted to acid upland soil and can be grown for seed, green manure, and fodder production. A 2-yr field experiment was conducted on an Aeric Tropaqualf in the Philippines to determine the effect of cowpea management practice on the response of a subsequent upland rice crop to applied urea. Cowpea was grown to flowering and incorporated as a green manure or grown to maturity with either grain and pods removed or all aboveground vegetation removed before sowing rice. Cowpea green manure accumulated on average 68 kg N ha−1, and aboveground residue after harvest of dry pods contained on average 46 kg N ha−1. Compared with a pre-rice fallow, cowpea green manure and residue increased grain yield of upland rice by 0.7 Mg ha−1 when no urea was applied to rice. Green manure and residue substituted for 66 and 70 kg urea-N ha−1 on upland rice, respectively. In the absence of urea, green manure and residue increased total aboveground N in mature rice by 12 and 14 kg N ha−1, respectively. These increases corresponded to plant recoveries of 13% for applied green manure N and 24% for applied residue N. At 15 d after sowing rice (DAS), 33% of the added green manure N and 16% of the added residue N was recovered as soil (nitrate + ammonium)-N. At 30 DAS, the corresponding recoveries were 20 and 37% for green manure N and residue N, respectively. Cowpea cropping with removal of all aboveground cowpea vegetation slightly increased (p〈0.05) soil (nitrate + ammonium)-N at 15 DAS as compared with the pre-rice fallow, but it did not increase rice yield. Cowpea residue remaining after harvest of dry pods can be an effective N source for a subsequent upland rice crop.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00010174
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