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Joshua Heitman

Professor

Williams Hall 3410

Publications

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Grants

Date: 07/01/21 - 6/30/24
Amount: $495,359.00
Funding Agencies: National Science Foundation (NSF)

Terrestrial wetting and drying cycles keep soil water in a state of continuous transition. Soil water status, in turn, controls myriad processes including biogeochemical cycling within soil, plant- to system-level evapotranspiration, and feedback loops between land and atmosphere, among others. Capability to quantify soil water status at a point in time and space has drastically improved over the past several decades, and continues to be an area of emphasis in sensor development. On the other hand, there remain very few ways to determine soil water characteristics and hydraulic conductivity in situ. Yet, these too are dynamic, not only because they vary with soil water content, but also because they vary with the arrangement of the soil solid phase (i.e., density and structure) and its composition. Capability to predict and or interpret how soil water status at a point in time may transition to a new state (or how it arrived there from a previous state) depends on understanding how soil water characteristics and hydraulic conductivity will dictate change in soil water status under external forcing. Our objectives are to: 1) Determine co-variation in hydraulic, electrical, and thermal properties for structured and unstructured soils; 2) Develop models for prediction of soil water characteristics and hydraulic conductivity from electrical and thermal properties; 3) Evaluate hydraulic property models for prediction under transient field conditions.

Date: 09/01/20 - 8/31/23
Amount: $473,871.00
Funding Agencies: US Dept. of Agriculture - National Institute of Food and Agriculture (USDA NIFA)

The proposed project will use a chronosequence technique to evaluate changes in soil carbon storage and soil health indicators that occur over a 20 yr period from transition from conventional to organic management. Soil samples will be taken from on-farm sites that have been in organic management for a range of time and ensure and event distribution from year 0 to year 20. Soils from nearby abandoned or re-forested sites will be used as the regions maximum potential carbon accrual, while sites in year 0 or 1 of transition will be the theoretical starting point for carbon stock buildup. In addition to the on-farm trials, two intensive field experiments will be established at research stations on the coastal plains. These experiments will focus on carbon stock accrual within the first 3 years of transition from conventional to organic. Treatments will fall along a spectrum on management intensity, ranging from high intensity carbon building with organic amendments to business as usual production systems. This complementary study will allow inferences to be made around if active soil carbon building during transition can push the system further in the chronoseqenece and derive the potential benefits of increased soil health.

Date: 01/01/20 - 5/31/23
Amount: $122,594.00
Funding Agencies: NC Department of Agriculture & Consumer Services

To be widely adopted in North Carolina, a bioenergy cropping system must be compatible with existing farm practices, be productive enough to sustain an industry, and enhance environmental quality. We propose here that integrating short-rotation coppice (SRC) American sycamore for bioenergy into conventional agriculture will achieve all three goals. Our data from Butner, NC, suggests that sycamore can sustain high productivity with low inputs (no fertilizer/herbicides), may improve ag soil properties, and has shown no decrease in stool survival or productivity over two coppicing cycles (9 years). We propose here to test the generality of these results by: 1) continuing the original Butner study through a third rotation (up to12 years old), 2) expanding the study to include new ag fields near Butner and Wallace, NC, to contrast with lower coastal plain sites, 3) to work with ENVIVA to test sycamore biomass wood quality for pellet production and energy yield, 4) get input from local farmers on the potential to integrate sycamore biomass farming to produce purpose-grown feedstock for ENVIVA, and 5) quantify benefits to ag soil properties from sycamore SRC. Data will be available for use in new proposals, economic modeling, and life cycle analysis in cooperation with collaborators.

