Composting Agricultural Byproducts

Why Compost? l Rapidly degrade plant and animal byproducts l Destroys weed seeds and pathogens l Reduces mass and volume of byproducts that must be stored or hauled to other locations l Increase market value of ag residues l Produces a more stable source of plant nutrients than raw manure

Why Compost? l Compost can improve cropland through addition of organic matter »improves soil structure & water retention »speeds infiltration...reduces runoff »increases cation exchange capacity and retention of soil nutrients (reduces potential for leaching) l Combining municipal yard/garden organics with livestock manure improves C:N ratio of composted materials...exactly the situation you have at the platforms near Calarasi

Why Compost? l Combining municipal yard/garden organics with livestock manure improves C:N ratio of composted materials...exactly the situation you have at the storage platforms near Calarasi

Composting Near Calarasi l Solid manure-bedding-waste is collected and stored at manure platforms l Composting can be enhanced with little extra effort l A more uniform, less odorous product will result

Elements of Successful Composting l Composting is a natural decay process carried out primarily by bacteria. l If conditions within the compost are optimal, bacteria will thrive and decay or organic matter will be rapid and thorough.

Fundamental Parameters Affecting the Composting Process l Moisture Content l Carbon:Nitrogen Ratio l Oxygen Content l Temperature l Particle Size

The “Ideal” Composting Process Compost Pile Carbon Nitrogen Inorganics Water Microorganisms O2O2 Water Heat CO 2 O rganic Matter Inorganics Microorganisms

Steam Shows the Heat Produced

Composting l Produces a humus-like final product that is »Stable »free of pathogens and plant seeds »can be beneficially applied to land as a source of organic matter and nutrients (generally low)

Moisture Content l < 40%...too dry »Insufficient moisture to transport nutrients through bacterial cell wall l >65%...too wet »Pore spaces in compost matrix that normally let oxygen in and toxic gases out, become blocked by excess water »Can lead to anaerobic conditions and odors

Adding Water With liquid from the holding tanks at your manure platforms you may be able to adjust the moisture of the compost

Carbon : Nitrogen Ratio l Too High (too little N…not enough manure in the bedding) slow decomposition l Too Low (excess N…bedding too wet with manure) ammonia released (toxic to microorganisms, mildly odorous) l Recommended C:N ratio 20:1 - 30:1 Notice wet manure on top, and dry bedding below. They are mixed to adjust both the C:N ratio and moisture

Carbon : Nitrogen Ratios for Manures l Typical C:N ranges Source: NRAES -54 Straw 200

Open Feedlot Compost Raw materials Finished compost

Oxygen l Composting consumes large amounts of oxygen »For maximum composting speed - frequent turning or mechanical ventilation necessary to achieve aerobic conditions throughout the pile at all times »Static pile composting typical of on-farm operations generally do not achieve this level of O 2, but the outer layers of the pile are kept sufficiently aerobic to maintain acceptable odor releases

Oxygen l Aerobic decay products are less odorous than anaerobic products l Aerobic decay releases much more heat than anaerobic decay »helps to maintain thermophilic temperatures

Temperature l Different compost materials produce different internal temperatures carcass surface

Temperature l Too high OR too low....slows decomposition l Biochemical reaction rates approximately double with each 10 degree C increase in temperature l Extremely high temperatures Do Not guarantee high degradation rates

Temperature l Recommended operating temperature degrees C l Temperatures above 55 degrees C kill human and animal pathogens l Temperatures above 63 degrees C kill weed seeds l Excessive temperatures call for cooling via higher aeration rates

Temperature l Temperatures exceeding 60°C cause microorganism to die or go dormant »leads to premature “shutdown” »incomplete decay »compost that will continue to decay and may produce odors upon cooling l Aeration sometimes necessary to limit maximum temperatures

Temperature l Composting will proceed during cold weather »Piles must be large enough so they don’t cool too much »Composting process must get started before the material gets cold »Do not try to compost frozen materials…it will not work

Cold Weather Composting- Weis Turkey Farm

Mixing and Turning l The compost will be mixed initially when building the row l For fastest action it should be mixed periodically based on temperature readings l If not mixed it will still compost, but more slowly than if it’s mixed

Mixing and Turning Piles that won’t be mixed should be limited in size 2 m Air

Mixing and Turning

Turning Cattle Manure Compost

Particle Size l Rate of decay depends on microbial “access” (i.e. available surface area to attack) to the organic material to be decomposed l Small particles »High surface area : volume ratio »Rapid degradation l Large particles »Low surface area : volume ratio »Slow degradation

Particle Size l Extremely small particles cause low porosity….poor gas transport through the composting material »Impedes movement of oxygen in, and CO 2 & NH 3 out l Recommended particle size range 1/8 - 2 inch diameter

Composting Systems l Non-reactor systems »Windrow »Passively aerated windrow »Aerated Static Pile l Reactor systems »Static bin »Rotating drum »Rectangular agitated bed »Silo system

Windrow

Windrow Turner

Aerated Static Pile

Bin System Concrete bins Wooden bins

Carbon : Nitrogen Ratio l Too High (too little N) slow decomposition l Too Low (excess N) ammonia released (toxic) l Recommended C:N ratio 20:1 - 30:1

Particle Size l Rate of decay depends on microbial “access” (surface area) l Small particles »High surface area : volume ratio »Rapid degradation l Large particles »Low surface area : volume ratio »Slow degradation

Compost Research at ISU

Odor Evaluation l Weekly odor samples using equilibrium chamber »during first 4 weeks of trial »collected from surface of compost piles AND cover material stockpiles l Olfactometry panel evaluation of odor threshold (strength) & odor “characterization” (what does it smell like?)

Pile Construction & Maintenance l Substantial settling, particularly during warm seasons will occur »Can lead to pile “cracking” and need for occasional “repair” (need to stockpile extra cover material) l Surprisingly little wind or water erosion noted day 45 – 1.23 m pile heightday 1 – 2.15 m pile height

Composting & Agriculture Go Hand in Hand l Virtually all food production and food processing byproducts can be composted & recycled l Soil conditioning and crop production are primary end uses for composted organics l Basic requirements for composting are generally available on the farm (land, loader, nitrogen sources, carbon sources)

Marketing Compost l Must be uniform l Must be dry and odor free l Must not contain foreign materials »Plastic »Metals »Wood

Marketing Compost l The biggest worry US farmers have about using manure is ….WEED SEEDS Proper composting (with high temperatures) will kill weed seeds

Mix When Temperature Goes Down Mixed

Winter Operation l Composting works well in the winter, as long as it’s started while it’s still warm. l Do not put frozen material into the compost piles l But…you can put cold waste on top of “cooking” compost, then mix it in.

Steam From Hot Compost NOTE: Cold weather conditions

Adding Value l By making a very high quality product you may be able to add value to your compost »Be sure it’s clean –Screen it to remove metal, plastic, wood, etc. »Be sure it’s uniformly dry »It must be odor free »It should be in easy to use containers

Granular Uniform Compost

Marketing Compost l Successful US Compost Marketers »MooDoo – Dairy farm compost »Milorganite – Milwaukee municipal sludge…has been on the market nationally for years in the US. »Cockadoodle Doo – pelleted chicken manure

Selling Compost

Dairy Farm Compost

Compost for Sale l At our local Walmart these bags of compost were for sale… »Garden Compost$1.60/cu ft »Organic Humus & Manure$1.21/40 lb l Equivalent to approx.$60/ton

Summary l Manure platforms with mixed bedding/manure/household waste should compost well l Mixing and controlling moisture will speed up the process l Good clean compost may be valuable enough to do some additional processing and bagging