Using a Chlorophyll Meter to Optimize Nitrogen Fertilizer Application for Intensively‐Managed Small‐Grain Cereals

Most methods used to estimate N status require collection, processing and analysis of soil and/or plant tissue samples. In this study, leaf chlorophyll content of cereals, determined in the field with a portable chlorophyll meter (Minolta SPAD‐502), was used to predict N availability of wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), oats (Avena sativa L.) and rye (Secale cereale L.). The results indicated that accurate nitrogen (N) fertilizer recommendations based on chlorophyll content have both environmental and economic advantages. Determination of leaf chlorophyll content with a chlorophyll meter accurately indicated plant N status allowing N fertilizer requirement to be accurately determined and resulting in increased N uptake efficiency. Applying N fertilizer on this basis improved production economics and improved physical input‐output ratio during grain yield formation. Using a chlorophyll meter, responsive and non‐responsive categories can be determined at the stage of maximum number of florets per ear primordium (Zadoks' GS 37‐41) and at pollination (i.e. pollen grains on well‐developed stigmatic hairs, GS 52‐58).