The value of crop residues for water conservation
1989
Papendick, R.I. | Parr, J.F.
The value of crop residues for water conservation depends upon several factors including the quantity, type, and placement of residues, potential evaporation, length of fallow, precipitation characteristics, tillage practices, and soil type. Studies in dryland areas of the USA show that 1000 kg/ha of grain residues left on the surface during fallow are worth up to 85 kg of wheat in terms of water conserved for the next crop. Sorghum yield increases from water conserved by residues were considerably higher. Residues are most effective for water conservation during the rainy season. After rains cease, evaporation losses from residue-covered soils can exceed those from bare soils. This effect is most pronounced with fine-textured and untilled soils. During extended dry periods, residues may provide little direct benefit for water conservation. Process-oriented soil-residue models are available for evaluating the effectiveness of residues for conserving water over a wide range of climatic conditions, and soil-and-crop management practices. While these models have manageable input requirements, some basic field experiments will be needed for validation. Future application of soil-water residue studies should give high priority to optimizing the use of residues in an integrated crop/livestock farming system
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