SOIL ORGANIC CARBON DYNAMICS UNDER LONG TERM RICE-BASED CROPPING SYSTEM IN CALCIORTHENTS OF BIHAR
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Date
2022
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DRPCAU, PUSA
Abstract
The research was carried out as part of an ongoing field experiment under
the AICRP on Micro Secondary and Pollutant Elements in Soil and Plants, which
began in Kharif 1985 in light-textured calcareous soil. The experiment was in
randomized block design with four fertility levels 0, 50%, 100%, and 150% of the
recommended dose of fertilizer (RDF) for each crop), and six replications with two
cropping systems viz. Rice-Mustard-Moong (R-M-M) and Rice-Wheat-Sorghum (RW-
S). The RDF for wheat and rice were 120:60:40; for moong-20:50:30; for
Sorghum-60:50:30; and for mustard-60:40:30. After ten cropping cycles, because of
substantial micronutrient deficiencies, particularly zinc, in plots receiving 150% of
the RDF, out of six replications, 4 replication were superimposed with (10 kg/ha
Zinc, 10 kg/ha Zinc + 5 t/ha FYM, 10 t/ha FYM and 10 kg/ha Zinc + 10 t/ha FYM).
The superimposed treatments were applied in alternate years. No replication was
left for statistical analysis in RBD due to superimposition in four replications. To
compare the superimposed treatments, a paired t-test was used. After the 109th rice
crop was harvested in 2021, during the 37th crop cycle, the current research was
conducted.
From the current study, Among superimposed treatment the conjoint
application of 10 kg Zn along with 10 t FYM/ha proved the best treatment with
respect to soil organic carbon dynamics in both the cropping system. The combined
application of 10 kg Zn along with 10 t FYM/ha, it was observed that there were
significant changes in soil organic carbon, fractions of soil organic carbon, total
organic carbon, soil organic carbon stock, lability index and soil microbial biomass
carbon while in subsurface soil no significant effect of different superimposed
treatments on soil organic carbon dynamics.
The values of different fractions of soil organic carbon such as very labile
carbon, labile carbon, non labile carbon and less labile carbon content in treatment
receiving with 10kg Zn/ha with 10t FYM superimposed treatment over control was
found to be 0.41%, 0.19%, 0.12% and 0.67% in R-W-S crop rotation while in R-MM
rotation it was found to be 0.44%, 0.23%, 0.08%, 0.58%.
Among different fractions of soil organic carbon, the content of very labile
and labile carbon fractions were found more in R-M-M rotation than in R-W-S
rotation for each superimposed treatment. However, less labile and non-labile
organic carbon fractions were higher in R-W-S rotation. A similar trend was also
observed for total organic carbon, soil organic carbon stock and soil microbial
biomass carbon.
Soil organic carbon, total organic carbon, and microbial biomass carbon the
percent increased in superimposed treatment over control was found to be 26.3%,
39% and 32.9% in R-W-S crop rotation while in R-M-M was found to be 30.7%,
38.4%, and 24.5%.
Rice grain yield was positively and highly significantly correlated with the
soil's very labile carbon, labile carbon, and organic carbon in R-W-S cropping
system and in R-M-M cropping system rice yield was was positively and highly
significant with very labile carbon, labile carbon, organic carbon and microbial
biomass carbon. It was also positively and significantly correlated with less labile,
total organic carbon content in both the cropping system. However, the non-labile
carbon fraction didn‘t significantly improve rice grain yield in both the cropping
system.