Year 1
Fieldwork
Participating farmers have been recruited and several hundred of suitable field sites identified across 11 states (Arizona, Georgia, Illinois, Iowa, Kansas, Michigan, North Carolina, Ohio, South Carolina, South Dakota, Utah). Soils were collected at 0-10, 10-30 and 30-60 cm depth at sites in Arizona, Iowa, North Carolina, Ohio, Utah and Virginia using a common protocol and core soil analyses are in progress including total soil carbon (C), soil organic carbon (SOC) and nitrogen (N), bulk density, soil texture, pH, cation exchange capacity, and soil-test phosphorus (P) and potassium (K). Additional secondary soil health properties and processes were included by some investigators, based on their areas of expertise. A protocol for measuring and estimating forest biomass carbon has also been created and tested preliminary at farm woodlots in Ohio.
Preliminary Results: Year 1
Great Basin Region
In Utah, the preliminary data indicated that the variability in soil bulk density decreased with sampling depth, except at the 30-60 cm depth in loamy fine sand under 35 years of grass at one farm. On average, the SOC stock tends to be higher in plots with longer years of grass and in plots with manure application, although there were some exceptions.
Midwest Region
Long-term no-till (NT) management resulted in high SOC stocks in Ohio but the NT benefit for SOC maintenance was reduced by soil erosion. Meadow land use resulted also in high SOC stocks.
International
In collaboration with the Inter-American Institute of Cooperation in Agriculture (IICA) and the Living Soils of the Americas (LiSAm) Initiative, the project team completed a literature review on C sequestration within the Americas. Communication with policy makers in the Latin American and Caribbean (LAC) region was strengthened through numerous seminars and high-level meetings.
Year 2
Fieldwork
More than 400 field sites were sampled across 11 states (Arizona, Georgia, Illinois, Iowa, Kansas, Michigan, North Carolina, Ohio, South Carolina, South Dakota, Utah) and 2 countries. Soils were collected at 0-10, 10-30 and 30-60 cm depth using a common protocol with more than 6000 soil samples retrieved in total. Core soil analyses include total soil carbon (C), soil organic carbon (SOC) and nitrogen (N), bulk density, soil texture, pH, cation exchange capacity, and soil-test phosphorus (P) and potassium (K). Additional secondary soil health properties were assessed by some investigators such as soil microbial community structure (16S rRNA amplicon sequencing). A subset of soils underwent evaluation of permittivity measurements obtained from Soil Carbon Sensing using RF Signals and Soil Images (SCARF) to validate it's capability in detecting the impact of SOC on permittivity. Fieldwork stretched into Uruguay via Instituto Nacional de Investigación Agropecuaria (INIA) to assist with identifying national vs. global trends, and to support C- farming approaches in countries with degraded soils. Spatially explicit environmental data was collected in Brazil to support the development of an SOC model. A protocol for measuring and estimating forest biomass carbon has also been created.
Modeling
The modeling team assembled geospatial datasets of soil, climate, and land use of continental US and created a regular spatial grid at 4 km across US agricultural land. The model setup includes three process-based agroecosystem models (Daycent, Ecosys, and DNDC). Additionally, a modeling framework for SOC monitoring purposes was developed for the Brazilian Cerrado region. This framework integrates remote sensing data at different temporal and spatial resolutions and a process-based model (RothC) to assess, predict, and monitor SOC changes over time.
Social Science
Three focus groups were conducted with stakeholders from Ohio, Michigan, Utah, and Oregon. Focus groups were instrumental in eliciting information about the composition of organizations involved in C-farming across the US as well as the scope of ways in which organizations collaborate to implement activities, exchange information and other resources, or otherwise interact to affect policy and management outcomes. Interactions among more than 1500 organizations participating in more than 500 C-farming-related policy forums were identified.
Outreach
Project members participated in the Farm Science Review, an annual farm show, presented by the College of Food, Agricultural, and Environmental Sciences (CFAES), aimed at highlighting the latest trends and innovation in production agriculture. The event attracts over 100000 visitors from across the US and Canada. Additionally, the very first carbon academy (CA) was held at the Controlled Environment Agriculture Research Complex at the Waterman Agricultural and Natural Resources Laboratory, targeting undergraduate Agronomy and Soil Science students. The project also completed one annual project summit and one project advisory board meeting.
Preliminary Results: Year 2
Overall
Distinct bacteria+archaea and arbuscular mycorrhizal fungi microbiomes were found in tilled and untilled soils.
Great Plains Region
In Kansas, the variability in soil bulk density decreased with increase in sampling depth indicating decreasing effect of soil and land-use management on compaction. The SOC and total soil N stocks were higher in fields with longer years under grass vegetation and in fields with a history of manure application.
Midwest Region
Enhanced C-farming practices under forage management in Ohio resulted in increases in SOC stocks by up to 25 percent compared to traditional management. Further, grazed pastures had up to 20 percent higher SOC stocks than traditionally managed hayfields. Among the best management practices to increase SOC stocks were the use of rotational grazing with well-defined grazing targets, use of complementary mixtures of forage species, overseeding and grazing of cover crops into perennial stands, and fertilization based on soil tests.
Southeastern Region
In Virginia, preliminary results suggest that well-managed grazing systems are storing at least half of SOC and total soil N amounts due to management-induced compared with pedogenic-controlled accumulation. In North Carolina, (i) soil aggregation under grazed pastures was stable at a higher level than under cropland, (ii) soil bulk density at 0-10-cm depth declined with increasing level of conservation management, (iii) water-stable mean-weight diameter was more related to soil-test biological activity than to sand fraction, (iv) high soil stability index under mature grazed pastures may help mitigate against soil erosion and nutrient loss, and (v) evidence was not supportive of rotational stocking as a practice to improve surface-soil properties. North Carolina work found the following: (i) particulate organic C was 32 percent of total SOC at 0-10-cm depth and this proportion declined with depth, (ii) ratio of root-zone enrichment to baseline non-particulate organic C was 1.0, but was 5.8 for particulate organic C, (iii) root-zone enrichment of particulate organic N was greater under grassland than under woodland and cropland, (iv) root-zone enrichment of soil-test biological activity reached 95 percent of maximum at 25 years of pasture age, and (v) root-zone enrichment of soil-test biological activity was optimized at a cattle stocking rate of 1.2 Mg live weight ha-1.
International
In collaboration with the Inter-American Institute of Cooperation in Agriculture (IICA) and the Living Soils of the Americas (LiSAm) Initiative, the project team recognizes that region-specific recommendations are needed to support higher adoption of C-farming practices. In the Latin American and Caribbean (LAC) region, monitoring changes in SOC stocks has been recognized as key to facilitating and identifying sustainable land use practices in the context of climate change mitigation, managing food security, and minimizing risks of soil degradation, among others. A modeling framework for SOC monitoring purposes was developed for the LAC region. This framework integrates remote sensing data at different temporal and spatial resolutions and a process-based model (RothC) to assess, predict, and monitor SOC changes over time. Additional testing is needed to determine whether this model can be applied in other data-scarce regions in LAC. Several webinars on soil health and carbon sequestration were presented in-person and virtually to a range of stake holders including farmers/land managers, private sector, policy makers and academicians. An attempt is also made to explore the possibility of upscaling LiSAm to Sub-Saharan Africa (LiSAf) and implement with regional cooperators such as AGRA, CGIAR centers (IITA, ICRAF, ICARDA, ICRISAT) and other institutions (APNI, FAO).