Date: 10/01/18 - 12/31/22
Amount: $3,377,183.00
Funding Agencies: US Dept. of Energy (DOE)

The Southeast U.S. needs affordable, sustainable, high-yielding, readily-convertible biomass to promote biofuel and bioproducts production. Our project team has made advances toward establishing a biomass supply chain for miscanthus, a perennial grass with superior dry matter yields, beneficial nitrogen cycling mechanisms, and physical properties conducive to multiple crop production strategies. We have developed 15 advanced, high-yielding triploid hybrids and have over 6 years' experience establishing and managing significant acreage of standard miscanthus lines to support project evaluation goals. This project will build on this experience and address these objectives: 1) Evaluate performance (above and below ground) of newly developed hybrids in different geophysical regions of NC with varying nutrient management strategies; 2) Assess production impacts on nutrient and water use efficiency, greenhouse gas fluxes, soil health and microflora; 3) Develop cost-efficient supply chains to deliver on-spec miscanthus to emerging biofuels and bioproducts producers; 4) Support Bioenergy Feedstock Library and related databases within DOE National Labs and USDA. University of Iowa Biomass Fuel Project will serve as our primary conversion technology developer for biopower and monitor end-use economics, product quality, and supply chain sustainability. Data from this miscanthus cropping system will support grower acceptance, industry needs, and environmental and economic sustainability.

Date: 10/15/21 - 7/31/22
Amount: $19,993.00
Funding Agencies: The Sunrock Group

Research to evaluate water holding and crusting of candidate soil materials produced by Sunrock.

Date: 08/01/18 - 5/31/22
Amount: $373,358.00
Funding Agencies: NC Department of Transportation

Soils disturbed by roadway construction often exhibit reduced soil porosity, precipitation storage capacity and infiltration rates, thereby yielding increased surface runoff. Poor performance of vegetation in these locations also leads to long-term aesthetic and erosion problems. Research has demonstrated that tillage can be used in conjunction with compost to improve soil conditions on disturbed, pervious areas. This year, NCDEQ formally recognized soil improvement as a stormwater best management practice (BMP). The soil improvement BMP has potential advantages to NCDOT with respect to lowering the cost of regulatory compliance while also contributing to goals such as beautification of the right-of-way via healthy landscape plantings, wildflower beds, and permanently stabilizing eroding areas caused by poor soil conditions. Given the broad applicably of soil improvement as a BMP throughout NCDOT’s transportation network, it is important to optimize soil improvement specifications to ensure the lowest-cost effective solution is achieved. There has been very little research to specifically determine optimal compost application rates to concurrently improve stormwater infiltration and/or storage, limit potential for offsite losses of nutrients and metals, and aid in timely vegetation establishment. These are all potential benefits of soil improvement BMPs, and the addition of compost at a proper rate is anticipated to be the most costly consideration for BMP implementation. The proposed research is designed to determine optimum compost amendment rates for soil improvement BMPs in North Carolina. The project will include a series of complimentary activities: i. A literature review on the performance of compost amendments, application rates and pollutant transport mechanisms. ii. Laboratory assessment of the effects of compost amendment rate on hydraulic properties of North Carolina soils. iii. Bench-scale testing of nutrient and metal losses from compost/soil blends in leachate waters at target amendment rates. iv. Greenhouse testing of vegetation establishment and performance with compost amendment at target incorporation rates. v. Field evaluation of optimized compost amendment rate effects on runoff water quantity and quality, infiltration, and vegetation establishment. vi. Development of recommended specifications for optimizing compost amendment rates for soil improvement BMPs.

Date: 05/15/18 - 4/30/22
Amount: $402,674.00
Funding Agencies: National Science Foundation (NSF)

Soils play a fundamental role in myriad global processes. The need to understand the flow of elements, energy, and water through soils is immense and widely accepted across the geosciences community. Yet, the number of scientists trained with specific soils expertise is rapidly declining. The BESST REU Site utilizes a diverse, multi-disciplinary team of scientists to deliver individualized student research experiences in state-of-the art soil science topics, synergized through unifying themes and team training opportunities. Specific objectives are to: i) recruit outstanding students without extensive previous experience in soil science, with an emphasis on those from under-represented groups; ii) train these students by providing a substantive research experience and exposure to broad opportunities in basic and environmental soil science; and iii) develop a pool of future professionals empowered to advance understanding of soils in the geoscience community. Activities are supported by a university with well-developed infrastructure for undergraduate student research, and hosted by a department with a long-standing tradition of international excellence. Student recruitment is pursued through departmental and university collaboration with undergraduate-serving institutions, HBCUs, and national undergraduate research organizations. The program is assessed by external experts to ensure that it is rigorously evaluated and didactic impact maximized. The intellectual merit of the REU Site lies in constructing a critically needed pipeline for the next generation of geoscience researchers, equipped to address wide-ranging basic and environmental research problems in soils. Broader impacts are derived from training a diverse group of students to engage in addressing important societal and ecological issues throughout their careers. The REU site seeks to develop a new paradigm for soil science, extending student recruitment and training beyond traditional foundations in agriculture, and transforming soil science into an integral part of the geoscience research community. Student research opportunities highlight relationships between human activities and terrestrial environments, which are central topics in modern soil science that are broadly applicable to many other sub-disciplines of the Earth and environmental sciences.

