Cover crops and tillage influence soil organic matter and nitrogen availability in a semi-arid vineyard

Resumen

Little attention has been given to the utilization of permanent cover crops in vineyard agroecosystems in semi-arid Mediterranean climatic conditions to increase soil organic carbon or its effects on N availability. We evaluated the effect of permanent cover crops with resident vegetation on labile organic matter fractions and inorganic N availability with respect to conventional tillage in a semi-arid vineyard. The field experiment was conducted on Typic Haploxerept soil, located in La Rioja area (Central River Ebro Valley). Soil samples were collected during June 2009, 5 years after covers crops were established. Soil organic carbon (SOC), water-soluble carbon (WSC), potentially mineralizable nitrogen (PMN), nitrate (N-NO 3 -) and ammonium (N-NH 4 +) were measured. At soil depths of 0-2.5 and 2.5-5 cm the cover crops increased SOC, WSC and PMN. So the results indicated a soil quality improvement. The cover crop treatment reduced soil N-NO 3 - and increased the WSC to inorganic N ratio at 0-45 cm depth. PMN and WSC increments suggest a more active microbial biomass that could promote the immobilization and recycling of N-NO 3 -, and therefore might partially explain the reduction in N-NO 3 - pools under cover crops. © 2012 Copyright Taylor and Francis Group, LLC.