Nitrogen Management in Sorghum/Pigeonpea Intercrop uri icon


  • Conriderable gaps remain in our undmtanding of the extent to which nitrogenIN) fertilizer application in cereal/legume intercropping sytems could be synergisticin term of maximizing biological nitrogm fixation (BNF) by the le.gurne, and optimizing grain yield of the cereal component. There is a highpotential to inneuse the grain yield of ~orghuma nd enhance BNF by pigeonpeathrough intercropping, without greatly innearing the use of fertilizer N. Thisreview suggesrs thut: ( I ) Medium-durotion pigeonpea can reduce t k Kr; ferrtlizationneeds of sorghum bv 50% in a sorghum/pigeonpea intercrop. (2) Split-&&? of modest N rates is a sound strategy to increme X-use efficienq, and toenhance BNF by pigeonpea in the semi-arid tropics. This is because of thek t yr a i t~ha t a no cwr at the owet ofthe rainy season, leading to a substantbldownward water Pou, coupled with the innensed chance of water deficitsduring the growing searon. (3) In areas where soil mineral ?\: is relaricely highso as to suppress BNF by legumes, interrropping cereals with legumes is rtital toreduce the inhibitoh. effects of soil Tu' on BNF. This is supported by theexperimental evidence that starter doses of 20-25 kg N ha.' suppressed BNFby sole-cropped, but nor ~nterc~oppepdi geonpea. (4) lnternopped legumesremoved less N from the soil than their respectitle sole crops, suggesting thepotential of reducing N mrning from rhr soil through interflopping. (5) Formore efficient use of X b> interflopping sperm, companion naps that exhibitdifferent root system architecture are vi:al to prevent competition for uutrrand N by roots

publication date

  • 1997