- Long-term yield response of corn, wheat, and double-crop soybean to tillage and N placement , AGRONOMY JOURNAL (2022)
- Nutrient Management Effects on Wine Grape Tissue Nutrient Content , PLANTS-BASEL (2022)
- Irrigated grain sorghum response to 55 years of nitrogen, phosphorus, and potassium fertilization , AGRONOMY JOURNAL (2021)
- Review of Phosphite as a Plant Nutrient and Fungicide , SOIL SYSTEMS (2021)
- Soil Fertility Management for Better Crop Production , AGRONOMY-BASEL (2020)
- Upscaling Evapotranspiration with Parsimonious Models in a North Carolina Vineyard , Agronomy (2019)
- Corn Yield and Grain Nutrient Uptake from 50 Years of Nitrogen and Phosphorus Fertilization , AGRONOMY JOURNAL (2017)
- Nitrogen and Phosphorus Fertilizer Effects on Establishment of Giant Miscanthus , BIOENERGY RESEARCH (2015)
- Micro-Bowen ratio system for measuring evapotranspiration in a vineyard interrow , AGRICULTURAL AND FOREST METEOROLOGY (2013)
- Soil fertility and fertilizers: An introduction to nutrient management , (2013)
Sufficient N supply to wine grape plants especially during veraison is required to support optimum grape yield, fruit quality, and desired flavors in the final wine product. Due to the potential for excessive vine vigor and disease pressure associated with soil applied N, wines are often N deficient during veraison, reducing concentrations of yeast assimilable N (YAN) in harvested grape and grape must. Field studies will be conducted with two varieties at Shelton Vineyards to evaluate late-season (pre-veraison) foliar N and ABA application effects on foliar and grape N concentration, in addition to grape quality components including pH, total acidity, brix, malic acid, and YAN.
Sufficient nitrogen (N)supply to wine grape plants especially during veraison is required to support optimum grape yield, fruit quality, and desired flavors in the final wine product. Due to the potential for excessive vine vigor and disease pressure associated with soil applied N, wines are often N deficient during veraison, reducing concentrations of yeast assimilable N (YAN) in harvested grape and grape must. Field studies will be conducted to evaluate late-season (pre-veraison) foliar N application effects on foliar and grape N concentration, in addition to selected grape quality components (pH, total acidity (TA), Brix, Malic acid, and YAN).
Excessive grape vine vigor as a result of environmental factors like rainfall, climate and soils is a significant concern to the Eastern wine grape industry. Wine grape producers have struggled with finding a reasonable approach to balance vine vigor management, crop yield and wine quality. Extensive research conducted in peaches in North Carolina demonstrated that peach tree growth and yield can be manipulated by managing herbicide strip width and irrigation. Additional research in peach orchards has shown that weed competition for moisture in the weeks leading up to harvest reduce fruit size. Clearly the objectives of peach production differ from wine grape production, however results from the peach studies offer insight to the possibility of easily implemented management practices having desirable effects on wine grape production. Preliminary research in North Carolina has demonstrated that weed competition and herbicide strip width can influence grape vine growth and yield.
Grapes are grown under a wide range of natural water (and climate) regimes because of their high value and desirability for many cultures throughout the world. As such, vineyard management systems must be highly diverse and locally adapted. The total amount of water available to the grape vines, naturally or through irrigation, is greatly influenced by practices in the inter-row. In arid regions such as Israel, the inter-row is typically maintained with a bare soil surface. Bare soil allows direct soil water evaporation, a net loss of water that is unnecessary for grape production and undesirable under water-limited conditions. In vineyards where annual water scarcity is not a concern such as the Southeastern U.S., the inter-rows are typically maintained with grassed surfaces. Grass transpires soil water throughout its growth cycle. This is beneficial during periods under excess water, but can be detrimental to water availability during periods when rainfall is scarce, particularly during flowering. Growers using grassed inter-rows risk significant yield loss when soil water availability fails to meet early season grape vine demand. The overarching goal of this project is to improve understanding of vineyard water management related to the critical inter-row zone. Experiments will be conducted in both moist temperate and arid regions in order to address inter-row water use under high and low water availability conditions. The intended outcome from both locations is to develop a low-input modeling tool that can be used to adapt local vineyard water management strategies (i.e. surface cover conditions) for the inter-row without the need for extensive instrumentation. Measurements will directly address practices in the Southeastern U.S. and Israel. In the Southeastern U.S. (North Carolina), specific practices for grass and bare soil inter-row management will be tested in order to develop an appropriate inter-row cover strategy to meet grape vine water needs. The work will allow fundamental improvement in a fledgling wine-grape industry. In Israel (Arad Valley), irrigation methods (above ground vs. buried or mulched drip lines) will be tested in order to estimate the potential water conservation in water management of wine-grape vineyards through minimization of soil evaporation. In view of the continuously decreasing amounts of available fresh water in the region, this work will advance water conservation practices in vineyards.
