By 2050, the global water demand is expected to increase by 55 percent, much of which is attributed to agriculture. No wonder, since a good 40 percent of all food worldwide is grown on artificially irrigated land. Any savings in agricultural water use can free up water for other pressing needs like drinking water. A TU Hamburg-project shows how water and fertilizer use can be drastically reduced with a new cultivation concept.
Peas, beans, potatoes, and rice. Agriculture feeds us, but it pollutes groundwater with “unhealthy” nutrients especially nitrates and a variety of biocides. These are used in farming to control the growth of harmful organisms. But that also makes them potentially dangerous to humans, the environment and other organisms beneficial for plant growth. At the same time, agriculture worldwide uses about 80 percent of all freshwater withdrawals. Of this, about 40 percent is used in rice cultivation alone. This is a trend that has been going on for a long time. In the densely populated regions of South and Southeast Asia in particular, huge investments were made in additional irrigation systems between the 1960s and 1980s in order to keep increasing yields.
Dr. Tavseef Shah, with the help of his team from Hamburg University of Technology, has tried out new cultivation methods on site and in field trials in Kashmir in northern India. His idea is to significantly improve the dry rice cultivation (System of Rice Intensification, SRI) propagated mainly by Cornell University in the USA. At Hamburg University of Technology, he developed an intercropping concept that involves the simultaneous cultivation of different crops in one field. He combined SRI rice with bush beans. In this way, the nitrogen requirements of the rice plants could be supplemented with the help of the beans, which bind it to their roots. If this type of cultivation were used worldwide, it would save about 20 percent of the world's water needs as well as some of the fertilizer requirements.
And the bush beans provided an additional effect: the weeding requirement, which is otherwise very considerable for dry rice, fell by about 70 percent. Shah expanded his research even further for this purpose and founded the “Environmental Robotics” working group last year in 2021. In parallel with the development of rice cultivation in Kashmir, the group invented and built a selective weeding robot that has automatic plant recognition and is thus able to mechanically remove only the weeds that are harmful to the crops without chemicals. This development is in prototype status and is led by doctoral student Mr. Durga Nasika.
3 Questions for Dr. Tavseef Shah of the working group Environmental Robotics at the Institute of Wastewater Management and Water Protection about the project:
How does intercropping work, alternating rice and bush beans?
In intercropping, we plant rice and beans together in one plot. The beans are sown between the crop rows two weeks after the rice is sown. Since we use the dry rice cultivation method, the beans find good growing conditions. We have tested this method in fields in Kashmir with success. We observed reduced weed infestation, better and more diverse crop yields, and thus diversified income streams.
How much water can be saved with dry farming?
The SRI method can save up to 40 percent water in rice cultivation. We have observed this time and again in our trials at the TU Hamburg and in our field trials in Kashmir. We have to consider that on average 5,000 liters of fresh water are consumed to produce 1 kilogram of rice using the conventional flood rice method. Even if this method is slow to spread, the water savings will be significant. With intercropping, the dry rice cultivation method provides an added incentive to the farmers and the environment! We are currently looking at the possibility of using this methodology to grow rice in saline soils.
What has been the reaction of farmers to the weeding robot?
The farmers we talked to here in northern Germany were really excited about such an agricultural aid that eliminates weeds without the use of agrochemicals. For them, it's the kind of environmentally friendly and cost-effective solution that they're hoping for from a technical university. The idea was initiated by Prof. Otterpohl and Mr. Nasika has been working on this project since the very beginning.
