This is in extreme drought times, I thought it might be good to finally tell us a bit more about how our irrigation systems in forest garden, the associated nursery and cultivation conditions works. Briefly summarized, the system is based on:
- Seasonal Storage of rainfall
- Simple solar technology to lift water
- Self-Press to distribute the water.
We started installing the system early summer 2015 after we had received a small grant from Flory Gates foundation Peace with the Earth to install the system and have developed continuously since then. When we started we had no prior knowledge, and I thought it was very difficult to find good advice, both online and in the literature (For example, in the actually quite arcane book "Drip Irrigation for Every Landscape and All Climates" by Robert Kourik) of simple irrigation systems that work without being connected to the mains or public waters. Therefore, there has been much "trial and error" for us, but now we know that the system works well and want to share with you how we made. It is safe to do things better or differently, so please let me know if you have any comments or suggestions. Although literature hints are appreciated.
The key to the system is our dam system, in particular, the largest dam lying on the ground lowest point and that all the runoff from forest garden must get through before it leaves the ground. Although we hardly had any rain since the snow melts, and even though we have pumped between 500 and 1.000 liters of water out of the pond every day keeps the time of writing still above 100.000 liters of water level in the dam has not fallen more than an inch since the start of the growing season.
The electricity and the pump
Since the big pond is lower than everything else on the property, we need to move the water from the dam to the farms. Initially watered us all by hand with water jugs, but in the scale we grow now it is impossible to continue with the. That we are not connected to the electricity grid was a bit of a challenge to get to a working system. To install a full-scale solelssystem with inverters and everything did not question us purely economic, so we chose a very simple 12V solution. It consists of a diaphragm pump of the brand Shurflo, model 2088 Deluxe which we bought from a German supplier. They are not the world's best service, but was clearly the cheapest when we bought the pump and still seems to be the. The pump is on land, and draws in water through a filter fitted pipes from the large pond next. Then press the up water in the pipe leading to the distribution tanks (the nedan).
The pump is connected to a solar systems with two solar panels on a total of 180 W.. except panels behövs även en regulator, both we bought from another German vendor also with mediocre service. To make everything work required it is also a usual leisure battery that stores surplus production which allows the pump to go when the sun does not shine too.
Since a few weeks back, we have installed a timer that functions like an egg timer, so we do not need to be in place to turn the pump. We also tested a so-called float starts the pump when the water level is too low in tanks (the nedan), but it did not work really well for us and we have therefore chosen a timer instead.
The tanks and pressure
The diaphragm pump is good at moving water far both in sid- and height, but it is not good to pressurize the. Therefore, we need to move the water only up to later drop it down again with just the right pressure for our irrigation system.
In the current situation, we use three so-called IBC tanks (also known as cubic thoughts), which can accommodate a total 3000 liter. They are located on our property's highest point located 6 meters of greenhouse and nursery where we use the most water. The small pump has no problem filling them, even though the cable length is 50 m and the lifting height of 7 m.
The tanks are connected by hoses as shown below, which means that the water level in all three tanks is always the same.
In addition to the tanks at the highest point, we have several thoughts scattered in the cultures that we can use to fill water jugs when we do not want to hose. They are connected to the tanks on the land's highest point through pipes.
In the vegetable lands, greenhouse and parts of the nursery, we use drip irrigation to reduce the unnecessary loss of water as the water comes directly into the ground without getting stuck on the leaves and branches where some evaporates. To drip irrigation tubing we chose (the nedan) to work, we need a pressure of at least 0,3 bar in the lines and the optimum is 0,6 bar (is the pressure in lines of 1,05 bar needs a pressure regulator that reduces the pressure). Each meter drop gives a press 0,1 bar, which in our case means that we will have a press 0,65-0,7 a bar at the outlet of the conduit, depending on the filling level in the tanks, thus is perfect for tubing we have.
In order to minimize friction losses in line (that allows the pressure at the outlet decreases significantly) we use a wire with a diameter of 40 mm. When the pressure loss is negligible, concomitantly a wire having a diameter of 20 etc. result in rather large pressure losses (corresponding 0,5 m lower vertical at a flow of 300 liters / hour). How much pressure loss will be for different cable lengths, flows and diameters can easily work out with one of the many räknesnurrorna available online, for example this.
The large lead from the tanks to the nursery area is equipped with a disk filter to particles which could clog the drip hoses removed. Drip hoses are to make T-Tape med en diameter på 16 mm and a distance of 20 cm drop between points. We chose this makes for a recommendation from our supplier. The optimum pressure for them to say 0,6 bar, but different brands have different values for optimal pressure. Since the pressure loss becomes larger the longer the line you have, you can not have as long drip hoses anywhere. At the T-Tapes part is 114 m length which is maximum at 0,6 bar. Since we have almost 300 m drip hose in crops and greenhouse, we needed to divide the system into several circuits that we can control separately.
Before all the circuits we have installed a simple valve with a timer that also serves as an egg timer. After this valve is then taps one gets open by hand to remove the water in the drip hoses. In our greenhouses, we have 3 circuits (it would be enough with a), the cultivation conditions, it is also 3 and there is a circuit for the part of the nursery where we have collected our parent material that we take cuttings and scions from.
In the forest garden we have no drip irrigation, without punktvattnar with a hose that is directly connected to the tanks, but on a smaller scale, it would certainly be possible to make use of drip irrigation including forest garden plants.
That said, the system works fine now, but we have normally gone through some tough failures also.
Frost: When the various components of the system are full of water, they are sensitive to frost. 2017, when we had -8 degrees at night until May, froze both the pump and the disk filter as well as several valves apart. Now we therefore much longer in the spring before we launch the system and bring in the most sensitive components and empty the entire system when there is a risk of frost. The drop hoses seems strange enough to be fairly insensitive to frost as long as they are not filled with water. Before winter we open all the valves so that the water can slowly drain out, and let it all out of the pump system and filter should be left where it is. So far there has been some frost damage to this procedure.
Sork: Sorken really messed up properly for us på sistone och även droppbevattningssystemet drabbades den gångna vintern. Voles must have been so desperate for food that they even chewed out parts of drip hoses, with the result that we had to replace almost 200 m droppslang. In the future, we will therefore still pick up all dripping hoses in safe custody, even if it means a few hours of extra work both spring and fall.
In summary, then, we have built the system on the basis of our specific conditions where we do not have electricity- and water connection, but where we have the topography of both the seasonal storage of water in natural ponds and pressurization of water by gravity. The diagram below summarizes how the various parts are connected.
In other places, in other circumstances, it may look completely different. For example, it would go to collect water from the roof instead of pumping it, which would simplify the system significantly. Already 3 m drop is enough to get the drip hoses work, so most people who are able to takvatteninsamling could use it, provided that one can build a stable position can handle water tank weight 1 tons when filled. Please share your experience, either here in the comments or on Facebook, there are certainly many more ways to solve the irrigation issue!