Investigating the elasticity of biochar: manure handling, compost feedstock, soil amendment and carbon storage.
Our collaborative team of beef producers, commercial composters, diversified vegetable farmers, and research and extension professionals will assess the impacts of biochar on manure handling, composting, and soil quality in western Washington. Biochar feedstocks will be sourced locally, from both coniferous and deciduous woody biomass. Two biochar products from two different locally sourced feedstocks will be added to cattle bedding at Midnight’s Farm in a controlled, replicated experiment that will assess the influence of biochar on nutrient content of the bedding feedstock. The bedding- biochar blends will then be co-composted with other on-farm feedstocks at Midnight’s Farm, which is a Department of Ecology farm-exempt facility. The finished compost will be tested for agronomic mineral concentrations, and along with compost-only, biochar-only, and no amendment control, the co-composted products will be amended to research plots on two participating farms (Lopez Harvest and Helsing Junction), and cropped to cabbage. Following the growing season, crop yield will be measured, and soils from research plots will be tested for nutrient content and carbon dynamics. Participating farms will conduct education and outreach activities related to biochar application in the form of on-farm demonstrations, workshops, outreach to other western state extension professionals, and field trips from local schools. This collaboration is especially well suited to take on this project as it combines two extension professionals from WSU, a U.C. Berkeley graduate student with farm to school educational expertise, one biochar consultant, and five producers. The combined expertise and enthusiasm of this group lends great momentum to the research question at hand: can biochar be a multi-use farm product that improves farm based co-composted products and vegetable production, and promotes soil C sequestration?
The objectives of this Professional + Producer collaboration are to answer the following questions: what are the physicochemical effects on livestock bedding when different biochars are incorporated, and then composted? Subsequently, what is the effect of biochar co-compost on promoting plant growth, soil health, and fertility? Specifically, our objectives include:
- Evaluate two different biochars, one sourced from coniferous woody biomass and the other from deciduous woody biomass, as livestock bedding additives and test whether biochar incorporation improves feedstock nutrient concentration (i.e., nitrogen). Assess whether the different bedding feedstocks (i.e., 2 different biochar blends and a control) alter the physicochemical properties of finished composts (e.g., water content and nutrient concentration).
- Demonstrate, compare, and document effects of co-compost, compost, and biochar soil amendments related to:
- Crop yield in field application
- Soil health and fertility
- Evaluate biochar as a carbon storage farming practice.
- Educate other farmers in the region interested in producing and/or applying biochar to their farming systems on how to do so and what to expect (from the feedstocks used in this trial).
- Educate other researchers and cooperative extension specialists about biochar co-compost applications and how to communicate and advise interested farmers.
The long-term goal of this project is to improve soil and water quality while sequestering carbon in soils. Our objective is to evaluate the nutrient content of two biochar blended, cow bedding feedstocks, observe and document how the resulting composts differ, and then test the different co-compost as soil amendments. We hypothesize that: 1) blending biochar into cow bedding will result in greater N retention, reducing the potential for environmental loss, 2) adding the biochar bedding blend to compost will increase nutrient content, thereby adding value to the compost product, and that 3) compost with biochar as a feedstock will lead to increased soil carbon, cation exchange capacity, and pH when applied to soil.
- The coniferous biochar is made commercially as a byproduct from Douglas fir and pine forestry residuals, heated to 870 degrees C in a low oxygen environment and sieved to a particle size of 1 – 4 mm. Deciduous biochar will be produced during the fall of 2019 with input from Forage, Shorts, and FinnRiver farms – all who have experience producing biochar. To ensure that comparisons between biochars represent feedstock differences and not those of production, manufacturing conditions for the deciduous char will be matched to those of the coniferous char.
- Currently, Midnight’s farm cows are bedded on ground wood debris where manure is incorporated. The two biochars will be integrated into the manure-handling process in a controlled, replicated (n=3) experiment. Biochar and wood debris bedding will be mixed in shallow containment vessels and manure will be collected weekly, homogenized, sampled for nutrient content and re-distributed at a known amount into each vessel during a 3-week incubation period. Following incubation, the feedstock blends will be tested for nutrients then composted (see below). To include 10% biochar (v/v) at the beginning of composting biochars will be incorporated into cow bedding at 40%; manure addition will dilute this by half and then additional composting feedstocks will dilute by half again.
