Combat Soil Erosion Research Articles

Modeling the impacts of integrated small watershed management on soil erosion and sediment delivery: A case study in the Three Gorges Area, China

Summary Soil erosion poses a serious problem for sustainable agriculture and the environment. Owing to long-term anthropic pressure including overuse and inappropriate development, soil erosion has become a serious issue in the Three Gorges Area (TGA), China. Recently, integrated small watershed management (ISWM) for soil conservation in the TGA was rapidly developed. This study was conducted to investigate the impact of ISWM on soil erosion and sediment delivery in the Wangjiaqiao watershed in the TGA. The WATEM/SEDEM distributed erosion and sediment transport model was used to evaluate the effectiveness of the ISWM project. The model was calibrated against long-term measured suspended sediments at the watershed outlet. Land use and conservation measures were mapped and analyzed for 1995 and 2005, paying particular attention to quantification of changes in soil erosion and sediment delivery due to ISWM. The results showed that a combination of decreased soil loss (from 18.5 t ha −1 y −1 in 1995 to 13.2 t ha −1 y −1 in 2005) and increased sediment deposition (from 7.7 to 12.4 t ha −1 y −1 ) has led to a strong decrease in sediment yield (from 8.4 to 3.9 t ha −1 y −1 ) and the sediment delivery ratio (from 0.454 to 0.295). The results of scenario analysis showed that soil conservation measures taken in fields effectively reduce on-site soil loss and sediment yield. However, off-site sediment control measures appear to be much less effective at reducing sediment yield. This diachronic comparison of soil erosion and sediment delivery revealed that ISWM is quite effective and efficient; therefore, it is the appropriate method to combat soil erosion in the TGA and similar areas.

Soil functioning and conservation tillage in the Belgian Loam Belt

One of the most frequently used techniques to combat soil erosion on agricultural fields is conservation agriculture (CA). Conservation tillage techniques (CT), together with residue management and rotation are the pillars of CA. Studies have shown that CT can indeed be very effective in combating soil erosion. While several studies have demonstrated how CT may affect (the distribution of) carbon in the soil and documented compaction risks under CT, much less information is available with respect to the potential effects of CT on within-soil water movement and nutrient status. We therefore investigated the effect of superficial (0.15–0.2m depth) and deep (0.3–0.4m depth) CT on soil properties of agricultural silt loam soils in Belgium. From 2008 to 2010, we analyzed the effect of CT on water content, hydraulic conductivity, penetration resistance, bulk density, organic carbon and nitrate content of the soil. At the same time the effect of CT on root growth and crop yield was analyzed.We found that soil structural differences between conventional mouldboard ploughing and deep CT tended to be very small and did not have any effect on root growth and/or crop yield. Furthermore, we were not able to detect any significant difference between the different implements used in CT. The application of superficial CT however, led to an increase in penetration resistance in the upper soil layer hindering vertical soil water movement and root growth on one trial field. Crop yield was not affected due to a sufficient water and nutrient supply. Effects of deep CT on water availability and water movement were very limited and suggest that deep CT may slightly improve water availability only during dry summer periods.Total carbon content was not affected by CT, but its distribution through the plough layer changed whereby the carbon content in the upper few centimetres of soil increased while a decrease was noted at greater depths. The reduction of the nitrate content observed in deeper soil layers indicates that reduced tillage did not lead to increased nitrate leaching and may even help to reduce this problem if adequate catch crops are planted.We conclude that, on the Belgian silt loam soils, deep CT can be practiced whereby good soil functioning can be ensured. As crop yields were also similar, deep CT is a viable alternative that may contribute to soil protection. The use of superficial CT cannot be recommended due to a compaction risk.

Effects of rock fragment cover on hydrological response and soil loss from Regosols in a semi-humid environment in South-West China

