BALANCE-SHEET OF NITROGEN, PHOSPHORUS AND POTASH IN SOIL AS INFLUENCED BY WHEAT (TRITICUM-AESTIVUM) - BASED CROP SEQUENCES

A field experiment was conducted during 1983-1985 to study the influence of 4 wheat (Triticum aestivum L. emend. Fiori & Paol.)-based crop sequences on the balance sheet of N, P and K in medium black-cotton soil. Total N in the soil after a 2-year experiment showed a deficit of 13 kg N/ha in 'CSH 5' sorghum [Sorghum bicolor (L.) Moench]-'WH 147' wheat sequence, whereas the N status improved in soil in the other crop sequences, particularly those including legumes. The highest average gain in soil N was 65.5 kg/ha in 'JS 72-44' soybean [Glycine max (L.) Merr.]-wheat sequence. The available P showed deficit in all the crop sequences and ranged from 91.2 to 97.3 kg P/ha. The available K was improved ranging between 26.9 and 140.2 kg/ha in sorghum-wheat sequence. Other crop sequences showed deficit of soil K. Of the 4 sequences, soybean-wheat sequence was the most remunerative sequence.