The Effect of Irrigation Scheduling and Manure Application on a Sweet Corn/Guar Intercrop

Maximizing resource utilization in the semi-arid region of the Texas High Plains is a critical goal. When an input like drip irrigation is supplementing precipitation, intercropping is a cultural practice that can increase resource capture. A greenhouse study and a two year field study were conducted in 2013 and 2014 to determine the suitability of intercropping sweet corn (Zea mays var. saccharata) with guar (Cyamopsis tetragonoloba). The factorial design of the greenhouse experiment had three replications, three cropping treatments of sole sweet corn, sole guar and the intercrop of those two, and two watering treatments. The sole sweet corn produced 21% more green ear yield (GEY, unhusked ears) than the intercropped sweet corn. The lower watering treatment (LOW) produced twice as many ears than the higher watering treatment (HI), but the HI treatment produced 52% more sweet corn GEY than the LOW treatment. At the WTAMU Nance Ranch near Canyon, TX, the factorial design of the field experiment had four replications, three cropping treatments of sole sweet corn, sole guar and the intercrop of those two, two drip irrigation levels and two manure application rates of 22 Mg ha-1 yr-1 and 67 Mg ha-1 2 yr-1. In 2014, sweet corn fresh ear yield (FEY, husked ears) was higher in the sole sweet corn (0.67 Mg ha-1) compared to the intercropped sweet corn (0.27 Mg ha-1). In 2013, the higher manure rate produced 62% higher total FEY than the lower manure rate, but no differences were observed between the manure application rates in the second year. In 2013, the highest weed dry matter (DM), 5.72 Mg ha-1, was measured in the sole guar treatment with 4.41 and 3.13 Mg ha-1 of weed DM measured from the intercrop and sole corn, respectively. As a result of this study, intercropping sweet corn and guar to maximize resource utilization, improve productivity and control weeds in the Texas High Plains is not recommended.