Soil Nutrient Dynamics Following Conversion of Long-term Poplar Based Agroforestry to Rice-Wheat Rotation

Abstract

Different land use systems lead to variation in soil properties and nutrient status of soil. A study was conducted to observe the changes in soil pH, EC, organic carbon, available macronutrients (N, P and K) and DTPA extractable micronutrients (Zn, Fe, Mn and Cu) on the sites where poplar based agroforestry system (AFS) was being raised for the last 35 years, sites with rice-wheat rotation for last 35 years, sites converted to rice-wheat rotation after 30 years of poplar based AFS and sites with no plants (control) at Khera bet village, Ludhiana, Punjab. Soil samples were analyzed under these four land use systems in four soil depths (0-15, 15-30, 30-45 and 45-60 cm). The rice-wheat system showed the lowest pH (7.09-7.30), while EC values were comparatively higher in this system. The soil OC content was highest in poplar based AFS followed by converted sites, rice-wheat rotation and control. Available N was statistically at par in poplar based AFS and rice-wheat rotation. Available P was significantly higher in rice-wheat rotation and available K in poplar based AFS in various depths than the other land use systems. Average DTPA extractable Zn, Mn and Cu contents were significantly higher in poplar based AFS (2.29, 5.49 and 1.27 mg kg-1) than rice-wheat rotation whereas Fe was statistically at par between these two systems (12.39 and 12.81 mg kg-1, respectively). The converted sites had lower values of macro and micronutrients than poplar based AFS. Soil OC and all the macro and micronutrients were higher in surface depth than the lower depths. Thus, the greater micronutrient availability under poplar based AFS highlights its importance in maintaining long-term micronutrient balance and soil health.