@article{carvalho_aguilos_ile_howard_king_heitman_2023, title={Water use of short-rotation coppice American sycamore (Platanus occidentalis L.) for bioenergy during establishment on marginal land in the North Carolina Piedmont}, volume={276}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2022.108071}, abstractNote={American sycamore (Platanus occidentalis L.) is a hardwood species that can be integrated into short-rotation coppice (SRC) production systems for bioenergy in the southeastern USA. Due to high growth rates and low input requirements, sycamore is regarded as a promising second-generation bioenergy woody crop suitable for degraded or marginal lands. However, little is known about sycamore water use for the conditions of North Carolina (NC), especially during the establishment year when trees are most sensitive to soil water deficits. We evaluated energy fluxes and actual crop evapotranspiration (ETc act) rates of sycamore SRC during the establishment year on marginal land in the Piedmont physiographic region of NC. Our overall goal was to better understand the factors controlling the evaporative demand of sycamore and its sensitivity to drought stress during establishment. Total ETc act was 482 mm, which was 95% of the total rainfall at the site. ETc act rates increased with precipitation and with tree development, reaching a maximum of 5.7 mm d−1. Although severe water stress was not observed during the study period, a moderate drought occurred from mid-August to mid-September, during which a 13-day drying cycle caused ETc act rates to decrease by 30%. The sycamore SRC transitioned from an “energy-limited” to a “water-limited” ETc act regime when water content in the upper 5 cm of soil was about 0.10 m3 m−3, indicating that the sycamore field relied on water available within the upper soil layers. Measurements suggested that trees may not yet have developed a root system sufficient to sustain transpiration during dry spells and that water use of the sycamore field was highly coupled to precipitation during the establishment year.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Carvalho, Henrique D. R. and Aguilos, Maricar M. and Ile, Omoyemeh J. and Howard, Adam M. and King, John S. and Heitman, Joshua L.}, year={2023}, month={Feb} }
 @article{havlin_austin_hardy_howard_heitman_2022, title={Nutrient Management Effects on Wine Grape Tissue Nutrient Content}, volume={11}, ISSN={["2223-7747"]}, url={https://doi.org/10.3390/plants11020158}, DOI={10.3390/plants11020158}, abstractNote={With limited research supporting local nutrient management decisions in North Carolina grape (Vitis vinifera) production, field studies (2015-17) were conducted to evaluate late season foliar nitrogen (N) application on leaf and petiole N concentration and yeast assimilable N (YAN) in the fruit. Foliar urea (1% v/v) was applied at different rates and application times beginning pre-and post-veraison. Compared to soil applied N, late season foliar N substantially enhanced petiole N and grape YAN. Smaller split N applications were generally more effective in increasing YAN than single larger N rates. These data demonstrate the value of assessing plant N content at full bloom with petiole N analysis or remote sensing to guide foliar N management decisions. Additional field studies (2008-11) were conducted to evaluate pre-bud soil applied phosphorus (P) and potassium (K) effects on petiole P and K nutrient status. Fertilizer P and K were initially broadcast applied (0-896 kg P2O5 ha-1; 0-672 kg K2O ha-1) prior to bud-break in 2008-09 and petiole P and K at full bloom soil test P and K were monitored for three to four years after application. Soil test and petiole P and K were significantly increased with increasing P and K rates, which subsequently declined to near unfertilized levels over the sampling time depending on site and P and K rate applied. These data demonstrate the value of annually monitoring petiole P and K levels to accurately assess plant P and K status to better inform nutrient management decisions.}, number={2}, journal={PLANTS-BASEL}, author={Havlin, John L. and Austin, Robert and Hardy, David and Howard, Adam and Heitman, Josh L.}, year={2022}, month={Jan} }
