Location: Crops Pathology and Genetics Research
Title: Cover Crops Enhance Soil Organic Matter, Carbon Dynamics and Microbiological Function in a Mediterranean Vineyard Agroecosystem Authors
Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 11, 2008
Publication Date: October 1, 2008
Citation: Steenwerth, K.L., Belina, K.M. 2008. COVER CROPS ENHANCE SOIL ORGANIC MATTER, CARBON DYNAMICS AND MICROBIOLOGICAL FUNCTION IN A MEDITERRANEAN VINEYARD AGROECOSYSTEM. Applied Soil Ecology. Vol. 40, Issue 2, pp359-369. Interpretive Summary: We investigated how agricultural management practices influence soil organic matter content and soil C dynamics. Impacts of tillage and cover crops on soil carbon dynamics, soil organic matter content, and microbiological function were studied in a vineyard in California’s Mediterranean climate. We 1) compared soil organic matter (SOM), C dynamics and microbiological activity of two cover crops with cultivation, and 2) evaluated seasonal effects of soil temperature, moisture, and precipitation on soil C dynamics. Soils from two different cover crop treatments and a cultivated treatment were sampled biweekly Nov. 2005 – Nov. 2006. Few differences in cover crop tissue C content and soil C dynamics between cover crops existed, but labile C pools and carbon dioxide emissions were consistently 1.5 - 4 fold greater than in ‘Cultivation’. Cover crops were more effective at adding soil C than ‘Cultivation’. Despite similar labile soil C pools, annual emissions of CO2 and aboveground plant tissue C content between the two cover crops, greater aboveground net primary productivity and SOM in the cover crops had different potentials for increasing soil organic matter content and soil C storage.
Technical Abstract: Impacts of soil tillage and cover crops on soil carbon (C) dynamics and microbiological function were investigated in a vineyard grown in California’s Mediterranean climate. We 1) compared soil organic matter (SOM), C dynamics and microbiological activity of two cover crops [Trios 102 (Triticale x Triosecale), (‘Trios’), Merced Rye (Secale cereale), (‘Rye’)] with cultivation (‘Cultivation’), and 2) evaluated seasonal effects of soil temperature, moisture, and precipitation on soil C dynamics (0-15 cm depth). From treatments established in Nov. 2001, soils were sampled every two to three weeks from Nov. 2005 – Nov. 2006. Gravimetric water content (GWC) reflected winter and spring rainfall. Soil temperature did not differ among treatments, reflecting typical seasonal patterns. Few differences in C dynamics between cover crops existed, but microbial biomass C (MBC), dissolved organic C (DOC), and carbon dioxide (CO2) efflux in ‘Trios’ and ‘Rye’ were consistently 1.5 - 4 fold greater than ‘Cultivation’. Cover crops were more effective at adding soil C than ‘Cultivation’. Seasonal patterns in DOC, and CO2 efflux reflected changes in soil moisture, but MBC displayed no temporal response. Decreases in DOC and potential microbial respiration (RESPmic) (i.e., microbially-available C) also corresponded to or were preceded by increases in CO2 efflux, suggesting they provided C for microbial respiration. Despite similar MBC, DOC, RESPmic, annual CO2 efflux and aboveground C content between the two cover crops, greater aboveground net primary productivity and SOM in ‘Trios’ indicated that ‘Trios’ provided more soil C than ‘Rye’.