Bulgarian soils are increasingly feeling the consequences of climate change, but a much greater threat remains the way in which man cultivates the land. The changing climate only deepens the problems accumulated over decades. The oasis of fertility will depend not only on nature, but also on state policies, sustainable agriculture and the preservation of forests. And what else… Prof. Emel Gachev from the Institute for Climate, Atmosphere and Water Research at the Bulgarian Academy of Sciences spoke to FACTI.
- Prof. Gachev, how serious is the risk of desertification in Bulgaria and can we already talk about irreversible processes in some regions of the country?
- Desertification is a process of soil and vegetation degradation, which limits the ability of the landscape to retain moisture and reduces its biological productivity. This process is related to climate development, but much more to incorrect and suboptimal agricultural practices. In Bulgaria, about 85% of soils are affected by erosion to one degree or another, and about 30% are subject to deflation (wind blowing). Over 65% of soils in the country exhibit medium to very high susceptibility to erosion, especially in the Foreland, the Kraishteto and the Eastern Rhodopes, but also in a number of other places. In principle, soil formation can occur relatively quickly, but this applies to primitive soils with low humus content. The formation of mature fertile soils (such as chernozems) requires centuries and even millennia. The damage to these soils is particularly problematic. Loss of productive material and soil depletion has been observed not only today, everywhere where the land is subjected to intensive cultivation. So it is normal for our soils to be affected to one degree or another by these processes.
- Which regions in Bulgaria are most at risk of drought and soil degradation and what are the main reasons why they are the most vulnerable?
- The soils in northwestern, northeastern and southeastern Bulgaria are the most vulnerable. These are flat regions with a large share of agricultural land and active cultivation, which have suffered negative impacts from climate change in recent decades. But soil degradation is far from being related only to drought. A century ago, for example, the semi-mountainous rural areas, which were heavily deforested, were most at risk of erosion. With the adoption of the Nature Protection Act in the 1920s, mass afforestation of these lands began, and now erosion processes in them have been largely controlled. Now the problems are primarily in the plains and valleys.
- How does climate change change the water balance of soils and what do scientific observations show for the last decades?
- In recent decades, climate warming has been observed (0.2 - 0.3°C per decade on an average basis for the country) in the absence of clear trends in changes in annual precipitation amounts. At the same time, in a number of places, especially in Northern Bulgaria, a decrease in precipitation is observed in the summer, which is the most risky season in terms of drought. The increase in temperature leads to an increase in evaporation, which is one of the components of the water balance. If there is no significant change in precipitation, the increase in evaporation is at the expense of a decrease in river runoff and soil water reserves.
For me, a very significant effect is the reduction in the thickness of the snow cover and the drastic reduction in the snow retention period in the non-mountainous parts of the country.
On the one hand, this leads to a more uneven runoff and a deficit of soil moisture, because evaporation from the bare soil increases. The snow cover also contributes to lower temperatures due to its high reflectivity. The early disappearance of snow leads to additional warming and drying of the ground. At the same time, in winter, the soil, deprived of snow protection, is vulnerable to short-term but harmful frosts.
- Annual precipitation does not change dramatically, but its distribution is becoming more uneven. How does this affect agriculture and soil fertility?
- Indeed, in recent decades, along with the noted changes in the precipitation regime, there has also been a change in the way it manifests itself. Precipitation is concentrated in fewer but more intense precipitation events, which are separated by longer dry periods. This again creates the prerequisites for an increase in the frequency and intensity of droughts, with the risk of pulverization and blowing away of the surface soil layer, while heavy rainfall, on the other hand, carries the risk of increased soil erosion.
- To what extent do human activities - intensive agriculture, deforestation and improper irrigation - contribute to drought compared to climatic factors?
- For me, the main threat to soils comes from improper or otherwise suboptimal land cultivation, while climate change helps to exacerbate problems that already exist. Some of the standard agricultural practices are particularly harmful to the soil. For example, the standard way of plowing the land leads to a violation of the mechanical strength of the arable horizon and to its faster drying and pulverization. Leaving the soil without plant cover after harvest and for the time between plowing and sowing exposes the rich humus layer to the force of winds, especially after a prolonged drought, and heavy rainfall directly carries it away. Excessive irrigation under poor drainage conditions can lead to excessive salt accumulation in the soil (salinization), and overly intensive grazing compromises grass vegetation and leaves the soil bare.