 @article{rivers_heitman_mclaughlin_howard_2021, title={Reducing roadside runoff: Tillage and compost improve stormwater mitigation in urban soils}, volume={280}, ISSN={["1095-8630"]}, DOI={10.1016/j.jenvman.2020.111732}, abstractNote={Soils adjacent to urban surfaces are often impaired by construction activities that degrade the natural structure and function of the soil, resulting in altered physical, hydraulic, and vegetative properties that limit the infiltration, storage, and filtration of stormwater runoff. A management approach to enhance the efficacy of vegetated roadside soils for runoff control is the use of compost in conjunction with tillage to improve soil conditions and facilitate improved hydrological function, the establishment of vegetative biomass, and increased nutrient and pollutant attenuation. The purpose of this study was to determine the efficacy of soil improvement measures to reduce runoff volumes and improve water quality along roadsides over time. The effects of tillage with and without compost on 1) bulk density and infiltration rates, 2) runoff volumes, and 3) runoff water quality were evaluated during multiple storm events along two long-established interstate roadsides in North Carolina during 2015 and 2017. Experimental plots were established in the grassed areas adjacent to roads and consisted of an untreated control, tillage only, and tillage amended with compost. Tillage alone did not reduce runoff in roadside soils, however, tillage with compost did improve runoff capture. The patterns in hydrologic performance within and among sites suggests that the incorporation of compost in tilled soils may influence storage potential through different effects on soil properties, such as decreasing bulk density or improving vegetation establishment, thereby increasing evapotranspirative withdrawals, depending on soil texture. Tillage increased sediment concentrations in runoff, however, net export of sediments was reduced with the inclusion of compost due to the reduction of runoff quantities compared to undisturbed areas and tillage alone. Control and treatment plots were equally effective in reducing dissolved nutrient and metal concentrations, however, the improved hydrologic performance in plots with compost decreased net nutrient and metal export in most storms. The results of this study suggest that the incorporation of compost in compacted urban soils may provide significant improvements for biological and physical soil properties that affect stormwater interception and infiltration.}, journal={JOURNAL OF ENVIRONMENTAL MANAGEMENT}, author={Rivers, Erin N. and Heitman, Joshua L. and McLaughlin, Richard A. and Howard, Adam M.}, year={2021}, month={Feb} }
 @article{dold_heitman_giese_howard_havlin_sauer_2019, title={Upscaling Evapotranspiration with Parsimonious Models in a North Carolina Vineyard}, volume={9}, ISSN={2073-4395}, url={http://dx.doi.org/10.3390/agronomy9030152}, DOI={10.3390/agronomy9030152}, abstractNote={Water stress can positively or negatively impact grape yield and yield quality, and there is a need for wine growers to accurately regulate water use. In a four-year study (2010–2013), energy balance fluxes were measured with an eddy-covariance (EC) system in a North Carolina vineyard (Vitis vinifera cv. Chardonnay), and evapotranspiration (ET) and the Crop Water Stress Index (CWSI) calculated. A multiple linear regression model was developed to upscale ET using air temperature (Ta), vapor pressure deficit (VPD), and Landsat-derived Land Surface Temperature (LST) and Enhanced Vegetation Index (EVI). Daily ET reached values of up to 7.7 mm day−1, and the annual ET was 752 ± 59 mm, as measured with the EC system. The grapevine CWSI was between 0.53–0.85, which indicated moderate water stress levels. Median vineyard EVI was between 0.22 and 0.72, and the EVI range (max–min) within the vineyard was 0.18. The empirical models explained 75%–84% of the variation in ET, and all parameters had a positive linear relationship to ET. The Root Mean Square Error (RMSE) was 0.52–0.62 mm. This study presents easily applicable approaches to analyzing water dynamics and ET. This may help wine growers to cost-effectively quantify water use in vineyards.}, number={3}, journal={Agronomy}, publisher={MDPI AG}, author={Dold, Christian and Heitman, Joshua and Giese, Gill and Howard, Adam and Havlin, John and Sauer, Tom}, year={2019}, month={Mar}, pages={152} }
 @article{kustas_agam_alfieri_mckee_prueger_hipps_howard_heitman_2018, title={Below canopy radiation divergence in a vineyard: implications on interrow surface energy balance}, volume={37}, ISSN={0342-7188 1432-1319}, url={http://dx.doi.org/10.1007/s00271-018-0601-0}, DOI={10.1007/s00271-018-0601-0}, number={3}, journal={Irrigation Science}, publisher={Springer Science and Business Media LLC}, author={Kustas, W. P. and Agam, N. and Alfieri, J. G. and McKee, L. G. and Prueger, J. H. and Hipps, L. E. and Howard, A. M. and Heitman, J. L.}, year={2018}, month={Oct}, pages={227–237} }
