Using Optical Sensors to Determine Optimum Biomass Levels for Improving Grain Yield and Nitrogen Efficiency in Winter Wheat.

For Kansas producers, increasing grain yield of winter wheat (Triticum aestivum) has been their primary focus.  The common method for increasing grain yield of winter wheat is to maximize biomass/tiller numbers, thus increasing the total number of potential heads.  Kansas producers qualitatively assess wheat biomass at early spring green up, to determine if a high rate of Nitrogen (N) is needed to stimulate more tillering for generating higher grain yield.   However, the amount of biomass needed to produce a given level of grain yield is often overestimated.  This results in increased susceptibility to issues that can reduce grain yield, such as water stress and disease depending on the growing environment.

A study was conducted from 2006 to 2014 to determine the optimum biomass levels for the various growing environments observed throughout Kansas.  In order to quantitatively assess biomass levels, optical sensors were employed and the Normalized Difference Vegetation Index analyzed.  This research has shown that improvements to grain yield and N efficiency can be made by producing wheat biomass levels that match the resource provisions of its growing environment.  These results have been incorporated to the KSU winter wheat N recommendation algorithm to assist Kansas producers with assessing and optimizing biomass levels for their growing environment to increase grain yield, stability, and N efficiency.