Written by Jed ‘Red’ Garner
Dairy basics - Manure
Dairy basics - Manure
When we look at the future of dairy manure management with the proper perspective, we see manure as an extremely valuable resource.
For many dairymen now, manure is just waste with serious handling and waste management expenses – a liability on the balance sheet. What would it take to move manure into the asset column?
Many paths have been traveled attempting to make money out of manure, ranging from low-tech paths like spreading it on fields raw, to more intensive methods of composting, all the way to high-tech, automated anaerobic digesters for the production of energy. There are many rusting tanks and empty lagoons attesting to their results.
A 2,000-year-old process has recently been adapted as a possible solution to concerns in the dairy industry. Biochar is one of the products from the process of converting biomass (forest/municipal waste, manure, crop residue, etc.) into a carbon-rich soil amendment.
The best-known biochar is the Terra Preta (dark earth) that has been a part of agriculture for more than 2,000 years in the Amazon Basin.
Biochar is produced in specifically designed bioenergy systems that heat biomass either through pyrolysis (no oxygen) or gasification (reduced oxygen). These systems can capture the liquids, solids and gases for beneficial use.
Each element of the process can be optimized to convert what was once a costly waste stream to several value-added products – the solids as biochar, and the gases to fuel the system and produce extra power.
From pyrolysis, the liquids can range from wood vinegar to bio-oil, depending upon the process. Each technology has its benefits.
After “manure happens” at a dairy, it is conveyed to a solids separator, and then dried thermally with excess heat from the gasification or pyrolysis system.
The dried material can be directly charred or further processed to produce pyroligneous acids similar to wood vinegar before the remaining solids are charred.
In the charring process the manure is heated and the resultant gases are directed to the production of heat to sustain the process.
With pyrolysis, any excess gases can be condensed to produce bio-oil or utilized in some other function.
In gasification they are combusted to produce heat that can be used for process heat, steam or power. The nutrient-rich charred manure is biochar.
However, not all biochars are created equal. The different feedstocks and methods of producing biochar can significantly alter its beneficial properties. Depending on the process, the pH can range very low to very high.
Care must be taken to match the characteristics of the soil with the right biochar so as to not be counterproductive.
The benefits of biochar can be remarkable. Not only do we improve the soil by retaining valuable elements, this very act reduces leaching and runoff of nutrients and makes a substantial reduction in gases that are said to be plaguing the environment (methane, CO2, and nitrous oxides).
Biochar also increases soil tilth, porosity, moisture retention capacity, CEC, soil biology and fertilizer efficiency. This is not an exhaustive list, but provides some very good indications of biochar’s intrinsic value.
On top of that, the fine-grained, highly porous char is a persistent, stable form of soil organic carbon. This means that both the carbon structures and its benefits last for hundreds to thousands of years. This will benefit the asset column for a long time to come.
Even directly applying biochar to the soil can provide some of its benefits almost immediately. Yet there is a more valuable process of “priming” the biochar so that it is able to take much greater advantage of current dairy waste streams.
The first step in the biochar “priming” process works similarly to the activated charcoal in a water filter. Instead of removing undesirables from tap water, it is used to filter valuable nutrients and particulates from dairy lagoon effluent.
The biochar is also colonized by beneficial microbes from the lagoon. The biochar and effluent slurry, enriched with nutrients and microbial populations, is then incorporated back into the manure stream during composting and replaced with fresh biochar.
Priming and then composting the enriched biochar with the manure reaps additional benefits by enhancing microbial activity and reducing the normal loss of nitrogen during the decomposition process.
Utilizing the biochar this way effectively converts an already powerful soil amendment into a biologically active media that is pre-loaded with concentrated nutrients and microbial populations.
When this “primed” biochar compost is land-applied, the needed nutrients and microbials continue a synergistic benefit that could otherwise take years to fully manifest in the soil, had it not been further developed.
Business leaders, scientists, politicians, environmentalists, venture capitalists and entrepreneurs are uniting in their belief that biochar truly is the future of manure management.
It is important to keep in mind that many valuable uses have been found for biochar, yet the biochar industry is very much in its infancy.
Although very fertile, char-rich soils were described long ago, the vast majority of research pertaining to biochar has occurred in the past 10 to 15 years.
Most biochar now available is wood-sourced, as only a handful of proven technologies can produce it consistently and fewer still can handle the throughput of various manures.
Due to the infancy of the biochar industry, while large-scale biochar equipment does exist, it isn’t sitting on a showroom floor just waiting to be installed. It is best to work with an experienced reputable company who can determine the best system design to maximize the needs of your operation.
Biochar demand far outstrips the supply, which is another supporting illustration of the infancy of the biochar industry. This lack of availability has produced a fair amount of frustration among researchers and consumers alike.
As a result, many researchers have had to build their own small charring units just to produce enough specific material so they could conduct the needed research.
Dr. Collins, a USDA soil scientist, stated that he has successfully demonstrated a model of using dairy manure to produce biochar, but has been unable to find a pyrolysis unit that can process enough material to allow widespread field application.
What does this mean for our dairies and manure management? The framework of the future and our part in it are still to be determined.
While each step has been proven individually in certain scenarios, the concepts discussed here are still in the formative stages and are being shaped by the needs of industry. We are the ones defining those needs and with every decision we make, we are choosing the architecture of our future.
Will we choose to continue “handling” manure as a waste product and incurring the associated expenses? Or will we adjust our vision to begin seeing the many benefits naturally contained in one of dairy’s valuable resources?
I guess it boils down to just one simple question: Will we make it a reality, that is, will we choose to realize more value in manure to benefit the environment and our bottom line? PD
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Garner has been working with biochar and studying its potential impact for the dairy industry for two years. He has previous experience providing quality assurance and testing for a large composting operation.