Soil Carbon Pools and Cationic Micronutrient Fractions Under Prominent Cropping Systems of Western Uttar Pradesh

Abstract

Cropping systems significantly impacts soil organic carbon pools, micro-nutrients distribution and transformations due to their location-specific different management practices. Therefore, the present study was conducted to assess soil carbon pools, cationic micronutrients (viz. Zn, Cu, Fe and Mn) availability and their transformations (chemical pools) in soils of western Uttar Pradesh under six prominent cropping systems viz., ricewheat, rice-mustard, rice-potato, sugarcane-ratoon-wheat and vegetable-vegetable as well as barren land as control. Soil samples from 0-15 cm, 15-30 cm and 30-45 cm depth were collected from farmer’s fields and analysed for different soil carbon pools and cationic micronutrient fractions at department of Soil Science and Agricultural Chemistry, SVPUAT, Meerut. Results of the investigation revealed that soils of the study area were neutral to alkaline in soil reaction and non-saline in nature. Soils having more sand per cent representing the coarse nature of soil and texture ranged from sandy clay loam to clay loam. Among the cropping systems rice-potato and sugarcane-ratoon-wheat cropping sequences recorded significantly higher TSOC, MBC, WBC, CVL, CL, CLL, CNL, PmOC and WSC at all three depths. Averaged across under different cropping systems, different OC fractions were in order: CNL (2.04, 1.52 and 1.23 g kg-1) > CVLC (1.83, 1.27 and 0.70 g kg-1) > CLC (0.85, 0.71 and 0.64 g kg-1) > CLL (0.75, 0.62 and 0.56 g kg-1) at D1, D2 and D3, respectively. The DTPA-extractable Zn, Cu, Fe, and Mn were significantly higher in soil under all the cropping systems as compared to barren land. Higher levels of DTPAextractable Zn, Mn and Cu and Fe were recorded in rice-wheat and sugarcane-ratoon-wheat cropping systems, respectively. These DTPA extractable micronutrients decreased with the depth. Among the chemical fractions significantly higher levels of Zn and Mn (WSEX) and Mn and Cu (OM bound) were recorded under rice-potato and rice-wheat cropping system, respectively. On the other hand significantly higher levels of Fe and Zn (MnOX and AFeOX), Cu (CFeOX and OM bound) were recorded under sugarcane-ratoon-wheat cropping system, while Cu (WSEX and AFeOX) were under rice-wheat cropping system. In a nutshell our study concluded that the in comparison to other cropping systems, rice-potato and sugarcane-ratoon-wheat cropping sequences in which huge quantity of organic matter added through FYM, crop residues and root biomass played a predominant role in gaining more labile carbon and micronutrient transformations in the soil and the building up of micronutrient pools in soils.