Brown lays out very simple formulas to make in-season nitrogen application rate adjustments based on whether April tissues levels are adequate, low or high, and whether visual field estimates for yield in April and May differ from preliminary predicted yields.

The protocol also lays out four different scenarios for leaf tissue analysis and expected yield, and specific recommendations for how to make in-season adjustments. In years of lower-than-expected yield with adequate April tissue N analysis, a specific reduction in mid-season N fertilization is suggested, while higher-than-expected yields might require an increase in N applications. Similar adjustments can be made in accordance with sampling results.

In addition, the research team has created a spreadsheet and other resources for these calculations, which can be downloaded at http://bit.ly/10YkoAc. Under “What’s New,” choose “Nitrogen Prediction Models for Almond.”

Together, these resources create a valuable set of new tools for further fine-tuning nitrogen applications in almonds and other crops at a time when nitrogen fertilizers are under the regulatory microscope.

By Bob Curtis, Associate Director, Agricultural Affairs and Gabriele Ludwig, Associate Director, Environmental Affairs, Almond Board of California.

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