Understanding how the Roller-Crimper implement affects N dynamics in no-till organic systems:
Generally, soils in organic production have shown dramatic increases in organic matter and microbial biomass, in part due to the addition of organic and carbon rich sources of nutrients such as cover crops. The goal of this project is to quantify nitrogen -fixation and N-mineralization potential of 14 different legumes, including 4 hairy vetch cultivars, 4 crimson clover cultivars, 2 Austrian winter pea cultivars, and others. In non-organic systems, terminating cover crops prior to planting is mainly accomplished by the use of herbicides, however organic standards strictly prohibit the use of synthetic inputs. Along with soil nutrient management, weed control is another challenge for organic growers. Organic grain production relies on cultivation for weed control rather than herbicide use. Over the course of a growing season, organic corn and soybeans are typically cultivated 6 to 10 times, raising questions about the impacts of this practice on soil resource sustainability.
The roller-crimper is an implement technology that is showing success in allowing organic farmers in the Southeast to develop no-till grain systems that successfully terminating winter legume cover crops and controlling weeds without the aid of synthetic herbicides or cultivation. The tool works by rolling over the cover crop and crimping the stem with blades when the crop is at full bloom-killing it and forming a thick mat on the soil surface that can suppress weeds as well as contribute fixed N to soil pools as legume biomass is decomposed. The cash crop is then no-till planted into the rolled cover crop.
This project was a collaboration with Dr. Chris Reberg Horton's laboratory at NCSU and was funded by an NRCS Conservation Innovation Grant and a North Carolina Corn Growers award.
Nutrient management in Pasture Raised Pork operations in North Carolina
In recent years, consumer demand for pork products from outdoor-raised (marketed as "pasture-raised) hogs has increased substantially. Current outdoor-raised hog production systems in North Carolina differ considerably from confinement operations in that sows and piglets are raised outdoors and allowed to engage in innate behaviors of rooting, wallowing, and eating in their natural habitat. Production practices typically include a range of managerial activities that assure animal comfort and well-being, such as open space that allows for natural animal behavior and the avoidance of concrete flooring. Regardless of the merits associated with animal welfare and profitability, there are significant concerns about management of the soil resource. Many small-scale farms are overstocked and lack documented guidance on how to manage the animals in an integrated cropping/grazing system to prevent soil degradation. Growing pigs have a feed conversion rate of three to one, thus approximately two-thirds of the feed they consume ends up as waste. The concentration of manure and urine over the landscape combined with volatilization and movement through the soil profile and overland present challenges to outdoor hog managers. Our project seeks to understand the movement of soil nutrients in outdoor pig production systems in North Carolina. We will look at the effect of rotation of pigs within the paddock to more evenly distribute nutrients (N03- and NH4+) as well as reduce damage to forage vegetation.
This project was a collaboration with the Center for Envirornmental Farming Systems and was funded by a North Carolina Agriculture Foundation award and an NRCS Conservation Innovation Grant.
Julie's past projects:
The Role of Soil Organisms in Carbon Cycling in Anthropic Soils of the Brazilian Amazon
Left: The A horizon of Terra Preta soils can be up to 1 meter in depth.
Right: Oxisols are typically low in organic matter and available nutrients.
In this project we, in close collaboration with Brazilian scientists at the Centro de Energia na Agricultura, looked at how the soil microbial community influences a fascinating tropical soil system known as "Terra Preta" (Anthropogenic Dark Earth). Terra Preta (TP) soils found in the Brazilian Amazon are known for their unusually high soil C contents. It is now widely accepted that these soils were created between 500 and 2,500 years before present by indigenous pre-Colombian Indians for their own agricultural use. Since the existence of Terra Preta soils is a strong piece of evidence supporting the hypothesis of high population densities in the Amazon prior to Spanish conquest, fertility characteristics of TP soils are of great interest to scientists and local farmers as well. However, their biological properties remain a mystery. Because the carbon cycling in TP has been shown to be very different from other soils, we think that soil microbial life in TP soils will also be distinct, and characterized this diversity through our research. We used both traditional and novel molecular techniques to assess microbial abundance and diversity, including Polymerase Chain Reaction (PCR) to amplify target sequences of organism DNA, and Denaturing Gradient Gel Electrophoresis (DGGE).
Nitrogen Fixation in Organic Coffee Agroecosystems in Chiapas, Mexico
Coffee throughout Latin America is cultivated under both shaded (a traditional practice for small landholders) and unshaded (full sun and high external inputs of agrochemicals, especially nitrogen fertilizer) conditions.In the early 1970's a steady increase in coffee prices in Latin America stimulated a transformation from diverse shaded coffee agroecosystems, where many productive tree species were intercropped with the coffee plants, into homogenous coffee systems containing no trees and coffee that needed to be fed with technological packages of agrochemicals such as N fertilizers. Many of the best-preserved traditionally shaded coffee farms are found in Chiapas, Mexico. This project looked at alternatives to fertilization with synthetic N-fertilizers in Chiapas, with particular emphasis on biological nitrogen nitrogen fixation. Coffee ecosystems are agricultural systems and therefore export most of the nutrients in the harvestable products such as berries and firewood. To sustain annual yields, these lost nutrients need to be subsidized either with inorganic purchased fertilizers, or bio-fertilizers such as leguminous tree leaf litter or compost. Full sun systems require the use of chemical inputs to make up for the loss of the shade tree leaf litter that they once had. Inputs often need to be purchased from large corporations, offsetting profits of increasing yields. Many small-scale poor farmers just cannot afford the fertilizers and thus their coffee goes without the N that would possibly increase their coffee yields. Interest in the use of leguminous species for N addition in shaded systems has increased in recent years. Leguminous tree species, 'fix' N through a symbiotic association with soil bacteria and can therefore serve as a biological N addition to the system without needing purchased inputs. This is an important mechanism of bio-fertilization for farmers who are either certified organic, or are in the processing of becoming certified. Organic coffee producers are restricted from using agrochemicals, thus rely in part on nitrogen fixation to provide N to their crop. This research addressed numerous facets of N-fixation on organic coffee farms. These include farmer understanding of soil fertility enhancement processes that they use as a basis for decision-making and experimentation, diversity of N-fixing organisms that are in symbiosis with the shade tree Inga, and the effectiveness of the Inga-rhizobia symbiosis as a source of N for organic coffee.