New Production Methods

Either application of fertilizer or additions of soil organic matter can make rice grow better. A combination of the two makes rice try to jump out of its roots.

The reason is that rice is mostly grown on poorly drained land where other cash crops give mediocre yields; consequently, it is almost impossible to use the rotations that are so successful elsewhere. The virgin soils of our rice-growing regions contain fair amounts of organic matter, but it decomposes rapidly in the warm, humid climate that rice likes. Farmers generally agree that the humus must be restored after a few years of growing rice. But how? Heavy soils deficient in organic matter are usually compact, rather impervious to water, and hard to work. Rice grown on them, moreover, often fails to respond well to commercial fertilizers or to rotations with legumes.

An attempt to correct the shortcoming is being made in Louisiana and Texas, where more than 950,000 acres of rice were grown on the coastal prairies in 1945 and where some farmers grow only rice. Other growers have both rice and beef cattle, a logical combination that controls weeds, maintains soil productivity, and provides two sources of cash income. They plant rice usually in alternate years, or once in 3 years, on land that otherwise is fallowed or left in stubble pasture. The stubble comprises volunteer red rice, native grasses, some legumes, and weeds—not very good grazing for cattle during late winter and early spring.

Few farmers use improved pastures. They, as we shall see, can solve the problem, although each farmer must decide for himself whether it will pay him.

Yields of rice in coastal Louisiana average 40 to 50 bushels an acre. At the Rice Experiment Station at Crowley, La., the average in 2-year rotations ranged from 47 bushels, following red clover, to JJ bushels an acre, following cotton which had been dusted until residual arsenic was in the soil. The average following the usual practice of alternate pasture was 45 bushels. Similar yields followed Italian ryegrass, fallow, soybeans and bur-clover, and crotalaria.

Notable results have been had in experiments with improved pastures at the station at Crowley. A mixture of Dallis grass, lespedeza, white clover, and California and southern bur-clover are sown; volunteer native grasses are allowed to stand 4 years before the land is plowed up and planted to rice. A complete fertilizer is applied at the rate of 400 pounds an acre every other year. The pasture is clipped now and then during the growing season, but the clippings are not removed. When rice is planted, 400 pounds an acre of a complete fertilizer that contains phosphorus from three sources are applied. The average yield on unfertilized plots is 57 bushels. The average on the fertilized plots, following improved pasture, is 72 bushels.

Thus, the usual system of rice and native pasture gives an average yield of about 45 bushels. Fertilizers increase that figure 5 bushels; 4 years of improved pasture between rice crops raises the yield about 12 bushels more, and fertilization, in addition to improved pasture, lifts the yield about 27 bushels. Besides, on such pastures, organic residues are returned to the soil and cause the rice to respond better to fertilizers.

Agronomists at the Louisiana Agricultural Experiment Station learned from experiments that the production of beef per acre is two to four times as much on improved fertilized pastures as on unfertilized native pastures. Improved pastures also have at least 50 percent higher carrying capacity and supply good grazing for a longer period each year. The calf crop on improved pastures is said to be a fifth greater than on ordinary pasture. Obviously, then, a more extensive use of improved pastures for grazing, with rice, promises well for the Gulf Coast section.

Further evidence on the benefits to the rice crop from additional organic matter is' given in the larger yields obtained from the application of straw in preparation for a succeeding rice crop. At Crowley, the average yield of unfertilized rice, grown in alternate years, was 47 bushels an acre. Plots on which three tons of straw were turned under in the fall yielded 52 bushels an acre; plots on which three tons of straw were turned under, plus 400 pounds of complete fertilizer (half applied with the straw and half at seeding time), gave a yield of 62 bushels. Thus, application of straw alone in alternate years increased the yield 5 bushels. Fertilizer alone usually increased the yield by the same amount. The application of both straw and fertilizer increased the yield 15 bushels, or 32 percent. The increases for the same treatments on land cropped each Year, with a yield of 38 bushels for unfertilized rice, were again 5 bushels for straw alone, and 15 bushels an acre for straw plus fertilizer.

The combine-drier method of harvesting, which is replacing the binder-thresher, leaves the straw on the fields. This is desirable, but straw stacks for winter roughage are not available to cattle grazing on stubble pastures. Thus, on combined stubble fields it is advisable to provide better winter pastures and some hay for supplemental winter feeding.

Average rice yields in California are relatively high, but on the older rice lands ammonium sulfate increases yields. Recent studies indicate, however, that the time is approaching when it probably will be necessary to use both phosphates and nitrogenous fertilizers to maintain yields.

Fertilizer experiments at the Biggs Rice Field Station in California showed that rice responds well to applications of nitrogen. Ammonium sulfate was the most profitable nitrogen carrier tested. At first, 100 pounds an acre of ammonium sulfate appeared to give the most profitable returns. Later, rates of 150 to 200 pounds were found to be more profitable. Increases in the yield of Caloro rice from the application of ammonium sulfate have averaged about 22 bushels for the 150-pound rate, bringing the average yield up to 100 bushels an acre. The early-maturing Colusa variety gave an average increase of 30 bushels an acre for the 200-pound rate, or from 64 to 94 bushels an acre, and gave a net return of about $30 an acre on the fertilizer applied. In more recent experiments on less fertile land, the average increment has been about 26 bushels for the 200-pound rate and 42 bushels for the 350-pound rate.

A vital point that the farmer weighs carefully is the relative cost of developing improved pastures and the value of the increased yields of rice and beef. When the costs of pasture development and fertilizers are high and the prices of rice and beef are low, the extra yields of rice and beef may not result in a profit. But high prices for these products and relatively low costs of improved pastures should make the practices pay. Because costs and prices vary from year to year, it usually is good practice to apply fertilizers liberally when they are relatively cheap and rice and beef cattle high.

THE AUTHOR

Since 1931 Jenkin W. Jones has been in charge of rice investigations in the Bureau of Plant Industry, Soils, and Agricultural Engineering. From 1912 to 1931 he was successively the superintendent of the Cheyenne Field Station at Archer, Wyo., superintendent of the Nephi Substation in Utah, and then in charge of the Biggs Rice Field Station in California. In 1925 he went to Japan, Korea, China, Java, and the Philippines to collect rice varieties and study methods of production and improvement. Mr. Jones is the author of various scientific publications on dry-land crops and rice.