By John Hay, Energy Extension Officer
As QFFs Energy Audit Program wraps up proving that Real Energy Savings can be made by implementing new technology, like that of soil moisture sensors, it poses the question of what technology can further improve energy and resource efficiency. Digital IoT and Artificial Intelligence may be the next logical step. As the Digital IoT Project ramps up, we will begin to provide information on how plant science and Ag IoT sensors work to unlock further resource and time efficiency measures using real business cases. This article summarises some of the technology that is available.
The biosphere is in effect a real-time sensor, with constant changes due to fluctuations in the climate. Trees regulate the amount of water that moves from the soil solution into the roots, up the xylem (branches/stems), and out to the atmosphere by opening or closing stomatal pores on the leaves. The cumulative use of water and energy from the sun then drives photosynthesis to convert plant sugars over the season to give the total dry matter/yield.
If nutrients are not available in the soil solution (dependent on soil moisture) then yields can be reduced. In contrast, if paddocks are being over irrigated, leaching can occur removing fertiliser from the root zone, and Water Use Efficiency (WUE) is reduced. To achieve greater efficiencies, and increase production while minimising resource use, a suite of sensors is available for real-time monitoring, and these include;
- Energy – uses current transformers to measure energy consumption or generation like those in QFFs’ real-time and microgrid trial HERE
- Soil Moisture – measures soil moisture with recommended install depths at 15,30 and 90cm, but it is dependent on the depth of the root zone for the crop.
- Sap Flow – uses a heater and two temperature sensing needles logging very low and reverse sap flow, data logging in litres per hour of water used by the plant. The water used is completely independent of evaporative losses in the soil, runoff or through drainage.
- Plant Psychrometer – measures plant water potential considering environmental parameters such as solar radiation, temperature, humidity, wind speed and soil water. It can continuously log changes in plant water status/potential, which directly reflect the energy required to access water or the stress the plant is under. Useful for most crops including sugar cane, wheat, rice, maize, almond, grape, citrus, mango, coffee, avocado and greenhouse crops capsicum, cucumber, tomato.
- Stem Diameter (Dendrometer) – measures the diameter of fruits, plants, and trees. Monitors the swelling and shrinkage of stems during the day and night. The maximum Daily Shrinkage (MDS), is calculated from the difference in daily minimum and maximum stem diameter, commonly used for irrigation scheduling.
- Light; Photosynthetic Active Radiation (PAR) – The light wavelengths of 400-700 nm utilised by plants for photosynthesis is measured as PAR. Light falling onto a surface is measured as photosynthetic photon flux density (PPFD) in units of μmol/s-m2. If PAR levels are low plant growth and carbon assimilation is reduced, while too much may damage the photosynthetic apparatus. Plant light interception efficiency- is a key determinant of carbon uptake by plants.
- Infrared Canopy Temperature – allows estimation of canopy transpiration and crop stress using a calculation such as Crop Water Stress Index (CWSI).
- Leaf Wetness – measures water on the canopy caused by rainfall, dew, or guttation. Leaf wetness duration (LWD) is a concern for the development of disease.
- Normalised Differentiation Vegetative Index (NDVI) – Leaf chlorophyll absorbs red light (FR- 680nm), and the cellular structure of the leaves strongly reflect near-infrared light (NIR- 730nm). When the plant is water-stressed or diseased plants absorb more of the NIR. Observing change provides an indication of the presence of chlorophyll, therefore, plant health.
Soil moisture sensors placed throughout the soil profile let you know if under or over-irrigating, which could lead to inefficient energy use. Be aware though, that contact with the soil is a small sample of what could be occurring across a larger area due to varying soil properties (spatial variability). In some cases, the volume of water moving through tree stems is measured to maximise WUE. It can get complex, for instance when two trees of the same species are close to one another they undertake hydraulic coupling, transferring water and nutrient through the root systems.
Water levels, quality, and volume applied can assist to monitor in real-time, or show potential to forward-project for the season while ensuring crop health is maintained. Additional sensors that are available include GPS to track vehicle movements and livestock to investigate pasture utilisation.
Coupling energy efficiency, smart IoT, automation with Microgrids when designing new systems will unlock easier decision-making processes, improve productivity, increase resilience while keeping a close eye on all your precious resources.
Find Out More
For more information and resources click HERE or to see our range of agricultural energy efficiency case studies including implemented projects HERE and for more on the Digital Agriculture Project head HERE
If you have any energy efficiency-related questions for the team, get in touch at firstname.lastname@example.org.