Controlling soil hydrological processes and combating soil erosion on agricultural fields are high priorities for crop production and ecological environments. In this research, the effect of land application of rock fragments on surface runoff, subsurface runoff, infiltration and soil loss on Regosols had been investigated under field conditions using a portable rainfall simulator. Experimental twin-plot (two subplot with 1-m wide by 2-m long, 32% slope) with different rock fragment covers ranging from 0–40% were exposed to three rainfall intensities, low (57±2mmh-1), medium (91±3mmh-1), and high (122±5mmh-1). Fifteen treatments were conducted in the experiments in duplicates. Surface runoff, subsurface runoff, soil moisture and sediment were measured. Results show that surface rock fragment cover retarded surface runoff, increased infiltration and subsurface runoff, and diminished sediment concentration and soil loss. The final infiltration rates, which increased with increasing rock fragment covers, were 16.5–42.7mmh-1 at low intensity, 19.7–50.8mmh-1 at medium intensity and 23.8–56.4mmh-1 at high intensity. Compared with bare soils, surface runoff rates were reduced to 24%, 51% and 64% in soils with 40% rock fragment cover at low, medium and high intensity rainfall, respectively. Subsurface runoff volume was significantly higher and time to start subsurface runoff was shorter as surface rock fragment cover increased. Compared with bare soils, subsurface runoff coefficients increased to 3.5, 3.3 and 2.9 times in soils with 40% rock fragment cover at low, medium and high intensity, respectively. Sediment concentrations increased from 9.8gL-1 for 40% rock fragment cover under high intensity rainfall to 51.5gL-1 for bare soils with rain falling at high intensity. The erosion rate was <12gm-2min-1 for soils with 40% rock fragment cover, even when rainfall intensity was high, while it was >15gm-2min-1 for bare soils under low intensity. The relationship between rock fragment cover and soil loss ratio can be expressed by an exponential function with a high degree of reliability, regardless of rainfall intensities. Overall, results indicate the surface rock fragments can be influential in shaping hydrological processes and soil loss from sloping farmland.

Historical Development of Non-Formal Environmental Education in Turkey

The article discusses the periods of environmental education development in connection with internal social and international global influences, mainly the effect of the First United Nations Conference on Human environment in Stockholm 1972, the 1992 Earth Summit in Rio de Janeiro and the 2002 Earth Summit in Johannesburg. The article pays attention to the impact of the social background and the role of science and pedagogical research on the different stages in the curriculum and textbook development. The content of school subjects and educational technologies has also evolved towards student-centered interactive education in and out of school. From past to present, there have been many institutions in Turkey which provide environmental education. Some of these organizations most of whom work on a voluntary basis providing only informal training are: The Turkish Association for the Conservation of Nature (TTKD) 1955, World Wild Fund (WWF-DHKV) 1975, Research Association of Rural Environment and Forestry (KIRCEV) 1989, Directorate of Intramural Physical Education and Scouting (OBESID) 1989, The Foundation for the Protection and Promotion of the Environment and Cultural Heritage (CEKUL) 1990, The Turkish Foundation for Combating Soil Erosion, for Reforestation and the Protection of Natural Habitats (TEMA) 1992, Scouting and Guiding Federation of Turkey (TIF) 1992 and Nature Society, 2002. Although there are lots of studies carried out regarding the environmental education in Turkey, the studies regarding the topic started in real terms in 1999. The environmental education programs, conducted outside schools and the college systems, have been in operation in Turkey since 1999 and are carried out in collaboration with The Scientific and Technological Research Council of Turkey (TUBITAK), Universities, the General Directorate of National Parks and Environmental Protection and local authorities. The environmental education programs have 2 levels: theory and implementation. On the, ‘theory’ level, experts in the field disseminate their knowledge of the features of the ecosystems of the protected sites and surrounding areas. On the, ‘implementation’ level, all these features are studied in the field and the problems are identified and solutions are proposed. The target population of this environmental education project consists of teachers, scout leaders and those in post-graduate study. The program aims, through its teachings on nature, to popularize science among a wider population and to provide ways for the existing accumulation of knowledge to be used and implemented by this population. The program has provided a developmental framework for implementing field work and similar environmental education projects in the regions concerned and has brought about a more comprehensive and higher quality standard of education in the participating institutions. It is hoped that in the future the programs will reach more people and instill a lifelong desire, curiosity and motivation regarding ecosystems and the environment. Still there are many unsolved problems in environmental education.

