Biologically Integrated Farming Systems in California Rice

R. G. Mutters and J. W. Eckert

The majority of rice grown in California is cultivated in the Sacramento Valley. Over 222,750 ha of rice were planted in 1999. The soils in this region are typically heavy clays with an underlying hard pan. This makes them good soils for growing rice but not suitable for other crops. Crop rotation is not an economically viable option for many rice growers.

Rice yields in California are the highest in the world. Recent yields averaged 9000 kg/ha compared to 6000 kg/ha in the southern U.S. and about 2800 kg/ha in Southeast Asia. This is due, in part, to the use of semi-dwarf rice varieties with high harvest indexes, input of chemical fertilizers and pesticides, and precision land leveling. The conventional rice system is water-seeded with chemical control for pests. N fertilizers are applied pre-plant and as a midseason top dressing at total rates of 112 to 179 kg/ha N/acre.

Aquatic weeds are the key pests in California rice fields. The two most widely used herbicides are bensulfuron (Londax“) for broadleaf control and molinate (Ordram“) for watergrass (Echinochloa sp.) control.

An increase in herbicide resistant weed populations accounted for the recent downward trend in use of these two compounds. Conversely, increased use patterns for other herbicides (e.g. thiobencarb, Bolero“) occurred to compensate for the loss of efficacy.

Rice water weevil (Lissorhoptrus oryzophilus) is the principal insect pest in California rice fields and is controlled with carbofuran (Furadan“). An insecticide for weevil control is applied once per season and routinely on only 35% of the rice acreage. Compared to many other crops, rice production is a small user of insecticides.

Synthetic N fertilizers represent significant chemical inputs. The imminent ban on rice straw burning due to health concerns resulted in unexpected operational costs associated with the straw incorporation. However, recent University of California research demonstrated that N input can be reduced by 34 kg N/acre while maintaining yields when straw is soil incorporated. Sustainable production practices afford the opportunity for the timely reduction in two key chemical inputs: herbicides and N fertilizers. The rising cost of herbicides and their reduced efficacy, loss of crop subsidies, the implementation of the Food Quality Protection Act, and international competition necessitates the use of cost effective sustainable production strategies. Thus, the objectives of this study are to:

• Demonstrate alternative rice production strategies that address soil health, cultural control of weeds, and reduction of chemical inputs;
• Monitor trends in pesticide use;
• Compare the production costs of conventional and alternative cultural practices;
• Distribute information using a farmer to farmer extension model.

The alternative farming practices address whole-system concerns and the integration of rice cultivation into the larger landscape. Alternative practices used are based on grower experience and University of California research.

Our education and outreach effort employs a farmer-to-farmer extension model to facilitate the exchange of ideas and experiences. Active and sustained participation by growers involved in the Biologically Integrated Farming Systems project is central to the success of the program. A management team composed of a coordinator, University of California faculty, Farm Advisors, mentor growers, and a pest control advisor provides focus and structure. Outreach and education efforts include organized meetings, field visits, newsletters, and professional presentations.

This is the first year of a three-year project. During the 1999 growing season eight growers participated in the project. There were 14 side by side (conventional versus alternative) demonstration sites ranging in size from 2 to 101 ha totaling over 540 ha enrolled in the project (323 ha in alternative plus 217 ha in conventional fields). Collectively, participating growers manage over 6480 ha. Alternative practices focused on non-chemical weed control strategies, reduced use of chemical N fertilizer, and use of winter cover crops as a source of N. Some practices were replicated across location.

Fields were monitored for key production variables, such as weed populations and soil nutrients. Pesticide use information for the period of 1995 through 1998 is used as a baseline for comparison with future trends. Historical and current year production inputs and management practices were archived for all demonstration sites. This information is used for the economic analysis currently underway comparing cost effectiveness of the contrasting production strategies. Preliminary results are inconclusive as to the effectiveness of the alternative practices.

This project is supported by matching funds from the State of California and the US EPA that are administered by The University of California Sustainable Agriculture Research and Education Program (UC SAREP).

R.G. Mutters and J.W. Eckert
University of California Cooperative Extension
2279B Del Oro Avenue
Oroville, California 95965
Tel: (530) 538-7201
rgmutters@ucdavis.edu
jweckert@ucdavis.edu

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