Assessment of Cereal Nitrogen Requirements Derived by Optical On‐the‐Go Sensors on Heterogeneous Soils

Abstract

Variable N management is one of the most promising practices of precision agriculture to optimize nitrogen-use efficiency (NUE) and decrease environmental impact of agriculture. The objective of this study was to test the performance of fertilization in winter wheat (Triticum aestivum L.) and triticale (Triticosecale Wittm.) determined by reflection measurements of on-the-go sensors under heterogeneous field conditions. In 2004 geo-referenced yield and N fertilization data were collected in four heterogeneous fields in southern Germany. Nitrogen demand of plants was determined throughout the growing season and the corresponding amount of N fertilizer was broadcast with the N-Sensor (Yara, Germany) in real-time. The sensor uses the red edge position (720-740 nm) as an indicator of crop N status and relates this to crop N demand. The sensor algorithm is designed to stimulate plant growth in areas with low biomass and reduce risk of lodging in areas with high biomass. Fertilization was evaluated by calculating site-specific N balance maps to delineate zones with N surplus in the soil. The results revealed some general limitations of this sensor approach in areas with yield-limiting factors other than N. Nitrogen surplus above 50 kg ha 21 was calculated for subfield areas dominated by shallow soils. The results of this study indicated that sensor-based measurements can be used efficiently for variable N application in cereal crops when N is the main growth-limiting factor. However, the causes for variability must be adequately understood before sensor-based variable rate fertilization can safely be used to optimize N side-dressing in cereals.

Mobile sensor platforms: categorisation and research applications in precision farming

“…As most commercially available sensors are based on the signals of a single sensor, this can lead to misinterpretation of the situation in the field (Zillmann et al, 2006). Samson et al (2000) showed that nitrogen and sulphur deficiencies have different effects on the laser-induced fluorescence spectral signatures of a field sensor.…”

“…In some cases, this leads to misinterpretation of the truth for variability or heterogeneity (Zillmann et al, 2006). In order to strengthen the reliability of implemented sensor signals, the idea of using a combination of sensors is gaining popularity.…”

Promoting sustainable intensification in precision agriculture: review of decision support systems development and strategies

“…Lammel et al (2001) point out that the Yara N-sensor is valuable to avoid over-and under fertilization within a field resulting in increased yield, decreased lodging and more homogenous ripening. Other researchers accentuate that usage of the N-sensor only have resulted in small differences in yield (Berntsen and Thomsen et al 2006;Jørgensen et al 2006) and Zillmann et al (2006) point out that the N-sensor technology work when nitrogen is the main growth-limiting factor. The usage of Yara N-sensor reduces nitrogen leaching if areas with lower requirements for nitrogen fertilization within the field can be identified (Delin and Stenberg 2014).…”

Responsive in-season nitrogen management for cereals

“…They showed variable-rate N applications would result in significant N savings compared to uniform N application, when using N priced at $0.55 kg −1 . Researchers in Europe and elsewhere (Schroder et al, 2000;Olfs et al, 2005;Berntsen et al, 2006;Tremblay and Belec, 2006;Zillmann et al, 2006) have also shown that this approach can be used to direct variable in-season N applications in cereal grains that improves NUE, crop harvest ability, and/or quality. Some of the aforementioned research involved use of the Yara N sensor system for variable N applications, which has been available for about a decade in Europe (Yara UK Limited, Lincolnshire, UK) as a commercialized service, and is being adopted by growers.…”