Harnessing sustainability, resilience and productivity through conservation agriculture: the case of likoti in Lesotho

Subsistence farmers in Lesotho have been able to boost agricultural yields and increase food production by adopting conservation agriculture. The practice, locally known as likoti, also contributes to combating soil erosion and to enhancing fertility. The socio-economic and environmental benefits help poor households to rehabilitate and strengthen their livelihood capital base and ultimately help rural communities to build system resilience in the face of widespread poverty and increasing vulnerability that affect the country. This paper discusses the major advantages associated with the spread of likoti. By drawing on primary data collected by FAO-Lesotho, it enquires into the determinants of adoption, thereby highlighting constraints and options for future up-scaling. The results show that attending appropriate training is a crucial prerequisite for the correct adoption of likoti. However, training is more effective when trainers pursue true participation and when social capital among farmers is stronger. Further important determinants of adoption are the level of education and the economic incentives provided to vulnerable households. Stronger policy and institutional support in all these areas would thus help address the cultural and resource constraints that limit the full potential of likoti to be harnessed and ultimately hinder its further spread throughout the country.

Soil Erosion Control and Moisture Conservation of Arid Lands with Stone Cover

Soil moisture conservation and combating soil erosion on agricultural fields are the highest priorities for crop production in arid lands. In this research, the effect of land application of rock fragments on runoff, soil loss, and vegetative cover on a silt loam soil has been tested under natural rainfall conditions. Field plots of 2 m wide by 10 m long were prepared in two locations with a deposit installed at the downstream end of the plots to collect runoff and sediments after each storm during the 2004/2005 winter season. Three treatments were used in the experiments in duplicates including plots covered with 5% and 15% stone and a control. Experimental results showed that rock fragments were highly effective in reducing runoff and soil loss. Runoff depth from plots covered with rock fragments at a rate of 5% and 15% was reduced by 17% and 30% compared to the control, respectively. The corresponding reductions in soil loss for both stone treatment levels were as high as 35% and 53%, respectively. The average soil moisture measured at the center of the plots during the entire season was always higher for stone treated plots and increased with stone coverage percentage compared to control. Consequently, vegetative cover was higher in the plots with 5% rock fragments cover. For higher stone coverage of 15%, rock fragments occupy more soil surface area and, therefore, reduce the space available for vegetation.

Pathogenicity of dried-shrink disease and evaluation of resistance in a germplasm collection of sea buckthorn ( Hippophae L.) from China and other countries

Sea buckthorn ( Hippophae L.) is a woody, dioecious plant that can be grown in dry and poor soil conditions. It has recently received world-wide attention as a new berry crop with a very high nutritional value and unique medicinal properties, as well as a means of combating soil erosion. A major problem is, however, dried-shrink disease (DSD), which destroys sea buckthorn plants and halts commercial production. In this study, we investigated symptoms and pathogenicity of DSD, isolated and identified pathogens using a combination of morphology and ITS sequences, and evaluated the disease index (DI) of different cultivars in the field. DSD infection causes isolated yellowing of plant tissues, and as the disease develops the bark putresces, dries and shrinks, and finally the plant dies. DSD infects older plants (>3 years), often at the plant base. Death of plant parts above the infected area does not influence root vitality, and a new plant can therefore be regenerated. Combining morphological characters and ITS sequences, we isolated and identified four fungal pathogens causing DSD, including Fusarium acuminatum, F. oxysporum, Fusarium camptoceras and Phomopsis spp. DI values for 27 cultivars ranged from 0 to 10.4. About half of the cultivars were regarded as resistant (DI < 3.2) to DSD, and half as susceptible (DI > 6.7). Cultivar ‘Zhongguoshaji’ (DI = 4.2) showed an intermediate level of DSD resistance. Our data provides basic information for further studies of the mechanism of pathogenicity, and for breeding of DSD-resistant cultivars.

Assessing the effect of soil tillage on crop growth: A meta-regression analysis on European crop yields under conservation agriculture

