EFFECT OF SUNN-HEMP AND PEANUT INCORPORATED AS GREEN MANURES ON GROWTH AND NITROGEN UPTAKE OF THE SUCCEEDING WHEAT

Effect of summer legumes incorporated is given manures, sunn hemp (cv. Kobutoriso) and peanut (cv. Chiba-handachi), was examined for nitroge n contribution to the succeeding wheat (cv. Norin 61). The dry weight of sunn hemp, of which the stem occupies the largest proportion, was h igher than that of peanut at time of incorporation. Total nitrogen con tent was higher in peanut compared with sunn hemp. The amount of nitro gen fixed by each legume was estimated by the 'difference method' with non-nodulating peanut (cv. Tarapoto) as a reference crop. In peanut, 18 g N per m2 was calculated as the amount of nitrogen fixed at the la te maturity stage. The percentage of nitrogen fixed to the total nitro gen was 60-70% in both legumes. On the yield and nitrogen uptake of th e succeeding wheat, the peanut plot was superior to the sunn hemp plot . The percentage contribution of nitrogen accumulated by each legume t o total nitrogen of the succeeding wheat was 11.2% on the peanut plot and 9.4% on the sunn hemp plot. In peanut, the C-N ratio was approxima tely 20 at time of incorporation. In sunn hemp, it was 40, and the dec omposition rate was found to be slower than that of peanut by a modifi ed method using glass fiber filter papers. The results indicated that peanut crop contributed more nitrogen to the succeeding wheat compared with sunn hemp.