Page Banner

United States Department of Agriculture

Agricultural Research Service

Title: On-Farm Assessment of Soil Quality in California's Central Valley

Authors
item Andrews, Susan
item Mitchell, Jeff - UNIV. OF CALIFORNIA DAVIS
item Mancinelli, R - UNIV. OF TUCIA, ITALY
item Karlen, Douglas
item Hartz, Tim - UNIV. OF CALIFORNIA DAVIS
item Horwath, Willi - UNIV.OF CALIFORNIA DAVIS
item Pettygrove, G. - UNIV.OF CALIFORNIA DAVIS
item Scow, Kate - UNIV.OF CALIFORNIA DAVIS
item Munk, Dan - UNIV. OF CALIFORNIA

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 10, 2001
Publication Date: N/A

Interpretive Summary: The intensification of high-value, large-scale crop production in the San Joaquin Valley of California has resulted in more frequent tillage, fewer additions of organic matter to the soil and, for some, a perceived decline in soil quality. We examined the use of several potential soil quality enhancing practices with farmer participation and on-farms research sites. The practices included in the study were determined by each cooperator but all included organic matter additions such as cover cropping, animal manure application and compost use. Several soil fertility and organic matter measures were significantly higher in the experimental fields after three years. In addition, a longer-term comparison of an established organic and an adjacent conventional field at one farm revealed significant differences in 16 of 18 soil quality measures. We used the results from this farm to demonstrate a soil quality index. Using the index, the organic system received a significantly higher soil quality score than the conventional system. Results from this study suggest that despite intensive tillage and a hot, semi-arid environment, significant changes in soil quality occur when a variety of practices that add organic matter to soils are implemented. Both the organic amendment practices and the index method to track soil quality changes have potential for sustainable soil resource management in these irrigated production systems.

Technical Abstract: The intensification of high-value, large-scale crop production in the San Joaquin Valley of California has resulted in more frequent tillage, fewer additions of organic matter to the soil and, for some, a perceived decline in soil quality. Our objective was to examine the effects alternative soil management practices, including use of cover crops, composts, and manure applications, on various soil quality indicators. To increase farmer participation and outreach, we conducted the study on farms using several crop rotations common to the region. Data from a number of soil properties showed significant differences as a result of organic amendment treatments including soil organic matter (SOM), total nitrogen (TKN), microbial biomass C and N, exchangeable K, Oslen-P, and extractable Fe, Mn and Zn. A longer-term comparison of an established organic and an adjacent conventional field at one farm revealed significant differences in 16 of 18 soil quality indicators. Demonstration of a soil quality index for this farm scored the organic system significantly higher than the conventional system. Results from this study suggest that despite intensive tillage, significant changes in several potential soil quality indicators occur when a variety of practices that add organic matter to soils are implemented. This is especially important considering the changes were positive even in the hot, irrigated, semi-arid environment of the San Joaquin Valley, California.

Last Modified: 8/21/2014
Footer Content Back to Top of Page