Many strategies exist to combat soil degradation through erosion and compaction on agricultural fields. One of these strategies is conservation agriculture (CA). Reduced or no-tillage techniques, together with crop residue management and crop rotation are the pillars of CA. The term reduced tillage covers a range of tillage practices but it never involves inverting the soil. In this way, soil disturbance is minimised and crop residues are left on the soil. Studies in many European countries have shown that CA can indeed be very effective in combating soil erosion. However, soil and water conservation do not appear as main drivers in farmers’ decisions to shift or not to CA. Economic factors tend to be more important, but there are a lot of uncertainties on this domain. Studies show that production costs are mostly reduced, mainly by reduced fuel costs. Although many European studies have investigated the effect of reduced soil tillage on crop yields, a lot of uncertainties still exist. Most of the studies only cover a small range of field experiments, in one region. We present a meta-regression analysis (47 European studies, 563 observations) that compares crop yields under conventional tillage (CT), reduced tillage (RT) and no-tillage (NT) techniques. We analysed the possible influence on the relative yield ((RT or NT)/CT) of crop type, tillage depth, crop rotation, climate, CT yield and length of application of RT or NT. Our analysis shows that, while the introduction of conservation tillage in Europe may indeed have some negative effect on yields, these effects can be expected to be limited: the overall average reduction we found was ca. 4.5%. NT reduces crop yield on average with 8.5%. However, RT leads to a reduction in crop yields for maize and winter cereals only. By applying a linear mixed model, the importance of tillage depth and crop type as classification effects could be confirmed. Surprisingly, no-tillage did perform worse under drier climatic conditions. Negative effects such as an increased prevalence of pests and a lower quality of seed placement seem to outweigh possible gains due to increased water availability. On clay and sandy soils, however, this negative effect of no-tillage is counteracted, and all conservation tillage techniques perform better under drier climatic conditions. Another important finding is that, in cereals only rotations, relative yields under conservation tillage tend to decrease with time. Our analysis shows that conservation tillage is certainly a viable option for European agriculture from the viewpoint of agricultural productivity. Potential negative effects on agricultural productivity can be strongly reduced by applying sufficiently deep tillage and using a crop rotation including crops other than cereals.

A LASTING STORY: CONSERVATION AND AGRICULTURAL EXTENSION SERVICES IN COLONIAL MALAWI

AbstractHistorians have written extensively about agricultural extension services and the linkages between colonial administrations and rural communities in British Africa. Most studies argue that it is possible to identify a qualitative shift in strategies between the inter- and the post-war periods. The former is characterized by modest attempts at promoting soil conservation, while the latter is described as a period when colonial governments in British Africa – guided by scientific knowledge – tried to transform peasant agriculture to increase production. This article questions this division by using colonial Malawi as a case. It reveals that the strategies and intensity of agricultural extension services changed over time but that the aim of intervention, i.e. to combat soil erosion, remained the focal point throughout the colonial period. This shows that it is important to distinguish between strategies and scale of intervention on the one hand and their aims and contents on the other. Changes in the former took place within the conservation paradigm. Additionally, this article reveals that agricultural extension services were directed by colonial officials' perceptions about African farmers rather than detailed empirical knowledge about existing farming methods.

To terrace or not: the short-term impact of bench terraces on soil properties and crop response in the Peruvian Andes

Soil erosion is considered as a serious threat to agricultural development in developing countries. Soil and water conservation measures, such as terraces, are often promoted to combat soil erosion and to increase agricultural production. In this paper, the short-term impact of bench terraces, 2–4 years after their establishment, on soil properties and maize yield in the Peruvian Andes is analysed and discussed. The results show that bench terraces did not result in any short term change in soil properties, such as fertility or infiltration capacity. Nevertheless, the bench terraces resulted in 20% higher yields, due to a higher planting density, compared with adjacent sloping fields. However, this increase in yield was nullified by the loss of area occupied by the bench terraces. Bench terraces should therefore be accompanied with other measures to intensify agriculture, such as irrigation or cash crops, to improve the profitability and uptake of bench terraces in the Andes.

Improvement and Valorification through Forest Crops of the Degraded Land Located in the Improvement Perimeter of Livada, Cluj County

Through studies and research, which were carried out within this paper, one tried to relieve the necessity to develop and manage the territory taken in discussion, from point of view of its valorification through forest crops. Forest-tree planting of the degraded land exerts an important multifunctional role in environment improvement, pollution abatement, conservation of water resources and combating soil erosion. One studied in details all physical, economical and social causes that leaded to the degradation of these lands. In addition, one inventorized all degraded lands; the inventory was made using simple measurements with different expeditious means. The perimeter is located in the Transylvanian plateau, Cluj county, on the effective area of Livada locality, precisely the land improvement of Livada, with an area of 11, 4 ha, is located on the left side of the Mare brook.

Sea buckthorn (Hippophae rhamnoides L.)

