Red clover (Trifolium pratense L.) was direct seeded into a grass sod after spraying with dalapon (2,2-dichloropropanoic acid), glyphosate [N-(phosphonomethyl) glycine], or paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) at rates of 5.6, 2.2, and 0.6 kg ai/ha respectively. Dalapon applied a few days prior to planting did not improve red clover stands in comparison to seeding in unsprayed sod. Applying glyphosate a few days prior to seeding in spring and summer invariably increased red clover stands, but paraquat was effective in only one of four spring or summer applications. Glyphosate applied the fall preceding a spring or summer seeding produced red clover stands superior to those after all spring treatments. Where glyphosate or paraquat was applied, water content of the upper 20 cm of the soil profile was greater during the first 10 days after treatment, relative to unsprayed plots or those treated with dalapon. By 30 days after application, the glyphosate-treated sods used less soil water than those treated with paraquat. Applications of glyphosate and paraquat greatly suppressed water utilization by oats (Avena sativa L.) in the greenhouse, based on water potential of the potting soil. Dalapon had little effect on water use by oat seedlings in the greenhouse.

The purpose of this paper was to quantify economic and energy use implications of new improved irrigation and limited tillage production systems for the Texas High Plains. Per hectare uses of natural gas and electricity under alternative irrigation distribution systems for corn, sorghum, wheat, cotton, and soybeans were utilized to estimate total amounts of natural gas and electricity used in the production of these crops on the High Plains of Texas. The amount of diesel fuel used was estimated for conventional and limited tillage systems under dryland and irrigation production. Total amounts of water used for the five crops under the improved and conventional irrigation systems were also estimated for the High Plains. Results indicated improved irrigation and limited tillage systems reduced energy and water use on the High Plains. Total natural gas and electricity were estimated to decline over 20 percent, diesel fuel declined 32 percent, and water use for irrigation declined about 23 percent. Use of the improved irrigation and limited tillage production systems was also shown to significantly increase annual net returns to farmers ($40.0 million or 13.3 percent).