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Soil erosion

Soil erosion -the process by which grains of soil are dragged by the action of water or wind- is becoming increasingly common on the planet. It is, of course, one of the major players in the geological cycle. It is usually slow and takes millions of years. Erosion is caused by different climatic factors: water precipitation from rain and snow, wind and temperature changes. These physical factors cause an accelerated detachment and dragging of soil particles - clay, silt and sand - by surface water currents or wind.

Over the past 50 years, erosion has increased dramatically worldwide, causing irreversible degradation and damage which affect biodiversity, agriculture, freshwater systems, and mankind in general. The end result of the continuous degradation of land and vegetation, coupled with the erosion and loss of the topsoil is called desertification.

 

Impact of soil erosion
Dominican soil degradation
Soil conservation measures in the Dominican Republic
 

Impact of soil erosion

Loss of soil causes a series of very direct impacts: the loss of the elements of fertility; the loss of the useful soil thickness (considering that a half-inch layer of soil can take 1,000 years to form and can be lost in a week or in a day when there is heavy rain and it is unprotected); the eventual desertification, and the loss of usable space for plant growing.

According to the United Nations Food and Agriculture Organization (FAO), nowadays soil erosion affects 20% of agricultural land, 15% of grassland and 30% of the world's forests. The Organization notes that this erosion has been at its worst for the past 20 years. According to a recent study by FAO and its partners, in the middle of the first decade of the XXI century, land degradation affected more than 1,5 billion people. This report details that erosion is caused mainly by poor land management, due to poverty, the abusive felling of trees, overgrazing and poor irrigation practices. The end results is that world citizens suffer the damages affecting the natural resources on which they depend, biodiversity is lost, there is a sharp decline of agricultural productivity, and finally, it brings hunger, a phenomenon that causes migration of human populations to less affected areas, which are often already densely populated.

Nowadays, land degradation caused by soil erosion continues to take place, even though a total of 193 countries have ratified the 1994 United Nations Convention to Combat Desertification (UNCCD) in their attempt to fight land degradation. Thus, experts in edaphology - soil science- and specialists in agronomy, silviculture and livestock believe that if the process of erosion of natural resources cannot be stopped and reversed, the world will not achieve the Millennium Development Goals (MDGs), particularly the goal of halving extreme poverty and hunger by 2015. Bearing in mind that soil erosion eventually causes desertification, UNCCD seems to be the most suitable international political mechanism to coordinate and advance in coherent global fight against soil erosion. In fact, this struggle deserves a clear and general commitment from politicians and social actors in the affected countries, including the Dominican Republic.

In order to control the problem of soil erosion, it is important to make progress towards a better management of irrigation in agricultural lands. It is also crucial that the forest cover be increased through tree plantations. Therefore, well-protected watersheds which have dense forest covers, will allow an increased infiltration and surface storage of water, which would prolong the process of runoff, thus stabilizing soil and waterways. It is also key to restore soil fertility, since erosion will always cause a loss of minerals and organic matter at that level.

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Dominican soil degradation

As for the Dominican Republic, it is known that 25% of its territory is suitable for agriculture, and a similar proportion has soils suitable for pasture and permanent crops such as coffee, cocoa and fruit trees, while 50% is forest land. In a detailed study, the Department of Environmental and Natural Resources of the Dominican Republic (DIARENA for its Spanish acronym), an agency of the Ministry of the Environment and Natural Resources (SEMARENA for its Spanish acronym), reports that 15% of the country's soils are being overused, meaning, they are used beyond their natural capacity, and therefore, they are subject to processes of degradation or loss of physical, chemical and biological characteristics that determine their properties. These lands are concentrated in mountain areas with steep hills and soils under intensive use, without good conservation practices. By contrast, 40% is being underutilized, meaning, their usage is below its productive capacity, for example, soils with huge agricultural potential being used for extensive grazing. Similarly, it has been identified that almost 30% of the country's soils are being used properly, including among them the territory occupied by national parks and other protected areas.

Close to 60% of Dominican Republic soils are located in mountainous areas, while the remaining 40% is distributed in flat and undulating areas and include soils with high fertility, such as the San Juan de la Maguana and Cibao valleys, among others. However, most of these soils are not yet well protected. Specialist Roberto Sanchez mentions that in the Ocoa River basin, one of the most degraded in the Dominican Republic, about 500 tons of soil per hectare are lost annually. Sanchez indicates that in the country, the main causes of soil erosion are: 1) removal of permanent vegetation cover (deforestation) of some soils located on hillside areas and the development of intensive agriculture in them; 2) construction of highways and roads without proper protection, thereby facilitating the occurrence of erosion; and 3) mining operations which move large amounts of land and destabilize large areas.

