Seasonal changes in soil health parameters affected by nitrogen and residue management practices under long term conservation agriculture in maize system.

Abstract

Conservation agriculture based management found to be effective for enhancing productivity, profitability and soil properties in maize based cropping system. We have assessed changes in the key soil enzymatic activities under long-term CA in spring and kharif season. In our experiment, the zero􀀐tillage practices with residue (WR) and without residues (WoR) with two maize cropping system (MMuMb: Maize-Mustard-Mungbean and MWMb: Maize-Wheat-Mungbean) considered as main-plots and further in four different nitrogen management (F0: RDN, F1: 33+GS (green seeker), F2: 50+GS, F3: 70+GS) in sub􀀐plots. The soil was sampled after harvest of spring 2019 and kharif 2019 for analysis of the soil organic carbon and NPK in the experiments started at fixed site since kharif 2012. The enzymatic properties were analyzed at the flowering stage of the crop during spring mungbean and kharif maize. Compared to CT plots, the soil physical properties like penetration resistance (PR) showed significant (P < 0.05) declined at various depths. The soil organic carbon (SOC) increased in MWMb in F1 at with residue in 0-15 and 15– 30 cm depths while SOC increased in MMuMb without residue in F3. In all enzyme activity assays, at flowering of kharif season showed better enzyme activity as compared to summer season whereas in macronutrients (NPK) showed higher values in soils after harvest of summer season. For microbial biomass carbon (MBC), MMuMb showing highest activity in both the depths but at different nitrogen management practices. For florescein diacetate (FDA), at 0-15 cm depth, MMuMb showed highest activity with residue at F3 whereas at 15-30 cm depth, MWMb has highest activity without residue. At both the depths, highest urease activity was observed in same cropping system i.e. MWMb but with different nitrogen doses (F4 and F1). Alkaline phosphatase activity was more in MWMb with residue at RDN in 0-15 cm depth whereas in 15-30 cm depth, MMuMb showed highest activity with residue at RDN. In glucosidase enzyme assay, MMuMb has highest activity in RDN with residue and at 15-30 cm depth, highest activity was observed in another cropping system MWMb but with same dose of nitrogen. The nitrogen was highest in MMuMb with F2 at 0-15 cm and in 15-30 cm. The potassium content in both the depths was highest in MWMb system at F3 whereas highest phosphorous was observed in MMuMb at 0-15 cm depth while in MWMb at 15-30 cm depth. Hence, it can be concluded that residue retention in the conservation agriculture improved the enzymatic activities and NPK content along with decreases the penetration resistance.