Browsing by Author "Frame, William"
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- Effects of Nitrogen Fertilization on Forage Sorghum Nutrient CompositionLawton, Nathaniel A. (Virginia Tech, 2020-05-03)Whole plant nutrient composition was investigated as forage sorghum (Sorghum bicolor (L) Moench) nitrogen (N) fertilization regimes were changed for Virginia production systems. Five N rates were applied to forage sorghum plots using a randomized complete block design with four replications. Total digestible nutrients (TDN), crude protein (CP) concentrations, neutral detergent fiber (NDF) and acid detergent fiber (ADF) were analyzed from two harvests, 40 days post emergence and 45 days after first cutting, using near infrared spectroscopy. No significance for TDN, CP, ADF or NDF across N rates was found for either cutting. Means for TDN were 57.0% and 59.0% for the first and second cutting and means for CP concentrations where 9.0% and 10.4 %, respectively. Plant height and normal difference vegetative index readings were taken twice for each harvest period and were not significant across N rates. Dairy manure had been applied in previous years which could have led to higher plant available N rates. Lower than average rainfall may have limited growth for the second growth period.
- The impact of nitrogen treatment and short-term weather forecast data in irrigation scheduling of corn and cotton on water and nutrient use efficiency in humid climatesSangha, Laljeet; Shortridge, Julie; Frame, William (Elsevier, 2023-06)Irrigation adoption is increasing in humid regions to offset short-term dry periods, especially at the peak of the growing season. Low soil moisture at the peak growth stage impacts yield and limits the plant's capacity to uptake nitrogen, resulting in low nutrient use efficiency (NUE). However, heavy rainfall on fields with supple-mental irrigation may result in waterlogging and surface runoff, leading to nutrient leaching and runoff. This ultimately can lead to lower NUE, poor water use efficiency (WUE), reduced yields, and water quality impacts. This makes irrigation management challenging in humid regions, as irrigators must avoid both limited and excess water conditions. This field study aimed to develop and test an irrigation management methodology using real-time soil water availability, crop physiological status, water needs, and short-term weather forecasts information from National Weather Service. A rule-based approach determined by soil moisture depletion and short-term weather forecasts was used to trigger irrigation to avoid both stress and excess water conditions. This method was tested in two years of field trials in Suffolk, Virginia to quantify its impacts on yield, NUE, WUE, and financial returns in corn and cotton under four nitrogen application treatments. The relative impact of irrigation and nitrogen treatment was quantified using mixed effects models. The yield, NUE and WUE were impacted by both precipitation and irrigation patterns. Significantly different yields were observed under Nrates treatments for both corn and cotton. The trends of economic returns were similar to yield and were significantly different between recent and historic prices. This study also discusses the impacts of reliability and practical challenges of using Weather Informed irrigation in a field study.
- Using UAVs and NDVI Readings to Predict Grower N Rates in North Carolina CottonPendleton, Brittany; Frame, William; Collins, Guy; Holshouser, David (Virginia Tech, 2022-12-23)This research project was completed in conjunction with an ongoing research effort in Virginia cotton using remote sensing to predict nitrogen (N) application rates. It was conducted to provide additional N prescription data by Unmanned Aerial Vehicle (UAV) for Northeastern, North Carolina. The study was conducted in Scotland Neck, Halifax County, NC (36.1331597, -77.5026541). This county produces 95,000 bales during in 2021 (USDA NASS, 2022). As one of the largest acreage counties in NC, it was ideal for the UAV study and its algorithm creation. The objective was to determine if N rates prescribed by NDVI readings from a UAV flight resulted in improved and/or similar cotton yields than grower standard N rates in North Carolina and Virginia cotton. There were two treatments during the study with the first being the grower practice of N fertilization and the second being UAV determined N application rate at five weeks after planting (5WAP) with four replications of each treatment. The UAV was flown at 5WAP to determine N rates needed at lay-by/top dress. Nitrogen was applied at a grower standard rate of 92 lbs. N/acre on four control replications and at a UAV prescription rate of 114 lbs. N/acre on four test replications. Harvested acres were summed, bale weights were taken, and lint samples were collected time of harvest. The lint samples were micro-ginned at the Tidewater Research station in Suffolk, Virginia for lint percentage. Nitrogen prescription provided by UAV resulted in an 83 lbs. lint/acre increase over the grower standard, though not statistically different. At a 42.7% turnout, the grower standard N application resulted in a yield of 1,806 lbs. lint/acre and the UAV prescribed N resulted in a yield of 1,889 lbs. lint/acre. This trial will be used as part of a larger data set to encourage validation of UAV prescribed N.