Sunday, October 10, 2010

Composting for Nutrition in Blueberries

Bob Wilt
Sunset Valley Organics/ Wilt Farms is an organic blueberry farm outside of Corvallis that is owned and managed by Bob Wilt. The farm has around 75 acres of northern highbush blueberry, with varieties including Bluecrop, Jersey and Duke. The farm includes blueberry plants up to 40 years old, the original blueberry plants that Bob helped to plant with his father when the farm was started. The farm was conventionally managed up until the last decade, when Wilt Farms made the shift to organic and began using compost.

The compost at Wilt Farms is made from many different locally available waste streams, including horse, cow and chicken manure, sawdust, straw, and seed screenings. These different organic materials are mixed into long windrows where they will be turned an average of once a week with a ride-on compost turner for 12-14 weeks. The compost piles are carefully managed during the “active” phase and the mix is adjusted if the temperatures are too low or too high, and moisture added if needed. Once this active phase is done and the pile’s temperature drops below 110F the windrows are moved into a large pile and left to cure for at least 1 year before application, leaving a fine particle size for the finished product. The compost is usually applied at a depth of around 3/8” with a sawdust spreader, although the farm is currently working to fabricate their own large capacity over-therow compost spreader.

Bob has stated that for the last five years compost has been, “The cornerstone of the nutrition for our farm, so we work at it pretty hard.” He has significantly decreased the nitrogen fertilizer application rate to his fields since he began applying compost. He stated that he has seen a decrease in the amount of diseases and harmful pests, and has also seen the infiltration rate of his soil greatly increase. Bob also reports that penetrometer measurements demonstrate reduced soil compaction with compost (soil is looser) application, making it more suitable for roots