Where is soil degradation

It is a serious environmental problem. Soils are a fundamental natural resource, and are the basis for all terrestrial life. Avoiding soil degradation is crucial to our well-being. Soil degradation is the physical, chemical and biological decline in soil quality. It can be the loss of organic matter, decline in soil fertility, and structural condition, erosion, adverse changes in salinity, acidity or alkalinity, and the effects of toxic chemicals, pollutants or excessive flooding.

Soil degradation can involve:. This program began in and has established a baseline for soil condition and land capability at paired sites across NSW. This represents the largest data set of its kind in Australia. To measure progress towards achieving these targets a Monitoring, Evaluation and Reporting MER program was developed in This program established a baseline for soil condition and land capability at paired sites across NSW.

Department of Planning, Industry and Environment is leading the implementation of this program. Stay up to date on the latest news and events about landscapes, soils and systems in New South Wales. If you are happy for us to follow up on your feedback, please provide your name and email. The use of chemicals under the form of pesticides and fertilizers on often monocultural crops is a very usual way of helping farmers improve their yields.

However, the excessive use of phosphoric chemicals ends up causing an imbalance of microorganisms in the soil moisture, stimulating the growth of harmful bacteria. As the soil gets degraded, the risk of erosion increases and the sediments sweep via the actions of water and wind into rivers and nearby regions, possibly contaminating nearby ecosystems. At the same time, tillage techniques that turn over crops and forages commonly used by farmers to prepare seedbeds by incorporating manure and fertilizers, leveling the soil and taking out invasive seeds also have a large impact.

Instead, it runs off to flood nearby lands, speeded up erosion in these areas. Moreover, motor-based activities such as motocross also have the potential to disturb ecosystems and change even if at a smaller scale compared with other causes and erode the soil. Soil is a very important resource that allows the production of food, fiber, or forages. Despite it being a renewable resource, it renews slowly — generating three centimeters of topsoil takes 1, years.

Therefore, protecting it is very important to bet on long-term, sustainable agricultural practices since one of the main issues associated with soil erosion is that it comes along a decrease in soil productivity. These productivity losses reduce the quantity and quality of the food we eat. A study based on the results of 40 soil associations reported that the effects of soil erosion on soil productivity were mostly the result of subsoil properties such as soil water availability, root growth or plow layer fertility — which impact yield results.

In the end, with an unfavorable subsoil, erosion is easier and yields and productivity are more greatly affected. Despite the fact human activities have accelerated soil erosion, there are ways of repairing the damage we have created. From reforestation and windbreaks to stone walls or more sustainable agriculture techniques. Regenerative agriculture techniques have the potential to preserve and restore ecosystems and habitats and improve the quality and health of the soil.

Windbreaks are linear plantings of shrubs and trees with the goal of improving crop production, protect the soil, people, and livestock. According to FAO , windbreaks can reduce wind velocities for a distance approximately 15 times the height of the tallest trees.

As a result, there is a lower rate of soil loss across large crop areas. According to Camera et. According to FAO , reforestation helps reduce sedimentation rates in downstream valleys. According to this UN agency, reforestation on unstable land and around water regions such as rivers increases the water-retention capacity of land and improve water quality, both of which benefit food production.

Moreover, according to a recent study published in Nature , reforestation also has a tremendous potential to help fight climate change as trees capture huge amounts of CO2. Conservation tillage stands for as any form of tillage that minimizes the number of tillage passes. Conservation tillage techniques have the potential to reduce the vertical movements of soil.

In this way, more crop residues are left on the soil surface reducing the exposure to water or wind erosion. FAO, bringing attention to the fact that a lthough soils are essential for human well-being and the sustainability of life on the planet, they are threatened on all continents by natural erosion.

The dirt beneath our feet is getting poorer and on many farms worldwide, there is less and less of it. Quote by Franklin D. While artificial fertilisers replace - to some extent - the loss of nutrients, they do not replace the loss of organic material. Over time, this seriously reduces soil quality, leading to soils with a lower water holding capacity, less air, and soils that are more susceptible to erosion and hence also degradation. Soil degradation can be classified into four main types of degradation: water erosion, wind erosion, chemical deterioration and physical deterioration.

