Dehydrogenase activity of Normal, Saline and Alkali soils under different agricultural management systems

Dehydrogenase activity (DHA) was measured in normal soil (pH 7.2 to 8.9; EC 0.9 to 3.9 dS m⁻¹); an alkali soil (pH 9.0 to 10.4; EC 1.8 to 21.6 dS m⁻¹) and in saline soil (pH 7.5 to 8.0; EC 1.3 to 67.8 dS m⁻¹) under different cropping systems. In normal soil, dehydrogenase activity was 103% greater under tree canopies compared to rice-wheat system, whereas in saline soil it was 100% greater under pearl millet-wheat cropping sequence than under tree canopies. In alkali soil, DHA was 58% greater under rice-wheat (with 50% G.R.) and 37% greater under Karnal grass (Leptochloa fusca, without gypsum) as compared to tree canopies. However, when dehydrogenase activity was compared for barren soils at all the three sites, it was 19.42 μg TPF g⁻¹ soil in the normal soil under Desmostachya bipinatta, 0.44 to 6.70 μg TPF g⁻¹ soil in alkali soil and 0.00 to 4.47 μg TPF g⁻¹ soil in saline soil. Average DHA was 40.22, 36.79 and 13.73 μg TPF g⁻¹ soil for normal, saline and alkali soils, respectively. Alkali soil showed minimum DHA, whereas, it was almost on par for saline and normal soils.