Sea buckthorn (Hippophae rhamnoides L. of the Elaeagnaceae family) is a spiny, dioecious shrub with small orange berries. It is a pioneer plant that naturally grows on the Himalayan foothills, in Russia, and as far as the southern French Alps. Sea buckthorn has created great interest on multiple levels and to varying degrees, depending on the country. The high content of vitamin C and other antioxidants in its berries makes it an attractive source of nutrition; as such, a number of products, such as sea buckthorn juice and syrup, have appeared on the market. In addition, its fruit is noteworthy for its oilproducing properties: the oil extracted from the seeds or pulp has properties long recognized in Tibet and Russia. Sea buckthorn seed oil is especially rich in polyunsaturated fatty acids, while the plant’s pulp oil mainly consists of saturated and monounsaturated fatty acids; both types of oil contain high levels of vitamin E. Anecdotal and historical evidence and modern research have confirmed the effectiveness of sea buckthorn oil in protecting and regenerating the skin and mucous membranes. Various studies, notably in China, are exploring the therapeutic potential of sea buckthorn in other areas of healthcare (for instance, the prevention of cardiovascular disease). Moreover, sea buckthorn has demonstrated high ecological value; it has been planted on a large scale to combat soil erosion, particularly in China and Canada.

Control of Rainfall-Induced Soil Erosion with Various Types of Polyacrylamide (8 pp)

Several types of organic polymers with various molecular weights and surface charges are produced for various industrial and agricultural purposes, and recent studies have shown that high molecular weight anionic polymers are the most effective in reducing runoff and soil loss. However, anionic polyacrylamide (PAM) is marketed under various commercial names with variable molecular weight and length according to its chemistry (Barvenik 1994). Consequently, its interactions with soil and efficiency in reducing soil erosion are expected to vary. Moreover, types of PAM other than those recommended for erosion control may also be effective in reducing soil erosion. The objective of this research is to test the influence of 9 types of polyacrylamide (PAM) on water infiltration and soil loss of an arid silt loam soil under simulated rainfall conditions. logy. Nine types of organic polymers varied in surface charge, ranging from +20 to –75, and molecular weight ranging from very low to very high were used in this study. Soil plots with dimensions of 60 cm by 120 cm having moderate slope of3 to 5% were constructed in the field and equipped with runoff collection installations. A specific type of PAM was spread on soil plots at a rate of 10 kg/ha. Rainfall was supplied from a drip type rainfall simulator at constant intensity and duration of 80 mm/h and 50 min, respectively. Runoff, infiltration and soil loss were measured for each plot subjected to a specific type of PAM and compared to control plots. Land application of PAMs significantly increased infiltration prior to runoff but had insignificant effect on total infiltration volume and final infiltration rate under the present experimental conditions. Experimental results confirmed that anionic polymers were more effective in reducing soil loss than that of non-ionic or cationic polymers. In fact the cationic, low molecular weight and low surface charge non-ionic PAMs had insignificant effect on soil loss. High molecular weight anionic PAM with 30% surface charge (A-130) was more effective(46% reduction) than those having a high molecular weight and a lower surface charge of 20% (A-110 and A-120) with an aver-age soil loss reduction of 24%. The PAM A-836, described assoil erosion polymer with 20% surface charge and high molecular weight, reduced soil erosion by 41%. Unexpectedly, the anionic PAM with low molecular weight but very high surface charge was also effective in reducing soil loss (47% reduction). Land application of PAM improves water infiltration and highly reduces soil erosion thus improving agricultural production. Application of PAM could be the only viable way to improve arid land farming. It seemed that various types of PAMs, other than those specifically produced for erosion protection can be used to combat soil erosion. This means that farmers in poor countries can use any type of PAM that is available to them to improve agricultural production.

