CURRENT RESEARCH:
The lab works to find socially, environmentally and economically viable pathways to enhancing urban and peri-urban food production systems by turning organic underutilized resources (OURs) into productive resources that reduce financial and environmental burdens on both producers and consumers. A variety of wasted or underutilized organic materials (by-products of the food system, urban and suburban landscapes, and the built environment) could be used to produce nutrient-rich plant growth media and carbon-rich fertilizers to support urban and peri-urban food production. We are particularly interested in serving the needs of urban community gardeners and peri-urban growers who are spatially positioned to take advantage of complementary urban and rural OURs to produce nutritious food for urban populations. The work will build on the principles of circular economy, which aims to shift economic systems from a linear “take-make-waste” model to one that minimizes waste, keeps materials in circulation, and regenerates nature. Our central proposition is to develop the theoretical, technical, and social basis for the production of OURs-based horticultural media and fertilizer products, with urine as a key source of nutrients for peri-urban crop production.
CIRCULAR BIONUTRIENT ECONOMY: KENYA
The status quo is not sustainable for agriculture, waste management, or aquatic resource management. Circularbionutrient economies integrating these fields could have profound impacts on human and planetary wellbeing. Our CBE project in Kenya will engage with a suite of partners to advance a CBE system in western Kenya and beyond. Our prior work has assessed the (large) quantities of food waste and human waste in Kisumu, the available markets for CBE products, and market opportunities for vegetables and poultry products that can drive change. We are also connected with important stakeholders who are concerned about the health of Lake Victoria. Existing linkages to a local university (Maseno University, where Prof Midega teaches) and CCRP’s regional agroecology hub at Manor House Agricultural Centre will enable current and next-generation practitioners and researchers to engage and contribute to innovation around the CBE.
To be effective in the long run, is it critical to envisage the complete nutrient cycle, from collection of material in markets, schools, households and businesses, to aggregation and transport, to transformation and finally to the sale and utilization of the product(s). At each step, there are social, technical and logistical challenges to be understood and addressed. Our lab will explore the ways in which organic waste streams can be converted into resources that enhance food production and livelihoods for people in peri-urban areas. Kisumu will serve as the initial pilot area for a longer-term effort to advance the CBE for the larger Lake Victoria basin, which includes Kenya, Uganda and Tanzania. We will work with the existing FRNs in western Kenya and eastern Uganda, facilitated through linkages with Manor House. With a range of urban, peri-urban and rural partners, we will advance CBE models that enable transformation of organic wastes into products that benefit local agroecological production across the urban-rural continuum.
Work by the Cornell group will include a desk study, geospatial analysis, and experiments that will serve as the technical basis for advancing urine-powered composting efforts and biochar-based methods for enhancing soil health. Parallel work in the USA and eastern Africa, engaging a Ugandan graduate student and the Cornell student organic farm, will also address the psychological barriers to making change in the area of CBE.
"YOU GO" GARDENING
Soil contamination often prohibits conventional crop production in urban and other areas. We desire to create a soilless growth media can be produced from NYS’ organic underutilized resources (OURs), enabling novel crop production approaches. We have explored ways of using cereal residues, compost, biochar and urine to produce horticultural media. Our experiences and desk study have highlighted the potential for raised-bed horticulture using OURs, areas requiring further research, and risks requiring management.
We will further explore the use of corn stover as a carbon source to replace peat and coir, and urine as a source of nutrients. Corn residues are the largest agricultural residue of Finger Lakes farms, accounting for 57% of byproducts. Processed dairy waste and composted food scraps are also OURs of interest.
Our hypotheses concern the evolving physical, chemical and biological properties of the media. We expect that the cereal residues and amendments used will influence the water-holding capacity and disease suppression of the matrix over time. We will determine how stover processing and input materials such as biochar, rock dust, compost and urine influence microbial succession, and thus the medium’s physical and chemical properties. Risks include mycotoxins in stover, pharmaceuticals in urine, and microbial contaminants.
SOIL FACTORY
The Soil Factory is a community art-science-activism space in Ithaca, NY. Located at 142 Ithaca Beer Dr., the space features a large warehouse, a workshop, a darkroom (non-digital), three gardens, an artist residency, and a lot of space to meet, play and work. Over the past couple of years, a dynamic and multifaceted community has grown up around the Soil Factory.
A lot of what happens at the Soil Factory focuses on sustainability, circularity and community resiliency. In the food garden, we test out formats and formulations for raised bed gardens. Work at the Soil Factory is a collaboration with the community, Johannes Lehmann, and Neil Schill of WEAVE Community.
NUTRIENT RECOVERY
A crises exists at the nexus of sanitation, agriculture, food security, water pollution and climate change, which collectively threaten the health of soils, farms, aquatic environments and people. The challenges are many and varied. Agriculture depends on synthetic fertilizer, the production of which relies on limited petrochemical and mineral reserves, and creates excessive GHGs. The unsustainability of dependency on synthetic fertilizers is acutely palpable: synthetic fertilizer prices are extremely volatile. Limited fertilizer access constrains food production and a global food crisis looms. The nutrients in excreta, if recovered, could replace much of this fertilizer. Biosolids are commonly recovered but capture only a fraction of nutrients and often contain dangerous contaminants. Evidence is emerging that PFAS-laden biosolids are irreversibly contaminating farmland. Nutrient pollution from agriculture and wastewater damages waterways, causing environmental and economic harm. However, stakeholders may distrust technological interventions and concerns about potential contamination may limit adoption of new amendments.
Process flow diagram showing how the treatments we are developing (pyrolysis, Mg enrichment, P retention, sequential NH3 and CO2 sorption, and ammonia stripping) could be integrated to produce nutrient-enriched biochar, using the liquid sidestream from wastewater treatment.
