Orchard Spray Volume Rate
Introduction
While striving to improve my skills I soon realized that trying to learn Object Oriented programing by yourself can be difficult, so I’ve decided to use some examples from my working expertise, pesticide application, using Python.
On this notebook, I will bring together some formulas usually used to plan a proper pesticide application. They have been used for long time, published, proved and presented in training sessions. I will just connect them on a train of thought.
It’s funny that I’ve started trying to learn OOP and I’ve ended thinking about pesticide spraying in a quite different way. I’ve learned that bringing agriculture and computers together is not only developing new apps and interfaces. First off all it is building a new approach to old problems using computer science.
And the result is one possible way to organize our pesticide application process, using very simple classes that explain the formulas. I’ll be using this method here, on the ag-tech solution development in Impactwave, aiming to a more efficient and sustainable agriculture.
First of all
I will need some libraries…
…and some data on nozzles.
When, early in my work, I started to work on reducing volume rate, I used Albuz ATR 80 hollow cone nozzles. I went back, remembered those times, and came up with some examples.
Preparing the machinery
First of all I need to describe the orchard (vineyard will be analysed later). I can be pretty sure about distances and the area, but what is the tree height and width? For now, let’s use some average values and I will talk about sampling later.
- Height and width are tree canopy parameters (in meters)
- Row and tree distance tell us how far are the trees and then how many trees we have in the orchard (in meters,too)
- The area of the orchard is in hectares
I’ve been using the Tree Row Volume method. Although it is a very simple model (with lots of limitations), it can quantify a very simple fact: there are not two identical orchards. You can read details about it on Sutton and Unrath paper. You can find an interesting infographics on that subject that we’ve made for Agrozapp Newsletter.
Probably you have some mold or bug annoying you and decided to apply some pesticide. By now I just want to know its name and dose to be applied per hectare.
What do you use to spray? Well, most of the times, a sprayer…
…with some nozzles on it…
and pulled by a big and strong tractor.
So, the application itself, uses all this objects to work.
Let’s spray
So, let’s get started. I have a small pear tree orchard from which I know a few things:
- The height of the canopy,
- And its width
- The distance between rows and between trees
- And the area
We’ve decided to use an copper based fungicide.
And all the machinery in the farm.
After all this work, I want some answers. So, what nozzle should I use?
ORANGE
15.0And what tank mixture?
'Mix 1000 L of water with 4706 g of pesticide in tank'Some more issues on TRV
By the way, did you notice that volume rate is a linear function of Tree Row Volume? The intercept is 200, which it means that every orchard will receive 200 L per hectare and the slope is 0.02, 20 L per 1000 m3 of tree row. Let’s make a simple plot to show it.
The TRV, besides addressing the variation between diferent orchards can also deal with variation inside the same orchard along the phenological state. Again according to Sutton and Unrath, 1984, we know the coeficients:
and we can create a slightly diferent Orchard class (inheriting from the first), expanding the one that we’ve been using until now:
YELLOW
21.0'Mix 1000 L of water with 5424 g of pesticide in tank'Conclusion
I showed some evidence that the concentration depends on the dose and spray volume rate. When you change one of them, you must recalculate the others. That is the beginning of a good pesticide application.
This little work is not only useful by now, but also to the future. Classes could be reused in different scenarios — fertilization for instance, and could be “expanded” to add new features like dosis calculation, pressure adjustment and air flow rate.
Resources
This work is made of four ingredients: some ideas, lots of discussion with coleagues and farmers, support from Impactwave team (specially Gonçalo Martins) and all the effort of the Python community:
