Gurpreet Singh2017-02-202017-02-202011http://krishikosh.egranth.ac.in/handle/1/5810001823Rice-wheat, maize-wheat and cotton-wheat are predominant cropping systems, being practised by majority of farmers in Punjab. The adoption of these three cropping systems depletes a huge amount of macronutrients (N, P and K) and micronutrients (Zn, Cu, Fe and Mn) causing deficiency of these nutrients mainly in light textured soils. So, to overcome the deficiency of Zn, Cu, Fe and Mn in such soils, alternative cropping systems like maize-potatao-mungbean, cotton-gobhi sarson, groundnut-toria+gobhi sarson etc., are required. Lot of research work has already been done on the predominant cropping systems without inclusion of short duration crops like mungbean, toria, gobhi sarson and onion crop. So, there is need to explore research on inclusion of short duration crops in the main cropping systems, which helps in mobilization of Zn, Cu, Fe and Mn. Therefore, the present research study has been conducted with a prime objective to investigate the transformation (chemical pools) and depthwise distribution of Zn, Cu, Fe and Mn under different cropping systems. Surface (0-15 cm) and profile (0-120 cm) soil samples were collected from an ongoing field experiment (in progress since 2000) with 10 cropping systems at research farm of Department of Agronomy, PAU, Ludhiana. The plant samples (grain and straw) from each cropping system were also collected both for Rabi and Kharif crops. These soil samples collected at different stages were analyzed for DTPA-extractable and total Zn, Cu, Fe, and Mn and their chemical fractions using atomic absorption spectrophotometer (Varion AAS-FS Model). The grain and straw samples were also analyzed for their Zn, Cu, Fe, and Mn concentration with Varion AAS-FS Model. The levels of DTPA-extractable Zn, Cu, Fe, and Mn were significantly higher in soil under all the 10 cropping systems as compared to their initial levels. Higher levels of DTPA-extractable Fe and Mn and Zn and Cu were observed in rice-wheat and cotton-wheat cropping systems, respectively. Among maize based cropping systems, maize-potato-mungbean cropping system reported significantly higher concentrations of DTPA-extractable Zn, Cu, Fe, and Mn. The DTPA-extractable Zn and Cu decreased and Fe and Mn increased in soil under maize-potato-mungbeen cropping system. The DTPA-extractable Zn, Cu and Fe decreased with increase in the soil depth. Among chemical fractions, higher levels of Fe and Mn (WSEX and SpAd) were reported in the rice-wheat cropping system. On the other hand higher fractions of Zn [WSEX, SpAd, MnOX and CFeOX] and Cu [WSEX and OM bound] were reported under maize-potato-mungbean and cotton-gobhi sarson cropping systems respectively. Higher uptake of Fe was reported in rice-wheat cropping system, whereas Zn, Cu and Mn reported their higher uptakes in groundnut-potato-bajra (fodder) cropping system. Our study further, investigated that inclusion of short duration crops like mungbean, toria, gobhi sarson and onion helps in mobilization of Zn, Cu, Fe and Mn to ameliorate their deficiencies. Among fractions, SpAd, held on organic sites, oxide bound and amorphous fractions of Zn, Cu, Fe and Mn contributed towards plant available (water soluble and exchangeable) fraction. However, WSEX, SpAd, oxide bound and organically bound fractions contributed towards uptake of Zn, Cu, Fe and Mn by plant grain and straw.ennullThesis