Enzyme activity Equation(s) R2*
Amylase activity = -0.5643 + 3.37 OC 0.927
= -15.1584 + 0.89 OC + 2.23 MC 0.997
= 1.958 + 0.00452 TN 0.918
= -38.37 + 0.00327 TN + 6.3 pH 0.998
= -8.853 + 1.367 Clay 0.582
= -19.598 + 0.201 Clay + 2.702 MC 0.995
  Invertase activity = -104.1 – 236 OC 0.909
= -1215.7 + 321 OC + 709 BD 0.985
= 73.609 + 0.315 TN 0.888
= -654.3 + 93 Clay 0.531
= 441.3 – 78 Clay + 372 OC 0.984
Protease activity = -27.5281 + 55.9 OC 0.830
= -0.6948 + 15.7 OC + 0.581 EP 0.998
= 11.3733 + 0.082 TN 0.984
= -0.4019 + 0.0656 TN + 14.2 OC 0.998
= -145.12 + 20.54 Clay 0.427
= -27.35 + 4.47 Clay + 0.0754 TN 0.998
= -181.99 + 10.45 Clay + 0.0727 TN + 71 BD 0.999
Urease activity = -4.3476 + 15.46 OC 0.927
= 0.1819 + 8.5 OC + 0.0109 TN 0.996
= 7.205 + 0.02074 TN 0.921
= -27.131 + 0.01473 TN + 3.43 Slit + 14.9 BD 0.998
= -41.7 + 6.2 Clay 0.569
= -91.41 + 0.8 Clay + 12.5 MC 0.990
= -181.16 + 5.75 Clay + 11.24 MC + 44.8 BD 0.998
= -398.68 + 63.94 pH 0.734
= -172.3 + 28.05 pH + 0.01518 TN 0.996
= -271.48 + 40.21 pH + 0.01404 TN + 14.772 BD 0.998
Phosphatase activity = -73.644 + 11.4 Clay 0.757
= 7.126 – 1.2 Clay + 27.5 OC 0.990
= -149.561 + 5.9 Clay + 23.1 OC + 68 BD 0.996
= 19.8 + 0.2692 EP 0.746
= -77.1 + 0.1181 EP + 9.63 Slit 0.990
= -155.86 + 0.0927 EP + 12.82 Slit + 32 BD 0.996
= -252.88 + 0.1065 EP + 6.72 Slit + 86 BD + 9.3 Clay 0.999
= -693.25 + 112 pH 0.891
= 87.93 – 14 pH + 28.3 OC 0.990
Dehydrogenase activity = -0.36384 + 1.0629 OC 0.910
= -0.01734 + 0.5305 OC + 0.00084 TN 0.994
= -1.95461 + 0.8176 OC + 0.00061 TN + 1.1754 BD 0.998
= -15.52356 + 0.2734 OC + 0.00085 TN + 1.5362 BD + 2.1088 pH 0.999
= -2.829 + 0.514 Clay 0.530
= 2.123 – 0.355 Clay + 1.68 OC 0.988
= -1.797 – 0.192 Clay + 0.93 OC + 0.426 MC 0.997
= -7.26 + 0.053 Clay + 0.61 OC + 0.531 MC + 1.95 BD 0.999
*All R2-values are significant at p<0.001. BD: Bulk density; MC: Moisture content; OC: Organic Carbon; TN: Total Nitrogen; EP: Extractable Phosphorous.
Table 5: Stepwise multiple regression analysis of soil enzymes (amylase, invertase, protease, urease, phosphatase and dehydrogenase) on soil physicochemical characteristics.