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Description:
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Cotton (Gossypium hirsutum , L . ) is planted on more land area than any other crop on the Texas High Plains . Much of this area is considered highly erodible and must have a conservation compliance plan to participate in government farm programs . Because this region is semiarid , water conservation and efficient water use are important aspects for maximizing cotton lint yields . One popular conservation compliance practice is to plant cotton into a chemically terminated small grain crop that provides wind protection to the growing seedlings . Our hypothesis is that in this semiarid region the use of a small grain cover crop under irrigated conditions could use more water than it conserves compared to conventionally tilled cotton , thus reducing cotton lint yields . This study was conducted during two years and on two soil textures with each soil texture study independent of the other . One was a loamy fine sand (fine -loamy , mixed , thermic , Tortertic Paleustalf ) near Brownfield , TX and the other a clay loam (fine , mixed , thermic Tortertic Paleustoll ) near New Deal , TX . The main treatments were tillage systems (conventional and conservation using terminated winter wheat residue ) . The two split plot treatments were water supply based on replacement of calculated potential evapotranspiration (PET ) . Our results indicated that residue or tillage treatments did not affect the amount of water used by the cotton crop at either location ( < 7 % difference ) except for the 80 % ET irrigation treatment at New Deal where the bare soil treatment used 10 % more water than the residue treatments for both years . The residue treatment decreased cotton lint yields at both locations (generally > 12 % decrease ) except for the 50 % ET irrigation treatment at Brownfield in 1995 where the residue treatment yielded 14 % more cotton lint than the bare soil treatment . The use of terminated wheat residue did not impact the storage of water during any part of the year . During a five -month period associated with wheat growth , the wheat used 20 to 40 mm more water than w as lost through evaporation of soil water at both locations . Our results showed that during this two -year period the use of terminated wheat residue did not benefit the water balance of cotton crops in the southern High Plains , but it did have a negative impact on the cotton yields (usually over a 12 % decrease ) . With these results , we concluded that our hypothesis is correct for the two year study in two locations . |