We all know that in the summertime, the weather at the beach can be vastly different from conditions more inland. And that the temperature in the countryside is higher with respect to the conditions high up in the mountains. But did you also know that temperatures at different heights close to the surface can vary greatly as well? These differences within the first couple of meters above the soil can have a large agronomical impact. Crop leaves and roots experience different conditions than measured at standard weather station height. These crop conditions, though, determine the risk of infection with crop diseases or the effect of crop protection products and are measured with our FieldMate, of course!
Throughout the day, the effect of the energy of the sun on the surface of agricultural soil is twofold. On the one hand, it leads to evaporation of water from the soil and transpiration from the plant. On the other, the energy is used to warm the surface itself. In a mature crop that is well supplied with water, most of the energy is used for evapotranspiration. The drier the soil however, the more solar energy is converted into heat. The heat and water vapour generated during this ongoing process are dissipated by wind and convection from the surface to higher levels.
As a result, the air at higher levels will get warmer as well as more humid. If little mixing takes place, generated heat, and moisture will remain close to the surface. It is then that we start to witness relatively large differences between our FieldMate measurements in and above the crop and at 1.5 meters. Under windy conditions and with well-watered, mature crops, those differences will be only small. But, with an open or small crop on a dry soil at low wind speeds, the vertical variations can be quite significant – with a topsoil that’s 5°C or even 10°C warmer. At night, the opposite occurs. At low wind speeds the surface can be 5°C to 10°C colder than at standard height and extreme drift conditions exist.
You can imagine that such differences can have its effect on your crop protection activities (e.g., crop damage, reduced effect) or your disease risk assessment (e.g., prolonged leaf wetness). Only by getting an exact picture of both temperature and humidity at crop height, we make can make accurate predictions and take accurate measures. Thanks to the ultra-local measurements of the FieldMate, we can factor for all those influences where conventional measurements only capture the general well-mixed atmospheric conditions.
We’ve mentioned a 5°C difference. That’s 5°C of being more accurate, 5°C of taking the optimal measures and 5°C of leading the way to the most efficient, sustainable, and profitable decisions. Only with accurate data, we can provide you with the relevant information to make the right decisions of when and how to best protect you crop.