Vol. 10, Special Issue 12 (2021)

Author(s):
V Venkatesh, N Chandra Sekaran, G Sridevi, S Meena and KT Parthiban

Abstract:
Soil quality assessment includes physical, chemical and biological properties of the soil, is an important decision support system which aids in checking the efficiency of the adopted management practices in an ecosystem. In recent years, soil quality index assessment in qualitative evaluation is gaining importance. Hence, to assess the impact of constant and continuous application of fertilizers and manures on the soil quality, a study was carried out during 2019-20 in the permanent manurial experiment, which was established during 1909 at the Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore. For which, Soil Quality Index (SQI) was developed for the soil receiving different treatments constantly and continuously for a period of 112 years. There were 18 treatments, of which eight treatments were with inorganic fertilizers in different permutation combinations, five treatments with manures of different sources and doses, two treatments with inorganics + organics including one STCR-IPNS recommendation and the remaining three treatments were farmers practice, control and an absolute control (fallow land) . The effect of the treatments on the soil quality was compared by developing the soil quality index at three different soil depths viz., 0-15, 15-30 and 30-45cm’s. Totally 27 soil physical, chemical and biological properties along with phosphatase, urease and dehydrogenase enzyme activities were analyzed and Principal Component Analysis (PCP) was used for selecting the indicators to be retained in minimum data set. The PCs with >1 eigen values were selected with a variance of 92.90%. Linear scoring functions were used to convert the indicators into unitless values between 0 and 1. Weighed factor was calculated and soil quality index was developed with the help of weighed factors and scores. Three different methods of soil quality index were analyzed i.e., weighed additive soil quality index, relative soil quality index, additive soil quality index and nemoro soil quality index. In all these methods, the treatments which received inorganics + organics namely100% NPK+FYM and STCR – IPNS had shown their superiority in sustaining the soil health in all the soil depths viz., 0-15, 15-30 and 30-45cm’s.