Impact of potassium and zinc application on nutrient content and their uptake by green gram (Vigna radiata L.) and post-harvest soil fertility status under coarse textured soil of south-west Haryana

The studies were conducted during kharif 2018 at CCS HAU, RRS (Bawal) on green gram cultivar MH-421. The results indicated that the total nitrogen, phosphorous and potassium content and uptake in seed and straw were significantly influenced by different potassium and zinc levels. Both K20 and K30 treatments recorded significantly higher N (3.55 and 3.67%), P (0.48 and 0.50%) and K (1.14 and 1.16%) content and uptake of N (38.70 and 41.91 kg ha-1), P (5.23 and 5.71 kg ha-1) and K (12.43 and 13.25 kg ha-1) in seed as compared to control. Similar in case of straw, K20 and K30 treatments recorded significantly higher N (1.33 and 1.43%), P (0.22 and 0.24%) and K (1.40 and 1.47%) content and uptake of N (16.32 and 19.10 kg ha-1), P (2.70 and 3.21 kg ha-1) and K (17.17 and 19.69 kg ha-1) in straw over the control. The content of Zn, Mn and Cu were not significantly influenced by the application of potassium except Fe whereas the uptake of all the micronutrients under consideration was significantly increased with the potassium application. Results further revealed that different zinc treatments significantly influenced only Zn content in seed and straw while the uptake of both macro and micronutrients except phosphorus in both seed and straw were found to be influenced significantly by different zinc levels. It was observed that the availability of particular nutrient increased by its application to the soil. Significantly maximum available K and Zn (176.40 kg ha-1 and 1.60 mg kg-1, respectively) was recorded with the application of potassium @ 30 kg ha-1 and zinc @ 37.5 kg ha-1. Due to the K and Zn application the soil fertility status was found to improve. After the harvest of the crop, availability of all the nutrients increased with the fertilization of potassium and zinc.