MEENA, SUNITA KUMARIKUDI, BABITA2023-02-102023-02-102022M/SS/089/2020-21https://krishikosh.egranth.ac.in/handle/1/5810193568A Study entitled “Impact of sugarcane cultivation on soil carbon pools and soil health in Samastipur district of Bihar’’ was carried out at Department of Soil Science, Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur, Bihar with the objective to establish the relationship between soil carbon pools and soil health parameters. Soil samples were analyzed in the laboratory for different physical, chemical and biological properties by Cornell Soil Health Laboratory Comprehensive Assessment of Soil Health (CASH) standard operating procedures. Sugarcane is a long duration, heavy feeder and nutrient exhaustive crop. The excessive and imbalanced use of chemical fertilizer has deterioration of soil health. The soil organic carbon content is continuously declining due to the non-addition of organic matter and to continuous cultivation of sugarcane crop which is extensive in nature. Restoration of organic matter is thus, needed for maintaining soil health and improving productivity through breakdown of continuous cultivation of sugarcane and the addition of organic amendments. A wide variation was observed for soil quality parameters which included pH mean value was 8.35±0.14 in 0-15 cm soil depth and 8.20±0.15 in 15-30 cm; electrical conductivity (EC) mean 0.59±0.18 dS m-1 in 0-15 cm and 0.48 ± 0.18 dS m-1 in 15 - 30 cm; bulk density (BD) mean 1.49 ± 0.10 g cm-3 in 0-15 cm and 1.58±0.08 g cm-3 in 15-30 cm; Wet Aggregate Stability (WAS) mean 26.9±6.6 % in 0-15 cm and 24.67±9.93 % in 15-30 cm. Among the major soil nutrients, the mean value of available N was 192±14 kg ha-1 in 0-15 cm and 187±14 kg ha-1 in 15-30 cm; mean value of available P2O5 was 29.2±5.4 kg ha-1 in 0-15 cm and 25.8±5.2 kg ha-1 in 15-30 cm soil depth; mean value of available K2O was 161±24 kg ha-1 in 0-15 cm and 154±24 kg ha-1 in 15-30 cm soil depth and available S was 8.52±1.40 mg kg-1 at 0-15 cm and 7.30±1.38 mg kg-1 in 15-30 cm soil depth. The variation in available soil micronutrients were as follows: Zn mean value was 0.57 ± 0.21 mg kg-1 in 0- 15 cm and 0.44 ± 0.22 mg kg-1 in 15-30 cm soil depth; Cu mean value was 1.24±0.58 mg kg-1 in 0-15 cm and 1.11±0.59 mg kg-1 in 15-30 cm soil depth; Fe mean value was 9.83±2.58 mg kg-1 in 0-15 cm soil and 8.44±2.52 mg kg-1 in 15-30 cm soil depth; Mn average value was 4.50±0.93 mg kg-1 in 0-15 cm soil and 3.36±0.89 mg kg-1 in 15-30 cm soil depth. Among the soil biological properties, soil protein (autoclaved citrate extractable protein), soil respiration, dehydrogenase activity and MBC mean values were 1.59±0.55 g kg-1, 0.72 ± 0.22 mg CO2 g-1 96 hrs-1, 4.86 ± 0.78 μg TPF hr-1 g-1, 113±15 mg kg-1in 0-15 cm soil and 1.19 ± 0.55 g kg-1 ,0.58 ± 0.23 mg CO2 g-1 96 hrs-1 , 3.59 ± 0.80 μg TPF hr-1 g-1 , 96.63 ± 16.90 mg kg-1in 15-30 cm soil respectively. The mean value of different soil carbon pools were as follows: Walkley-Black carbon was 5.23±1.06 g kg -1 in 0-15 cm soil and 4.56±0.96 g kg -1 in 15-30 cm soil; total organic carbon was 7.64 ± 1.20 g kg-1 in 0-15 cm soil and 7.10±1.49 g kg-1 in 15-30 cm soil; KMNO4 –C was 263±55 mg kg-1 in 0-15 cm soil and 235±54 mg kg-1 in 15-30 cm soil. Percent contribution of different SOC pools to the total SOC followed as: Non labile (32%) > Less labile (28%) > Very Labile (20%) > labile (19.7%) in 0-15 cm of soil and Non labile (35.6%) > Less labile (28.6 %) >Very Labile (18.6%) > labile (17.1%) in 15-30 cm depth of soil. Correlation coefficient of oxidisable organic carbon (0-15 cm soil) with various fractions of carbon and soil biological parameters ranged from 0.846 to 0.974. For 15-30 cm soil depth, correlation coefficient of OC was found significantly positive with TOC (0.925) and VL-C, L-C, LL-C (0.875, 0.899, 0.924, respectively). Therefore, it was recommended that the inclusion of other crops in a crop rotation leads to a build-up of active fractions of carbon, thus the biological activity that will support soil sustainability.EnglishThesis