Abstract

Population, N fertilization, and row spacing of grain sorghum were studied on Springer loamy fine sand. In the presence of adequate N, production of grain and residue increased with increasing populations. Optimum populations for both grain and residue production were between 40,000 and 60,000 plants per acre.

Maximum yields of grain and residue were obtained with 50 pounds of N, except under above-average moisture conditions and high plant populations. At populations of 40,000 plants per acre, grain and residue yields in 20-inch rows equaled or exceeded those in 40-inch rows. Increased yields with increasing populations and N rates resulted from increased water-use efficiency rather than from an increase in the amount of water used.

Plant populations had little effect on grain residue ratios. Ratios decreased with increasing N rates in one season and increased with increasing N rates in the following season.

Nitrogen content of grain and recovery of applied N in grain indicate low efficiency of applied N.

The results of this study indicate that grain sorghum, grown continuously, can produce sufficient residue to provide satisfactory wind erosion control on the easily erodible soils of the Southern High Plains. To do this, plant populations must be high (40,000 to 60,000 plants per acre) and sufficient plant nutrients must be supplied to give maximum or near maximum plant growth.

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