Responses of Sweet Cherry Productivity and Soil Quality to Alternate Groundcover and Irrigation Systems.

Ground and water management are two major production practices in sweet cherry production in Oregon and the Pacific Northwest. This study was designed to assess the impacts of converting micro sprinkler irrigation into double-line drip irrigation, the effects of changing no groundcover to straw mulch groundcover, and their interactions on water use, plant nutrition, fruit yield, quality, and storability of sweet cherry and soil quality. A field experiment was conducted near The Dalles, Oregon from 2006 through 2008. Two irrigation systems (micro sprinkler irrigation as the control, double-line drip irrigation) and two groundcover systems [no groundcover but herbicides were used to control weeds as the control, wheat straw mulch] were compared in a randomized complete block split-plot design with four replicates. The three-year results showed that double-line drip irrigation saved 50-57% of irrigation water compared with micro sprinkler irrigation each year. Straw mulch lowered irrigation water use by 5-16% relative to no cover each season. Fruit yields were similar for double-line drip irrigation and micro sprinkler irrigation. However, there was a trend of yield increase with straw mulch. Fruit quality including fruit size, firmness, color, titratable acidity, and sugar content did not differ significantly regardless of irrigation and groundcover system. Double-line drip irrigation showed a tendency of increasing the proportion of marketable fruit by reducing fruit surface pitting and bruising over micro sprinkler irrigation. Straw mulch seemed to enhance electric conductivity and populations of active bacteria and fungi in the soil. In summary, sweet cherry under double-line drip irrigation has the potential to significantly reduce water use while maintaining comparable productivity compared with to those with micro sprinkler irrigation. Straw mulch not only reduces irrigation water use by cherry, but also eliminates herbicide applications and improves soil quality as well relative to no groundcover.