Avoiding emissions plays an important role in sustainable agriculture. However, the input of too much nitrogen into the soil and the import of animal feed leads to an increase of nitrate and CO2 emissions. But how can the risk of nitrogen entering groundwater be reduced? In addition, can imported soy be replaced by domestically grown feed in the future? The solution to these problems lies in commercial hemp.
A team of scientists from the Research Institute for Farm Animal Biology (FBN) Dummerstorf and the University of Applied Sciences Neubrandenburg as well as the service company FPS Anklam GmbH from Murchin and a farmer from the Hemp Farm Co. KG in Melz are convinced that they are able to tackle this challenge. As part of the "ZwiHanf" project - funded by the European Agricultural Fund for Rural Development - the project partners are investigating how the cultivation of hemp as an intercrop leads to a reduction in nitrate concentrations in the soil and how the feeding of hemp leaves can replace the share of soy in the feeding ration of dairy cows. The new research project under the leadership of the FBN is funded with about 300,000 euros. The project name "ZwiHanf" is an abbreviation for the German term “Zwischenfrucht Hanf” (meaning catch crop hemp). Hemp is planted in the fall after the main crop or between two main crops.
Hemp - the rebirth of a universal genius
Commercial hemp (Cannabis sativa), not to be confound with medicinal hemp, was cultivated in Germany for many centuries. It served people mainly for fiber and oil extraction. The oil is rich in valuable unsaturated fatty acids. The fibers were used to make textiles, carpets, sacks, nets, insulating materials and paper. People used the protein-rich residues as feed for cows, pigs and chickens. However, the cultivation of rapeseed and cheap production of soy abroad replaced the cultivation of commercial hemp in Germany in the last two centuries.
However, hemp cultivation has experienced a renaissance in recent years. New varieties contain only traces of the intoxicating substance THC. The plants have low demands on fertilization, require little water and do not require the use of pesticides. They are thus optimally prepared for the challenges of climate change and increasingly strict requirements of plant protection.
"The plants can root up to three meters deep," explained farmer Rafael Dulon from the hemp farm in Melz in the Mecklenburg Lake District. "Due to its rapid growth, it absorbs a lot of nitrogen from the soil." However, we have not yet found out how large the nitrate uptake is in the respective soil layers. "To find out, the nitrogen uptake of the hemp plants will be recorded over the next two years using hyperspectral measurements and biomass surveys, and soil samples will be taken at different depths on both conventionally and organically farmed areas," explained Prof. Eike Stefan Dobers of Neubrandenburg University of Applied Sciences.
The plant and soil samples taken are then analyzed in a modern laboratory of FPS Anklam GmbH in the district of Vorpommern Greifswald. "Our service company specializes in investigations and developments of new methods in the field of environmental sciences," said Managing Director Prof. Beatrice Großjohann. "In preparation for the project, our team was also able to establish a method for detecting THC from hemp. Strict rules apply to the use of hemp as animal feed, according to which a THC content of 0.2 percent must not be exceeded."
Amazing feed value
Scientists from the Institute of Nutritional Physiology "Oskar Kellner" at the Research Institute for Farm Animal Biology (FBN) are investigating the suitability of THC-free hemp leaves as a soy substitute for feeding dairy cows. "Although soybean extraction meal is with over 50 percent very high in protein, hemp leaves have up to 23 percent more protein than, for example, native legume crops such as clover or alfalfa. In addition, the fat content of hemp leaves can be up to 20 percent. This means that hemp leaves contain a lot of valuable nutrients," explained project leader PD Dr. Björn Kuhla from FBN. However, it is still unclear how digestible the protein and fat of hemp leaves are or whether other ingredients negatively affect digestion or even methane production in animals. This gap in knowledge is also to be closed in the new research project.
The project team hopes to find practical methods for the cultivation of hemp as a catch crop in order to further reduce nitrate emissions from arable soils in so-called red areas, to reduce CO2 emissions from soybean imports and, if necessary, methane emissions from dairy farming. In this context, hemp can be used universally. The first results will be presented at information events for farmers in the coming year.
The ZwiHanf team is looking for solutions to reduce nitrate and greenhouse gas emissions from agriculture - Dr. Mohamed Amine Daly (FPS/from left), Prof. Beatrice Großjohann (FPS), PD. Dr. Björn Kuhla (FBN), Rafael Dulon (hemp farm) and Prof. Eike Stefan Dobers (HS-NB). Hemp is a catch crop in terms of cultivation time.
Research Institute for Farm Animal Biology (FBN)
Wilhelm-Stahl-Allee 2, 18196 Dummerstorf
Director: Prof. Dr. Klaus Wimmers
T +49 38208-68 600
Institute for Nutritional Physiology "Oskar Kellner"
Management: Prof. Dr. Cornelia C. Metges
Project Manager ZwiHanf: PD Dr. Björn Kuhla
T +49 38208-68 695
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T +49 38208-68 605