Decomposition and Nutrient Release Dynamics of Cover Crop Materials

Project Overview

Project Type: Research and Education
Funds awarded in 1997: $41,064.00
Projected End Date: 12/31/2002
Matching Non-Federal Funds: $2,125.00
Region: Western
State: California
Principal Investigator:
Dr. Jeff Mitchell
University of California, Davis

Annual Reports


  • Agronomic: barley, cotton, sorghum (milo)


  • Crop Production: continuous cropping, cover crops, double cropping, nutrient cycling, organic fertilizers
  • Farm Business Management: whole farm planning
  • Production Systems: agroecosystems, holistic management
  • Soil Management: green manures, organic matter, soil analysis, nutrient mineralization, soil quality/health


    Replicated field studies were conducted in conjunction with the West Side On-Farm Demonstration Project during the 1998 – 99 and 1999 – 2000 winters in Five Points, CA to determine growth and decomposition characteristics of barley, vetch, Phacelia and a barley/vetch mixture. Biomass production of these cover crops from October to mid-March ranged from 8,142 lbs/acre for the barley/vetch mixture, to 4281 lbs/acre for vetch. By six weeks following incorporation or burial, 50% of the original biomass of each cover crop had decomposed, and by 16 weeks following burial, more than 80% of the biomass had decomposed. These results indicate rapid breakdown of each of these materials during spring and summer in this region.

    Project objectives:

    • The objectives of this research were:

      1. To compare potential cover crops or cover crop mixtures in terms of dry matter production and total nutrient content

      2. To monitor the loss of weight and the percentage of nutrients remaining as indicators of cover crop decomposition

      3. To compare the estimated amount of nutrients released from cover crops by the bag method vs soil sampling, and

      4. To showcase this work by holding periodic field data update meetings for interested people including local participating farmers in the West Side On-Farm Demonstration Project

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.