2019 ASHS Annual Conference

In orchards, ground cover and nutrient management strategies impact soil and tree health. Many sweet cherry orchardists manage weed competition by maintaining a bare herbicide strip in the tree row. Alternative ground cover management strategies, such as mulching can reduce weed competition and improve edaphic properties, such as soil organic matter (OM), cation exchange capacity (CEC), water infiltration, and the availability of certain mineral nutrients. In some instances, mulch applications can also increase fruit yield and tree growth. Despite these benefits, mulch is not widely applied in orchards due to availability and cost. Common orchard nutrient management strategies involve ground or foliar applications of fertilizers based on soil and leaf mineral nutrient analyses. However, there is growing interest in intensive nutrient management programs that assess and correct small changes in plant mineral nutrient status throughout the growing season. Beginning in 2017, we compared the effects of four management systems on cherry yield and quality, plant mineral nutrition, and soil quality in a commercial ‘Skeena’/ ‘Gisela 6’ cherry orchard. Management systems included: (1) Standard orchard management- a bare herbicide strip in the tree row with a standard nutrition program. (2) A single 10 cm application of mulch with a standard nutrition program. (3) A bare herbicide strip with a “bio-intensive” foliar nutrition program. (4) A combination of 10 cm of mulch and the bio-intensive foliar nutrition program. After two years, mulching or bio-intensive nutrient management did not increased cherry yield, fruit size, or soluble solids compared to the bare herbicide strip or the standard nutrition program. Mulching reduced fruit firmness by 6% compared to the bare herbicide strip. Bio-intensive nutrient management increased fruit firmness by 5% compared to the standard nutrition program. Compared to the herbicide strip, mulching reduced water infiltration time by 78% and increased soil OM by 42%. However, mulching did not affect soil active carbon or CEC. The bio-intensive program did not increase soil quality measures compared to the standard nutrition program. These results are consistent with previous research that suggests mulching can enhance soil quality, but may not increase crop yield or quality. Our result suggest that bio-intensive nutrition programs may increase some fruit quality measures, and that a single mulch application can improve soil edaphic properties after two years. However, orchardists that apply mulch should consider adjusting their irrigation regiments to maintain fruit quality.