Biomass Related Nitrogen Fertilization with a Crop Sensor

Abstract

In cereal crop production, approximately 30% of nitrous oxide (N2O) emissions and 47% of total energy inputs are attributed to the use of mineral N fertilizers. Furthermore, leaching of surplus N can contaminate ground water and promote eutrophication. In recent years, sensor-based systems for variable-rate N fertilization have been developed to optimize the ratio of grain yield to N application rate. Most commercially available sensors are based on opto-electronics; however, a mechanical crop biomass sensor (Crop-Meter) has been recently developed. Thus, the objective of this study was to evaluate the Crop-Meter for N application in cereal crops. The sensor was attached to conventional farm equipment, allowing on-the-go variable-rate N application and was evaluated during a three-year research project (2005-2007) on five large-scale farms in East Germany. In strip experiments, sensor-based crop biomass analysis and subsequent N fertilization contributed to a median increase in N efficiency of 14.4%. The observed increase in N efficiency was caused by a 10% to 15% reduction in N fertilizer and was not attributed to gains in yield. In field-scale experiments, a reduction in N of 17 kg N ha-1 was observed, which was similar to the value obtained in strip trials (21 kg N ha-1). Annual use of the biomass sensor on an area of 250 ha or more can increase profits of grain cultivation.