3.3. Soil quality
For productivity goal, a total of 25 soil attributes of 131, 198 and 122 soil samples were collected from EZ, CZ and WZ were analyzed using PCA. Seven PCs from each EZ and CZ were pondered, while eight PCs were identified in WZ that showed 74.9, 68.3 and 69.3% of the cumulative variation, respectively. Variables which consisted high factor loading, eigenvalue >1 and explained at least 5% of the variation from each PC in EZ, CZ and WZ were mull as best representative attributes. The variability explained under each PC in EZ, CZ and WZ were varied (Tables 5). In EZ, Na, Ka, Fe, SOC, Pa, Sa and AZO were considered as best representative under MDS from PC1, PC2, PC3, PC4, PC5, PC6 and PC7 due to high factor loading, respectively. In CZ, Na, AZO, ALP, SOC, Fe, Sa and BSR were highly weighted attributes in PC1, PC2, PC3, PC4, PC5, PC6 and PC7, respectively. In WZ, Na, SOC, AZO, Ka, ALP, Sa, BSR and Zn had high factor loading value in PC1, PC2, PC3, PC4, PC5, PC6, PC7 and PC8, respectively, hence retained as the final MDS for indexing procedure of SQI. After completing the MDS process, the shape of the expected response i.e., ”more is better” soil function was decided to all the variables retained in EZ, CZ and WZ, except for Fe content which was adjudged as “optimum is better” soil function (Table 6). The thresholds values were allotted taking into account the site specific characteristics and management goal. Weights were assigned to the MDS indicator using the PCA outcomes (Table 6) which were equal to the percentage of total variance explained by the PC. The single weighted variables were hold in each PC, hence, the full weight equal of each PC was entrusted to each variable. Thus, each of the MDS parameters was changed to a value between 0 and 1. Soil quality index was computed by sum up of the entire weighted variable retained under MDS as follows:
SQI for eastern zone (EZ)
[0.237S Na+ 0.135S Ka + 0.107S Fe+0.829S SOC + 0.0722S Pa+0.0632S Sa+0.0513S AZO]/0.75
SQI = 0.316S Na+ 0.180S Ka + 0.143S Ka+0.111S SOC + 0.0963S Pa +0.0844S Sa+ 0.0684S AZO
SQI for central zone (CZ)
SQI=[0.212S Na+0.127S AZO+0.0936S ALP+0.0724S SOC+0.0639S Fe+0.0628S Sa+0.0508S BSR] /0.68
SQI = 0.312S Na+0.187S AZO+0.138S ALP+0.106S SOC+0.0940S Fe+0.0923S Sa+0.0747S BSR
SQI for western zone (WZ)
SQI=[0.194S Na+0.108S SOC+0.0858S AZO+0.0736S Ka+0.0651S ALP+0.0581S Sa+0.0568S BSR+0.0511S Zn]/0.69
SQI=0.281S Na+0.157S SOC+0.1248S AZO+0.107S Ka+0.0904S ALP+0.0840S Sa+0.0823S BSR+0.0741S Zn
The SQI varied from 0.469 to 0.972 across the cane producing zones of Uttar Pradesh with mean values ranged from 0.708 to 0.795. The SQI followed in the descending order of CZ (0.795)>WZ (0.785)>EZ (0.708) soils with coefficient variations of 11.5, 6.83 and11.2, respectively. The contribution among the MDS retained in EZ, CZ and WZ towards the soil quality development fluctuated, but Na showed closely comparable contribution across the cane producing zones of Uttar Pradesh (Table 7). The sensitivity index was lowest in CZ (1.42) followed by WZ (1.81) and EZ (1.94).