mobillas canopy sensor - figaro project · 2016. 2. 19. · lai and rre. open circles indicate...
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MobilLas Canopy SensorAnton Thomsen (1,2), Jens Bonderup Kjeldsen (1) and Uffe Schmidt (1)
1) Aarhus University, Foulum. 2) AgroSens
Figure 1. MobilLas canopy sensor seen from tractor cab. Top arm supports GPS and activespectrometer (ACR-430) measuringmultispectral reflectance.Bottom arm supports scanning laser range finder (AccuRange 4000) measuring canopy structureincluding leaf area index
IntroductionThe MobilLas double sensor is developed for site specific farming including:• Nitrogen fertilization• Irrigation• Plant protectionNitrogen (N) fertilization of winter wheat introduced here.
MobilLas measurements include leaf area index (LAI) and multispectral reflectance. By combining LAI and a spectral index - e.g. RRE calculated as the ratio of nearinfrared and red edge reflectances – the canopy N-status can be obtained more accurately than with current single sensor instruments.
AcknowledgementsThe current version of MobilLas developed aspart of the FIGARO precision irrigation project(www.figaro-irrigation.net)
Summary and conclusionsMobilLas has been succesfully applied to a range of crop types: • Winter wheat• Spring and winter barley• PotatoesN fertilization algorithms developed for winter wheat, spring barley and potatoe.
Results indicate the benefits of the double sensor approach over current single sensor instruments.
Figure 5. Recommended N-rates between 0 and 60 kgN/ha from Fig. 4shown as a function of LAI and RRE. Open circles indicate N-status measurementsabove target rate. Figure indicates the limitation of the single spectral sensor approach to precisionfertilization.
Figure 4. Final dressing N-application map for a 12 ha field based on N-status measured on May 31, 2015. Mean N-status approx. 130 kgN/ha. Field fertilized with 140 kgN/ha as slurryand liquid fertilizer. The recommended N-application rate calculated as the differencebetween actual N-status and a target rate of 160 kgN/ha.Mean recommendedrate approx. 30 kgN/ha.
ResultsMaterials and methodsSensor measurements made in winter wheat fields at Aarhus University, Foulum.Winter wheat variety: Hereford.
Development of N fertilizationalgorithm
Figure 2. Measurements of early developmentin LAI and RRE as a function of N levels. Data from April 15 to May 6, 2014. N applied on March 11 (80 kgN/ha) and April 15 (the rest).
Figure 3. N algorithm. Same data as shown in Fig. 2. N-status for measurement approx. 145 kgN/ha. N-status here defined as the apparent amount of plant available N (including correction for canopy density).
Presented at the national Plant Congress in Herning, Denmark, January 20-21, 2016