2.3 Analysis of soil properties
The soil pH and EC were estimated in 1:2.5 soil to water suspension (Jackson, 1973). The BD was estimated using a soil core method (Blake, 1965). Ammonium acetate extractable cations like sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) (Hanway & Heidel, 1952) were estimated using atomic absorption spectrophotometer (AAS) (nova400P, Analytik Jena, Germany). The SOC was analyzed by Walkley & Black (1934) wet oxidation method. The soil available nutrients were estimated as - soil available nitrogen (N) by alkaline potassium permanganate method (Asija & Subbiah, 1956) and soil available phosphorus (P) by a colorimetric method (Bray & Kurtz, 1945). Diethylenetriaminepentaacetic acid extractable micronutrients like iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) (Lindsay & Norvell, 1978) were determined using AAS. The 0.15% CaCl2 extractable sulfur (S) (Williams & Steinbergs, 1959) and hot water-soluble boron (B) (Gupta, 1967) were estimated using a spectrophotometer. The soil properties were tested for normality and under the situation of non-linearity Box-Cox transformation was used to make it normal for model development and the model estimation were back-transformed to original units for those soil properties for evaluation (Table 1).