|Residue Incorporation - 72
Project Leader and Principal UC Investigators
F.E. Broadbent, R.S. Rauschkolb,Rice Residue Management by Soil Incorporation
R.A. Kepner, T.H. Burkhardt, Machinery and Costs for Soil Incorporation of Rice Straw and Stubble
RESIDUE-INCORPORATION EFFECTS ON YIELDS
Should a grower choose to incorporate his rice residues, that won't change his nitrogen fertilization needs in the succeeding year. In two long experiments, no matter what residue management was tried (burning or various degrees of soil incorporation), response to succeeding nitrogen fertilization was the same. Yields were not affected by straw management at UC Davis or in experiments at the Geer ranch. (At neither place had stem rot yet become a contributing factor.) Manipulation to give sufficient soil contact can speed the decomposition of rice residue to the point that nitrogen need not be added to the straw in the spring. (RM7)
For information on interrelations between disease and yields with various straw-management methods under conditions favoring stem rot, see the section on "Stem Rot Disease."
Incorporation is easiest and most effective when straw is chopped into short lengths and spread reasonably uniformly. Results have been good with a shear-bar field forage harvester with added spreader, adjusted to chop straw from the combine windrow into pieces mostly 1 1/2 to 4 inches long. Straw usually isn't shortened enough for easy incorporation if one uses impact-type flail or rotary shredders, including currently available shredder attachments for combines.
In 1971-72, several incorporation systems were compared with burning plus conventional tillage in regard to the types and numbers of operations required from harvest through seedbed preparation in the next spring. Research is continuing. (RM11)