Seven days a week, you're out in the elements. Low temperatures, rainfall, and short daylight hours are nothing new. Yes, that's it, hello, wintertime! We're two-thirds of the way through. What this means is that it's all up from here!
What wintertime also means is that grazing rotations are stretching out past 45 days. In most cases, the rotation length is touching 60 days. In extreme cases, 90 days. This time of year is a critical time for the remote pasture measuring and most importantly, your farm. First, growth rates are low due to the aforementioned environmental conditions. Secondly, a slower grazing rotation equals a lower growth rate demand. Well, not precisely, growth rate demand has a lot to do with supplementary feeding and stocking rates too, but that's a story for another day. Thirdly, managing your pasture through winter is a critical aspect of taking advantage of spring pasture growth and for long term sustainability of your pasture sward.
Now, before I get too off-topic, let's dive into the current impact of an extended rotation length on the pasture measuring models. The model starts to rely less on grazing records at day 45. By day 60, the influence of grazing records peters off, and the model begins relying heavily on weather and satellite images. And you know what that suggests, a flatter looking feed wedge where the lows and highs flatten out. The fun nuances of satellite imagery!
So what's the good news above? Well, asides from grazing rotations starting to shorten back into the goldilocks zone, be aware that measurements on paddocks with long grazing rotations may show some variability. And the worst-case scenario is that the flat feed wedge symptoms will manifest themselves until your grazing records sort them out. See the two feed wedges below. The flattest looking feed wedge has days since the paddock grazed in the range between 45 and 90 days. You guessed it, this farm winters their cows off-farm as it's a wet farm in winter. The sharp-looking feed wedge has days since grazed in the range between 0 and 50 days. Yep, this farm winter milks and has dryish hillsides to avoid the wetter river flats.
This modelling behaviour might sound odd. Truly it isn't. The operation of the model was an excellent stopgap in the early days of the model to stop a runaway train. Think of trying to train something that has no concept of physics other than the information you feed it. In the early days of the model, we had a large amount of data for pasture grazed fewer than 45 days. This amount of data meant we could with a high degree of confidence feed the model to understand the relationships between satellite images, weather data and farm records. When we hit 45 days, this information started to slim, by the time we hit 60 days, we had a skinny data set.
The reason for the thin data set is that most paddocks only ever have at most, 1x 60-day grazing interval in a year. Whereas, by quick calculations, the average grazing rotation sits around 30 days for the year.
The back of the envelope calculation is:
( pre-grazing - post grazing ) / yearly average growth rate = average round length
Formula with numbers:
( 3000 - 1500 ) / 50 = 30 days
The better news, we're working on a fix to super measure your grass past 45-day grazing rounds and well into 60-day grazing rounds and beyond! I'm assuming you're wondering why we haven't implemented a fix earlier. As above, and with all the support of customers that have signed up-to-date, we're in an excellent position to start putting more resources back into improving the services we provide.
Firstly, we have more wintertime data to analyse. Secondly, we have been working on a bleeding-edge time-series model. Thirdly and most importantly is that your support has allowed us to allocate more significant resources to improving the platform.
It'd help us to learn what your longest grazing rounds reach in winter if you can share in the comments below - we read and respond to every comment.
You might find a couple of other posts interesting to read on winter grazing tips. The posts "who left that gate open?" and "wait, you feed out on the road?" are to promote out of the box thinking. Take a quick read, and let us know your experiences in the comments below - we read and respond to every comment.
- Ollie Roberts, 24 Jul 2019