A site-specific fertilizer application system that uses optical reflectance measurements of growing plants to estimate fertilizer requirements and that can apply liquid nitrogen fertilizer at a grid level of four square feet is under development. The objective is to determine if the...

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...

This paper estimates the relative profitability of using optical reflectance-based measures to predict crop needs for topdress nitrogen application to hard red winter wheat (Triticum aestivum). The data are from nitrogen yield response experiments where midseason optical reflectance data were...

A variable rate nitrogen applicator based on optical reflectance measurements was developed to increase profits in wheat production by reducing the cost of production or by increasing grain yield. This paper determines if yields and profits from the variable rate treatments are significantly...

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...

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...

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.

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...

Plant-based precision nitrogen fertilizer application technologies have been developed as a way to predict and precisely meet nitrogen needs. Equipment necessary for precision application of nitrogen, based on sensing of growing wheat plants in late winter, is available commercially, but...