Phosphorus fertilizer could become scarce in the future. The fossil reserves are exhausted. Russia as an important supplier is absent. In this way, the existing phosphorus in the soil can be better utilized.
Phosphorus is an essential nutrient for plants . However, the forms bound in the soil are hardly available for plants. Farmers in the EU therefore apply 2.6 million tons of phosphorus fertilizer every year. However, the global fossil phosphorus reserves could be exhausted in the future.
In addition, part of the phosphate rock is often contaminated with heavy metals. Substances such as cadmium or uranium end up on the field with the fertilizer. Limits of 60 to 20 mg cadmium per kg phosphate fertilizer are therefore now in force in Europe. Therefore, only part of the deposits are suitable for the production of fertilizers. For example, a large occurrence is in Russia .
A working group of agroecologists and soil scientists from the French university UniLaSalle Beauvais has now summarized how the phosphorus can be better utilized.
Ground cover keeps water in the ground
In the future, it will be important to make better use of organic phosphate fertilizers, to limit losses through leaching and, above all, to improve the availability of phosphorus in the soil. European farmers have the advantage that the soil is generally well supplied with phosphorus due to the long history of arable farming. It’s just not always available to plants.
Leaching of the existing nutrients can be avoided by soil cover. Cultures with many fine roots are particularly effective here. They encourage the soil to store a lot of water and only slowly release it again. This prevents nutrients from being washed out, for example by heavy rain.
These cultures make phosphorus available
Some crops can improve phosphorus availability in the soil. The white lupine in particular stands out here . With the help of root exudates, she breaks down more nutrients than she needs herself. Longer roots and dense hair roots help it absorb the nutrient. Lupins, but also field beans, lentils and grasses also form partnerships with mycorrhizal fungi in the soil.
These fungi excrete organic molecules that release the phosphorus bound in the soil for the plants. Alexandrian clover, tawny oats and phacelia, on the other hand, are less attractive to mycorrhiza . Some soil bacteria also help with phosphorus mobilization. They have special enzymes (phytases) that can mineralize organic nutrients.
Diverse cover crops help
The combination of different cover crops therefore helps to improve phosphorus availability. Diverse crop rotations and undersowings fulfill similar functions. The plants absorb the released nutrients. The mineralized residues then benefit the subsequent crop. Organic or mineral phosphate fertilizers cannot yet be completely replaced, but existing nutrients can be better utilized in this way. However, there is still a need for research into which types and mixtures will optimize the availability of phosphorus.
The plants thrive well in the dry northern German soils, according to Norddeutscher Rundfunk. Bread, ice cream and coffee are said to be made from the seeds. The trick is to use the lupine protein and neutralize the bitter substances.
Bread and drinks made from lupins
Organic baker Christian Fries is constantly looking for new ways to refine his breads with local flavors. For the first time he kneaded lupins from Mecklenburg-Western Pomerania in a dough. The result surprised even him: his juicy, high-fiber protein bread sells like hot cakes at the Schwerin market. With her organic roastery, Michelle Roth also wanted to offer beverages that didn’t have to be imported from long distances to Germany. She also came up with the lupine.
Lupins fertilize soil for the following year
The plant will only have what it takes to replace imported soy if customers all over the country also discover lupine as a food. The starting position is favorable, according to the NDR. The plants actually also thrive on the dry soil in Mecklenburg-Western Pomerania. And Brigitte Roost-Krüger from the Holthusen agricultural community sees a lot of potential in the lupine plant, but the extreme drought also worries her. The harvest threatens to be bad.
Nevertheless, researcher Christel Baum from the University of Rostock encourages farmers. The roots of the plants fertilize the soil for the following year. In the long term, the lupine is guaranteed to bring new power to the fields, says the NDR.
