Stemilt Hill orchardist Kyle Mathison has been able to reduce his fertilizer costs dramatically by making his own compost out of local materials.
His 750-acre orchard near Wenatchee, Washington, is planted with cherries, apples, pears, and apricots, along with some wine grapes and blueberries. About 280 acres are organic, though the plan is for the whole orchard to be organic within ten years, said orchard manager Efrain Reyes.
When Mathison started growing cherries organically, he applied chicken manure as fertilizer, at a rate of four or five tons per acre. Later, he bought compost from Canada or Yakima, Washington, but found it too expensive. It cost $64 per ton delivered, and he was using six to eight tons per acre.
Four years ago, he decided to make his own compost, which has worked out much cheaper. Now, he’s producing at least 5,000 tons of compost annually and applying it to the entire orchard, not just the organic blocks, although a little additional fertilizer is applied to the conventional blocks. It’s reduced the orchard’s fertilizer bill by about 70 percent, Reyes estimates.
During a nitrogen fertility management field day at the orchard this spring, Reyes explained how the compost is applied in a mature block of Skeena cherries. The block has a black fabric mulch in the tree row to control weeds. Up until now, the fabric has been rolled back by hand so that compost could be applied to the soil by machine, and then the cloth was put back over the compost.
Reyes said the fabric mulch costs $330 per acre, plus $100 for labor to install it and should last about ten years. Opening it up to apply the compost costs $200 per acre and moving it back and forth probably reduces the lifespan of the cloth, Reyes said.
The fabric keeps down weeds, and saves a lot of money in weed control, but mice get underneath in the winter. In the future, he intends to apply compost to the ground on either side of the fabric mulch, since the roots of the mature trees should extend into that area.
The compost is produced on site, with two full-time employees dedicated to the operation. It costs between $13 and $15 per ton to make, plus the cost of hauling it to the various orchard blocks.
The recipe includes: cow manure and spoiled hay from area farms; horse manure from stables in Wenatchee; cherry and apple leaves and debris from the Stemilt packing houses; wood chips from the Chelan County Public Utility District’s landscaping department; and spent lime from controlled-atmosphere storage facilities. The lime, which starts out as calcium hydroxide, turns into calcium carbonate as it absorbs carbon dioxide in storage and becomes solidified. It has to be ground up by machine before it can be added to the compost. It adds calcium to the mix.
The composting process takes between two and three months. The mixture must be turned every day for the first three weeks, and the temperature and carbon dioxide level are monitored every day. Then, it’s turned alternate days. For the last two weeks, it’s turned only twice a week. Water is added to maintain a 50 to 60 percent moisture level. The composting operation starts up in April and ends in November for the winter.
David Granatstein with Washington State University’s Center for Sustaining Agriculture and Natural Resources said that most organic growers use compost because it provides nitrogen at the lowest cost per pound, although other materials are available.
When done, Mathison’s compost has a nitrogen level of about 1.2 percent. Granatstein said that’s a relatively low nitrogen level, but if the cost is low enough, it can still be economical to apply higher rates to achieve the desired nitrogen level. With a carbon-to-nitrogen ratio of 40-to-1, which is relatively high, the compost is not likely to release nitrogen quickly, he added.
Often, a composting operation starts with a waste product that needs a home, but Mathison’s situation is different in that it started with a need for compost and he has to find waste products to make it from, Granatstein noted.
Reyes also applies a compost tea to the ground in spring and fall, but the tea is made from vermicompost, which he buys. Leaf nutrient analyses are done annually.