The Value of Regional Annual Nitrogen Needs Information for Wheat Producers in Oklahoma

Crop producers are increasingly interested in reducing nitrogen use without sacrificing yield. Technology is available for precise application at the sub-field level, but adoption has been sluggish. This paper estimates the relative profitability of a field level annual predictor of mid-season N requirements and a regional predictor of the same.nitrogen seeds, nitrogen use efficiency, precision agriculture, wheat, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Precision Nitrogen Fertilization Technology with Micro Grids

Sensor-based precision fertilizer technologies are being developed and researched by production scientists. One such technology uses normalized difference vegetation index (NDVI) reflectance measurements of growing winter wheat plants and a nitrogen fertilizer optimization algorithm (NFOA) to determine nitrogen requirement necessary for plants to reach their yield plateau. A number of precision fertilizer application systems that use this technology are considered in this paper. A linear response stochastic plateau wheat yield function conditional on NDVI reflectance measurements is estimated and used within an expected profit-maximization framework to estimate upper bounds on the returns from the precision nitrogen application systems. The on-the-go precision system that assumes perfect information was approximately $7 per acre more profitable than the convention of applying 80 pounds of nitrogen prior to planting in the fall. The whole-field precision system was break-even with conventional methods.Research and Development/Tech Change/Emerging Technologies,

Maximum Value of a Precise Nitrogen Application System for Wheat

Research is ongoing to develop sensor-based systems to determine crop nitrogen needs. The objective is to determine the expected maximum value of an in season precision nitrogen application system for winter wheat. Farmers could not afford to pay much more than $9 per acre for a precision system.Crop Production/Industries,

Replicability of nitrogen recommendations from ramped calibration strips in winter wheat

Ramped calibration strips have been suggested as a way for grain producers to determine nitrogen needs more accurately. The strips use incrementally increasing levels of nitrogen and enable producers to conduct an experiment in each field to determine nitrogen needs. This study determines whether predictions from the program Ramp Analyzer 1.2 are replicable in Oklahoma hard red winter wheat (Triticum aestivum). Predictions are derived from 36 individual strips from on-farm experiments—two pairs of adjacent strips at each of nine winter wheat fields in Canadian County, OK. The two pairs of strips within each field were between 120 and 155 m apart. Each strip was analyzed three times during the 2006–2007 growing season. Nitrogen recommendations from Ramp Analyzer 1.2 are not correlated even for strips that were placed side by side, and recommendations from strips in the same field show no more homogeneity than randomly selected strips throughout the county. The results indicate that ramped calibration strips are unlikely to produce accurate nitrogen requirement predictions at any spatial scale, whether at the county level or for subsections of a single field. In contrast, a procedure that uses only measures from the plot with no nitrogen and the plot with the highest level of nitrogen applied does show replicability. Thus, improvements in the ramped calibration strip technology are needed if it is to become viable.Fertilizer; Nitrogen; Precision agriculture; Ramped calibration strip; Winter wheat

Economics of Pre-Plant, Topdress, and Variable Rate Nitrogen Application in Winter Wheat

Past research about the efficiency of nitrogen application in winter wheat (Triticum aestivum L.) based on source and timing has produced inconsistent results. The majority of the literature used data from few locations over short time periods. This study used a unique data set of yields and nitrogen quantities from 2002-2009 at ten different locations in Oklahoma, USA. The objective of this research was to determine wheat yield response for granular pre-plant, uniform foliar topdress, and variable rate foliar topdress. Topdress liquid nitrogen had a 19% higher NUE than pre-plant urea, and was the most profitable source of nitrogen.linear stochastic plateau, nitrogen use efficiency, profitability, wheat, Crop Production/Industries,

Pumps for low pressure ground sprayers

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311.Biosystems and Agricultural Engineerin

Get your nitrogen-rich strips out early

Plant and Soil Science

Low-pressure ground sprayer

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-631

Calibrating a low pressure ground sprayer

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

Selecting nozzles for low pressure ground sprayers

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311.Biosystems and Agricultural Engineerin