Crop Residue Management

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Summary by:

Mel Androus, manager, Rice Research Board


The inauguration of the comprehensive Rice Research Program in 1969 by the California rice industry was motivated by the industry's need, through research, to increase its efficiency and competitive ability. Although variety improvement was given top priority, research on how to turn crop residues into an economically useable asset was a close second because growers wanted to reduce their dependence on field burning as a crop. residue disposal method.

Beginning in 1969, and every year since, the research program has included residue management projects conducted by scientists and engineers from the University of California in Davis and Berkeley and from the USDA in Davis and at the Western Regional Research Center in Albany, California.

Care was used to make certain Rice Research Board projects complemented or supplemented research on the rice residue management under way by the California Air Resources Board and the Solid Waste Management Board.

Since 1969, your Rice Research Board has invested $500,000 on residue management research. When background research such as that on plant breeding to create varieties which produce less straw and the cost of facilities to conduct research at the Rice Experiment Station, at UCD, and in the field by U.C. Cooperative Extension farm advisors are included, the total is about $4.4 million.

The many areas investigated have included straw handling systems, improved field burning techniques, and the long-term effects that incorporating rice straw into the soil have on yield and crop pests. The research-developed technique of into-the-wind, strip burning of rice fields has helped cut emissions by 40 to 50 percent.


Table 1. Rice Research Board Sponsored Residue Management
Research, 1969 - 1980

Research Area Project/years*
Effects of residue (including hulls) management practices on yield, diseases, and insect pests 12
Machinery requirements and costs for incorporation 8
Methods of gathering rice straw for feed and energy production and other uses 11
Reducing environmental emissions by developing improved burning methods for rice straw and stubble 6
Treating rice straw to improve its feed value and feeding tests with sheep, dairy and beef cattle 7
Converting rice straw into commercially useful products
       a. Sugar syrup, yeast and protein             (2)
       b. Paper and cloth                                   (2)
Economic analysis of residue management and alternatives to open field burning of rice straw 2
* In some years more than one project was funded in some areas. On an average, five residue management projects were funded each year.

Use Outlook Changing

The outlook for utilization of rice straw is changing rapidly because of the escalating cost of fossil fuels and competitive products such as wood chips. Your Rice Research Board is funding a literature review to find out what is going on around the world on rice residue management. We also are increasing study of the economics of straw removal for various uses, including the manufacture of building materials and pulping for making paper and cloth. More projects are on the drawing boards, including field tests of gasification of rice straw to generate electricity on the farm.

We have baled 46,000 bales of straw for research use. Numerous requests for the straw have come from both private industry and government researchers. The use for energy seems to be the most studied; however, other uses also look promising. California Solid Waste Management Board engineers were given 40,000 bales for experiments with their new mobile pyrolyzer which is designed to make fuel oil, gas and char from straw and lumber wastes.

Rice growers are going through an interesting period. We hope our urban neighbors will give us needed time to develop straw management alternatives so we can minimize burning. At this time we believe there will not be one use for rice straw but several. We do maintain, however, that burning must always be retained as an alternative for sanitation of fields badly infected with disease. Also, substantial rains could make it impossible to remove straw front the fields in many areas, and that straw must then eventually be burned. In addition, there will always be the problem of weedy drainage ditches, levees, and straw that cannot be picked up because it is knocked down by the tracks of combines and bank out wagons.

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