Fertility Management

Soil Preparation

Fertility management at Blue Fruit Farm started in 2008 with cover cropping the field with organic oats and wheat undersown with organic red clover seed. These cover crops were selected for their ability to scavenge nutrients, suppress weeds, and prevent erosion. Instead of harvesting these crops, they were tilled back into the soil as a green manure to maximize their soil building potential, all for the sake of our future trees and shrubs. Buckwheat followed these cover crops in the 4' wide tilled windrows. Quick growing and tender in our zone 4 climate, buckwheat is an excellent cover crop for suppressing weeds and building soil organic matter. It also makes a beautiful white blossom providing pollen to our native pollinators and lush foliage, as you can see from the photo! In addition to cover cropping, there was a fair amount of picking rocks needed in preparation years in order to provide our plants with the conditions they would eventually need to grow strong, deep roots.


Soil tests were done several times during preparation years, with the addition of a balanced mineral mix, 0-2-12, provided by Midwestern Bio-Ag based in Utica, MN. These included potassium sulfate, potassium magnesium sulfate, phosphate rock, calcium sulfate, dehydrated chicken manure, manganese sulfate, copper sulfate, borate and zinc sulfate. Sulfates were preferred due to the soil acidification they provided. We also added their Chicken Crumbles CWP Pellet 5-3-2 product, which is OMRI listed. 


Due to their preference toward acidic soil, blueberries presented a unique challenge. Addition of peat moss and composted horse manure was added to blueberry windrows to lower the pH of the soil, as well as sulfates. Incorporation of small grains as a green manure also aided in acidification. Elemental sulfur pellets are applied to blueberries as needed after soil testing for pH readings. Sulfur pellets have the advantage of slow release, so we don't burn plants and get a slow and steady lowering of the pH. We take pH readings twice a year in order to monitor the pH. Blueberries and some of our other blue fruits prefer a more acidic soil. Our soil pH started at between 6.8-7.2. We are now seeing readings of 5.0-6.5.


Ongoing Fertility Practices

When planting, more composted horse manure mixed with peat moss was added the soil around each plant. Horse manure continues to be an important source of plant nutrients at Blue Fruit Farm. Already mixed with hay and sawdust horse bedding, we source our manure from Barb Schuler in Witoka, MN. Jim actively composts this manure and clippings from mowed rows between shrubs to make our own fertilizer. You can see this nutrient rich fertilizer steaming with microbial activity! Records are kept of the turnings and temperature as per NOP Regulation for organic certification. The C:N ratio is determined by an easy-to-use online calculator.


We will continue to do soil testing annually. We have also done tissue sampling on blueberries when needed. MBA Chicken Crumbles may be added if additional nitrogen is needed, though as of the 2014 season this has not been an issue. Additional sulfur pellets will also be applied periodically to keep the pH in the 4-6 range. Occasionally we have used a kelp foliar feeding, Eco-Kelp, to give extra nitrogen to plants when they are in their initial stages of growth. Eco-Kelp is OMRI listed.