The cropping industry doesn’t currently measure its main inputs of light, water and temperature. And it doesn’t monitor how efficiently light and water are being captured and converted into crop biomass. Nor does it systematically measure temperature to monitor and forecast crop development. There is large variation in crop yields within and between fields, farms and years yet we often don’t fully understand the causes of this variation. In 2012 ADAS set up the Yield Enhancement Network (www.yen.adas.co.uk) to bring together farmers, industry and scientists to understand yield variation and to identify innovations that remove current limitations to yield. By combining soil information with weather data estimates are made of resources available and biophysical potential yields are calculated for each field. Farmers supply crop management information, verified yields and crop samples that ADAS analyse to give a range of crop measures that allow explanation of the yield achieved, and recommendations to overcome likely limitations. What is missing however is a measure of how much light the crop intercepts through the season. With such a measure we can envisage a ‘Crop Intelligence System’ that provides a dashboard of captured solar radiation, available soil water and accumulated temperature that growers could use to monitor their crops in real time, compare crops to each other and to benchmarks, and ultimately to aid crop management decisions.
Earth observation satellites now provide the opportunity to measure the light interception of crops at a fine enough scale and frequent enough time period to monitor crop progress for every field. It is feasible for satellite imagery to give information on a crop’s leaf area index (LAI), size & biomass, stage of development, nutrient status and water status. This could be a high value resource to farmers and agronomists, giving information on crop condition and vulnerability to damage. We shouldn’t however underestimate the calibrations and translation required from raw signals collected by satellites into something meaningful for crop management. Ultimately this information could support improved timing of management decisions and enable more targeted applications of pesticides as well as drive farmer-led innovation.
What can be measured using satellites?
By measuring the reflectance of radiation (optical, microwave or thermal) from crop and soil surfaces satellites can be used to infer a range of indicators related to crop development and growth. To date, most commercial use of satellite information in arable agriculture has been to map spatial variation for precision farming purposes. Its use for monitoring crop growth and condition over time has so far been limited. (See our previous article for more information on the applications of satellite data; Maximising the benefits of satellite applications of agricultural and environmental planning.)
The most commonly used measure from satellites is the Normalised Difference Vegetation Index (NDVI). Whilst this is simple to calculate and can be obtained from multiple sensors, it is not meaningful of itself and can vary with soil conditions, atmospheric conditions as well as between satellites. ADAS is involved in the Multiply project, an EU Horizon 2020 research project with partners including Assimila, University College London, Leiden University & LMU Munich. Multiply is developing a platform for assimilating satellite data from the Sentinel satellites with other sensors at different scales into consistent vegetation and soil parameters over time and space. This should allow LAI & light interception to be estimated as well as potentially providing information on leaf chlorophyll & water content. The system will be tested on YEN crops in 2018, we hope this will define differences between crops in canopy closure early in the season and canopy senescence at the end of the season.
Using satellites in ongoing agronomic research
Inspired by the YEN’s ambition to monitor crops on all its fields, ADAS has partnered with Assimila in an Innovate UK Feasibility Study to evaluate the technical and commercial feasibility of utilising satellite data within a Crop Intelligence System. A satellite based Crop Intelligence System gives the potential to monitor crop progress in every field in the country, allowing growers to benchmark their crops against neighbours and against previous years. When combined with soil and weather data in a crop dashboard there is potential to forecast yields and quality, as well as harvest dates and timings of key crop stages. This could provide a rational basis for a host of algorithms to support crop management decisions.
The big opportunity for crop researchers comes from combining this data with crop management information from growers, allowing the impacts of soil, variety, weather and management decisions on crop performance to be analysed and optimal practices to be identified and tested.
Utilising satellite information is only one aspect of our digital initiative under development. While earth observation data can provide a lot of useable information, other ground based and aerial sensors are also likely to play a big role. Feasibility studies, such as our current Innovate UK project, are essential in building the foundations for future developments that will make substantial impacts on crop management and production.
The ADAS Digital approach to food production and environmental management
You can read more about the ADAS Digital initiative here, and full details of our digital services can be found on our ADAS Digital webpage.
If you would like know more about maximising the benefits of satellite applications, please contact Ben Hockridge; Ben.Hockridge@adas.co.uk.
If you would like to know more about ADAS Digital and our associated services, please contact Lucy Wilson; Lucy.Wilson@adas.co.uk.