Field studies and simulations of corn yield response to nonuniform and deficit irrigation.

다국어 초록 (Multilingual Abstract)

Three experimental field studies were conducted to evaluate an irrigation catch device (IrriGage), sprinkler irrigation cyclical nonuniformity effects on corn yield, and compare an ET-based irrigation scheduling tool (KanSched) with a crop growth model (CERES-Maize) for reduced irrigation effects on seven corn production sites under south central Kansas environmental conditions.
Field studies under three different sprinkler packages (fixed-plate, grooved-disk, FP; spinning plate, SP; and wobbling plate, WP) were conducted to evaluate the measurement accuracy of 10 cm diameter IG10 collectors in south central and north east Kansas. IG10 collectors can accurately measure irrigation depth and uniformity under SP and WP sprinkler packages but not FP sprinkler packages. Under FP sprinkler irrigation packages collectors with 15.2 cm or larger diameter openings should be considered.
Fixed-plate sprinklers produce larger droplets that are less susceptible to wind distortion and evaporative losses. One of the major concerns with these sprinkler packages is a cyclical (periodic) nonuniform irrigation pattern. A study was conducted on a coarse textured soil to evaluate the effect of cyclical, nonuniform, deficit (65% of full irrigation) irrigation on corn yield. The low uniformity treatment had a coefficient of uniformity (CU) of 79 while the other two treatments had CU's of 91 and 92. Studies in 1999 and 2000 indicated that FP sprinkler package cyclical, nonuniform irrigation applications did not result in reduced corn yield.
Field studies were conducted on 7 corn production sites to evaluate corn yield response to deficit irrigation in south central Kansas. Those data were also used to evaluate the KanSched program. That program was used to mimic the field soil water status and seasonal crop water use under deficit irrigation practices on those sites. Additionally, the CERES-Maize growth crop model was used to simulate crop water use and yield response to deficit irrigation. Overall, deficit irrigation applications reduced yield especially in drier years. The KanSched program irrigation schedule agreed with the field-based net applied irrigation amounts, but under-estimated crop water use compared to CERES-Maize. The CERES-Maize model did not mimic deficit irrigated corn yield in south central Kansas.