Simulating and predicting the effect of longterm application of fertilizers and amendments for maizewheat yield and soil fertility in an acid alfisol

Abstract

The present study was carried out on a pre-established long-term experiment with an ongoing maize-wheat cropping sequence since rabi, 1972-73 at the experimental farm of Department of Soil Science, CSKHPKV Palampur in order to simulate and predict the effect of long-term application of fertilizers and amendments for maize-wheat yield and soil fertility in an acid Alfisol. The study employed randomized block design with eleven treatments and three replications. The soil texture at the experimental site was silty loam and was classified as quotTypic Hapludalfquot subgroup based on taxonomic classification. The grain and stover/straw yield of maize and wheat during the 50th cropping cycle (kharif 2022 and rabi 2022-23) was recorded after their harvest. Grain and stover/straw samples of both the crops were also analyzed for nutrient concentration and nutrient uptake was subsequently determined. After the 50th wheat harvest, the surface (0-0.15 m) and subsurface (0.15-0.30 m) soil samples were collected and their physical, chemical and biological characteristics were determined. Principal Component Analysis (PCA) was employed to reduce soil attribute data to a minimum data set for computing Soil Quality Index (SQI). To determine the long-term trends in soil fertility, periodical per cent changes were calculated and analyzed. For simulating crop yields and soil organic carbon dynamics, the DSSAT model was calibrated and validated for different nutrient management practices. The results indicated that the long-term balanced application of nutrients enhanced nutrient uptake and crop productivity, which however decreased with imbalanced application of fertilizers. newlineThe application of optimal fertilizer doses (100% NPK) integrated with FYM or lime resulted in significantly higher maize and wheat productivity as well as nutrient uptake compared to other treatments. Balanced fertilization improved the physical, chemical and biological properties of soil contributing to a higher SQI. The SQI after 50 years of balanced fertilization (100% NPK + FYM) reached 1.00 and 0.99 at 0-0.15 m and 0.15-0.30 m soil depths, respectively, highlighting the positive impact on overall soil health. The periodical assessment of soil fertility demonstrated that combining FYM with optimal fertilizer application effectively supported long-term soil health. The DSSAT-CERES model accurately simulated the days to anthesis and physiological maturity for both maize and wheat. Additionally, the model demonstrated good to excellent performance in predicting grain and stover/straw yields, nitrogen content and total nitrogen uptake. When calibrated and validated for soil organic carbon, the model also showed a close match between observed and predicted values, thereby highlighting its potential as a powerful decision-support tool in optimizing nutrient management practices for sustainable agriculture. newline