Crop residues are a great source for organic matter that can be put back into the soil. However, where there is continuous cropping, these residues can get in the way. Some farmers clean the fields and heap everything where they can be composted or burned. Other farmers may simply disc the crop residues in. Either way, they must be dealt with. In the situation where they are composted, there is an entire process and management plan spent on that. This is where we are going to discuss an alternative to composting. This is known as the "Bokashi Method" or the "EM® Method". It is a relatively fast process that results in not only providing valuable organic matter to the soil, but also all the benefits of fermentation by-products (metabolites) to help grow healthy crops and maintain healthy soils on the farm. All with significantly lower costs to the farm.
The Bokashi Methods is very similar to composting, however, there is not as much turning involved and the finished materials do not look like dirt when finished. Because there is not much turning, the materials are pickled more than they are decomposed. Pickling is a preserving process that preserves the nutrients in the materials, leaving more nutrients available for worms and plants when applied to the soil. The lack of turning not only saves the farmer a tremendous amount of money for fuel and labor and also benefits the environment as much less fossil fuels are burned to make the finished material.
Materials are gathered from the fields and put into windrows (long rows, usually over 100 feet long, 4-8 feet high and 6-12 feet wide, depending on the size of the machine used to turn the materials.) Activated EM•1® is added at a rate of 1 gallon per ton of material, molasses at the rate of 1 gallon per ton of material, and enough water to raise the moisture content to about 35%. This solution is sprayed on the rows as the materials are being mixed to ensure complete coverage in the rows. The final mix should be around 35% moisture for proper fermentation. (If done in the summer, the materials should be covered to avoid excessive evaporation and drying of the fermenting materials.)
The entire process takes about 4 weeks from start to finish. The fermentation starts when the rows are left to sit for two weeks. They are then turned once at the end of the two weeks. Moisture is checked and more water is added if needed, still maintaining the 35% moisture. Then are left to ferment for another two weeks. Note that there will not be any ammonia or foul odors from the materials, even if fresh manure was used. Following this process, there will many beneficial aerobic bacteria as well as facultative microbes that grow in the piles, including several beneficial fungi. You now have what is known as bokashi.
From here, there are a few options. The material can be spread on fields at a rate of 5 to 10 tons per acre. The materials could be left to ferment longer and turned a few more times to completely break down. Or, the materials could be inoculated with worms and turned into castings.