New crop varieties and new irrigation systems can help agriculture make ends meet even in dry times. This is reported by the magazine MIT Technology Review in its current issue 3/2023 (can now be ordered from the heise shop and is available in the station bookshop).
An important building block could be the use of treated wastewater. Thomas Dockhorn from the TU Braunschweig is researching this possibility in the HypoWave project. So far, the use of wastewater on fields in Germany has been prohibited by law, he says. The reason is that wastewater from sewage treatment plants can contain certain bacteria and viruses, as well as drug residues and heavy metals. “You don’t want that on your plate after the harvest.” There is an exception for the regions of Braunschweig and Wolfsburg. There, treated wastewater can be used, among other things, to irrigate silo maize and sugar beets – i.e. crops that are not eaten directly but are used as animal feed or processed industrially.
Benefits of treated wastewater
In the HypoWave project, Thomas Dockhorn, together with eleven partners – including water associations and research institutes – is investigating how wastewater can be treated in such a way that it can generally be used in agriculture without any problems, including for food that ends up on the plate. The team cleans wastewater in several stages. First, it is conventionally cleaned in a mechanical-biological treatment plant. This is followed by further processing to remove organic trace substances such as drug residues. To do this, the team uses so-called activated carbon biofiltration: With this process, the organic substances first stick to the activated carbon and are then broken down by microorganisms that have settled on the activated carbon. The final treatment step is disinfection by UV radiation.
“We were able to prove that the water is then clean enough to be used for irrigating crops without any problems,” says Dockhorn. Especially since the team does not water the plants from above, but only submerges their roots (hydroponics). “In this way we further reduce the risk of residues being left on the leaves.” The treated waste water could also be used in the field.
In a next step, the team now wants to test the process on a large scale. For this purpose, a greenhouse for tomatoes and peppers with an area of one hectare is to be built this year. The aim is also to determine the level of acceptance for such products. That’s why a local Edeka market is a partner. In countries like Spain, treated wastewater has been used in agriculture for some time, and many consumers will most likely have already consumed products treated in this way. And soon the procedure in the EU could even become standard: Brussels is working on a regulation that provides for the use of wastewater in agriculture throughout Europe. This should come into force in June and must then be transposed into national law.
There is no life without water – but too much can be just as deadly as too little. That’s why the new issue of MIT Technology Review sheds light on how we use the element. Highlights from the magazine:
Option: drip irrigation
Another important question is how to optimize irrigation, for example by using drip irrigation instead of large-scale sprinkling. Thin hoses with tiny holes are laid on the fields. However, the installation of such a hose system is many times more expensive, especially since the hoses have to be rerouted every year.
A middle way could be the solution of the Spanish start-up Spherag. This recently received venture capital from the Munich-based agricultural group BayWa, among others. It offers a system that allows farmers to digitize and automate their existing irrigation systems. To do this, the company mounts solar-powered digital modules on the control elements of the irrigation systems, creating a digital twin of the system. Farmers can then monitor and control it in real time on their smartphones. For example, they no longer have to drive to their fields to turn off their sprinkler systems and can react more quickly. Baywa writes that a third of the water consumption can be saved as a result.
Genetic engineering CRISPR for agriculture
New plant varieties can also be useful. Creating drought-resistant plants is considered one of the most important breeding goals worldwide – whether using conventional methods or genetic engineering. The cultivation of genetically modified plants is currently prohibited in Europe. However, the European Commission wants to relax the ban on new genetic engineering methods such as the CRISPR/Cas gene scissors. Experts are expecting a proposal to this effect before the end of this year.
In other countries, genetically modified plants are already growing in the fields. Argentina, for example, approved the cultivation of genetically modified wheat on licensed farms last year. A sunflower gene called HB4 has been introduced into the wheat, which helps it continue to grow even in intense heat. And drought-resistant corn is already approved in South Africa, Nigeria and Kenya.
However, breeding drought-resistant plants is considered difficult. Unlike resistance to certain pests, the tolerance of plants to heat and drought is not determined by individual genes, writes the industry portal Transgen. They used complex adaptation strategies to deal with drought, for example they intensified their root growth. In order to replicate such strategies through breeding, one must have a very precise understanding of which genes encode them and how they are regulated, writes Transgen. “Usually it’s not individual DNA sequences, but complex, mutually influencing networks.”
In addition, dryness is not a static problem. Sometimes she performs, sometimes not, sometimes she’s stronger, sometimes she comes earlier. Plants have to be able to handle this too. So it’s not enough to optimize them for a specific feature.
Read MIT Technology Review here: