Composting of organic or carbon-based waste materials has been utilized by humans for a long time. Egyptian and Chinese cultures have utilized reduced waste products to supplement crop fertility for thousands of years. George Washington wrote about the composting process in his memoirs when he was pursuing his love of farming. Currently many farms are using the composting process to diversify manure-handling operations.

Mike Jenson, an Elk Mound dairy farmer, began composting 18 months ago in April 2019. He has composted all his farm’s manure for 14 of those 18 months. He only skipped four months due to muddy lane conditions this past winter when we received 18 inches of snow following a thaw.

The Jenson family farm has a relatively new concrete manure pit, but it has become a complementary manure-handling system. Jenson told me he loves the compost process; the compost is easier to handle. The volume he now hauls to the fields is 75 percent less than when he was hauling and spreading all manure. He believes compost is more environmentally friendly, he said. And while this is only his second cropping season utilizing compost he can already see his feed quality increasing. His composted product has replaced the need to purchase commercial fertilizer.

Composting can be defined as a controlled aerobic method that utilizes the natural breakdown process of decomposing organic residues and solid wastes. Composting transforms raw organic-waste materials into biologically stable humic substances that make excellent soil amendments.

The composting process involves human inputs to maintain aerobic conditions that optimize internal heat and promote accelerated breakdown. The process takes advantage of naturally occurring microorganisms – fungi, earthworms, aerobic bacteria, rotifers, protozoa and other detritivores. They break down the organic material to manage the chemical process by converting the inputs into heat, carbon dioxide and ammonium.

The four major components of composting are carbon, nitrogen, oxygen and water. Certain ratios of those materials will provide microorganisms with a favorable environment to work at a rate that will heat the compost pile. Active management of the pile is needed to maintain sufficient supply of oxygen and the correct moisture level.

The air-water balance is critical to reaching and maintaining hot temperatures of 130 to 160 degrees until the materials are broken down. Achieving the hot temperature results in the composting process killing harmful pathogens and weed seeds that may be in the composting material.

Almost all organic composting materials have both carbon and nitrogen but the amounts vary widely. The most efficient composting occurs with an optimal carbon-to-nitrogen ratio of about 25:1. Composting of animal manure is gaining more acceptance as an additional handling strategy. Knowing the total carbon and nitrogen of inputs is important to starting and maintaining a successful composting process.

Properly maintained and ultimately finished compost will result in less material being hauled to the field; it can reduce the total volume by as much as 70 percent. The volume lost to the composting process is due to liquid evaporation, and carbon and ammonia volatilization. The reduced volume of the stabilized product allows for transport to fields further from the barn.

Compost has little or no odor from curing, storage or field applications. The finished compost product can be stacked, stored and transported more safely than traditional manure-handling operations. Some farm operations are using finished compost as an animal-bedding product and there’s the potential to sell the finished compost. The finished compost product has more soil-amending properties than manure, but less of a nitrogen nutrient value.

Composting of animal manure and greater-carbon bedding materials represent a great complement to traditional manure-handling systems.

Tim Boerner is a career agronomist who has worked in many regions of Wisconsin. Currently serving farmers in northwest Wisconsin, he's advising growers on Integrated Pest Management techniques, writes Nutrient Management Plans, works on composting projects, and employs GPS soil and data collection for precision-ag implementation. He has a passion for clean-water advocacy.