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Central Agricultural University, College of Post Graduate Studies in Agricultural Sciences, Umiam

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20211
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Subject: Soil Science and Agriculture Chemistry × Author: Ampi, Narang ×
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    ThesisItemOpen Access
    Development of soil physico-chemical quality index of rice-fish farming system in Apatani plateau
    (College of Post Graduate Studies in Agricultural Sciences, CAU-Imphal, Umiam, 2021-02) Ampi, Narang; Thakuria, Dwipendra
    The rice-fish (RF) farming in Apatani plateau practiced by Apatani tribe of Arunachal Pradesh is believed to be sustainable system of farming based on yield trends of rice (average 3.0 to 3.7 t ha-1 ) and fishes (average 550 to 600 kg ha-1) over the decades. This unique traditional system of farming has been tentatively listed as “World Heritage site” by UNESCO on 15th April 2014. The review of literatures indicated that there is lack of scientific data on comparative soil quality index (SQI) values of RF system relative to adjacent forest site (FS) in Apatani Plateau. So, the hypothesis of this investigation was that RF farming underpins better soil physico-chemical quality relative to adjacent FS. Soil samples at surface (0-15 cm) and subsurface (15-30 cm) depths during wet season (on 6th June 2019) and dry season (on 13th January 2020) were collected from Apatani plateau, which is comprised of 7 villages (Hong, Mudang Tage (MT), Hari, Hija, Bulla, Dutta and Bamin Michi (BM) including soil samples from two adjacent FS). The geo-positions of each sampling locations were recorded. Altogether 216 composite soil samples (2 composites per RF field x 3 RF per village x 7 villages + 6 composites per FS x 2 FS = 54 composites; 54 x 2 depths x 2 sampling times = 216 composites) were collected. These 216 composites were analyzed for 24 nos. soil physico-chemical quality attributes viz. pH, 1:2.5 soil water suspension; EC, electrical conductivity; SOC, soil organic carbon; AvlN, available nitrogen; AvlP, available phosphorus, AvlK, available potassium; AvlS, available sulfate; soil texture (sand, silt and clay), POM, particulate organic matter; BD, bulk density; PD, particle density; MWHC, maximum water holding capacity; DTPA extractable Fe (iron), Cu (copper), Zn (zinc) and Mn (manganese); CEC, cation exchange capacity; ExK, exchangeable potassium; ExNa, exchangeable sodium; ExCaMg, exchangeable calcium and magnesium; BS, base saturation; RSAl, readily soluble aluminium. Values of soil quality attributes were analyzed for group comparison (9 groups: 7 villages and 2 FS) using nonparametric Kruskal-Wallis H Test incorporating Monte-Carlo significance test at 95% confidence limit. The percentage change in soil quality attributes of RF sites were compared with values of FS sites scaled to 100% using Amoeba plot. The grouping/clustering behavior of RF sites and FS sites were presented by principal component analysis (PCA). The SOI values were deduced using the average factorial deviation from the values of soil quality indicators relative to their values of reference site scaled to 100%. Values of soil pH, EC, SOC and POM in RF sites were lower compared to their values in FS sites and values of pH were more in wet season compared to pH values in dry season. The content of SOC in RF sites decreased during dry season; whereas content of POM increased during dry season. Among macronutrients content of AvlN and AvlK in RF sites were lesser than their values in FS sites; whereas content of AvlP and AvlS were higher than that in FS sites. The content of AvlP,AvlK and AvlS were decreased and AvlN was increased during dry season. Values of BD, PD and MWHC in RF sites were higher than their values in FS sites. Soil texture of RF sites was loam (clay,16.24%; silt, 43.7%; sand, 40%) and FS sites was sandy loam (clay, 6.2%; silt 26.8%; sand, 66.9%). The content of DTPA-Fe, - Zn and -Mn were higher in RF sites compared to their contents in FS sites, except DTPA-Cu which showed a opposite trend. Ex.K and Ex.Na in RF sites were higher compared to that in FS sites. In contrast, Ex.Ca+Mg was lower in RF sites than that in FS sites. During dry season, the content of Ex.Na was increased and Ex.K and Ex.Ca+Mg were decreased. The values of CEC in RF sites were lower than that in FS sites and also decreased during the dry season. The values of BS in FS sites were higher than that in FS sites and values were increased during dry season. Overall, soil physico-chemical attributes varied significantly between RF sites and FS sites (P<0.05, Kruskal Wallis test). In Amoeba plot, the extent of percentage change of POM, AvlN, AvlP, AvlS, clay, silt and sand content, DTPA-Fe, -Zn and -Cu, Ex.K, Ex.Na, BS and RSAl in RF sites relative to their values in FS sites (reference sites) were more pronounced. The PCA plots clearly showed 3 distinct clusters i.e. the cluster of FS sites separated from the two clusters of 7 RF sites along the PC axis-1 that explained maximum variability ranged from (39.2 to 52.6%). The two clusters of RF sites were mainly separated along PC axis-2 that explained variability ranged from 13.3 to 21.2%. The SQI values of RF sites were higher relative to their FS sites. Among the 7 RF sites, SQI value of Hong village was the highest followed by the lowest SQI values in Bamin Michi during wet season and Bulla in dry season. In conclusion, SQI values indicated that soil quality in RF sites was aggraded relative to their FS sites. So, the present management practice of rice-fish farming of Apatani community seems to be sustainable from the view point of soil physico-chemical quality aspects.