The Last Irrigation in Durum at Buckey, Casa Grande, and Marana, 1996-97
MetadataShow full item record
AbstractBased on consumptive use, the last irrigation in wheat may be applied by the soft dough stage on the average sandy loam soil without loss of yield or shriveled grain. In two of the three locations reported here, this was the case although one of the soils was a clay loam. At the Buckeye location, applying the last irrigation at the soft dough stage resulted in a yield loss of 406 lbs /acre, but this yield loss was not statistically significant at conventional probability levels. Nevertheless, terminating irrigation at the soft dough stage is somewhat risky, and a less risky time to terminate irrigations may be between soft dough and hard dough for a sandy loam soil. The problem with this generalized recommendation is that neither soft dough nor hard dough are well -defined crop growth stages and sandy loam soils may vary greatly in their water -holding capacity. Also, it may be profitable to apply a final irrigation to carry late, green tillers to maturity. Assuming a water cost of $15 per irrigation and a grain value of $8 /cwt, a yield increase of 190 lbs /acre would pay for a final irrigation. Therefore, if water is inexpensive, terminating wheat irrigations unnecessarily early is not worth the risk of decreased revenue. Once the heads have turned color from green to brown, the crop has reached maturity and additional irrigations at this time will not affect yield even if other parts of the plant are green.