Resumen de Urease activity and its relationships to soil physiochemical properties in a highly saline-sodic soil
T. Zhang, S. Wan, Y. Kang, Huan Feng
To ascertain the levels of urease activities (UA) and their relationships with soil physicochemical properties in salt-affected soils during reclamation, soil transects of a saline-sodic soil with different planting years under drip irrigation were intensively sampled. An enhanced soil UA in root zone (0-40 cm beneath drip emitter) was found as the planting years increased. In all transects, soil UA ranged from 0.38 to 8.53 µg NH4+-N released g-1 dry soil h-1 at 37 °C, and showed a large spatial variability within transect. R² of multiple regressions increased gradually with planting years, indicating that variations in UA could be better predicted after amelioration. Path analysis showed that the negative direct effects of soil pH on UA were clearly dominant, with the direct path coefficients of -0.357 ~ -0.666 (p < 0.05). Soil organic matter yielded greater positive indirect path coefficients through pH and total nitrogen. An exponential relationship was found between soil UA and pH values (p < 0.01). Our findings demonstrate that after the cultivation under drip irrigation for 3 years, soil biological activities and fertility level increased, with the decrease of soil salinity and sodicity.
