The Conversation Spain
World Soil Day: A living entity that is sick
Soil is a living resource, and it can make you sick. We have modified it at will, fed and poisoned. We have damaged the health of the land on which we walk, on which we grow our food, and on which animals graze. And the responsibility for its quality is also ours. A concern that should not be limited to when the UN reminds us that there is a World Soil Day –on December 5– to act against the loss of fertile soil on the planet and its impact on food security. Those of us who investigate in this area know that the first thing is to diagnose how it is. And we can do it with simple methods, such as the tea bag, and better known, such as PCR. Yes, to the ground. Soil is more than we see Soil is, for many, a banal concept. It is the substrate on which we walk, whether at home or in the street or in the field. However, it is a vital resource. To cultivate the land, so that the cattle not only tread, but also find their food, as a support for the construction of buildings, infrastructures … The soil is a living entity, with a certain capacity for change, with a defined and relatively internal structure. fragile, and a composition that is conditioned by many factors. The man profoundly modifies it when he considers that it does not meet his expectations. Add fertilizers or other phytosanitary products to improve its agricultural productivity, modify its structure by mining activity and can make it toxic due to the accumulation of various salts and metals.Soil science studies its formation, structure, composition, and, above all, its characterization to evaluate whether or not a specific soil can be used for a specific purpose, such as being the substrate for a specific type of crop. There are certain parameters that study the composition and nature of the soil in its relationship with plants and the environment: * Chemical reactivity. Estimated by pH, which defines whether it has acid reactivity or alkaline reactivity. * Content in soluble salts. It is measured through the electrical conductivity of the water contained in the soil. * Organic matter content. It reflects its history as a substrate for the accumulation of plant and animal remains. * Grain size of its mineral components. It establishes as loamy soil that which has a certain proportion of the components sand, silt and clay. This type of soil, with this certain relationship between these components, is considered optimal for agriculture. Geochemical and mineralogical composition Certain crops require that the soil have a certain content of carbonates, or silica, or iron compounds. Additionally, the presence or absence of certain metals in the soil has health implications. Many of these metals are considered essential. For example, we need to eat enough iron compounds with food to make hemoglobin. But there are many other metals that also need to be present in the soil in sufficient quantity to be captured by the plants we feed on. We need to know reliably whether or not a soil is suitable for a certain agricultural activity, or whether The pastures that grow on a specific soil, used by a certain type of livestock, may pose a risk of incorporation of undesirable elements to the livestock used for human consumption. Here we enter the field of biogeochemistry: the study of the interrelationships between the composition of the soil and that of the plants that grow on it. Healthy or sick? Healthy soil is one that has the ability to support a certain plant cover, whether natural or agronomic. The diseased soil is the one that has lost this capacity, for various reasons, including human activity, either the excessive use of pesticides, or the introduction of metals from various activities, including mining. What methodologies are used to determine your health? Among the most used: * Tea bag method. It simply consists of burying a tea bag, the kind we take for breakfast or snack, in the ground, for a set period of time. After unearthing it and observing its evolution, we will have an indication of the biological activity exchanged between the tea leaves in the bag and the microfauna in the soil. Its cost is very low, and the results are increasingly interesting due to the amount of data already available on its interpretation. * Determination of the enzymatic activity of the soil. The microorganisms that exist in the soil have an important biological and biochemical activity, which translates into the presence in the soil of the enzymes produced during this activity. The analytical determination of this activity is currently relatively simple and inexpensive. On the contrary, it is not yet clear what significance the greater or lesser abundance of these numerous enzymes may have. * Quantification of the composition of the soil microbiological biomass. The development of PCR (polymerase chain reaction) technology, well known due to the Covid-19 pandemic, allows the identification of microorganisms that live in the soil, at the level of species, genus , or broad groups, as well as their greater or lesser abundance. This type of study has already allowed us to know that the microbiological composition of soils is very homogeneous in global terms, with quantitative and qualitative variations that can be related to specific processes, just as we lift our gaze to the sky to study climate change that we have caused by our way of acting and that threatens our existence, let us also lower our heads to observe and investigate the effects of human activity on the ground we step on. To keep it fertile and healthy and protect its biodiversity.This article was originally published in The Conversation. Read the original. Pablo L. Higueras Higueras receives funds from the National R + D + i Plan and the Castilla-La Mancha Community Board. José Ángel Amorós receives funds from the Ministry of Science and Innovation and the JJCC Castilla-la Mancha. Jose M. Esbri receives funds from the Ministry of Science and Innovation Francisco Jesús García Navarro, Juan Antonio Campos and Marta María Moreno Valencia do not receive salaries, nor do they carry out consultancy work, nor do they own shares, nor do they receive financing from any company or organization that can make a profit of this article, and have declared that they lack relevant links beyond the academic position cited.