Gully erosion: Impacts, factors and control

Gully erosion attracts increasing attention from scientists as reflected by two recent international meetings [Poesen and Valentin (Eds.), Catena 50 (2–4), 87–564; Li et al., 2004. Gully Erosion Under Global Change. Sichuan Science Technology Press, Chengu, China, 354 pp.]. This growing interest is associated with the increasing concern over off-site impacts caused by soil erosion at larger spatial scales than the cultivated plots. The objective of this paper is to review recent studies on impacts, factors and control of gully erosion and update the review on ‘gully erosion and environmental change: importance and research needs’ [Poesen et al., 2003. Catena 50 (2–4), 91–134.]. For the farmers, the development of gullies leads to a loss of crop yields and available land as well as an increase of workload (i.e. labour necessary to cultivate the land). Gullies can also change the mosaic patterns between fallow and cultivated fields, enhancing hillslope erosion in a feedback loop. In addition, gullies tend to enhance drainage and accelerate aridification processes in the semi-arid zones. Fingerprinting the origin of sediments within catchments to determine the relative contributions of potential sediment sources has become essential to identify sources of potential pollution and to develop management strategies to combat soil erosion. In this respect, tracers such as carbon, nitrogen, the nuclear bomb-derived radionuclide 137 Cs, magnetics and the strontium isotopic ratio are increasingly used to fingerprint sediment. Recent studies conducted in Australia, China, Ethiopia and USA showed that the major part of the sediment in reservoirs might have come from gully erosion. Gullies not only occur in marly badlands and mountainous or hilly regions but also more globally in soils subjected to soil crusting such as loess (European belt, Chinese Loess Plateau, North America) and sandy soils (Sahelian zone, north-east Thailand) or in soils prone to piping and tunnelling such as dispersive soils. Most of the time, the gullying processes are triggered by inappropriate cultivation and irrigation systems, overgrazing, log haulage tracks, road building and urbanization. As exemplified by recent examples from all over the world, land use change is expected to have a greater impact on gully erosion than climate change. Yet, reconstructions of historical causes of gully erosion, using high-resolution stratigraphy, archaeological dating of pottery and 14C dating of wood and charcoal, show that the main gully erosion periods identified in Europe correspond to a combination not only of deforestation and overuse of the land but also to periods with high frequency of extreme rainfall events. Many techniques have proved to be effective for gully prevention and control, including vegetation cover, zero or reduced tillage, stone bunds, exclosures, terracing and check dams. However, these techniques are rarely adopted by farmers in the long run and at a larger spatial scale because their introduction is rarely associated with a rapid benefit for the farmers in terms of an increase in land or labour productivity and is often contingent upon incentives.

Impact of climate change on soil erosion, runoff, and wheat productivity in central Oklahoma

The potential for global climate changes to increase the risk of soil erosion is clear, but the actual damage is not. The objectives of this study were to evaluate the potential impacts of climate change on soil erosion, surface runoff, and wheat productivity in central Oklahoma. Monthly projections were used from the Hadley Centre's general circulation model, HadCM3, using scenarios A2a, B2a, and GGa1 for the periods of 1950–1999 and 2070–2099. Projected changes in monthly precipitation and temperature distributions between the two periods were incorporated into daily weather series by means of a stochastic weather generator (CLIGEN) with its input parameters adjusted to each scenario. The Water Erosion Prediction Project (WEPP) model was run for four climate scenarios including a recent historical climate and three tillage systems (conventional tillage, conservation tillage, and no-till). HadCM3-projected mean annual precipitation during 2070–2099 at El Reno, Oklahoma decreased by 13.6%, 7.2%, and 6.2% for A2a, B2a, and GGa1, respectively; and mean annual temperature increased by 5.7, 4.0, and 4.7 °C, respectively. Predicted average annual soil loss in the tillage systems other than no-till, compared with historical climate (1950–1999), increased by 18–30% for A2a, remained similar for B2a, and increased by 67–82% for GGa1. Predicted soil loss in no-till did not increase in the three scenarios. Predicted mean annual runoff in all three tillage systems increased by 16–25% for A2a, remained similar for B2a, and increased by 6–19% for GGa1. The greater increases in soil loss and runoff in GGa1 were attributed to greater variability in monthly precipitation as projected by HadCM3. The increased variability led to increased frequency of large storms. Small changes in wheat yield, which ranged from a 5% decrease in B2a to a 5% increase in GGa1, were because the adverse effects of the temperature increase on winter wheat growth were largely offset by CO 2 rise as well as the bulky decrease in precipitation occurred outside the growing season. The overall results indicate that no-till and conservation tillage systems will be effective in combating soil erosion under projected climates in central Oklahoma.

How China is Adopting Market Mechanisms to Foster Soil and Water Conservation

Soil erosion is a major environmental concern in China; it not only causes significant environmental damage, but also undermines the national economy. In the last half century, a series of soil conservation policies has been employed to combat soil erosion. During the period of the planned economy, government mobilization of a massive labour force to build soil conservation engineering works and plant trees in degraded land was a primary strategy to control soil erosion, while in the present era economic incentives like the Household Contracting Watershed (HCW) scheme have been introduced to encourage farmers to implement soil conservation. The market-oriented economic regime views this approach to be more effective. Nevertheless, an increase in government investment in soil conservation is playing a significant role in areas where soil erosion is most severe. Also in recent years, soil conservation laws and regulations have been introduced to deal with soil erosion generated by massive and rapid urbanization in China. Because of a history of state ownership of land, it is easier in China than in market economies to require farmers to control soil erosion, particularly as they are being given property rights at the same time.