Water erosion means that soil particles are detached either by splash erosion caused by raindrops , or by the effect of running water. Chemical deterioration as a type of soil degradation involves loss of nutrients or organic matter, salinisation, acidification, soil pollution, and fertility decline. The removal of nutrients reduces the capacity of soils to support plant growth and crop production and causes acidification.

In arid and semi-arid areas problems can arise due to accumulation of salts, which impedes the entry of water in plant roots. Soil toxicity can be brought about in a number of ways. Typical examples are from municipal or industrial wastes, oil spills, the excessive use of fertiliser, herbicides and insecticides, or the release of radioactive materials and acidification by airborne pollutants.

Chemical deterioration of soils is often also due to agricultural over exploitation, relying solely on replenishing nutrient losses through harvesting by artificial fertilisers. Artificial fertilisers most often not able to balance all nutrients, leading to an imbalance in soil. They are also not able to replenish the loss of organic matter, which is important for nutrient absorption.

Furthermore, artificial fertilisers can be polluted e. Physical deterioration involves soil crusting, sealing and compaction and can be caused by several factors like compaction through heavy machines or animals. This problem occurs in all continents, under nearly all climates and soil physical conditions, but has increased with the use of heavy machinery.

Soil crusting and compaction tend to increase runoff, decrease the infiltration of water into the soil, prevent or inhibit plant growth and leave the surface bare and subject to other forms of degradation. Severe crusting of the soil surface because of breakdown of soil aggregates can inhibit water entry into the soil and prevent seedling emergence. Sustainable governance of soil has therefore become a topic of fundamental importance This soil erosion estimate dates back to , first reported by Myers 21 and cited by several succeeding studies 19 , 22 , Accelerated soil erosion is primarily driven by modifications in land use and management.

Spatial patterns of land use and land cover change, especially in areas susceptible to accelerated soil erosion, provide further reason to re-evaluate former qualitative approaches, considering the worldwide increase of croplands and pastures by million hectares ca.

Following the publication of GLASOD, subsequent research aimed to improve the ability to predict soil erosion under global change Models placed greater emphasis on representing the physical processes This, led to a broader understanding of the processes and methodological improvements Scaling in space and time, however, was a great challenge for the new mechanistic models Nearing 9 observed that the disadvantage of the process-based models is the model complexity and their substantial data requirements.

The extremely high demand for input data 31 generally precluded their application above field or small catchment scales In a context where process-based physical models and the availability of input data are not yet mature enough for global scale applications 31 , simple, physically plausible empirical methods for predicting soil erosion such as RUSLE 33 , can provide reasonably accurate estimates for most practical purposes Supplementary Note 1.

This applies especially to wide spatial scale applications when prediction errors do not exceed a factor of two or three Notwithstanding the significant scientific contribution of the expert-based GLASOD 5 approach in the s and the need to further advance process-based physical models 28 , 35 , recent studies have shown the potential of RUSLE 33 model-based approaches as a significant step towards a change in global water erosion assessment 36 , These scoping studies 36 , 37 , compared to GLASOD, provided a more detailed view of the spatial patterns of accelerated soil erosion at a global scale.

They relied, however, on coarse model input data, particularly with respect to land use patterns and erosive power of rainfall. The predictive power of these models is therefore limited to assessments of the land use change effects In this study, we provide quantitative, thorough estimates of soil erosion at the global scale by means of a high-resolution, spatially distributed, RUSLE-based 33 modelling approach.

Unlike previous studies that dealt with soil erosion as a static process, here we shed light on the impacts of 21st century global land use change on soil erosion. Insights into land cover and land use change between and are achieved by combining the extent, types and spatial distribution of global croplands and forests measured by satellite imaging with agricultural inventory data.

The global rainfall erosivity patterns are quantified with a thorough methodology based on rainfall intensity instead of volume, using a time series of sub-hourly and hourly pluviographic records stations covering 63 countries spatialized through a Gaussian Process Regression GPR geo-statistical model. We present results for soil erosion based on data for and , taking into consideration the individual land cover type, vegetation cover dynamics and farming systems of each cell.

