Long-term effect of inorganic fertilizers and amendments on productivity and root dynamics under maize-wheat intensive cropping in an acid Alfisol

Abstract

Study on the soil nutrient status and crop productivity under continuous use of inorganic fertilizers and amendments in an acid Alfisol after 36 years (1972-73 to 2008-09) was carried out at Palampur, HP. Results showed that application of Recommended Dose of Fertilizer (120:60:40 kg/ha to maize and 120:60:30 kg/ha to wheat) with 10 t farmyard manure/ha applied once a year for 36 years resulted in 786 and 515 per cent increase in maize and wheat yields, respectively over control. Soil acidity rose from 5.8 to 4.58 with the application of fertilizers over 36 years. Conjoint use of FYM with 100 per cent NPK substantially improved the Organic Carbon status by 4.95 g/kg as well as available P, K and S by 154.1, 14.5 and 12.5 kg/ha, respectively in soil over its initial values, thereby indicating significant contribution towards sustaining the soil health. On the other hand, there was a drastic decline in the available N status of soil in all the treatments as compared to the initial value. The various root parameters viz., root mass density (4.08 kg m-3), root volume density (10.84 m3 m-3x10-3), root length density (2.60 m m-3 x 10-4), root surface area (204.12 m2 x 10-4) and root cation exchange capacity (8.37 c mol (p+) kg-1) were found to be highest in the plots with the application of 100% NPK + FYM. Thus, balanced use of fertilizers continuously either alone or in combination with amendments is necessary for sustaining soil fertility and productivity of crops.