How can we fertilize plants using dust and save humanity from nutrient deficiency in tomorrow's atmosphere?
Dr. Yoav Ben Dor
A significant part of life on earth depends on plants, wonderful creatures that acquired during evolution the ability to produce food from water, air and sunlight in the process of photosynthesis. Plants form the basis of different and complex ecological systems in different and diverse climate zones, and even support human society, which has evolved beyond recognition since humans learned how to grow and cultivate plants intended for food during the agricultural revolution about 11 thousand years ago. At the same time, in addition to air, water and sunlight, plants also need fertilizer and nutrients that allow them to carry out the necessary life activities to produce various substances and grow, and it is accepted to think that they get these substances from the soil in which they grow.
Nutritional processes of plants and the way in which they receive essential substances are important and central issues in agricultural and environmental studies. Optimal planning of irrigation and fertilization that will result in efficient growth and maximum yield while reducing waste - are important issues that require a thorough understanding. The need to understand these issues even sharpens in a world that is becoming more and more crowded under climate change, which involves changing the water balance and nutrients available to plants. One of the key factors that affect the ability of plants to grow optimally and produce the crop needed to support the growing human population is the availability of substances required by the plant in small concentrations for its proper functioning, including elements such as potassium, phosphorus, magnesium, iron and others (referred to in everyday language as minerals). These elements are also essential for the proper functioning of the human body and the population that consumes the plants. Therefore, these minerals can be seen as regulating the distribution of life on Earth.
The source of the minerals in the soils (in which the plants grow) derives from rock decomposition processes, and as several scientific articles have recently shown, also from dust particles (which themselves consist of rock decomposition products), which settle on the ground and vegetation. The Earth's atmosphere contains a very large amount of suspended particles from various natural sources such as dust, volcanic ash and fire ash. These particles are rich in minerals, and feed natural ecosystems when they settle on the ground. Plants manage to absorb the minerals necessary for their survival, and move them further up the food chain. Since plants, unlike animals, cannot move and search for the minerals they need, they have developed diverse strategies during evolution to collect the nutrients they require under different environmental conditions. One of these strategies is the ability to absorb minerals directly from the dust that settles on the leaves, and this is contrary to the popular assumption that the leaves are used by plants to absorb carbon dioxide (CO2) only in the process of photosynthesis, while they absorb the nutrients through their root system.
Common natural sources of particulate matter in the atmosphere (left to right): mineral dust from dust storms, volcanic ash from volcanic eruptions, and wildfire ash from vegetation fires.
As part of a series of studies, one of which was recently published in the scientific journal science of the total environment under the title Rare earth elements as a tool to study the foliar nutrient uptake phenomenon under ambient and elevated atmospheric CO2 concentration, researchers examined the effects of fertilization using dust on leaves on The chemical composition of the plant and its growth. The current publication was led by Anton Lokshin, a research student at Ben Gurion University of the Negev, together with Dr. Avner Gross from Ben Gurion University of the Negev, Dr. Daniel Falchan from Ariel University and Dr. Yoav Ben Dor from the Israel Geological Survey.
Generally, fertilization planning includes reference to the materials supplied to the plant through the soil, and often through the irrigation system, which combines fertilization, in a process known in English as fertigation, which is formed from the combination of the words fertilization and irrigation. In addition to changes in the water and mineral regime, scientists and farmers are worried about the dilution of the nutritional value of plants used for food due to increased growth that does not match the nutrients available to the plant as a result of an increase in the concentration of carbon dioxide in the atmosphere. Therefore, there is a risk that the nutritional composition of the foods we purchase in the store will change, and they will contain less nutrients that should reach consumers, due to the expected increase in the concentration of carbon dioxide.
