Showing papers on "Soil conservation published in 2010"

The effects of land uses on soil erosion in Spain: A review

Abstract: Soil erosion is a key factor in Mediterranean environments, and is not only closely related to geoecological factors (lithology, topography, and climatology) but also to land-use and plant cover changes. The long history of human activity in Spain explains the development of erosion landscapes and sedimentary structures (recent alluvial plains, alluvial fans, deltas and flat valleys infilled of sediment). For example, the expansion of cereal agriculture and transhumant livestock between the 16th and 19th centuries resulted in episodes of extensive soil erosion. During the 20th century farmland abandonment prevailed in mountain areas, resulting in a reduction of soil erosion due to vegetation recolonization whereas sheet-wash erosion, piping and gullying affected abandoned fields in semi-arid environments. The EU Agrarian Policy and the strengthening of national and international markets encouraged the expansion of almond and olive orchards into marginal lands, including steep, stony hill slopes. Vineyards also expanded to steep slopes, sometimes on new unstable bench terraces, thus leading to increased soil erosion particularly during intense rainstorms. The expansion of irrigated areas, partially on salty and poorly structured soils, resulted in piping development and salinization of effluents and the fluvial network. The trend towards larger fields and farms in both dry farming and irrigated systems has resulted in a relaxation of soil conservation practices.

Long-term fencing improved soil properties and soil organic carbon storage in an alpine swamp meadow of western China

Abstract: Overgrazing significantly affects alpine meadows in ways similar to grasslands in other areas. Fencing to exclude grazers is one of the main management practices used to protect alpine meadows. However, it is not known if fencing can improve soil properties and soil organic carbon storage by restraining grazing in alpine meadows. We studied the long-term (nine-year) effects of fencing on soil properties, soil organic carbon and nitrogen storage compared with continued grazing in an alpine swamp meadow of the Qinghai–Tibetan Plateau, NW China. Our results showed that fencing significantly improved vegetation cover and aboveground biomass. There were significant effects of fencing on pH value, soil bulk density, and soil moisture. Long-term fencing favored the increase of soil total nitrogen, soil organic matter, soil organic carbon, soil microbial biomass carbon and soil carbon storage compared with grazed meadows. Our study suggests that long-term fencing to prevent disturbance could greatly affect soil organic carbon and nitrogen storage with regard to grazed meadows. Therefore, it is apparent from this study that fencing is an effective restoration approach of with regard to the soil’s storage ability for carbon and nitrogen in alpine meadow of the Qinghai–Tibetan Plateau.

Principles of Soil Conservation and Management

Abstract: Humberto Blanco and Rattan Lal. Springer, Heidelberg, Germany. 2008. Hardcover. 617 pp. $229.00. Online version available at . ISBN 978-1-4020-8708-0. Conservation and sustainable management of soil are essential features of humankind's

Impact of soil and water conservation measures on catchment hydrological response - a case in north Ethiopia.

Abstract: Catchment management in the developing world rarely include detailed hydrological components. Here, changes in the hydrological response of a 200-ha catchment management in north Ethiopia are investigated. The management included various soil and water conservation measures such as the construction of dry masonry stone bunds and check dams, the abandonment of post-harvest grazing and the establishment of woody vegetation. Measurements at the catchment outlet indicated a runoff depth of 5 mm or a runoff coefficient (RC) of 1.6 % in the rainy season of 2006. Combined with runoff measurements at plot scale, this allowed calculating the runoff Curve Number (CN) for various land uses and land management techniques. The pre-implementation runoff depth was then predicted using the CN values and a ponding adjustment factor, representing the abstraction of runoff induced by the 242 check dams in gullies. Using the 2006 rainfall depths, the runoff depth for the 2000 land management situation was predicted to be 26.5 mm (RC = 8 %), in line with current RCs of nearby catchments. Monitoring of the ground water level indicated a rise after catchment management. The yearly rise in water table after the onset of the rains (�T) relative to the water surplus (WS) over the same period increased between 2002-2003 ( �T/WS = 3.4) and 2006 ( �T/WS >11.1). Emerging wells and irrigation are other indicators for improved water supply in the managed catchment. Cropped fields in the gullies indicate that farmers are less frightened for the destructive effects of flash floods. Due to an increased soil water content, the crop growing period is prolonged. It can be concluded that this catchment management has resulted in a higher infiltration rate and a reduction of direct runoff volume by 81 % which has had a positive influence on the catchment water balance.

Modeling of Sediment Yield From Anjeni-Gauged Watershed, Ethiopia Using SWAT Model

Abstract: The Soil and Water Assessment Tool (SWAT) was tested for prediction of sediment yield in Anjeni-gauged watershed, Ethiopia. Soil erosion and land degradation is a major problem on the Ethiopian hig ...

