Fertility Status of Soil and Nutrients Content of Spring Groundnut (Arachis hypogaea L.) as Influenced by Gypsum, Nitrogen and Phosphorus Application

The field investigation was carried out for two years at the Students’ Research Farm, Department of Agronomy, Punjab Agricultural University, Ludhiana during spring season of 2018 and 2019. The experiment was laid out in a split plot design with four levels of gypsum (0, 125, 175 and 225 kg ha-1) in combination with two gypsum application stages (full at sowing and 50 % at sowing + 50 % at flower initiation stage) in the main plot and three levels of nitrogen and phosphorus (15 kg N ha-1 + 20 kg P2O5 ha-1, 25 kg N ha-1 + 30 kg P2O5 ha-1 and 35 kg N ha-1 + 40 kg P2O5 ha-1) in the sub-plot. Application of 225 kg ha-1 gypsum resulted in maximum kernel N, P, K and S concentration and haulm P and S concentration, which was statistically at par with 175 kg ha-1 and 125 kg ha-1 gypsum, while significantly higher than control. Split application of gypsum recorded non-significant results on concentration of N, P, K, Ca and S in haulm and kernel during both the year. The concentration of N, P, K, Ca and S in haulm and kernel was maximum with application of 35 kg N ha-1 + 40 kg P2O5 ha-1, except for K and Ca in kernel which was significantly higher than lower dose. Soil characteristics such as pH, EC and organic carbon analysed after the harvest of crop were non-significantly affected by the application of different gypsum levels, stage of gypsum application and different levels of nitrogen and phosphorus during both the years. Available phosphorus in soil was highest with 225 kg ha-1 gypsum which was at par with 175 and 125 kg ha-1 gypsum, while significantly higher over control. Available calcium and sulphur of soil were maximum with 225 kg ha-1 gypsum, which was at par with 175 kg ha-1 gypsum while significantly higher than lower levels. Available nitrogen, phosphorus, potassium, calcium and sulphur in soil were non-significantly affected by different gypsum application stages. Available nitrogen and phosphorus in soil was highest with 35 kg N ha-1 + 40 kg P2O5 ha-1 and significantly higher over other levels of nitrogen and phosphorus. Available calcium and sulphur in soil were non-significantly affected by different nitrogen and phosphorus levels during both the years. The application of 225 kg ha-1 gypsum, gypsum applied in two splits and application of 25 kg N ha-1 + 30 kg P2O5 ha-1 resulted maximum pod yield of spring groundnut.