Impact of Potassium Fertilization and Foliar Sprays on Uptake, Soil Properties, and Potassium Fractions in Cluster Bean (Cyamopsis tetragonoloba L.)

A field experiment was conducted during kharif 2021 at Chaudhary Charan Singh, Haryana Agricultural University (CCS HAU), Regional Research Station, Bawal on loamy sand soil to assess the impact of potassium fertilization and foliar sprays on uptake, soil properties, and potassium fractions in cluster Bean. Results indicated that in seeds, treatment T9 resulted in nitrogen (N) content of 3.82%, phosphorus (P) at 0.47% and potassium (K) at 0.96%, with corresponding uptakes of 66.59 kg N ha⁻¹, 8.41 kg P ha⁻¹ and 17.36 kg K ha⁻¹. In stover, the N content was 1.27%, P at 0.29% and K at 1.45%, with uptakes of 58.17 kg N ha⁻¹, 13.28 kg P ha⁻¹ and 66.41 kg K ha⁻¹. These values were significantly higher compared to the control treatment. This suggests that integrating soil potassium fertilization with foliar nutrient applications can enhance nutrient content and uptake in cluster bean cultivation. The treatment involving 30 kg K₂O ha⁻¹ with foliar sprays of 2% urea and 2% multiplex nutrient at pre-flowering and pod formation stages (T9) resulted in the highest availability of nitrogen (146.70 kg ha⁻¹), phosphorus (15.90 kg ha⁻¹), potassium (188.70 kg ha⁻¹), and sulfur (12.90 ppm) in the soil after post-harvest of the crop. Conversely, the availability of calcium and magnesium decreased with increasing potassium levels. Significantly highest available K, water soluble K, exchangeable K, non-exchangeable K and total K (188.70, kg ha-1, 10.45 ppm, 83.90 ppm. 371.46 ppm and 1.34 %), respectively were recorded in treatment T9 (30 kg K2O ha-1 + 2% urea spray+ 2% multiplex nutrient spray). This study suggested that the application of 30 kg