Socio-economic factors influencing farmers' adoption of soil conservation practices in Europe

Abstract: This chapter aimed to review and summarize findings of existing studies on the role of socio-economic factors that influence farmer participation in soil conservation efforts, i.e. their adoption of conservation practices, with a particular focus on the European situation. In order to provide a structured overview we combined four groups of factors derived from previous concepts (Ervin and Ervin, 1982; Stonehouse, 1997) with the factors that influence the process of adoption (see model of acceptance in Figure 1). There is no evidence in the studies that either economic factors or social factors are superior in explaining adoption decisions. Rather, it is always a mix of personal, socio-cultural, economic, institutional and even environmental variables that explain behavior. Across the studies reviewed for the European context, we noted that there are several ways in which farmers or other land managers can participate in conservation efforts. We found three distinct pathways for the adoption of soil conservation practices: 1) an individual adopts a practice on their own initiative 2) an individual enrolls in an agri-environment scheme or soil conservation program and receives compensation (incentive payments) 3) an individual complies with legislation and conservation requirements. In a particular case a mixture of these may apply but there are distinct differences how these pathways determine the set of socio-economic factors that play a role in the adoption decision. A farmer may not consciously make the choice to take a certain pathway – in case of the third pathway, the choice is made externally. These pathways will also decide whether an investigation of adoption factors will focus on personal motivation, learning and experiences, on scheme characteristics that facilitate participation, or on compliance and enforcement of legislation. We infer that each pathway has a main driver. In the first case, the main driver is the personal motivation based on problem perception or intrinsic motifs and, if in a group, peer pressure. In the second case, the main driver is the incentive payment which must outweigh all other costs associated with program uptake and implementation of the measures in order for it to become effective. In the third case, the main driver is the threat of possible consequences of non-compliance such as a fine, loss of payments or reputation. For each pathway, a farmer considers the costs and benefits of soil conservation when deciding whether to adopt soil conservation practices or not. However, these costs and benefits go beyond direct costs and benefits associated with the practices and for some it may be difficult to quantify them (e.g. reputation, satisfaction, learning costs, costs associated with uncertainty on impact). Furthermore, the costs and benefits are determined by the environmental and economic context, institutional structures, and personal characteristics and they will thus differ between farmers and farms. Although based on a different sample (statistical analyses from regions in Africa and North and South America for conservation agriculture) we strongly support Bradshaw and Knowler’s (2007, 25) claim that there are few if any universal variables that regularly explain the adoption of soil practices and their conclusion that efforts to promote soil conservation in agriculture “will have to be tailored to reflect the particular conditions of individual locales.”

Chapter Four - Restoring Soil Fertility in Sub-Sahara Africa

Abstract: Sub-Sahara Africa can overcome the soil fertility depletion that has resulted from decades of nutrient mining by small-scale farmers and threatens the region's food security. Nutrient restoration is now technically feasible because its mechanisms are understood and the rural development community is alerted to this need. Rapid and inexpensive approaches of diagnosing soil fertility limitations are also becoming available and information generated is becoming systematically applied. For example, the recently initiated Africa Soil Information Service project aims at evaluating, mapping, and monitoring Africa's soil qualities for better targeting of soil fertility management technologies to improve crop yields while enhancing the environment. Practical knowledge is available on nutrient management in small-scale farming systems that combines increased biological nitrogen fixation, utilizes agromineral resources such as phosphate rock, better uses organic resources, and more efficiently applies mineral fertilizers. The new approach to managing soil nutrients, recognized as integrated soil fertility management, aims to increase food production through strategic combination of traditional and new technologies and is being stimulated through increased availability and more profitable use of mineral fertilizers by Africa's poorer farmers. This is building on already existing sparks of hope for restoring soil fertility in sub-Saharan Africa derived from such examples as the increasing adoption of the zai-type of pitting system originated in drier parts of West Africa which exemplifies the beneficial effects of integrating harvesting of water and applying nutrient sources at each planting station so as to increase yield in a region where both necessities are key limiting factors. Nitrogen fixation by indigenous and introduced legumes combined with improved agronomic practices has shown potential for kick-starting self-multiplying improvements in soil productivity. Such successes will be accelerated by broader initiatives which improve rural infrastructure, increase accessibility of inputs, improve marketing facilities, and make reinvestment into farming more productive and sustainable. Indeed, experience indicates that investments in farming and, by inference, soil fertility conservation are made when economic returns from smallholder production are sufficient to do so. So, while technical advances leading to improvements in farming practice must continue, policymakers must also recognize that agriculture ultimately forms the basis for economic recovery and act upon past promises to invest in agriculture, including the restoration of nutrient-depleted soils. Investments must address factors that have impacts both on the broad reforms for provision of services such as marketing and trade, as well as those directly constraining the poor farmers such as capacity to access and efficiently apply fertilizers.

