Soil micronutrient indexation under cotton-wheat and rice-wheat cropping systems in Sangat block of district Bathinda, Punjab

Micronutrient deficiency is a major concern for sustainable cropping systems, leading to low micronutrient contents in edible plant parts and health problems in human beings as well as animals. For this investigation, the available (DTPA-extractable) micronutrient contents in 100 soil samples collected at 0–15 cm and 15–30 cm depths were studied in cotton-wheat and rice-wheat cropping systems in Sangat block of Bathinda district. Data showed a large variation in DTPA extractable Zn, Cu, Fe and Mn contents in soils under cotton-wheat and rice-wheat systems. Mean micronutrient contents were higher for Cu (2.19 mg kg⁻¹), Fe (3.59 mg kg⁻¹) and Mn (4.87 mg kg⁻¹) under cotton-wheat system compared to rice-wheat system with mean values of 3.13 mg Fe kg⁻¹, 2.11 mg Cu kg⁻¹ and 4.37 mg Mn kg⁻¹ at 0–15 cm soil depth. The soil nutrient index values (NIV) at 0–15 cm depth were 2.9 for Zn, 3.0 for Cu, 1.2 for Fe, and 1.9 for Mn under cotton-wheat system which indicated that soils were low in Fe, high in Cu, and Zn, and medium in Mn availability. However, at 15–30 cm soil depth NIV for Zn, Cu, Fe, and Mn were 2.7, 2.9, 1.1, and 1.7 respectively, which indicated that soils were high in Zn and Cu, low in Fe, and medium in Mn availability. Similarly, NIV for rice-wheat system at 0–15 cm and 15–30 cm for Zn (2.6, 2.4), Cu (2.8, 2.8), Fe (1.4, 1.3) and Mn (1.3,1.3) indicated that soils were high in Zn and Cu availability, low in Fe and Mn and at both 0–15 cm and 15–30 cm depths. The results clearly indicated soils (0–15 cm layer) under rice-wheat system are deficient in Fe and Mn, while Fe deficiency is more under cotton-wheat system, and highlights the need to apply these micronutrients to sustain the soil fertility and crop productivity.