Source: Rich Earth Institute (for collaborative project)
PREVIOUS RESEARCH:
FOLIAR DISEASES
Foliar diseases take a toll on maize (corn) producers in the US and around the world, decreasing yields and provoking applications of costly, often hazardous fungicides. Our lab has studied several bacterial and fungal diseases, with a focus on northern leaf blight (NLB).
Our research has shown how different resistance loci affect different stages of pathogenesis, found pleiotropic loci for multiple disease resistance in several populations, and characterized a loss-of-function mutation that actually increases resistance to two diseases.
Past research in these areas sought to identify the genes underlying quantitative trait loci (QTL) by fine mapping and association studies; to understand the roles of specific genes and alleles in resistance by analysis of maize mutants and transgenic lines; and to explore the transcriptional and physical changes during the transition from biotrophy to necrotrophy.
Nested NILs for Genetic Association
With collaborators at NCSU and the USDA-ARS, the Nelson lab characterized a large set of near-isogenic lines, produced by Syngenta. These lines, around 1500 in total, resulted from the recurrent backcrossing of 18 mostly tropical parents of the Maize NAM (Nested Association Mapping population) into elite maize inbred B73, also the reference genome for maize.
The nested-NIL (nNIL) design offers many benefits over conventional genotypic association methods, and we have been using this population to investigate the genes and pleiotropic/linkage driven effects on other traits impacting resistance to the fungal pathogens we study.
By repeatedly crossing progeny back to recurrent parent B73, the inbred lines produced are >97% B73 in nature (hence “near-isogenic”), with localized chromosomal introgressions which contain non-B73 genetic material from one of the 18 initial parents. These introgressions span the whole genome, resulting from the homologous crossover of genetic material during meiosis. This greatly increases the power of association by reducing background noise due to population structure, an advantage over the diversity panels frequently used for GWA studies. And by including a diverse group of tropical founders as parents instead of only two parental lines, this population includes more diversity than is found in comparably sized biparental NIL or RIL populations.
For more info, check out our past NIL-related publications by Laura Morales, Judy Kolkman, and Santiago Mideros
MYCOTOXIN MITIGATION
While severe mycotoxin contamination can kill dozens, there is growing evidence that constant low-level exposure to mycotoxins can cause severe health issues, issues that may go unnoticed and unchecked.
Our survey work first documented the dangerous levels of fumonisin in the food supply of eastern and western Kenya and confirmed that traditional visual sorting did not reduce aflatoxin to a safe level.
Past research aimed both at characterizing the problem and finding effective interventions. Dr. Anthony Wenndt conducted comprehensive surveys across rural India to understand the social, agronomic, and economic drivers of mycotoxin exposure and a Gates Foundation planning grant provided support for us to develop intervention strategies to reduce mycotoxin exposure and mitigate child stunting in Tanzania.
Remote Sensing Modeling of Mycotoxins
The infection and colonization of mycotoxigenic fungi on crops is exacerbated under conditions where plants are stressed (e.g. drought) and fungi have optimal growth. We’ve used satellite-derived remote sensing datasets to identify key environmental factors that are associated with mycotoxin contamination. Modeling these relationships could be valuable to surveillance of mycotoxins, as they could help predict areas at risk of mycotoxin exposure.
The Nelson Lab has created these types of models in smallholder farming systems, which are largely unregulated and can be sites of extremely high mycotoxin levels. A barrier to this modeling is accurate ground-truthed mycotoxin data.
To address this issue, members of the Nelson Lab conducted multiple surveys of local grain mills in Kenya and Tanzania. Smallholder farmers frequent their local grain mills to process maize for household consumption or local markets. Using remote sensing data of environmental factors, we modeled the highly local variation in maize aflatoxins and fumonisins and identified spatio-temporally explicit pre-harvest growing conditions that are predictive of mycotoxin contamination (e.g. NDVI and soil carbon).
For more information see Smith et al. (2016).
Top right: Preparing maize for grinding at a local mill in Kongwa District, Tanzania.
Bottom right: Example of a remote sensing-based model predicting aflatoxin levels across Kongwa District, Tanzania.
HIGH-THROUGHPUT PHENOTYPING
For farmers, early detection of disease outbreaks can mean the difference between a successful harvest and a devastated field. For breeders and geneticists, high-throughput methods can evaluate many traits rapidly and reliably.
Together with the Gore Lab at Cornell and the Lipson Lab at Columbia University, we harnessed artificial neural networks to detect, classify, and quantify plant diseases. These algorithms were trained on large datasets of aerial images by both experts and lay-people.
This research was supported by NSF Award 1527232, “Deep Learning Unmanned Aircraft Systems for High-Throughput Agricultural Disease Phenotyping.”
GRAIN SORTING TO REDUCE MYCOTOXIN CONTAMINATION
Mycotoxins are distributed heterogeneously within a batch of maize kernels. We were interested in understanding which kernel characteristics are associated with mycotoxins and using this information to sort out contaminated kernels.
One method has been to leverage the association between small/light/low density kernels and mycotoxin contamination; with the assistance of a local inventor, John Fuchs, we have developed and tested a low-cost sorting device that uses suction to separate light and heavy kernels. Recent publications from our lab and collaborators demonstrated how this “DropSort” device effectively reduces fumonisin concentrations in contaminated maize samples (Aoun et al. 2020, Ngure et al. in prep).
Another approach has been to use reflectance spectroscopy to capture the spectral signatures of maize kernel or flour samples. Statistical models use the reflectance values across visible and near infrared wavelengths to predict the mycotoxin concentrations in a given sample. We investigated down-scaling this technology to make it feasible in resource-limited contexts (Staseiwicz et al. 2017).
