Yield Response to Variable Rate Irrigation in Corn

Ruixiu Sui,Daniel K Fisher,Krishna N Reddy

doi:10.5539/jas.v7n11p11

Abstract

To investigate the impact of variable rate irrigation on corn yield, twenty plots of corn were laid out under a center pivot variable rate irrigation (VRI) system in an experimental field near Stoneville, Mississippi. The VRI system is equipped with five VRI zone control units, a global positioning system (GPS) receiver, and computer software. Each zone control unit controls the duty cycle of the sprinklers in the zone to realize variable rate water application across the pivot lateral. The GPS receiver determines the pivot position for identification of the control zone in real time. Supplemental irrigation was scheduled based on evapotranspiration (ET) estimates. A randomized complete block design was used in this study, with five irrigation rate treatments (0, 50%, 75%, 100%, and 125% of the rate determined using the Arkansas Irrigation Scheduler) and four replications. During the growing seasons in 2012 and 2013, VRI prescriptions were created based on the experimental design, and wirelessly uploaded to the system to apply varying amounts of water to each plot. The corn was machine harvested for yield. Results indicated that effect of irrigation rate on yield was not significant in 2012 and was significant in 2013. The treatment of 125% irrigation rate had the highest yield for both years. No significant yield difference between treatments in the 2012 season could be due to the sufficient rainfall in that summer. The ET estimates used in the irrigation scheduling might be lower than actual water demand of the corn crops for a higher yield.

Highlights

The Mid-South US typically receives precipitation of about 130 cm per year
The ANOVA with the average data of 2012 and 2013 seasons indicated that the effect of irrigation rate on yield was significant (p = 0.0064), the effect varied from year to year
Understanding of crop yield response to various irrigation rates is required in variable rate irrigation (VRI) practices

Summary

Introduction

The Mid-South US typically receives precipitation of about 130 cm per year. Uncertainty in the amount and timing of precipitation becomes one of the most serious risks to producers in the Mid-South. Studies have shown that supplemental irrigation in this humid region could increase crop yield and reduce crop production risk (Cassel et al, 1985; Boquet, 1989; Sui et al, 2014). Producers in this region have become increasingly reliant on supplemental irrigation to ensure adequate yields. About 90% of irrigation water in the region is pumped from the Mississippi River Valley Alluvial Aquifer. Increasing groundwater withdrawal is resulting in a decline in aquifer levels across the region (Powers, 2007)

Methods

Results

Conclusion