In April 1994, a high density commercial orchard of `Golden Delicious' apples on EMLA.9 rootstocks was planted on four acres of a 35-acre apple farm in the Yakima Valley of Washington State. The farm is managed by two brothers, Andy and Eric Dolph, who decided with our help to set aside a portion of their farm and examine the sustainability of three different apple production systems: organic, integrated (i.e., low-input), and conventional. The four-acre, nearly level study site was divided into four blocks (or replicates), with each block further split into three plots representing the different treatments. Each of the 12 plots consists of four tree rows of about 80 trees per row.
The organic treatment uses no synthetic agrochemicals and utilizes only certified organic practices as stated in Washington State Organic Crop Production Standards. The organic treatment consisted of organic mulch in 1994 and synthetic mulch plus composted chicken manure in 1995. The integrated treatment minimizes use of agrochemicals, giving priority to agroecological practices that safeguard the environment and human health as prescribed in General Principles, Guidelines and Standards for Integrated Production of Pome Fruits in Europe. The integrated treatment consisted of organic mulch plus herbicide treatment in the tree row in 1994 and herbicide treatment plus composted chicken manure and synthetic fertilizers in 1995. The conventional treatment utilizes all of the current and emerging management practices of modern apple orchards. The conventional treatment consisted of herbicide treatment in the tree row both years, plus synthetic fertilizer applications
The objectives of our project were to measure the effects of organic, integrated, and conventional apple production systems on soil productivity, crop yield and quality, and farm profitability. We took baseline field and laboratory soils data on the four-acre study site prior to tree planting (April 1994). We found that all plots had similar physical, chemical and biological soil properties. We analyzed soil samples one year later and found some differences and temporal changes in soil characteristics under organic, integrated, and