Tillage and residue management effects on arylamidase activity in soils

Recent interest in soil tillage and residue management has focused on low-i nput sustainable agriculture. This study was conducted to investigate the e ffect of three tillage systems (no-till, chisel plow, and moldboard plow) a nd four residue placements (bare, normal, mulch, and double mulch) on a mos t recently detected enzyme in soils, arylamidase activity. This enzyme cata lyzes the hydrolysis of an N-terminal amino acid from peptides, amides, or arylamides. Results showed that arylamidase activity is greatly affected by tillage and crop residue placement. The greatest activity was found with c hisel/mulch, moldboard plow/mulch, and no-till/double mulch, and the lowest with moldboard plow/normal and no-till/bare. Arylamidase activity was sign ificantly correlated with organic C (r=0.59**) and soil PHCaCl2 (r=0.55**), and decreased with soil depth. Results of this work suggest that the activ ity of this enzyme is affected by soil management, and indicate its potenti al ecological significance because of its role in the N cycle.