1 Central Potato Research Station, Jalandhar - 144 003 (Punjab).
2 Central Potato Research Institute, Shimla - 171 001 (H.P.).
* Publicatlon No. 1436. CPRI, Shimla
A long term experiment was conducted from 1992 to 1996 on the alluvial soil at the Central Potato Research Station, Jalandhar, Punjab. India to assess the value of integrated nutrient management (INM) partly through fertilizers and partially through crop residues. The crop residues of preceding crop (produced - in-situ) were applied to the proceeding crop grown in succession in potato-sunflower-rice (P-S-R) and potato-sunflower-maize (P-S-M) systems of 300% cropping intensity. This approach enabled the addition of crop residues to the tune of 12 t/ha providing on an average, 160, 25 and 260 kg of N, P and K. respectively.
Potato was the most sensitive crop to PK stress followed by maize and sunflower or rice. The PK fertilisation to two crops (potato and cereal in the system) could sustain the crop yields while the PK fertilization to one crop (potato only in the system) could hardly sustain the yields. On the other hand, the integrated nutrient approach comprising crop residue management not only sustained the crop yields but also showed an improvement in crop productivity especially in potato with time. The effects of crop residues management on crop yields were more pronounced on sunflower and maize than potato and rice.
Mter four years, the integrated approach improved the organic carbon status of the soil by 27% and countered the acidification effect of fertilizer use. It also led to maintenance of fertility status of the soil (N,P,K,Fe and Zn) at a level higher than the fertilizers alone. The P-S-M system maintained higher availability of N, K and Zn but the P-S-R system maintained higher availability of P and Fe in the soil. The P-S-R system removed 935 kg NPK/ha/year as against 794 Kg/ha/year by the P-S-M system. The integrated approach maintained highest positive nitrogen balance and helped in narrowing down the negative balance of P, K, Fe and Zn in the soil. The economics was also in favour of the INM approach.
