Water for irrigation has been and will continue to be limited by drought as well as urban and industrial growth in semiarid South Texas and Mexico. Conservation tillage is being considered as an alternative to conventional cropping methods to reduce input costs, improve soil properties and enhance sustainability. Conservation tillage may also reduce water use. Effective planting techniques in order to get a good stand, and weed control are proving to be significant challenges when converting to conservation tillage in this subtropical environment. Crop yields are comparable for both tillage systems when these challenges are met. Initially crop water use is affected only slightly by cropping system. Water infiltration can be greatly improved when residues remain on the soil surface compared to freshly tilled land. This benefit is only realized, however, when an occasional heavy rainfall is received. Improvements in soil physical properties are difficult to retain due to rapid mineralization which occurs under good moisture and high temperatures of irrigated agriculture in a subtropical environment. Cool season cover crops enhanced organic residue without greatly increasing water consumption. However, how much this increases soil organic matter and improves soil properties has not yet been determined. Double cropping under conservation tillage has been found to be difficult due to planting problems caused by inconsistency in surface residues and soil moisture.
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See more of The ASA Southern Regional Branch (June 19-21, 2005)