- Bulgaria has a long tradition of building forest shelterbelts. What is their condition today and should their restoration become a national priority?
- Forest shelterbelts are linear strips of forest with a width of a few meters to several tens of meters. In the plains, they help reduce the wind force in the ground air layer and thus protect the soil from deflation (blowing away).
The most important are the field shelter belts in Dobrudja, where the winds are strong, the rainfall is low and the soil dries out easily.
Their creation began during the Romanian occupation, and became particularly widespread in the 1950s.
The total area of the field shelter belts in our country is about 10,700 ha, with the majority of them (72%) located in the municipalities of Balchik, Dobrich and General Toshevo. In the last decade, a significant deterioration in the condition of the field shelter belts has been established, with 30% being in particularly poor condition. A major problem is the invasion of invasive insects, as well as pathogenic fungi that damage trees, with the development of these pests being supported by warmer and drier summers. In this regard, collective efforts of scientists and local authorities are needed to restore and maintain these extremely valuable forests.
- What agricultural practices would you recommend to farmers to preserve soil moisture and limit the risk of erosion and loss of fertility?
- Various practices have been developed to protect the soil. It is important not to leave the soil unprotected for a long time. For this purpose, it can be covered with straw or leaves. Another practice for the time when the soil is without a main crop is to plant the so-called cover grass species - vetch, oats, white mustard, clover, etc. (this is the so-called green manure). Grassing is also a good idea between the trees in the orchards. In agricultural practice, no-till farming is encouraged, in which seeds are planted directly at depth, without plowing and turning the topsoil. The problem is that the implementation of this treatment requires the purchase of more expensive mechanization (seeders) and compliance with certain rules during treatment, for example, for certain methods of crop rotation and weed control. However, the benefits are significant - the soil is protected from wind and heavy rainfall, the moistening regime is improved, the structure of soil aggregates is not disturbed, as a result of which fluctuations in yields over the years are much smaller.
- What is the role of forests in preserving soil moisture and water resources and what could be the consequences of continued intensive logging?
- Forests are excellent protection of the soil from erosion, due to the deep penetration of the root system. With their deep roots, trees draw up groundwater and release moisture into the air through their leaves. In this way, they help prevent droughts and fires, due to the moisture-rich microclimate they create. However, the greatest effect is exerted by old, mature forests, not by low-productive and thinned bushes, which are considered forests only on paper. This is precisely why the destruction of old forests should be strictly prohibited and punishable.
- Are there enough state policies and financial incentives for soil protection, or is Bulgaria lagging behind in this area compared to other European countries?
- Efforts have been made in this direction for years. In light of Bulgaria's accession to the EU, the legislation related to soil protection has been brought into line with European standards. Documents concerning the problem include, for example, the National Action Program for Sustainable Land Management and Combating Desertification (2014-2020), the Communication Strategy for Sustainable Land Management in Bulgaria, the National Development Program: Bulgaria 2020 and a number of others. Soil protection is regulated in the Soil Law adopted in 2007, as well as in the Environmental Protection Law. A national program for the protection, sustainable use and restoration of soil functions (2020 - 2030) is currently in effect. As is usual in our country, the problems in soil protection are related to the practical application and implementation of what is set out in these documents, as well as to the many institutions involved, which have difficulty coordinating with each other.
- What will the situation with Bulgarian soils look like in 20-30 years and what will be the consequences for agriculture, food security and the country's economy if we continue like this?
- It is difficult to predict the state of the lands in Bulgaria in such a horizon, since it will be determined both by the development of the climate (for which there are several scenarios) and by social and economic processes of a supranational nature - on the one hand, our country is dependent on European policies in the field of agriculture, on the other, the development of the demographic situation and future migration processes is very important. In any case, key priorities for the coming years are the protection of forests and the introduction of agricultural practices that are as sustainable and as health-friendly as possible. Very important here is the adequate role of the state, which should influence through appropriate mechanisms of subsidies and information campaigns to educate farmers. What is clear is that the climate will continue to change, and in a direction that is rather unfavorable for the condition of the soils. Therefore, our correct behavior (as a society) towards the land that feeds us will be of particular importance in order not to lose this irreplaceable resource.