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ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Livestock Nutrient Management Research » Research » Publications at this Location » Publication #112238

Title: SOIL WATER ACCUMULATION UNDER DIFFERENT PRECIPITATION, POTENTIAL EVAPORATION, AND STRAW MULCH CONDITIONS

Author
item SHANGNING, JI
item Unger, Paul

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: Little or no water from small amounts of precipitation (rain or snow) is used effectively for crop production in semiarid regions. We determined the effects of water application (simulated precipitation) amounts, potential evaporation (PE) rates, and straw mulch amounts on water storage in two soils. Straw mulching increased water storage, but the benefit decreased as sPE rate increased. Water storage was affected in order by water applicatio amount (greatest), PE rate, mulch rate, and soil clay content (least). Water storage efficiency in both soils with 5-mm water applications and 3-mm/day PE was over 60% greater with 2.0 Mg/ha mulch and over 100% greater with 4.0 Mg/ha as compared with that in bare soils. More than 10% water storage occurred in mulched, but not in bare soils with 5-mm water applications and 6-mm/day PE. With 12-mm/d PE, more than 10% water storage occurred from 10-mm applications in soil with 57% clay when mulched, but not when bare. Factors that affected evaporation influenced water storage more during the early stages of drying when a mulch was present. Evaporation was slightly greater from mulched than from bare soil in the late stage. Early evaporation rates depended mostly on PE, but later they depended more on amount of water applied and soil water storage. Soil clay contents had little effect on early evaporation rates, but were related positively with accumulative evaporation in the late stage. Factors that reduced evaporation or increased water storage also increased soil wetting depth. Straw mulching has potential for increasing soil water storage and, therefore, crop production from small amounts of precipitation.

Technical Abstract: Effectiveness of small precipitation amounts is low for crop production in semiarid regions. We determined water application (simulated precipitation) amount, potential evaporation (PE) rate, and mulch effects on water accumulation in two soils. Mulching increased water accumulation, but its benefit decreased with increasing PE. Water accumulation was affected in order by water application amount > PE > mulch > soil clay content. Mulching at 2.0- and 4.0-Mg ha**-1 increased storage efficiency of 5-mm water applications by more than 60 and 100%, respectively, in both soils with 3-mm d**-1 PE. More than 10% water storage occurred in mulched, but not in bare soils with 5-mm water applications and 6-mm d**-1 PE. With 12-mm d**-1 PE, >10% water storage from 10-mm applications occurred in soil with 57% clay when mulched, but not when bare. Factors that affected evaporation had a greater influence on water accumulation during the early stages of drying when a mulch was present. Evaporation rates were slightl higher for mulched than for bare soil in the late stage. Initial evaporation also depended on PE, but late-stage evaporation depended more on amount of water applied and on accumulated water. Soil clay contents affected early evaporation rates slightly, but were correlated positively with accumulative evaporation in the late stage. Factors that reduced evaporation or increased water accumulation also increased soil wetting depth. Straw mulching has potential for increasing soil water storage from small amounts of precipitation.