Are runoff processes ecologically or topographically driven in the (sub) humid Ethiopian highlands? The case of the Maybar watershed

Abstract: Understanding the basic runoff processes in the Ethiopian highlands is vital for effective management and utilization of water resources and soil conservation planning. An important question for judging the effectiveness of conservation practices is whether runoff is affected by ecology (mainly type of crop) or topography (landscape). A study was conducted in the 113 ha watershed of Maybar, located in the highlands. This watershed has long-term records of rainfall and discharge. To study runoff processes, piezometers were installed in eight transects up and down the slope. In addition, infiltration rates (measured earlier) were compared with rainfall intensities. The results show that the amount of runoff at the test plots was greater for cropland located on mild to intermediate slopes than for grasslands and woodlands on the steeper slopes. Water tables were closer to the surface on cropland for the mild to intermediate slopes than on grasslands and in woodlands for the steeper slopes. Thus, although water table depths and plot runoff were inconclusive on the type of runoff mechanisms, infiltration rates that were generally in excess of the rainfall rates imply that any ecological effect on the amount of surface runoff is small. This is because water infiltration is independent of crop type. Only in cases where the soil was saturated did runoff occur. Piezometer readings show that saturation occurs at the foot of the steep slopes and, therefore, it demonstrates that topographic processes are dominant. Ecology becomes important when infiltration rates are in the same order as the rainfall intensities. Copyright © 2010 John Wiley & Sons, Ltd.

Assessment of integrated soil and water conservation measures on key soil properties in South Gonder, North-Western Highlands of Ethiopia

Abstract: Land degradation caused by erosion was an environmental threat that hampered agricultural production and the causes include: over cultivation, overgrazing, overpopulation and deforestation. Loss of productive land undermined rural livelihoods and national food security. The major factors discouraged farmers adoption of soil conservation measures were labour shortage, land tenure uncertainty, fitness of structures and the farming system. The study assessed effect of soil and water conservation measures on key soil properties in two micro-watersheds of Farta Wereda of South Gonder. Data analyzed using different soft wares. The results revealed that soil chemical and physical properties: soil organic matter, total N, available phosphorous (P), bulk density, infiltration rate and soil texture found a significant difference between conserved and non-conserved. Soil pH and electrical conductivity (EC) did not show significant difference. The non-conserved had the lowest soil organic matter, total N and infiltration rate with highest bulk density, clay content and available P. Soil organic matter content positively correlated with infiltration rate and total N and it negatively correlated with soil bulk density. Cation exchange capacity (CEC) positively correlated with soil pH and available P. The undulating lands were moderately suitable for rain fed agriculture. Hilly and valley lands found suitable for protective forestry and livestock production. Further research shall be conducted for a better understanding for sustainable land use.

Assessment of soil erosion processes and farmer perception of land conservation in Debre Mewi watershed near Lake Tana, Ethiopia

Abstract: Erosion is of great concern in the Ethiopian highlands. The objective of this study was to determine the soil erosion rates under actual farming conditions by measuring the dimensions and number of rills in 15 agricultural fields in the Debre Mewi watershed near Lake Tana, and to understand farmers’ attitudes towards land conservation through personal interviews with one-third of the watershed households. The annual rill erosion rate was 8 to 32 t ha−1. Greatest rates of erosion occurred at planting early in the season but became negligible in August. Major factors influencing land conservation decisions were the demand of labor and lack of technical support for implementing new conservation measures from experts.

An erosion model for evaluating regional land-use scenarios

Abstract: The conversion to pasture of indigenous forest on New Zealand hill country has led to increased mass-movement erosion and consequently increased sedimentation of waterways. Effective soil conservation requires a model that can evaluate erosion and sedimentation for different land-use scenarios. In this paper, we develop a model of mean sediment discharge related to mean erosion rates through a sediment delivery ratio. Mean erosion rate in a particular terrain (''erosion terrain'') is the product of (i) the square of mean annual rainfall with (ii) a cover factor and (iii) an erosion coefficient that depends on erosion terrain. Measurements of mean sediment discharge are used to estimate erosion coefficients for each erosion terrain. The model can be used to predict mean sediment discharge in response to land-cover/land-use scenarios. It is easy to execute and uses input data readily available in GIS layers in New Zealand. This makes it suitable for widespread management application, in contrast to physically based models which are presently only suitable for research catchments. We demonstrate the utility of the model for three different applications: evaluating land-use scenarios in the Motueka catchment; setting priorities for soil conservation in the Manawatu catchment; and determining national trends in agricultural erosion over a 30-year period. The general methodology is applicable to countries dominated by mountains and steep hills with high erosion rates.