Carbono do solo e a mitigação da mudança climática global

The soils of the world contain more carbon than the combined total amounts occurring in vegetation and the atmosphere. Hence soils are a major reservoir of carbon in terrestrial ecosystems and an important sink. Recently, emphasis has been placed on the need to sequester carbon from atmospheric carbon dioxide into soil organic matter because of international concerns about greenhouse gas emissions and global climate change. The best strategies to built-up carbon stocks in the soil are basically those that increase the input of organic matter to the soil, and/or decrease the rate of soil organic matter decomposition. Grain crop systems based on soil ploughing and harrowing lead to CO2 emissions combined with tremendous soil losses. In Brazil, no-tillage system was introduced to combat soil erosion by water and this soil management led to the build-up of soil carbon stocks with simultaneous high crop yields. However, the present procedure used to quantify carbon stocks in soils is laborious and of high cost. The use of infrared spectroscopy is very promising as an alternative low-cost method of soil carbon determination.

How China is Adopting Market Mechanisms to Foster Soil and Water Conservation

Soil erosion is a major environmental concern in China; it not only causes significant environmental damage, but also undermines the national economy. In the last half century, a series of soil conservation policies has been employed to combat soil erosion. During the period of the planned economy, government mobilization of a massive labour force to build soil conservation engineering works and plant trees in degraded land was a primary strategy to control soil erosion, while in the present era economic incentives like the Household Contracting Watershed (HCW) scheme have been introduced to encourage farmers to implement soil conservation. The market-oriented economic regime views this approach to be more effective. Nevertheless, an increase in government investment in soil conservation is playing a significant role in areas where soil erosion is most severe. Also in recent years, soil conservation laws and regulations have been introduced to deal with soil erosion generated by massive and rapid urbanization in China. Because of a history of state ownership of land, it is easier in China than in market economies to require farmers to control soil erosion, particularly as they are being given property rights at the same time.

Land degradation, government subsidy, and smallholders’ conservation decision: the case of the loess plateau in China

Land degradation is one of the severe environmental problems in China. In order to combat land degradation, a soil conservation program was introduced since 2000 to reduce soil erosion by converting slope-cultivated land into forestry and pasture. This paper represents the first systematic attempt to investigate the impact of the soil conservation program on land degradation in the loess plateau. The results indicate that the soil conservation program to convert slope fields into forest or pasture is an effective way to combat soil erosion. However, a subsidy that is higher than profit of land use activity of slope fields before their conversion into forest and pasture is needed to encourage farmers to join the conservation program. A policy measure to encourage and assist farmers to develop sedentary livestock by using crops produced from fields as well as fodder and forage grass from the converted slope fields might contribute to combat soil erosion. Increase in off-farm job opportunities may encourage households to reduce cultivation in slope fields. That implies a policy measure to encourage rural urbanization might contribute to combat soil erosion.

Carbon Sequestration and the Restoration of Land Health

Carbon sequestration, the conversion of greenhouse gas CO2 toorganic matter, offers a powerful tool with which to combat climate change. The enlargement of carbon sinks stored in soil and biota is an essential tool in buying time while mankind seeks means to reduce emissions of greenhouse gases and to reduce the elevated levels of atmospheric CO2. Carbon sequestration within the context of the Kyoto Protocol of the United Nations Framework Convention on Climate Change (UNFCCC) also has great potential as an incentive for combating land degradation and desertification and restoring fertility to degraded land.Decisions regarding carbon sinks during finalization of the operational details of the Kyoto Protocol in 2001 fit well the needs of countries facing land degradation and desertification. However, incentives for such mitigation through the Clean Development Mechanism of the protocol are limited to forestry issues. Iceland provides a good example of the multiple role of carbon sequestration in meeting national commitments to UNFCCC, conserving and restoring biological diversity, combating soil erosion, revegetation of eroded land and reforestation. Linking carbon sequestration with such goals has resulted in increased funds for soil conservation and restoration of degraded land in Iceland.