Introduction of Cover Crops Into Annual Rotation in Northern California

Introduction of Cover Crops Into Annual Rotation in Northern California

Summary

1. To collect and compile information on the practices currently in use for managing cover crops in annual rotations in the Sacramento Valley and Delta regions.
2. To produce a comprehensive summary of the problems associated with inclusion of cover crops in rotation with major annual crops and identify those problems and potential management options appropriate for further research.

Abstract of Results
Cover crops have many potential benefits in annual cropping systems and may enhance the sustainability of these systems. Although a significant cover crops research and extension effort has been made in California in recent years, relatively few California farmers have adopted the use of cover crops in their annual crop rotations. To address this situation, several researchers and extension personnel working with cover crops concluded that it was necessary to survey farmers about their cover cropping practices, attitudes and needs. This information will be used to set priorities for future cover crops research and education efforts and to provide information to farmers about various cover crop management options.
The survey was conducted by telephone interviews with 119 producers of annual crops in California's Central Valley. The survey questionnaire was developed by a multidisciplinary team of researchers and extension specialists with significant help and advice from county farm advisors. Of the 119 farmers surveyed, 29 grew cover crops. Compared to the non-user group, cover crop users tended to be younger, more educated and have fewer years farming experience and their farms tended to be smaller and more diverse. Cover crops were grown by eighty-seven percent of the organic growers, but only eleven percent of the conventional growers in the survey.
The survey showed that winter cover crops are preferred over summer cover crops with 88 percent of the users growing winter cover crops and 31 percent growing summer cover crops. Over 80 percent of the winter cover crop growers grew vetch cover crops and most planted their winter cover crops at about the same time. However, there was a significant amount of variation in the amount of field work performed both before and after growing the cover crops.
There were over twenty-five potential advantages of cover cropping listed by growers. Cover crop users tended to list more benefits that non-users. For both groups of growers, the most commonly stated advantages of cover crops were that they can provide nitrogen and increase soil organic matter. There were also several potential disadvantages and barriers to use of cover crops indicated by growers. The most common reasons cited for not growing cover crops were that winter cover cropping necessitated unacceptable delays in spring planting, that a cash generating crop could be grown in place of a cover crop, and that the total costs associated with cover cropping were too high for the perceived benefits.
The growers surveyed indicated a strong interest in information about cover crops. The greatest demand was for information about different types of cover crops for specific situations and/or with specific qualities and about the specific effects of cover crops on various aspects of the cropping system. Of the non-cover crops users, twenty percent indicated that they were considering trying cover crops while over two-thirds were interested in learning more about cover cropping and one third were interested in participating in on-farm research on cover crops.
This survey confirmed that relatively few growers are using cover crops, but also indicated that there is significant interest in cover crops on the part of non-users. In addition, cover crop users have a wealth and diversity of cover crop knowledge and experience which is potentially very valuable to other farmers and researchers. The information collected in this survey will be invaluable in developing research and extension priorities in the future and should prove very useful to growers wishing to learn more about various cover crop management options.

Economic Analysis
It was beyond the scope of this study to do an economic analysis of the 119 farming operations which participated in the study. However, the survey results indicated that economic play a role in growers' decision regarding cover cropping. Among some of the most frequently mentioned reasons for not growing cover crops or not growing cover crops on a higher percentage of field and row crop acreage were the belief that the overall cost of growing a cover crop was too high and the resistance to replacing a cash crop with a cover crop because of the loss of direct economic benefit

Potential Contributions
Because this project surveyed growers regarding their practices and attitudes and did not attempt to develop any new practices, it was not intended to have a direct impact on farming operations or communities. Rather, it was intended to impact research and education efforts in the future. As stated in the project proposal, the long term goal of the project was "to increase the use of cover crops in annual rotations." Because only some of the benefits of cover cropping in annual systems have been definitively documented and quantified, only a partial analysis of the effects of increasing cover cropping is possible. Based upon previous work by the project leader and others, it has been demonstrated in on-farm trials that cover cropping can significantly reduce the need for synthetic nitrogen fertilizers. This reduction can represent substantial energy savings because the production of nitrogen fertilizers requires large amounts of energy.
Based upon our previous work, cover cropping can replace approximately 150 pounds of nitrogen fertilizer per acre. Comparing the total energy use in fertilizing in a previously cover-cropped and a synthetically-fertilized crop, the cover cropped crop uses four million BTUs (or 65 percent) less energy than the synthetically fertilized crop. As pointed out by many of the growers surveyed in this study, cover crops have many other benefits related to soil tilth, soil-water relations, pest management, etc.

New Hypotheses
The two most interesting new ideas or hypotheses to emerge from this project are as follows:
1. It may be most fruitful to consider that there exist two fairly distinct groups of growers: cover crop users and cover crop non-users. These two groups appear to have different priorities and needs with regard to cover crops research and extension.
2. Future grower education projects should include experienced growers as educators. While we have previously conducted on-farm demonstrations and included growers in our educational programs, our survey results indicate that some of the more experienced growers have a wealth of information which is useful to inexperienced growers. Much of this information is not really known by researchers or even extensionists. We believe that in an area which is evolving as rapidly as cover cropping, a team effort by experienced growers and research/extension personnel, as equal partners in the educational process, has the greatest potential to effectively educate growers wishing to learn more.

Farmer Adoption
The results of the survey indicate that there is potential for much more widespread adoption of cover crops in annual systems in these regions. Twenty percent of the farmers surveyed who were not currently growing cover crops indicated that they are considering it as a viable option. The potential for higher adoption rates is also demonstrated in the high level of interest growers had in the educational activities related to cover crops in annual cropping systems.

Areas Needing Additional Study
The survey asked farmers if they had any suggestions for further research on cover crops in annual cropping systems, and if there was any information that they wanted about cover crops that was not currently available to them. The research suggestions that growers gave spanned a wide spectrum (more than forty different ideas were mentioned) and there was a lot of overlap with the responses to the question about information needs. The largest number of suggestions fell into two broad categories. The first category is that farmers want more information about new or existing cover crop varieties that can fit into a particular type of crop rotation, grow well in a particular soil or weather conditions, or possess certain characteristics (such as high biomass, fast growth, extensive root system or high nitrogen content). The second category of research and information that farmers were most interested in was the effects that cover crops have on parameters such as nutrient availability, soil structure, water use, weed composition and insect populations. Other categories of research and information suggestions that farmers gave were economic information (such as cost-benefit analyses) and operational information (such as different types of equipment and best times for planting and incorporating the cover crops).

Reported in 1995