Path Analysis for Soil Urease Activities and Nutrient Contents in a Mountain Valley Wetland, China

Abstract

Soil profiles from 0 to 90 cm depth were collected to investigate temporal dynamics and profile variations in soil urease activities in Carex meyeriana wetland and to capture the direct and indirect effects of soil nutrients on soil urease activities in the Changbai Mountain valley wetland of China during the periods from 2002 to 2003. Our results showed that soil urease activities decreased gradually with increasing depth along soil profiles with higher coefficients of variation in the upper soils, which were positively correlated with microorganism numbers. Soil urease activities during the growing season from May to September were higher than those in April. Path analysis showed that both NO 3 − –N and dissolved Mg (DMg) had direct positive effects on soil urease activities and they had the highest direct path coefficients and determination coefficients compared to other soil nutrients. Total contents of Cu and Fe showed direct and indirect positive effects on soil urease activities through NO 3 − –N, whereas they showed negative indirect effects through DMg. Despite that total Mg and dissolved K showed direct adverse effects on soil urease activities, the indirect effects through NO 3 − –N were much higher. In contrast, total Zn showed both direct and indirect adverse effects on this enzyme. However, the positive indirect effects of soil organic matter, total N, and total P on soil urease activities were more significant than their direct effects. The findings of this work had a potential important role in monitoring soil biological quality in N‐limited mountain valley wetland ecosystems.