Key Microorganisms for Crop Yield

Fungi and bacteria are important microorganisms for crop productivity. In organic farming, fungi and bacteria are not synonymous with disease. Thousands of products contain these microorganisms to enrich the soil and produce plants more resistant to diseases and stress such as drought.

It's six in the morning. Farmer Francisco López began his daily tasks on an organic cucumber and eggplant farm in Almería, where he has worked every day for more than 40 years. As if it were Dexter's laboratory, he prepares a mixture of fungi, bacteria and other compounds, which he then pours into his soil.

This combination that López is creating on a small scale is similar to thousands of commercial products that are increasingly used in agriculture to help plants grow in an environmentally friendly way. This means that microorganism-based products help improve yields, protect plants from diseases and even help them stay healthy in stressful situations such as drought.

"Microorganisms and organic matter contribute to soil fertility"The farmer said that the more fertile the place, the better the plants would grow. However, until recently the enormous diversity of microorganisms and their functions in the soil was unknown. “We know that there are microorganisms in the soil and some of them can be beneficial, but we do not know which ones, what importance some species have in relation to other species, or how they interact with each other.” - Carmen Gómez-Lama, expert in plant-microbe interaction and researcher at the Institute of Sustainable Agriculture (IAS-CSIC).

This information has come to light thanks to the arrival of massive DNA sequencing, or metagenomics, which is allowing us to better understand the microbial diversity hidden in leaves, roots and fruits. “These methods have become popular since the beginning of the 21st century and very revolutionary. They allow you to quickly study all the genes that make up a community, determine who lives in the soil and what their possible functions are. This method helps us consider the soil as an ecosystem that supports many forms of life, rather than simply supporting inert matter for vegetation.”says Marta Goberna, researcher at the National Agricultural and Food Research and Technology Institute (INIA-CSIC).

An expert in soil microflora explains that "In a gram of soil, equivalent to a teaspoon, there are millions of individuals belonging to thousands of different species".

This is similar to what happens to human gut microbiome. "We know that bacteria and fungi live in our intestines, but we do not know how they interact with each other, which are good and which are bad., nor what is its specific impact on our health"adds José Miguel Mulet, professor of biotechnology at the Polytechnic University of Valencia.

"Mining" microorganisms that break down phosphates

All these microorganisms work to help the plant eat the macroelements necessary for its growth: nitrogen, phosphorus and potassium.

"For example, phosphate is a very insoluble element and, therefore, difficult for plants to absorb. Bacteria convert it into organic phosphates through chemical reactions, allowing plants to absorb it.”, described the expert in molecular biology.

This process establishes a symbiotic relationship that benefits everyone involved: “The plant carries out photosynthesis and releases sugars into the soil as food for bacteria. This means that they exchange phosphate for carbon and both benefit”explains Mulet.

Some bacteria such as Pseudomonas putida or Bacillus, etc. They work this way. Additionally, these bacteria sometimes act as antagonists of pathogens: “If you kill all the bacteria in the soil with chemicals, you run the risk of developing pathogens. However, if we increase the number of beneficial bacteria, once the pathogens appear, there will no longer be a place for them.", he claimed.

Science has also studied bacteria that solubilize potassium and other minerals such as iron and magnesium, although this method is less common today.

On the other hand, there are bacteria that help fix atmospheric nitrogen, taking it directly from the air and creating compounds that can enter the soil or living organisms. This is a response to the current problem of excess chemical nitrogen in agriculture, which can alter natural ecosystems, causing acidification, nutritional imbalance and loss of biodiversity.

Fungi and mycorrhizae resist drought

Fungi are the next most common microorganisms in agricultural soils. “In particular, the most used fungi in agriculture around the world are those of the genus Trichoderma, which are used to combat diseases and because they increase the resistance of crops to drought and the salinity”. This is explained by Rosa Hermosa, professor of microbiology at the University of Salamanca, a pioneer in Spain in the study of plant responses to Trichoderma, a fungus widely used as a biological control agent for many different plant pathogens.

The growth in its use, which went from 21 registered commercial products to 144 products in 40 countries, demonstrates the interest of agriculture. The researcher patented the first biofungicide in Spain and since then she has not stopped following the properties of the Trichoderma genus.

All these mechanisms carried out by fungi and bacteria help to improve the supply of nutrients to plants and enhance their resistance to drought, salinity or diseases caused by other living organisms. All of this can help increase productivity.

Mycorrhizae, defined as symbiosis between fungi and plant roots, have similar benefits. In these relationships, fungi help expand the tree's roots and increase phosphorus solubility and nitrogen uptake, allowing plants to use water and nutrients more effectively.

Regulations on natural products

One of the problems that microorganism-based products still encounter is current regulations."because the regulation of microorganism-based pesticides is more complex and time-consuming than that of chemical pesticides due to biological complexity, genetic variability, environmental interactions, lack of unified standards, need for specific testing methods, and relatively limited knowledge. compared to chemicals. In the European Union, the precautionary principle is applied, which implies a more rigorous evaluation based on scientific evidence to guarantee high levels of safety and environmental protection.”said Gómez-Lama.

In fact, as the expert points out, this practice is “most common in Asia and Latin America, where regulations are not as strict. Furthermore, in Spain many of these products are registered as biofertilizers because the regulations are much simpler than those for phytosanitary products.".

Other factors, such as the origin of the microorganisms they contain, may be taken into account in the future when approving these products. “Many of these products are made with microorganisms from countries such as the United States and India, so we need to know how they adapt and interact with different environments and confirm that they are not altered.” - said Mario Javier Ruiz, researcher at the University Institute for Conservation and Improvement of Valencian Agrodiversity of the UPV.

The scientist mentioned that the European Community supports projects aimed at soil regeneration: "The objective is to prevent CO2 emissions generated by degraded soils and promote the absorption of compounds harmful to the living Earth planet.".

Ingredients from organic farming

These products provide an alternative to chemical fertilizers and plant protection products in today's growing organic farming environment. “Chemical fertilizers are very well researched and can maximize yields. But we have shown that this is counterproductive for the health of the soil and the planet"He explains.

"In addition, chemical plant protection products prevent the development of diseases usually caused by microorganisms, but at the same time they also negatively affect beneficial microorganisms due to changes in the natural balance of the soil.". The farmer from Almería shares this opinion because his experience forced him to go through difficult times to bring life back to the land.

"The land was severely degraded and lifeless due to exposure to agrochemicals. We need to enrich them with organic matter so that microorganisms can feed and survive. It is important to achieve that balance and, if necessary, help nature by providing it with more microorganisms to compensate for the frenetic pace at which we force it to produce.r,” said Francisco López, who tries to maintain balance in his harvest and not spend too much on products.

"We need to implement management practices that allow us to keep soils fertile and structured, aerated and porous, to create a system with rich and diverse biological communities where plants can develop well.
In parallel with the use of this type of renewable methods, the possibility of using inputs based on beneficial microorganisms, which are environmentally friendly and economically viable, can be considered.
"concludes Marta Goberna.

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