Soil degradation, a worrying and intensifying phenomenon

Despite the so-called soilless crops, whose roots draw nutrients directly from nutrient solutions or various substrates, being quite widespread today (especially in horticulture and floriculture), soil in agriculture continues to play an irreplaceable role, along with its fertility, which we have extensively discussed in this in-depth article.

The fertility of agricultural soils underpins their quality, a term that refers to their ability to adequately meet crop nutritional needs, a characteristic that derives from a combination of “well-being” conditions that soil must possess to be alive and vital.

However, as is well known, many cultivated soils today are in a state of degradation, more or less severe, due to a series of often interconnected reasons.
As usual, let us delve into the topic step by step.

According to the ISPRA website, the Italian Institute for Environmental Protection and Research, “Soil degradation is a reduction or loss of the biological and economic productive capacity of the resource. Often, the degradation process is indissolubly linked to biodiversity loss and the impacts of climate change.”

Other definitions, such as that provided by Wikipedia, are broader: “Soil degradation is a degenerative and irreversible process, often caused by humans or their activities, resulting in its total disappearance or a loss of fertility from a physical-mechanical, chemical, and biological standpoint. Due to the long times required for pedogenesis, soil degradation is fully part of the broader phenomenon of environmental degradation.”

In other cases, reference is made more generally to the loss of soil’s ability to provide ecosystem services such as food supply, water filtration, carbon sequestration, and biodiversity support.

Soil degradation, therefore, is not only an agricultural problem but also a broader issue for human quality of life. However, agriculture is closely connected to the phenomenon, both as a partial cause and as a sector that strongly suffers its consequences.

Focusing on cultivated soil degradation, we can identify its main causes, partly “endogenous” and partly more general:

Soil degradation has a direct and measurable impact on agricultural productivity, with significant economic and environmental consequences.

The FAO emphasizes that soil erosion could cause a 10% loss of agricultural crops by 2050, and that about 7% of Italian agricultural areas are at risk of salinization, with significant impacts on fertility and crop sustainability.

According to Re Soil Foundation, 28% of Italy’s arable land has been lost over the past 25 years due to desertification, erosion, and rural abandonment.

ISPRA reports that land consumption caused an average annual loss of over 400,000 tons of agricultural products between 2012 and 2021.

The extreme manifestation of soil degradation is desertification, defined by the Ministry of Environment and Energy Security, echoing the UN, as “the degradation of arid, semi-arid, and dry sub-humid lands attributable to various causes, including climatic variations and human activities,” and “manifested by the reduction or disappearance of biological or economic productivity and complexity of cultivated lands, whether irrigated or not, grasslands, pastures, forests, or wooded areas caused by land-use systems or one or more processes, including those resulting from human activity and settlement patterns, such as water and wind erosion; deterioration of physical, chemical, and biological or economic soil properties; and prolonged loss of natural vegetation (United Nations Convention to Combat Desertification – UNCCD Art. 1.f).”

The list of causes above highlights the crucial role of organic matter in preventing and mitigating this phenomenon. Organic matter positively influences soil physical and chemical properties and supports biodiversity, including microbiota.

A less emphasized aspect of soil degradation is its link to wildfire intensification. Soils rich in organic matter also have greater water retention capacity.

Consequently, vegetation (or crops) growing on such soils will be in an optimal water state, whereas where organic matter is lacking and soil is degraded, both soil and vegetation are drier: in such conditions, the likelihood of wildfire occurrence and its spread rate are much higher.

Wildfires themselves, which have greatly intensified in recent years in our country, are in turn one of the causes of soil degradation.