Luke Gatiboni

The Science and Technologies for Phosphorus Sustainability (STEPS) Center is a convergence research hub for addressing the fundamental challenges associated with phosphorus sustainability. The vision of STEPS is to develop new scientific and technological solutions to regulating, recovering and reusing phosphorus that can readily be adopted by society through fundamental research conducted by a broad, highly interdisciplinary team. Key outcomes include new atomic-level knowledge of phosphorus interactions with engineered and natural materials, new understanding of phosphorus mobility at industrial, farm, and landscape scales, and prioritization of best management practices and strategies drawn from diverse stakeholder perspectives. Ultimately, STEPS will provide new scientific understanding, enabling new technologies, and transformative improvements in phosphorus sustainability.

Producers are pushing the boundaries of traditional management strategies to achieve their high-yielding soybean goals. Best management practices help some soybean yields of NC to exceed 70bu/A while the historical statewide average yield of soybean mark 35 bu/A level. However, intensive agricultural practices may not provide long-term sustainability in increasing soybean yield levels. Achieving high yields and improving soil properties may differ substantially for each region of NC and require excellent field conditions and hence site-specific and climate-smart management strategies. Especially increasing need for agricultural products, and expensive and limited fertilizer inputs due to global issues require improvements in currently available management strategies like cover cropping and reduced or no tillage. Recently, management practices like those provide minimum disturbance, maximum soil coverage, economically profitable carbon farming, and restore or maintain soil health are critical. This research aims to develop site-specific cover crop and tillage practices where we can get the most benefit from interactions between cover crop and tillage applications to provide high economical return and enhanced soil health conditions. We will conduct plant and soil analysis including soil physical properties, microbial activities, N fixation, soybean yield, and biomass. We will also conduct an economic analysis and carbon credit evaluations. To conduct this project, we will hire a graduate student for 3 years co-sponsored with this grant and startup from department support by Crop and Soil Sciences Department. We are also requesting financial support for field supplies, travel costs, and soil and plant analysis associated with the project.

A notable upsurge in societal and regulatory awareness about per- and polyfluoroalkyl substances (PFAS) is in process due to their persistence, widespread distribution in the environment, and potential human-health impacts. North Carolina (NC) is one of the most affected states among the 50 in the United States. Considering the current state of PFAs contamination in drinkable water in North Carolina, a multi-site study is proposed here. The objectives are to look at exposure to multiple PFAS at sites across the North Carolina; conduct an experiment in growth chambers, using different biochar and PFAS levels added to soils collect in NC and AZ; and a field study will test biochar on contaminated fields, in selected Research Stations at NC.

Soil salinization due to salt-water intrusion is an increasing problem in agricultural fields along the coast of North Carolina (NC). Farmers these regions are changing cropping systems and even abandoning fields due to the advancement of this issue. This research aims to quantify the reduction of soybean yields with the increase in the soluble salts index (SS-I) measured within the soil. We propose to create a simple method by which the farmer can measure the SS-I in their soil and predict the potential yield loss, thus helping guide management decisions specific to the value of soybeans grown in salt affected fields. This scale will be developed for both salt-tolerant and sensitive soybean varieties. A greenhouse trial will also be setup to determine the tolerance of soybeans to soils saturated with salts driven by coastal flooding and storm surge commonly associated with hurricanes. The trial will test the impact that salt water concentration and duration of exposure have on plant survival. This information will help growers better understand where, and to what extent, to expect soybean damage resulting from storm surge and flooding from canals. As part of this proposed research we have secured funding for stipend and tuition of a M.S. student. The student is fully sponsored by a Fulbright Program and the NC State Crop and Soil Sciences Department for a total of $62,000 over two years. To cover the expenses with the research activities, we are requesting from the NC Soybean Producers Association $17,294 in year 1, and $15,294 in year 2 to cover costs with supplies associated with the field and greenhouse trials, travel, technician support, and soil/plant analysis.

