EFFECT OF PIGEONPEA (CAJANUS-CAJAN) PLUS SOYBEAN (GLYCINE-MAX) INTERCROPPING AND PHOSPHORUS FERTILIZATION ON NITROGEN REQUIREMENT OF WHEAT (TRITICUM-AESTIVUM)

An experiment was conducted during 1991-92 and 1992-93 to study the N requirement of 'HD 1553' wheat (Triticum aestivum L. emend. Fiori & Pa ol.) when grown after pigeonpea [Cujanus cajan (L.) Millsp.] + soybean [Glycine max (L.) Merr.] intercropping system at row arrangements of 1 : 1, 1 : 2 and 1 : 3 and phosphorus fertilization @ 0, 19 and 38 kg P/ha on deep Vel tisols at Bhopal. Yields of pigeonpea + soybean incre ased significantly at 1 : 3 row arrangement (33.6 %) compared with sol e pigeonpea at 90 cm. The N and F contents of grain and straw as well as their uptake. and status of available N and P in the soil were also significantly higher with this system. Wheat yield increased by 18% d ue to the residual effect of intercropping at 1 : 3 ratio compared wit h sole pigeonipea. and its N requirement decreased by 60 kg N/ha. Phos phorus Fertilization to intercropping system at 38 kg P/ha significant ly improved the grain (32%) and stalk yields of both pigeonpea and soy bean crops, and the uptake and availability of N and P in the soil. It had significant residual effect oil wheat, by giving 20.6% more yield than the control and reducing the N requirement by 30 kg N/ha besides improving the N and P status in the soil.