- The three feedstocks (two biochar/bedding blends and one bedding control) will be moved to the composting study to determine biochar effects on compost. Bedding will be combined at a 50% (v/v) rate with other feedstocks in 1.7 cubic meter composting vessels and composted until maturity. Compost from each vessel will be analyzed using standard compost evaluation (moisture content, total N, total C, and other plant macro- and micro-nutrients). The process will be repeated 2 additional times and each of the three composts from three compost periods will be homogenized and stored until amended to soil.
- For the on-farm field experiments and prior to amendment, soils at each farm will be sampled to a depth of 15 cm and analyzed to identify obvious deficiencies or imbalances (e.g., pH); if necessary, soils will be amended accordingly (WSU researchers).
- In a randomized complete block design with four replications, the three compost products, and each of the two biochars, as-is (6 treatments, including a control), will be amended to research plots (3m x 3m) at Helsing Junction (24) and Lopez Harvest farms (24) and then tilled to a depth of 15 cm. To equalize the amount of C that is added across treatments, an application rate that is equal to 10 Mg C ha -1 will be used as the target rate which, will be calculated following compost analysis.
- To evaluate treatment effects on crop yield, research plots at each farm will be cropped to cabbage and prior to harvest, biomass from two, 1 m length sections (~ 20 plants) will be collected, counted, and then weighed. The average of the two measurements will be taken as yield (WSU researchers).
- Prior to amendment and approximately one to two months prior to harvest, soils from both sites will be collected to a depth of 15 cm, incubated for 4 days and analyzed for CO2 concentration, a reliable estimate of soil microbial activity and physical availability of carbon compounds. In addition, soils will also be analyzed for permanganate oxidizable carbon (POXC), a good indicator of C storage potential. Both methods are included as soil health indicators in the NRCS draft technical note for 2018 (WSU researchers).
- At the end of the growing season, to evaluate soil fertility, soils from all research plots will be collected and analyzed for pH, cation exchange capacity, total N, total C, and plant available N forms (ammonium and nitrate) (WSU researchers).
- The on-farm field trials are both replicated, designed experiments; the 6 treatments combined with the two soil C experiments (i.e., incubation and POXC) will help to elucidate how biochar affects existing C mechanics and thus, potential C sequestration.
- To promote the project, a brief presentation will be communicated to attendees at the Washington Organic Recycling, or Tilth Alliance, conference in the fall of 2019 and 2020.
- In 2021, the San Juan Agricultural Summit will be used as the venue for educational outreach to local farmers, and others, interested in the use of biochar. Preliminary results from the biochar/bedding experiment and the co-compost field trials should be available by this time.
- Building off the interest created at the San Juan Agricultural Summit, Helsing Junction farm in collaboration with Midnight’s and Lopez Harvest farms, will host an on-farm workshop late in the Spring of 2021 that will specifically target regional farmers, researchers and extension professionals. By this time, most data will be analyzed (e.g., survey and soil evaluations) which will allow researchers to make appropriate recommendations for effective communication strategies and on-farm use. Full results will be communicated at the Oregon Small Farms conference in February of 2022.
Educational & Outreach Activities
The project began in early December and Nathan Stacey and Doug Collins have been able to integrate descriptions of to-date, research work into two presentations. Nathan Stacey described the project at the 2020 San Juan Island Agricultural Summit, where a portion of the research is located, and Doug Collins illustrated the research in one talk at the United States Composting Council annual conference and trade show.
As mentioned above, our collaborator, Midnight’s Farm publishes a marketing and informational email newsletter where a detailed description of the project was written and communicated to recipients.
Future outreach includes highlighting the project at a regional Soil Health workshop located at Finn River farms – another collaborator – and describing the project and preliminary data at farm walk sometime during the spring. However, at the time of this reporting, the COVID-19 pandemic is having considerable impact on our ability to meet in groups. As the situation evolves, we continue to re-schedule planned events or move to virtual delivery.