Date: 02/01/21 - 1/31/22
Amount: $20,838.00
Funding Agencies: NC Soybean Producers Association, Inc.

Some soybean equipment investments may have a large impact on soybean yield and growers need to know which investments are going to maximize profit in the long-run and where they have flexibility to use currently owned equipment. The most common question we get from growers about equipment regards investing in a narrow row soybean planter, typically on 15 inch row spacing. We have a lot of row spacing data in the state, but less is known about the optimal seed delivery method to achieve uniform emergence and optimize soybean yield. Growers in the Coastal Plain region also want to know if narrow row soybeans pay in their environment because they have seen wide-row ripped soybeans perform well on their farms. This project seeks to provide foundational information to growers on the equipment investments that are important in soybean production in the state. Two research studies will be conducted annually across North Carolina to address these research questions. Results will be effectively disseminated to County Extension Agents and soybean producers across North Carolina so informed equipment investment decisions can be made.

Date: 02/01/21 - 1/31/22
Amount: $4,165.00
Funding Agencies: Corn Growers Association of NC, Inc.

This proposal to to modernize Upper Piedmont Long-term Tillage experiment to ensure that the results generated from this site remain relevant to corn and soybean producers in this region. This includes maintaining 38 inch rows, but double cropping. In this year of modernization, metrics such as soil water dynamics as related to tillage and cover cropping will be documented. This site will continue to serves as an important source of information on soil health parameters.

Date: 10/20/20 - 9/30/21
Amount: $10,000.00
Funding Agencies: NC Small Grain Growers Association, Inc.

The invasive sugarcane aphid (SCA; Melanaphis sacchari) has caused major yield reductions in grain sorghum across the South and High Plains. For farmers, limited management options have severely impacted the viability of grain sorghum production. Here, we will help define approaches to minimize SCA colonization and damage. This project will focus on SCA resistant and susceptible sorghum varieties with conventional tillage or rolled winter wheat residue. Previous work in other systems have documented a consistent reduction in aphid colonization and damage for crops grown in high residues. Higher plant biomass in row middles has been shown to reduce the visual soil-crop contrast that aphids use as cues for landing. Although other research has shown this is an effective approach, few studies have extended this approach to ask if the use of rolled cover crops has the same behavioral effect on colonizing SCA. Climate change is predicted to increase the likelihood of extreme weather events. Specifically in the Southeastern U.S., rainfall is predicted to be more infrequent, and rainfall events more extreme. Maximizing the soil’s ability to receive and store water is critical in the rain-fed agricultural systems which predominate this region, to ensure the viability of future food production. The use of surface residues from cover crops or winter cash crops may decrease soil water evaporation when left on the surface as a residue. This project will also assess whether residue cover will offer a net-positive or net-negative effect on soil water balance in sorghum production, and ultimately whether residue impact yields. Lastly maximizing wheat and sorghum yields in a double crop system has potential to be an effective herbicide rotation strategy, that would increase the spectrum of management options when comparing to the more traditional wheat-soybean (24D/Dicamba) double crop. In this project, we will couple sorghum with winter wheat crops to better understand the benefit of integrating cover crops into the winter wheat-sorghum-soybean-sweetpotato production system in the Southeast. Our specific objectives are: 1) document SCA colonization in rolled wheat residue and conventionally tilled sorghum; 2) measure the additive benefit of SCA resistant varieties when coupled with rolled wheat treatments; 3) quantify soil water flux into and out of the soil in residue and non-residue treatments.


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