Spurred on by the demands of a burgeoning craft brewing industry, a strong public interest in locally grown ingredients, and a significant open-market price for hops (Humulus lupulus), farmers are experimenting with hops as an alternative income source. Over the past three years, growers across North Carolina have established hop yards and successfully sold their product to local craft breweries. These growers are working with information published for the Pacific Northwest hops industry, without the benefit of objective recommendations from recognized local sources with specific expertise in the regional climate and soil characteristics. The objective of this project is to help North Carolina growers identify the best performing hop cultivars, promising geographic areas for hops production, and the key issues related to nutrition, disease, and pest control. Local market conditions and production costs will also be addressed. We will accomplish this goal by continuing the research at the Raleigh experimental site while focusing our efforts on key agronomic issues in the Mountains. This proposal seeks to continue research funded during the 2010 Golden Leaf Open Grants Program cycle.
Enhanced education for agricultural and environmental professionals is needed to address increasingly complex agricultural, environmental, and ecological issues. The proposed regional distance education program will help place-bound students and professionals obtain training in science, education, and policy related to agriculture and related disciplines. While many colleges and universities in the Southern region offer distance education courses and programs, the proposed project will focused on three primary goals: 1) establish an operating structure to delivery graduate degrees throughout the southern region through distance education, 2) offer regional based graduate degrees in agricultural education and poultry science, and 3) conduct market surveys to determine additional priority graduate degree programs to offer following completion of the grant. The proposed program will create a unique opportunity for extension educators and other professionals to enhance professional skills and expertise essential to protecting the quality of our natural resources while sustaining economic opportunities. The program builds human capacity and knowledge in agriculture and the environment essential to sustaining healthy communities and the nation.
A research project entitled "Survey of Vitis Vinifera Nutrient Status in NC" has been conducted in cooperation between NC State University (John Havlin and Sara Spayd) and NC Department of Agriculture & Consumer Service (David Hardy). Results from field surveys evaluating the nutrient status in common vinifera varieties grown in the Piedmont and Mountain regions of NC indicated potential responses to P, K, B, and lime. Although survey data will be collected from several vineyards where only one year of data have been collected (2006-08 project), nutrient response studies will be conducted (2009-11). In these studies, wine grape growth response to soil applied lime, P, and K, and foliar applied B will be monitored. These data will assist in verifying the accuracy of the nutrient sufficiency guidelines developed from the 2006-08 studies and to begin development of nutrient response recommendations.
Field studies will be conducted to evaluate the nutrient status in common red and white vinifera varieties grown in the Piedmont and Mountain regions of NC. Nutrient concentration ranges in both leaf petiole and blade samples will be established, as well as the temporal changes in nutrient concentrations. Nutrient levels in tissues will be compared to soil test data collected from similar sampling areas within a vineyard. In addition, baseline reflectance data will be collected and related to tissue nutrient levels. These preliminary survey data are essential to guide vinifera management decisions and to identify future nutrient management research directions and priorities.
Confined animal production has substantially increased over the last decade, resulting in substantial quantities of nutrients accumulated on-farm. With manure rates typically based on crop N requirement, P applied in the manure is 2 to 5-fold greater than required. As a result, soil test P levels in these regions have dramatically increased, with a commensurate increase in the potential for P contamination of surface and ground water. Combustion of swine manure solids and poultry litter produces a granular animal waste by-product fertilizer [5-40-5-2 (S)]. The waste derived ash can be potentially utilized as a fertilizer P source in regions that require fertilizer P for optimum yields. In order to label and market this waste by-product as a fertilizer P source, agronomic response data are needed. The proposed project will compare corn, soybean, and wheat response to P applied as the waste ash source and conventional fertilizer. Field experiments on P responsive soils will be conducted in both eastern (field corn) and western (sweet corn) NC. At each field site, 12 treatments including 2 P sources [waste ash (5-40-5-2) and fertilizer P (0-46-0)] applied at 5 rates (10, 20, 30, 40, and 80 lbs P2O5/ac + unfertilized treatment) will be arranged in randomized complete block designs with 4 replications. Crop grain and forage yield and P content will be measured at harvest. Soils from each treatment will be sampled before treatment application and after harvest to quantify treatment effect on soil test P. Plant tissue will be sampled at three growth stages and total above ground biomass at harvest will be measured to quantify P concentration and uptake differences between P sources and rates. Results will establish treatment effects on soil test P, crop yield and P uptake, and fertilizer P recovery. Results will be widely distributed through printed and electronic formats, and field plot tours will be conducted. Project results will establishment waste ash as a viable fertilizer P source that will enable wider distribution of waste P, which will reduce localized waste P loading and the potential for P loss to surface and ground waters.