A flux gradient tower is currently being installed at the Tidewater Research Station in Plymouth NC. This systems allows for full field scale measurements of a variety of parameters. The field will be divided into four large quadrants each about ~8 acres in size. A trailer will be located at the center of the plots. Air intake towers will be placed in the center of each quadrant and air will be pulled into a trailers containing analyzers. Carbon dioxide (CO2), nitrous oxide (N2O), water vapor, evapotranspiration, net radiometry, soil moisture and soil temperature will be measured continuously throughout the year. In addition, background soil carbon stocks will be measured and at harvest crop yield, nitrogen uptake and residual soil nitrogen will be determined. This is planned as a 4-year study examining crop rotation management decisions. The following treatments are planned: 1. Business as Usual: Corn - Soybean - Corn - Soybean 2. Sustainable intensification: (Crimson Clover)- Corn-Wheat-Soybean-(Crimson Clover)-Corn-Wheat-Soybean 3. Cover Crop in Rotation: (Crimson Clover)-Corn-(Cereal Rye)-Soybean-(Crimson Clover)-Corn-(Cereal Rye)-Soybean 4. Continuous Corn: Corn-Corn-Corn-Corn This design allows for in-depth assessment of several corn growers identified priority areas. Including the use of cover crops as an N source in corn, the soil carbon sequestration potential of either double-cropping in rotation or using cover crops compared to business as usual corn-soy rotation. The continuous corn allows for an upper baseline of soil carbon sequestration due to the biomass being returned to the soil and also likely an upper baseline for nitrogen dynamics including nitrous oxide emissions and N leaching when compared to more complex rotations. Water budgets can be generated with technology in place, allowing for an assessment of water use dynamics over the 4 year period. Deep soil cores in at end of season will provide insights on N leaching as impacted by cover cropping. Corn will be harvested with yield monitor and grain N uptake will be measured. The 2023 season will be the corn phase of rotation and support is requested for an assessment of baseline soil carbon stocks, in-season nitrogen release dynamics of crimson clover in treatments 2 and 3, in-season N movement assessment after large rainfall comparing fertilizer only N application vs N fertilizer + cover crop N, corn tissue N for nutrient use efficiency assessments and end of season residual soil nitrogen. This is a one-of-a-kind experiment in the southeast and provides a true measure of GHG emissions and crop water use dynamics at a field scale. With the continued push for growers to consider climate-smart practices there is a great need for regional field scale assessments to ensure that these practices maintain or improve productivity in these systems.

This project will support efforts by cooperative extension agents to diagnose specific crop nutritional or disease problems in corn. This project is requesting $1,000 to fund a limited number of samples to be submitted by cooperative extension agents for analysis at the NCDA&CS Agronomic Division plant tissue lab, and at the NCSU Plant Disease & Insect Clinic.

Starter fertilization is one of the most important practices related to soil fertility management for corn. Many studies conducted in in North Carolina and in other regions of the United States show that starter nitrogen (N) is a key factor to ensure good yields. Commonly phosphorus (P) is also part of the starter fertilizers, however, there are mixed results regarding its benefit. The main factor seems to be related to the initial soil test P level, where soils with lower fertility are more likely to respond to starter P than soils with high soil test P levels. However, it is not clear what level of soil test P the starter P becomes unnecessary. Additionally, there are some fertilizer additives claimed to increase the P efficiency but there is a lack of studies testing its efficacy. To explore what would be the best strategy for starter fertilization for corn we will conduct trials in soils with medium, high, and very high soil test P levels testing treatments with no starter, starter N, starter N + P, and starter N + P + P-additive. We also will test starter fertilizer placement, comparing starter dribbled over the row and starter applied at 2x2 using coulters. We are asking to the Corn Growers Association of North Carolina $19,812 to cover costs with equipment purchases, supplies, and services related to the proposed trials.

This research and extension project will evaluate the yield of various soybean varieties to various soil water conditions. Excessive soil water, deficit soil water and adequate soil water condition will be considered. In addition, the project will evaluate the nutrient use of the varieties under each soil water scenario. This information will provide valuable data for variety selection and in season nutrient needs given observed and expected soil water conditions for individual farms.

Soil test calibration is a continuous process required to maintain up to date recommendations of fertilizers for different crops. Average crop yields are increasing yearly basis due to use of best management practices and the development of new varieties. NC State University is maintaining three long-term trials to check if phosphorus and potassium fertilizer recommendations based on soil testing are still adequate. The three long-term trials testing rates of phosphorus and potassium fertilizers are located at Tidewater Research Station (TRS), Peanut Belt Research Station (PBRS), and Piedmont Research Station (PRS). In one location, also poultry litter and levels of pH has been studied. These trials were initiated in 1966 (TRS), 1982 (PBRS), and 1985 (PRS), and they have been tested every year with row-crops, generally with a soybean-corn rotation. These trials are extremely important for checking if our recommendations are adequate or if increases in the fertilizer rates due to increasing yields are needed. This proposal had support from Corn Growers Association in 2021/2022, with a budget of $4,412 for supplies (travel, seeds, fertilizers, chemicals) and services (soil and plant tissue analysis); a graduate student was also funded. Starting in the next season, we will no longer have a graduate student working on this project, and thus field activities will be conducted by the research technician of our group. In this proposal, we are requesting $11,700 to cover two months of salary and wages for our technician.

On-farm trials will be used to measure mitigation of nitrous oxide and ammonia emissions from nitrogen fertilization of corn with and without the use of a urease and nitrification inhibitor. Control plots receiving zero N will be used to examine inherent soil health in the system and supply power relative to corn yields.