Home » Issue 25-2022 » FITZ training centre » Less mineral fertiliser? Yes! But not at all costs

Less mineral fertiliser? Yes! But not at all costs

In September 2022, the HORSCH Practical Field Days took place at the Ferme de la Lucine in France. The main topics: new impulses with regard to plant nutrition and soil management.

At the Ferme de la Lucine in the department Haute-Marne the basic fertililser inputs were reduced dramatically. At the same time, the development of phosphor and potassium in the soils are watched closely. Nitrogen remains the crucial challenge and thus, the cultivation system of the farm is reviewed. This was discussed on the occasion of the Journées de la Lucine.

To begin with, Nicolas Broutin, president of Yara France, looked back on the origins of the tensions on the fertiliser market. It started with an increase of the demand due to the economic revival at the end of the Covid 19 crisis. With the energy crisis they now have reached a historic level. The production costs for nitrogen fertiliser are directly linked to the costs for gas production. The fundamental component of fertiliser, ammonia, is produced by mixing the nitrogen of the air with hydrogen. Hydrogen is produced if methane molecules are broken at a high temperature. According to Nicolas Broutin, methane which is used as a raw material and as a combustible material accounts for 80 to 90 % of the production costs for fertiliser.
Because of the energy crisis, which was triggered by the conflict in the Ukraine, the gas price has been multiplying tenfold since 2021. Accordingly, the price for nitrogen fertiliser tripled and the farmers reduced their consumption by 15 %. The fertiliser plants, too, - because of the decreasing profitability – lowered their production in Europe by 50 %. The fertiliser supply on the European market is backed up with imports from countries where the gas price is not as high as in Europe.

New use and CO2-neutral fertilisers

According to Nicolas Broutin, this situation is not going to change at short notice. Point difficulties of supply might occur in case of consumption peaks or at the end of the season when the stock is almost empty. Therefore, the president of Yara France recommends splitting the purchases and preferring nitrogen forms that are easier available to the plant. Thus, and in combination with a precise control of the fertiliser inputs, farms can save 10 to 20 % of fertiliser. He also mentioned the market launch of CO2-neutral fertiliser that is scheduled for 2023 where hydrogen is extracted by the hydrolysis of water by using electricity and no longer gas. To make this work you at the same time have to produce green electricity – also, of course, CO2-neutral. The costs for this kind of fertiliser today are twice to four times as high but they should decrease when the production capacities increase again if the gas price remains high. In the medium term, Yara aims at 30 % of CO2-neutral fertiliser. In Nicolas Broutin’s opinion, the development of these fertilisers requires intensive discussions with the final consumers. A price increase for the end products will help to reduce the use of fossil energies. When asked about the possibility to produce liquid substrate from the digestate of biogas plants by means of reverse osmosis, Nicolas Broutin points out that the share of mineral nitrogen has to decrease in favour of new solutions that increase the value of organic nitrogen. These solutions, however, are still to be found.

Bio stimulants to optimise plant nutrition

It is not new that nitrogen is crucial for productivity. But you do not only have to take the economic factors into account, about also the environmental ones. On the farm AgroVation in Kněžmost, Czech Republic, the HORSCH agricultural engineer Josef Stangl has been trying for several years to produce wheat with 80 dt, 150 nitrogen units and 13 % of protein. Therefore, it is necessary to focus intensively on rotation, fractionation, forms of nitrogen, micronutrients but also on microbiology. Customers in Brazil research methods to lower the costs for agricultural inputs, to reduce the indicator for treatment frequency and to find substitutes for insecticides and fungicides. Bruno Reinhofer, farmer from Brazil, in addition, examines the biological dynamics of his soils to improve yield and to reduce the impact on plant health.
His 15,000 ha farm, part of it is forest, is located in the south of Brazil at a height of 860 to 1,120 m above NHN. The average annual rainfall amounts to 1,500 mm. He harvests twice a year and in winter grows barley and wheat and soya and maize in summer, moreover black beans at the end of summer. The soils consist of 65 % loam, 25 % silt and 10 % sand. He has developed a bacteria mixture he has been using for eight years. He takes humus from his forests and extracts the bacteria he breeds the culture from before applying them to his soils. He has an own production and analysis laboratory to control the quality of his preparations. It requires a certain know-how to master all parameters of the bacteria culture that are fed with flour (temperature, pH, oxygen). Bruno Reinhofer also purchases individual microorganisms but only if the suppliers are able to exactly prove the modalities and periods of use. By applying bacteria his fertilising costs decreased by 50 %. The yields are somewhat less high, but the system had a positive effect on the profitability of his farm. When asked if this method was compatible with crop care products, he explained that in this case you would have to take precautions: when using seed that is coated with fungicides, he sees to it that he inoculates the bacteria below the seed row to avoid any contact that might be detrimental to the inoculum. Moreover, the bacteria, if their quality is sufficient, contribute to degrade glyphosate. With regard to the utilisation of this technology in the climatic conditions of Europe, Bruno Reinhofer, stresses that everyone has to make his own experiences on his own farm to adapt this method to the respective soil-climatic conditions and the production system. His advice: Start with small lots to find the appropriate inocula and then extend the use step by step.

