SOIL ORGANIC CARBON DYNAMICS IN LONG TERM FERTILIZATION AND MANURING UNDER FINGER MILLET – MAIZE CROPPING SYSTEM
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Date
2023-03-25
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Abstract
A study on soil organic carbon dynamics in long term fertilization and manuring
under finger millet-maize cropping system was carried out during 2020-21 at ZARS, UAS,
GKVK, Bengaluru which has been in progress since 1986. The experiment consists of
eleven treatments (control, N, NP, different doses of NPK, NPK+FYM, NPK+lime and
NPK+FYM+lime) replicated thrice in a Randomized Block Design and for the presentstudy one more additional treatment of uncultivated land was considered. Soils samples were collected at 0-15, 15-30, 30-45 and 45-60 cm depth and were analysed for differents oil organic carbon fractions viz., organic carbon, water soluble carbon, microbial biomass carbon, particulate organic carbon, carbohydrate carbon, very labile, labile, less labile and recalcitrant carbon and total carbon. The results revealed that continuous application of fertilizers increased SOC over initial content. Irrespective of the soil depth, all carbon fractions and total carbon were higher in uncultivated soil (T12) followed by T10 (100% NPK + FYM + lime), T8 (100% NPK + FYM) and T3 (150% NPK). The rate of carbon mineralization and basal soil respiration (BSR) recorded significantly higher values in T10 and T8. Microbial quotient was higher in T4: 100% NPK + Hand Weeding. Mineralization quotient was higher in 150% NPK. Integration of balanced fertilizers with organics recorded significantly higher humic acid, fulvic acid content, total C and N in extracted
humic and fulvic acids and E4/E6. Soil quality index (SQI) and carbon management index(CMI) were highest for the treatments T10 and T8. All the forms of carbon were significantly and positively correlated with soil available nutrients and with grain yields. The absolute control and imbalanced fertilization treatments (N and NP) recorded lower values of all carbon fractions, carbon mineralization rate, BSR, microbial quotients, organic matter fractions, SQI and CMI.
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