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1. Evaluating Nutrient Uptake and Partitioning for Hybrid Carrot Seed Production in Central OregonHybrid carrot seed production is prominent in Central Oregon, however plant nutrient uptake dynamics in this crop are not well understood. The aim of this research was to evaluate nutrient uptake and partitioning during the production cycle of a modern Nantes-type hybrid carrot. Trials were conducted in two commercial carrot seed production fields planted to ‘Nantes 969’. Below- and above-ground plant biomass was destructively sampled and separated into roots, tops, and umbels throughout... E. Jeliazkova, A. Moore, J. Spring, T. Wilson |
2. Refining Nitrogen Management for Organic Broccoli ProductionSpecialty organic fertilizers used in organic vegetable production are expensive. So, from environmental and economic perspectives, growers want to maximize nitrogen (N) fertilizer use efficiency by the crop. This research was conducted to (1) determine sufficient N fertilizer rates for organic broccoli, (2) evaluate the efficacy of a specialty organic fertilizer (feather meal; 12-0-0), and (3) confirm the effectiveness of midseason soil nitrate analyses (0-30 cm) in determining appropriate sidedress... D. Sullivan, R.E. Peachey, A. Donaldson |
3. Alfalfa Contributes More Nitrogen to Following Crop Than Previously ThoughtAlfalfa in high-yielding environments fixes significant amounts of atmospheric N2, a portion of which benefits succeeding non-legume crops and reduces fertilizer N requirement by an amount sometimes called the “legume N credit”. Field research-based estimates of the legume N credit in California and other irrigated, semi-arid or arid environments are sparse in the literature. We conducted replicated plot experiments at three field station sites in California using wheat as an indicator... S. Pettygrove, E. Lin, D. Putnam, M. Lundy, S. Orloff, S. Wright |
4. Economics of Fertilization Under Site-specific Management ZonesSite-specific management of crop fields using variable rate application of inputs to manage in-field variability has now been around for over 15 years. However, the degree to which site-specific management strategies increase farm profitability is not well established. The objectives of this study were: to compare uniform and variable-rate Nitrogen (N) management strategies across productivity level site-specific management zones and to identify the most profitable N management strategy. This... R. Khosla, D. Westfall, W. Frasier, B. Koch |
5. Cool Season Mineralization of Recalcitrant Organic N in Undisturbed Cores of Manured SoilsThe objectives of this study were to (1) quantify cool season N mineralization from recalcitrant organic N in soils with a long history of manure application and (2) examine the relationship between cool season recalcitrant organic N mineralization and a fall mineralizable N index. “Cool season” was defined as October to February for fields with winter crops and October to May for fields with no winter crops. Two in situ trials were conducted with undisturbed soil... D. Moberg, D. Sullivan, R. Johnson |
6. Evaluation of N Uptake Analysis As a Tool for Determing Potato N StatusPlant tissue testing has become the primary method for evaluating nitrogen availability for potatoes during the growing season. This study was conducted to determine if plant N uptake rates referenced to absorbed solar radiation could also be used as a tool to quantitatively assess plant N status of different potato varieties. Nitrogen fertilizer, as NH4NO3 (34-0-0), was applied to Russet Burbank, Gem Russet, Bannock Russet and Summit Russet at three rates (0, 100, or 300 kg N/ha) using two... J. Stark, S. Love, C. Mcintosh |
7. Soil Zinc Application for Southwestern PecanPecan trees grown in the alkaline soils of the southwestern United States are prone to zinc deficiency unless supplemental zinc is regularly applied. Standard treatment involves multiple foliar zinc applications. Soil zinc application would provide several advantages. A field study was initiated in 2005 with three soil zinc treatments: no zinc (control), ZnSO4 (74 kg.ha-1 Zn), or ZnEDTA (19 kg.ha-1 Zn) were applied one time in March, 2005 in bands 18 cm deep and 1.2 m on both sides... J. Walworth, A. Pond, H. Nunez, B. Wood, M. Kilby |
8. Remote Sensing of Corn N Status with Active SensorsDetermining in-season corn (Zea mays L.) nitrogen (N) variability has been a research focus of agronomists for quite some time. One of the methods currently available to determine N variability in corn is remote sensing. Studies have shown that remotely sensed imagery can detect N variability in corn. However, this method can have some limitations, such as the timeliness in which this imagery can be acquired. Hand-held active remote sensing devices may overcome these limitations.... D. Westfall, R. Khosla, T. Shaver |
9. Improved Small Grain Nitrogen Use Efficiency with California Site-specific Decision SupportSmall grains are grown throughout the state of California (CA) on approximately 500,000 acres annually. They are generally fall-sown and grown during the winter months when most precipitation occurs. Because precipitation and irrigation patterns vary across CA and there is a strong interaction between total water and plant available nitrogen (N), determining fertilizer N application recommendations is particularly challenging in this cropping system. With recent fertilizer price volatility,... N. Clark, M. Lundy, T. Nelsen, M. Leinfelder-miles, S. Light, G. Galdi, T. Getts, K. Mathesius |
10. Biosolids-based Fertilizers as a Nitrogen Source in California Small Grains SystemsSituation/ conditions In response to regulatory and economic pressure, California growers are becoming more familiar with nitrogen budgets. In addition to seeking out ways to improve nitrogen management strategies, growers can possibly benefit by incorporating alternative sources of nitrogen to feed their crops. Liquid injected or pelletized biosolids-based fertilizers from local waste streams and processing facilities are one source that growers are beginning to explore. As... K. Mathesius, D. Geisseler, M. Savidge, M. Lundy, T. Nelson, N. Andersen |