For cropland, we ran an additional conservation scenario spatializing the information of the 54 countries that reported the application of conservation tillage practices to the FAO. In , we estimated an overall increase of 2. The area which had undergone a change during the study period totalled about 3.

The remaining 1. This results in an estimated overall increase of soil erosion for areas with land use change of about 0. This offset is the result of heterogeneous regional dynamics.

The spatial pattern of soil erosion in is illustrated in Fig. Areas classified as having very low, and low erosion rates class 1 and class 2 , represent about Moderate class 3 and high class 4 soil erosion values are predicted for about 4.

The remaining land surface classes 5—7 , about 7. Descriptive statistics about the severity of soil erosion across the continents in are provided in Table 1. Global rates of soil displacement by water erosion. Panel a illustrates the soil erosion rates divided into seven classes according to the European Soil Bureau classification.

The colour gradation from green to red indicates the intensity of the predicted erosion rates. The grey colour indicates the areas that were excluded from the modelling due to data unavailability i. Panel b illustrates the erosion reduction rates on cropland obtained from the comparison between the conservation and the baseline scenario for the year The green gradient shows the percentage of reduction.

The grey colour indicates the areas that were not modelled no data. Our modelling results suggest that water erosion is a common phenomenon under all climatic conditions encompassing all observed continents.

Country-specific results and changes of the estimated annual average soil erosion values between and are illustrated in Fig. According to the baseline scenario, at a continental level, South America shows the highest prediction of average soil erosion rate 3.

North America, Europe and Oceania show considerably lower predicted values, totalling 2. In , the latter group of continents indicated an estimated decreasing trend of soil erosion driven by land use change, with the highest decrease predicted in North America 4.

For Asia, we predict a slight increase of about one percent, mainly driven by a noticeable increase in soil erosion in the Southeast Asian countries.

This seems to be primarily driven by a widespread increase of erosion in the western and central African countries. Country-specific changes of the annual average soil erosion. Panels a and b share the same legend. The chromatic scale represents the percentages of increase or decrease of the annual average soil erosion rates obtained by comparing the pixel-based values in each of the countries under observation.

The delta between the two observed periods solely depends on the land use and land cover change outlined combining satellite-derived land use land cover information with agricultural inventory data.

Classified based according to the International Monetary Fund and United Nations classification, the least developed economies experienced the highest prediction of soil erosion rate in 4. The less developed economies have the second highest predicted rate of soil erosion 4. The less developed economies show the highest prediction of annual total soil erosion Notably, the least developed economies mostly located in Sub-Saharan Africa show a predicted increase in soil erosion that is three times higher than the less developed economies.

Comparing soil erosion based on land use types, we find a significant decline in the estimates of soil erosion rates from croplands to forests and other forms of semi-natural vegetation. In either period, the predicted average soil erosion in croplands is more than four times higher than the overall soil erosion rate It is estimated to be 77 times higher than in forests 0.

We assessed the dynamics in land use between and The total gross land stock changed about 3. Flow diagram of land use changes and their effects on the soil loss estimates. The arrows indicate the amount million km 2 of land use and land cover change between and A total of 2. In the baseline scenario, the change from forest to other land uses caused an increase of 0.

The substitution of forests for cropland 4. At the same time, a forest area gain of about 0. With regard to the soil erosion balance, this forest change accounts for an estimated overall decrease of soil erosion in forestland equal to 0. With regard to cropland, about The change in cropland loss or gain is equal to 1. The cropland abandonment amounts to 0. This translates to an increase in soil erosion of 0. Considering the overall increase in soil erosion of about 0.

In Fig. The conservation agriculture covers about Estimated soil loss reduced by conservation agriculture. The grey bars illustrate the estimated soil loss reduction in percent derived from the implementation of conservation agriculture 40 countries show the highest reduction values. The values refer to the model application for the year adjusted for the potential effect of conservation agriculture practices. The red error bars around the dots indicate the variation between the mean values of the conservation scenario, the baseline scenario positive bar and the maximum mitigation effect of the practices negative bar.