 @article{kustas_anderson_alfieri_knipper_torres-rua_parry_nieto_agam_white_gao_et al._2018, title={THE GRAPE REMOTE SENSING ATMOSPHERIC PROFILE AND EVAPOTRANSPIRATION EXPERIMENT}, volume={99}, ISSN={["1520-0477"]}, DOI={10.1175/BAMS-D-16-0244.1}, abstractNote={Abstract Particularly in light of California’s recent multiyear drought, there is a critical need for accurate and timely evapotranspiration (ET) and crop stress information to ensure long-term sustainability of high-value crops. Providing this information requires the development of tools applicable across the continuum from subfield scales to improve water management within individual fields up to watershed and regional scales to assess water resources at county and state levels. High-value perennial crops (vineyards and orchards) are major water users, and growers will need better tools to improve water-use efficiency to remain economically viable and sustainable during periods of prolonged drought. To develop these tools, government, university, and industry partners are evaluating a multiscale remote sensing–based modeling system for application over vineyards. During the 2013–17 growing seasons, the Grape Remote Sensing Atmospheric Profile and Evapotranspiration eXperiment (GRAPEX) project has collected micrometeorological and biophysical data within adjacent pinot noir vineyards in the Central Valley of California. Additionally, each year ground, airborne, and satellite remote sensing data were collected during intensive observation periods (IOPs) representing different vine phenological stages. An overview of the measurements and some initial results regarding the impact of vine canopy architecture on modeling ET and plant stress are presented here. Refinements to the ET modeling system based on GRAPEX are being implemented initially at the field scale for validation and then will be integrated into the regional modeling toolkit for large area assessment.}, number={9}, journal={BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY}, author={Kustas, William P. and Anderson, Martha C. and Alfieri, Joseph G. and Knipper, Kyle and Torres-Rua, Alfonso and Parry, Christopher K. and Nieto, Hector and Agam, Nurit and White, William A. and Gao, Feng and et al.}, year={2018}, month={Sep}, pages={1791–1812} }
 @article{holland_heitman_howard_sauer_giese_ben-gal_agam_kool_havlin_2013, title={Micro-Bowen ratio system for measuring evapotranspiration in a vineyard interrow}, volume={177}, ISSN={["1873-2240"]}, DOI={10.1016/j.agrformet.2013.04.009}, abstractNote={Sparse canopy systems such as vineyards are comprised of multiple components (e.g., vines, interrow soil and/or groundcover) that each contribute to system water and energy balance. Understanding component water and energy fluxes is critical for informing management decisions aimed at improving productivity and water use efficiency. Few methods are available to accurately and continuously measure component fluxes. We tested a novel micro-Bowen ratio (MBR) energy balance system for determining interrow evapotranspiration (ET) flux within a vineyard. Our objectives were to develop MBR methodology to measure ET flux from the vineyard interrow and to compare MBR ET measurements for bare soil and fescue interrow conditions to independent ET estimates. MBR methodology utilized measurement of air temperature and water vapor concentration at 1 and 6 cm heights within 2.7 m wide interrows. Measured ET rates were well correlated between MBR systems and micro-lysimeters for both fescue (R2 = 0.99) and bare surface (R2 = 0.89) interrow conditions, though MBR ET rates were larger than those determined from micro-lysimeters in both cases (20 and 60%, respectively). MBR daily ET estimates, determined by compositing measurements from fescue interrows and bare soil under vines, were also well correlated to (R2 = 0.70) and of similar magnitude as vineyard eddy covariance ET measurements during periods when the vines were dormant. Overall, MBR systems appeared to provide a reasonable approach to determine ET for the interrow component within the vineyard. Similar methodology may be useful to better understand components’ contributions to water and energy fluxes in other complex or sparse canopy systems.}, journal={AGRICULTURAL AND FOREST METEOROLOGY}, author={Holland, S. and Heitman, J. L. and Howard, A. and Sauer, T. J. and Giese, W. and Ben-Gal, A. and Agam, N. and Kool, D. and Havlin, J.}, year={2013}, month={Aug}, pages={93–100} }