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Birsa Agricultural University, Ranchi

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Subject: Soil Science and Agriculture Chemistry × Author: Verma, Shikha × End date: 2023 × Start date: 2020 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    SOIL QUALITY ASSESSMENT UNDER LONG TERM FERTILIZER EXPERIMENT IN RED AND LATERITIC SOILS OF RANCHI
    (Birsa Agricultural University, Ranchi, 2022) Verma, Shikha; Agrawal, B.K.
    An investigation was undertaken during 2018-19 on the soils of the ongoing long term fertilizer experiment (LTFE) in progress since 1972 at the experimental farm of Department of Soil Science and Agricultural Chemistry, Birsa Agricultural University, Kanke, Ranchi in Jharkhand state. The experiment consisted of ten treatments replicated thrice in a randomized block design i.e. T1:50% NPK, T2:100% NPK, T3: 150% NPK, T4: 100% NPK+ Hand weeding, T5: 100% NPK+Lime, T6: 100% NP, T7: 100% N, T8: 100% NPK+FYM, T9: 100% N(S)PK and T10: Control. Surface soil samples (0-15 cm) were collected during the soybean and wheat growth stages for analysis of moisture content, soil pH, soil organic carbon, available P and K. Surface (0-15 cm) and subsurface (15-30 cm) soil samples were collected after the harvest of wheat (2018-19) for analysis of various physical, chemical and biological properties for development of soil quality index (SQI). Sustainable yield index of the soybean wheat cropping system over the years of experimentation was calculated. System productivity was expressed in terms of mean wheat equivalent yield (WEY). Highest sustainable yield index (SYI) of the system (0.57) was recorded in 100% NPK+FYM treatment followed by 100% NPK + lime (0.50). The least value of SYI values was recorded 100% N treatment (0.04). System productivity in terms of mean WEY (q ha-1) over the years (1972-2019) followed the following order: 100% NPK+FYM (70.3) >100% NPK+Lime (67.0) > 150% NPK (58.5) > 100% NPK (57.8) =100% NPK +HW (57.8) > 50% NPK (44.5) > 100% NP (41.70) > 100% N(S)PK ( 35.3) >Control ( 16.5) > N (10.3). Amongst the soil properties analyzed at different crop growth stages, soil organic carbon, available P and K exhibited significant correlation with system productivity throughout the growing period of crops. Low variability (i.e. CV < 15%) was exhibited by all the soil measurements that were assessed during the crop growth stages (moisture content, soil pH, available P, available K and soil organic carbon). Among the various soil quality parameters (physical, chemical and biological), soil texture and DTPA-Pb showed no significant difference in both the soil depths and therefore dropped from principal component (PCA) analysis. The rest of the soil properties which showed significant difference among the treatments were subjected to principal component analysis (PCA) using the SPSS software to identify the minimum dataset (MDS) in order to compute soil quality index (SQI). The variables identified as the minimum dataset (MDS) indicators for development of soil quality index for surface soil (0-15cm) were: DHA, LOC, hot water soluble boron, soil pH and exchangeable Ca. The MDS indicators identified in case of subsurface soil layer (15-30 cm) were labile organic carbon, DHA, Hot water soluble boron, soil pH, exchangeable Ca and bulk density. 100% NPK+FYM recorded the maximum value of SQI followed by 100% NPK+Lime in both surface as well as subsurface soil layer. The SQI ranged from 0.00 to 2.21 and 0.00 to 2.10 in surface and subsurface soil layer, respectively. 100% N treatment recorded the lowest value of SQI (0.00) in both the soil depths. Percentage contribution of key soil quality indicators or MDS indicators for influencing SQI in the surface soil layer (0-15 cm) were: LOC (29.8%), DHA (28.4%), boron (21.9%), soil pH (14.8%) and Ca (5.0%). Percentage contribution of key soil quality indicators or MDS for influencing SQI in the subsurface soil layer (15-30 cm) were LOC (29.1%), DHA (27.25%), hot water soluble boron (20.41%), soil pH (16.02%), exchangeable Ca (5.13%) and bulk density (2.15%). The higher values of both sustainable yield index (SYI) and soil quality index (SQI) in 100% NPK+FYM and 100% NPK +Lime suggests that conjoint use of lime or FYM along with balanced NPK fertilizers are viable options for enhancing the productivity and sustainability of the soybean-wheat cropping system together with maintenance of soil quality in red and lateritic soils. Application of NPK fertilizer was found to be superior over imbalanced fertilization (N and NP) with respect to soil quality, system productivity and sustainability. All the soil chemical properties measured during crop growth stages (pH, available phosphorus, available K and soil organic carbon) responded consistently to management over time and hence their measurement at any time of crop growth can serve as an indicator to soil quality. Labile organic carbon, dehydrogenase activity, hot water soluble boron, soil pH, exchangeable Ca, soil pH and bulk density were identified as the key indicators of soil quality under soybean-wheat cropping system .