As part of the study, the researchers grew hummus plants in covered pots in a closed greenhouse where a system was installed that allows control of the carbon dioxide concentration. Next, the researchers prepared three powders representing different types of dust. Desert dust, typical of regions with Arabian and Sahara deserts, is very common in Israel. Volcanic dust, common in areas affected by volcanic activity, such as Central America, Iceland, various areas throughout the Pacific Ocean and Africa, as well as fire ash, which is a common product of fires and human activity for energy production and factories. The researchers germinated the plants in small pots in which they covered the soil in the pots with plastic, and sprinkled each plant with one of the powders twice during the experimental period, which lasted about two months. The experiment was performed on several plants from each group, as well as on a control group that did not receive any dust treatment, but was left to grow without any intervention. In addition, the experiment was carried out under the conditions of a modern carbon dioxide concentration, as well as in a reference scenario of a carbon dioxide concentration twice that existing today. During the experiment, measurements were also made to assess the rate of carbon fixation, which represents the extent of photosynthesis carried out by the plants. After the end of the experiment, which lasted for about two months when the plants grew to a significant size, the researchers harvested the plants, washed and dried them in an oven and then measured the concentrations of the various metals in the plants. The results of the measurements indicated absorption of metals through the leaves in the plants treated with volcanic dust as well as with desert dust compared to the control group, but the group of plants treated with fire ash did not show significant differences compared to the control group. Much attention was paid to the trace elements, among them the group of rare earth elements (rare earth elements) which make it possible to follow various processes in nature, and indicated the consumption patterns of the nutrients from the leaves.
"The research that has just been published is part of a broad study conducted at the Climate Change Research Laboratory at Ben Gurion University. This issue is essential because it is a very important discovery about the ability of plants to feed themselves, especially in ecosystems that are heavily affected by dust, such as plants in the desert and the Amazon forests. Over the years, we have discovered that the contribution of the struggle for leafy nutrition is a very important phenomenon for the cycle of elements in ecosystems, and can also be an important way of fertilization in light of the effects of climate change and the increase in atmospheric carbon concentration," says Dr. Avner Gross, from the Department of Environmental Sciences, Geoinformatics and Urban Planning at Ben Gurion University. "We are trying to characterize and quantify the contribution of dust to plants in diverse ecosystems, and to understand the implications of our findings on a global scale as well."
Through a comparison of the patterns of the rare ores, we were able to show that the composition of the rare ores in the plants does match the composition of the dust material that we scattered on them," says Lokshin. "In addition, these elements seem to have an effect on the biological activity in the plant, and it is possible that they help the plant in more efficient photosynthetic activity, while utilizing a wider range of the spectrum," he adds.
The laboratory work in the research was conducted under the leadership and guidance of Dr. Daniel Falchan at the Trace Elements Laboratory at Ariel University. "The microelements are such a tiny yet so significant part of my day-to-day life. Various differences between plants, such as color, weight, and nutritional composition are also reflected in the composition of the trace elements, which allow us to follow hidden processes.' Dr. Falhan explains. "Therefore, the fact that the experiments conducted in a controlled atmospheric environment in which the concentration of carbon dioxide is double that existing today indicated an increased absorption of various elements through the leaves, could indicate a possible solution to the dilution of minerals in plants that grow under these conditions. These findings are of great importance for the understanding of the absorption mechanism of the substances that fall on the leaf, and perhaps there is also a benefit in this in view of the expected increase in the concentration of carbon dioxide in the atmosphere, caused by human activity", he adds. "It is possible that using this mechanism will allow us to produce a new type of fertilizer to overcome limitations and challenges that normal fertilization has difficulty addressing, and this could have a substantial benefit to the nutrition of humanity." Additional preliminary results even show that edible plants have the ability to absorb iron in excess - which can help deal with a global epidemic of iron deficiency anemia, an iron deficiency anemia that affects old children and pregnant women. "Although there is another fact in front of us, it appears that if people eat more chickpeas from dusty plants there is a real chance of increasing their iron intake," Dr. Falchan concludes.
To read the full article in the Science of the Total Environment newspaper
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