|Rice Rotation - 72
Project Leader and Principal UC Investigators
M.D. Miller, James Quick, K.H. Ingebretsen,Agricultural Extension Service Improved Rice Production Systems
G.J. St. Andre
Poor returns have been the rule with crops planted in the first year after
several years of rice. Plant growth and yields have been poor in barley,
grain sorghum, safflower, and wheat. Many growers therefore leave the land
fallow for the first crop year after rice.
Now, however, the cause has been shown to be plant phosphorus deficiency. Research at UC (supported partially with Rice Research Board funds) shows that the deficiency develops when the draining of flooded soils allows reduced forms of iron to oxidize. The oxidized iron then adsorbs massive amounts of soil phosphorus, withholding it from crops in the first year after several years of rice culture.
The remedy is to band phosphorus fertilizer with the seed or no more than one inch below it. Such banding in field experiments has increased barley yields by as much as 3,000 pounds per acre, grain sorghum by 1,900 pounds, safflower by 1,800 pounds, and wheat by 3,700 pounds. In such use, phosphorus fertilizer (costing $5-15 per acre) will return $20-70 per acre above the fertilizer cost. An extra million dollars a year from such use is forecast in Glenn and Colusa counties alone.
Research shows that maximum yields in the first year after rice require at east 80-120 pounds of P205 per acre, the lower rate in grayish-brown basin and lighter textured rice soils, and the higher rate in the basin and lower terrace red soils. Barley and wheat yields can be improved significantly if the phosphorus is merely broadcast and soil-incorporated, but these increases (though profitable) are not equal to the yields with banding. Ammonium-phosphate phosphorus sources give better yields and returns than monocalcium phosphate in most cases, particularly where plant phosphorus deficiency is severe. (RM2)
SUNFLOWER ON RICELANDS
A potential new crop for rice growers is sunflower as an oil crop. In field trials without irrigation in the Sutter Basin in 1972, yields were 3,000 pounds per acre. Hybrid varieties of short stature available for commercial plantings are readily combined by rub-bar harvesters with inexpensive modification.
Cultural guidelines for producing sunflowers efficiently were established in 1971 and 1972 in 14 tests on ricelands in Yolo, Colusa, Butte, Sutter, and Fresno counties. Cooperating in the trials (supported by Rice Research funds) were the vegetable-oil industry, Agricultural Extension, USDA, and the UC departments of Agronomy and Range Science, and Entomology.
Sunflower produces a highly desirable oil, an economically attractive alternate crop during the world shortage of vegetable oils. Hybrid varieties of the near future could mean a gross income of $200 per acre on riceland. (RM2)