Date of this Version
Proceedings of the 24st Annual Central Plains Irrigation Conference, Colby, Kansas, February 21-22, 2012 Available from CPIA, 760 N.Thompson, Colby, Kansas
Irrigators in the western Great Plains and other irrigated regions face water restrictions caused by decreased well capacity, water allocations imposed by water policy, and/or rising energy costs. These growers require water management practices that optimize grain production. When not enough water is available to produce full yields, the goal for water management is to maximize transpiration and minimize nonessential water losses such evaporation of soil water.
It is generally believed that increasing crop residue levels leads to reduced evaporation. However, crop residue that is removed from the field after harvest is gaining value for use in livestock rations and bedding, and as a source of cellulose for ethanol production. It is important to know the water conservation value of crop residue so crop producers can evaluate whether to sell the residue or keep it on their fields.
Tillage also greatly affects the amount of residue on the soil surface. The effects of no-till and conventional tillage on soil and water dynamics are controversial. Producers have expressed concerns about production practices where high levels of crop residue are present on the soil surface. These concerns include the increased use of chemicals, and wetter soil and lower soil temperatures delaying planting and retarding plant development during early vegetative growth, and less uniform germination and emergence using planting equipment that cannot operate adequately in the residue.
However, in the semi-arid climate of the western Great Plains, vegetative growth of crops under no-till management can catch up to the growth of crops under tilled management by the reproductive growth stage. In the hot and dry summers of this environment, reduced soil temperatures and increased soil water under crop residue during and after the reproductive stage benefit the crop and outweigh the drawbacks experienced earlier in the cropping season.