**5. Field application of LARS systems**

Sugiura et al. (2007) mounted a thermal band camera on unmanned helicopter platform to estimate soil water status in paddy fields and correlation was obtained between the thermal image temperature and soil moisture content. The coefficient of determination (r2) for moisture content and temperature model at 10.00 a.m. and 3.00 p.m. were 0·69 and 0·64 respectively (Figure 9).

Fig. 9. Soil moisture content estimation with LARS images (Sugiura et al., 2007)

The r2 between moisture content and difference in temperature was 0·42. The development was intended assisting in proper irrigation scheduling and monitoring water stressed situations for rain-fed cropping. Ishii et al. (2005) developed a system that can generate a map regarding crop status obtained by mounting an imaging sensor on an unmanned helicopter. They achieved an accuracy of 38 cm using RTK GPS receiver and GDS unit. The maps are accurate enough to be used for variable rate nutrients and pesticides application for the farmland.

Lenthe et al. (2007) used unmanned helicopter based IR thermography imaging system as a tool for monitoring the microclimatic conditions promoting incidence and severity of diseases within wheat fields with a high spatial resolution. Zhou et al. (2009) used R44 helicopter for aerial electrostatic spraying system. The results of the studies showed that electrostatic spraying with helicopters could produce uniform and fine droplets with better droplet adhesion and distribution, higher depositing efficiency, lower environmental contamination; lower pesticide application rate and aerial spray can improve efficiency for prevention and cure pests in agriculture and forestry.
