2017 ASHS Annual Conference

A soil health survey of perennial strawberry (Fragaria x ananassa) fields in New York in 2012 indicated that many had low biological soil health scores. A major difference between strawberry and other row crop production practices in the same location is the use of straw mulch for winter protection, weed suppression and prevention of soil splashing on fruit. We hypothesized that incorporating straw mulch with a high C:N ratio in perennial strawberry fields decreases biological soil health and could lead to depressed yields. We incorporated 14.5 kg dry weight of three soil amendments with differing C:N ratios into a field in October 2013, prior to planting strawberries in May 2014. Treatments were sawdust (344 C:N), wheat straw (93), grass clippings (19) and a control. Amendments were incorporated both shallowly and deeply, with four replications of each treatment combination. Treatments were maintained over two fruiting seasons with additional amendment applied after harvest and incorporated in fall, 2014 and 2015. After the 2016 harvest, straw mulch in one half (16) of the plots was incorporated at renovation, whereas straw on the other half was removed before renovation. Two sheets of 1.5 oz row cover were used for winter protection each year. Fruit was harvested in 2015, 2016 and 2017. In addition, soil respiration, potential mineralizable N, bulk density and soil pH were monitored in each of the treatments. Although tillage depth had no effect on yield, straw mulch incorporation significantly suppressed total yield by 22 and 17% in 2015 and 2016, respectively. Differences in yield were not associated with measured soil biological or physical attributes. If differences exist in the 2017 harvest, we will have strong evidence that straw mulch incorporation is detrimental to strawberry production, although the mechanism will likely still remain unclear. Alternative management practices may be warranted.