Effects of agricultural management on chemical and biochemical properties of a semiarid soil from central Spain.

摘要

Long-term agricultural management may change soil C sequestration and alter soil C and N dynamics.\udThe objective of this study was to investigate the impact of several tillage regimes with different intensity\udon C and N stocks in a Calcic Haploxeralf with a leguminous/cereal rotation under semiarid conditions\udafter 15, 18 and 21 years of management. Seven chemical and biochemical properties (total C, total N,  13C,\ud 15N, FDA hydrolysis, -glucosidase and urease activities) were measured in a soil (0-5 cm, 5-10 cm, 10-20\udcm, 20-30 cm) under the following agricultural management: fallow (F), no-tillage (NT), zone-tillage\udsubsoiling with a paraplow (ZT), conventional tillage with mould board plow (CT), minimum tillage with\udchisel plow after NT (MTN) or CT (MTC). The results showed that soil reached a steady state of organic\udmatter sequestration 15 years after starting the experiment and that C and N stocks varied greatly with\udagricultural management, particularly in the top 0-10 cm, and followed the order: F . NT . ZT > MTN .\udMTC > CT. Fallow and less intensively cultivated soils (NT, ZT) exhibited strong vertical gradients of most\udproperties analyzed (total C, total N, FDA hydrolysis, urease and -glucosidase activities) with values\uddecreasing with depth, followed by minimum tillage treatments (MTN, MTC) whereas similar values along\udsoil profile were observed in CT treatment. No significant differences in soil  13C values were detected\udamong plots with different land use or tillage systems; however, the  15N values suggested that, although\udtillage system did not affect significantly N-cycling processes, a change from “open” to “closed” N cycling\udoccurred when cultivated soils were set aside.