First: understand, second: take action

We are well aware of the fact that the agricultural sector in the long run will have to do without agrochemistry. And we notice that the costs explode. Bruno Reinhofer spoke about his personal experiences with regard to this topic. We always have to keep in mind that nature will try to bypass our efforts to master our environment in order to create diversity. Before we establish our own rules to comply with our need for productivity, we have to listen to what the soil can tell us. What are the solutions of these worlds we hardly know: the soils and the microbiology of the soils? 

“What you see is not what is really there!“ the botanist, mycologist and soil scientist Marc-André Selosse confirmed in this introduction. He is a professor at the National Museum of Natural History in Paris as well as at the universities of Gdansk (Poland) and Kunming (China). “The world consists of plants and animals, but in reality, there first of all are the microbes.” According to the mycologist, less than 1 % of the microbes can be used to create a culture: “You cannot see the bacteria, but due to genetics we can get to know them better.” And their role is crucial, especially in the agricultural sector.
Soil bacteria use the same nutrient resources as the plants. If there were no amoeba, they would compete vigorously with each other. Amoeba feed on bacteria and put nitrogen and phosphate at the disposal of the plants. According to Marc-André Selosse there would be no plants without amoeba.
Another example: Plants consist of tissue that is permeable to air and that provides space for the bacteria: one gramme of leaves contains 100 million bacteria. Their existence controls the functions and the development of animate beings. In case of nitrogen-fixing plants it is the work of the bacteria which allows for the transformation of gaseous nitrogen to amino acids. Farmers have been using bacteria for centuries. Moreover, the quantity of bacteria increases in cultivated soils. The challenge is to find the approaches producers can use to benefit from the service of the bacteria without being a microbiologist. The bacteria activity does not only generate nutrients. They also interact with pathogenic agents and can form a defense wall for the plants (physical obstacle or toxicity of the virus).
Tillage, in turn, entails disturbances. The plough destroys the mycorrhiza threads which are created by the symbiosis between fungus and plant. The fungi are replaced by bacteria that do not have any nutrient-generating effect. Another effect of the plough is that it creates bare soil which though it has a weed-controlling effect, also acts on the microbial flora and limits the nutrient-generating resources of the fungi. From this point of view, Marc-André Selosse recommends avoiding uncovered soils, even selecting catch crops on the basis of their microbial activity. In his opinion, you should prefer organic fertiliser and then, if required, apply mineral fertiliser in a second pass. The increased use of organic fertiliser – of animal but also of human origin – favours mycorrhiza fungus as well as the storage of water and of carbon. Two hot topics!

One question from the audience was: does inoculation help to benefit from the services of the mycorrhiza fungi or of the bacteria? Marc-André Selosse does not have an empirical approach like Bruno Reinhofer to answer this question. In his opinion, without a confirmation by scientific methods it will be difficult to master microbes in nature. His suggestion for an approach is to choose cultivation methods with well-known and well-proven tools that favour the natural processes or disturb the soil as little as possible.
It is only recently that scientific research started to examine the biological mechanisms of the soils. In this respect, microbes still are a blank slate according to Selosse. A lot of knowledge is required, and the potential is enormous. He added: “The soil works by itself. We have to adapt our measures in such a way that we can make use of its resources.”

Summary

It is impossible to simply cut out nitrogen fertiliser – whether on a chemical or on an organic basis. Organic fertilisers cause less losses, the release lasts longer and is better distributed in terms of time. But it also is difficult to get them, especially for a merely arable farm. The solution is to split the fertiliser inputs and to understand the mechanisms of the symbiosis between plant, fungus and the microbial life that exists in our soils. As soon as we have internalised these processes, we will understand how we can use the bacteria without trying to control nature beyond a reasonable level. Control may be comforting. But nature needs variety!