Of these countries, 28 regularly reported the proportion of their cropland under conservation agriculture during the last decade for different time periods. From an analysis of the data, different dynamics of the continental conservation pattern can be inferred. The benefits of reducing soil erosion due to the adoption of soil conservation practices are notable. We estimate that if the countries with no information about conservation agriculture would follow the continental patterns obtained from the analysis of the 28 countries, ca.

This would redesign the global patterns described in the baseline scenario as follows. At continental level, Africa 3. The highest impact of conservation agriculture would be observed in South America 3. With regard to the socio-economic prospective, the situation of the conservation scenario does not differ from the baseline scenario. Land management and the related land use changes have an effect on the spatial patterns and magnitude of accelerated soil erosion which can affect land productivity and food security 12 , 18 , biological diversity 39 and carbon cycling 13 , 38 , Global soil erosion dynamics have been previously quantified based on scientific soil expert judgments 4 , 5 , through the extrapolation of plot and river sediment data 41 , 42 and RUSLE-based modelling 36 , While these approaches range in their degree of complexity, their lumped or coarse resolution modelling ca.

Our study investigates the global soil erosion dynamics by means of high-resolution spatially distributed modelling ca. The proposed geo-statistical approach, allows for the first time, the thoroughly incorporation of land uses and their changes, the extent, types, spatial distribution of global croplands, and the effects of the different regional cropping systems into a global soil erosion model. This, coupled with an improved global assessment of the global rainfall erosivity dynamics and the latest globally consistent dataset paved the path towards a state-of-the-art global RUSLE-based model.

The results of this study shed light on the impacts of the 21st century global land use change on soil erosion, providing insights into the potential mitigating effects attributable to conservation agriculture. The strong bond between remote sensing and inventory statistics formed the basis for globally consistent characterizations of soil erosion with local importance and utility Fig.

The knowledge derived from this global assessment can thus improve our understanding in both global and regional land degradation dynamics and forms an important starting point to develop concepts for a better management of the land and an effective mitigation of land degradation.

Examples of the local relevance and utility of the global soil erosion estimates. The area reported in the image is a region of Mato Grosso in Brasil.

The light green indicates forest loss between and The limited availability of globally consistent data on the amount of cropland under conservation agriculture constrained the ability of our study to comprehensively model the mitigating effects for all the countries under observation.

The confidence intervals refer to the variation between the conservation and baseline scenarios superscript and the conservation scenario assuming the maximum technical efficiency of the employed conservation practices subscript.

Previous global estimates of soil erosion on agricultural land span across two orders of magnitude The most cited estimate of global soil erosion in agricultural land by Pimentel et al.

However, recent studies using methods that more closely link models to measured erosion values report smaller global erosion rates. More recently, Doetterl et al.

This resulted in an estimated soil erosion by water in global cropland of Since RUSLE models do not include a description of gully and tillage erosion processes, and also do not represent other geomorphic processes such as landslides and river bank erosion, it is reasonable to assume that their estimates fall into the lower end of the The good correspondence of our results without using constraining factors with regional estimates US and Europe and Doetterl et al.

The estimates reported in this study rest on RUSLE, a deterministic and empirical-based model which was developed based on a statistical analysis of more than 10, plot-years of basic runoff and soil loss data 44 in 49 US locations covering a large variety of landscape conditions. Although RUSLE-based models are derived from the most comprehensive set of measurements available 45 including universally recognized factors that affect soil erosion by water 29 , 33 , they are predominantly built upon parameters that result from experiments conducted in the United States The application to a non-plot-level and in areas outside the range of the original estimates e.

The authors recognize that using an empirical-based prediction tool outside the original range of environmental variables could represent a legitimate concern Considering the proven capacity of RUSLE-based models to overcome their empirical origin 47 , the current lack of better performing models 9 , 31 , and the need for predicting the possible impacts of global change upon soil erosion 27 , the authors argue that at this stage the presented global RUSLE application represents a legitimate approach to narrow the current gap of knowledge and support the targeted soil conservation efforts aiming to mitigate soil erosion.

Given the quantitative and harmonized nature of the data set, there seemed to be no reasons to doubt the consistency between the estimates for the two time periods as well as the reliability of the resulting national trends.

The difference obtained from the comparison of the estimates for the two time periods was driven by land use change and was unaffected by the predictive limits of the empirical soil erosion model.