In turn, the fertile San Juan de la Maguana valley in the Dominican Republic has already lost some of its production capacity due to soil erosion and other damages, after several tropical storms. It is widely known that natural disasters by rain and strong winds reflect an increased vulnerability of the land. Because of these disastrous storms, the San Juan valley, known as the "breadbasket of the South", no longer produces the same amount of beans, as was evidenced by the 2008 harvest, for example, which was significantly reduced, resulting in a decrease in the total domestic production. As a result of the storms, several river systems, such as the San Juan, Yaque del Sur, Sabaneta, Macasías and Mijo were affected, with disproportionate flows and overflows. A subsequent incursion of these rivers on farm plots, among other factors, caused dozens of bean and rice producers to abandon their flooded farms.

Another example of soil degradation due to poor management is the low Yaque del Norte and the Valle de Neyba area. There, good soil quality has been strongly affected by a number of factors, including unsustainable water management and high pollution from overuse of agrochemicals, which in turn cause salinization and reduce the microbial life of the soil.

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Soil conservation measures in the Dominican Republic

In response to this growing problem, in the eighties the Dominican government formed a Soil Conservation Service within the Secretariat of Agriculture, now called the Department of Land and Water (DTA for its acronym in Spanish). The objective of this agency is to seek soil conservation through the development of land use plans, with the involvement of producers and national and international technical assistance. This entity is responsible for implementing rural engineering methodologies for the protection of slopes and the construction of small water storages, among other things. This agency has trained many technical specialists who are working in various public and private organizations, aimed at the control and prevention of soil erosion.

Soon after, the Secretariat of Natural Resources created the Department of Inventory of Natural Resources (DIRENA for its acronym in Spanish), with the objective of spreading knowledge that would allow the implementation of zoning plans. The Department also seeks to support farmers, among others, with useful information for the sustainable management of productive land. The application of the Geographic Information Systems (GIS) has been a key to the success of this program. However, a comprehensive, detailed nationwide land inventory is still necessary, so that soil may be organized in an integrated manner, in terms of both production and preservation. This information is vital so that land use plans can be adjusted in a way that can be adapted to the local conditions of each area, not only in terms of soil, but also other environmental aspects of the land.

At the legal level, there is now a series of measures for soil conservation within the framework of the General Law on Environment and Natural Resources (No. 64-00). This legal framework highlights that the Secretary for Soil and Water, which is part of the Secretariat of the Environment and Natural Resources (SEMARENA) is the agency responsible for issuing land use permits for physical and legal persons who request them, thereby regulating any activity that may involve a change in land use in the rural areas of the country.

Keeping in mind that the situation is still alarming throughout the nation, the Inter-American Institute for Cooperation on Agriculture (IICA) prepared a study on Dominican soils, in which it recommended: 1) to strengthen the Soil Conservation Service so it will continue the work already carried out and extend it to all land uses; 2) to investigate the usefulness and feasibility of establishing a cooperative survey and information system in regards to soil and related natural resources covering the country’s entire territory, in a systematic and prioritized manner; 3) to continue supporting the development of technologies for the analysis of geo-referenced information on natural resources, along with information on economic aspects and population, among other things; 4) to study the possibility of strengthening the country’s hydrological and meteorological information system and, among other tasks, update the information and analysis of rain intensity for purposes of designing infrastructure and planning land use; 5) to investigate the importance of the Water Culture Program as a way of getting the community to contribute to the fulfillment of the government’s responsibilities; 6) to strengthen the Water Culture Program; and 7) to develop equitable funding mechanisms with society as a whole as the beneficiary, which will provide permanent sustainability for these services and help decide on the destination and ways of using these resources.

In turn, expert Roberto Sanchez mentions two key strategies to successfully prevent and control the potential damage from changes in the use of the Dominican land: 1) the need to include in environmental impact studies of developing projects, a proper assessment of the impacts of such action on the state and quality of the soils, and 2) the inclusion of restorative soil practices such as reforestation, soil conservation at the farm level, a decrease in the use of agrochemicals and the promotion of organic agriculture.

It is hoped that by incorporating these and other strategies of integrated management and soil conservation based on scientific knowledge, the health of watersheds, rivers, vegetation, biodiversity and agricultural productivity can be restored, given that the quality of all these resources depends on the presence of healthy and well preserved soils, in order to contribute to the welfare of the Dominican population in the Caribbean island in the long term.

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