Enzyme activities and litter decomposition in agricultural soils
Although enzyme activities were extensively investigated in soils with reference to abiotic environmental conditions and human impact, their role in litter decomposition is not fully understood. Therefore, decomposition rates and enzyme activities were studied using nylon bags and three litter types buried in silty-loamy Cambisols and Luvisols in northern, central and southern Germany under similar averaged temperature and precipitation and a maritime to continental gradient. After 180 days, the ash-free mass remaining ranged between 15 to 68 % for the Triticum, Secale and Lolium litter. The enzyme activities were mainly controlled by the litter type and the decomposition time and less but significant by site. The highest decomposition rate occurred at the central German site for Lolium litter associated with highest arginine ammonification and urease activity in litter. In contrast, the recalcitrant Secale and Triticum litter were decomposed more rapidly at the northern and southern site where urease, protease and arginine ammonification was high in the bulk soil. The ß-glucosidase activity was similar in soil and litter at the three locations and was not correlated to the velocity of litter decomposition. Since the abiotic environmental factors at the maritime to continental gradient did not explain the site-specific velocity of both rapidly-decomposing and refractory litter, enzyme activities related to the N cycling like arginine ammonification and urease activity were recognized to velocity of litter decomposition.