Soil conservation beneath grass cover in hillside vineyards under Mediterranean Climatic conditions (Madrid, Spain)

Abstract: The use of plant cover for soil protection in Mediterranean hillside vineyards may jeopardize the viability of crops due to the scarcity of water under semiarid conditions. Erosion control, soil characteristics and vineyard production were evaluated using three different treatments: (i) traditional tillage as the control group, (ii) soil covered by Brachypodium distachyon and (iii) soil covered by Secale cereale. Such plant cover for soil protection among woody crops is not frequent under semiarid conditions. Sediment yield and runoff were collected from nine (3 treatments × 3 replications) plots of 2 m2. Soil moisture, organic carbon content and aggregate stability were measured for one year. Simulated rainfall on plots was used as a source of complementary data. A reduction of 50% in the production of the vineyard was noticed in the Brachypodium-treatment, probably due to the lower degree of soil moisture at 35 cm depth. Nevertheless, there was efficient erosion control and the soil's organic carbon content increased. The Secale-treatment produced more runoff than tillage treatment. Traditional tilling produced the greatest yield, though it is considered unsustainable in the long term for hillside vineyards, as it lost 1059 g m−2y−1, compared to 62 and 70 g m−2y−1 lost in soil covered with Secale and Brachypodium, respectively. A high variability was found in the runoff coefficient, which was usually less than 1% under moderate rainfall, although it reached 45% under extreme events. The blind tasting of wine showed a slight preference for wine produced on vines subject to the Secale treatment. Copyright © 2009 John Wiley & Sons, Ltd.

Impact of climate change on soil erosion and the efficiency of soil conservation practices in Austria

Abstract: The goal of the present study was to assess the impact of selected soil protection measures on soil erosion and retention of rainwater in a 1·14 km2 watershed used for agriculture in the north-east of Austria. Watershed conditions under conventional tillage (CT), no-till (NT) and under grassland use were simulated using the Water Erosion Prediction Project (WEPP) soil erosion model. The period 1961–90 was used as a reference and results were compared to future Intergovernmental Panel on Climate Change (IPCC) scenarios A1B and A2 (2040–60).The simulations for the NT and grassland options suggested runoff would decrease by 38 and 75%, respectively, under the current climatic conditions. The simulation results suggest that, under future climate scenarios, the effectiveness of the selected soil conservation measures with respect to runoff will be similar, or decreased by 16–53%.The actual average net soil losses in the watershed varied from 2·57 t/ha/yr for conventional soil management systems to 0.01 t/ha/yr for grassland. This corresponds to a maximum average annual loss of about 0·2 mm, which is considered to be the average annual soil formation rate and therefore an acceptable soil loss. The current soil/land use does not exceed this limit, with most of the erosion occurring during spring time. Under future climate scenarios, the simulations suggested that CT would either decrease soil erosion by up to 55% or increase it by up to 56%. Under these conditions, the acceptable limits will partly be exceeded. The simulations of NT suggested this would reduce annual soil loss rates (compared to CT) to 0·2 and 1·4 t/ha, i.e. about the same or slightly higher than for NT under actual conditions. The simulation of conversion to grassland suggested soil erosion was almost completely prevented.The selected soil conservation methods maintain their protective effect on soil resources, independent of the climate scenario. Therefore, with small adaptations, they can also be recommended as sustainable soil/land management systems under future climatic conditions.However, based on the available climate scenarios, climate-induced changes in the frequency and intensity of heavy rainstorms were only considered in a limited way in the present work. As the general future trend indicates a strong increase of rainstorms with high intensity during summer months, the results of the present study may be too optimistic.

Assessment of production losses due to water erosion in rainfed areas of India.

Abstract: Soil erosion by water has a debilitating effect on crop productivity. Though limited and scattered data is available on loss of production due to water erosion in India, no systematic effort has been made to compute the losses in crop production based upon experimental data, major soil groups, and prevailing erosion rates. The objective of this study is to estimate on-site physical and economic loss of production of major cereal, oilseed, and pulse crops cultivated on rainfed areas of India due to soil erosion by water. The estimation is done by integrating the available experimental data of a crop with the rainfed area of that crop under each erosion intensity category for each of the three major soil groups (alluvial, black and red) in a given state. Following this approach, the total production loss due to water erosion of rainfed areas under major cereal, oilseed, and pulse crops in India was observed to occur at 16%, which in actual physical terms was estimated as 13.4 million t (13.2 million tn) and in economic terms as $2.51 billion (INR 111.3 billion) (the conversion has been given in US dollars as per average conversion rate of 2005 to 2006, i.e., at INR 44.273 per US dollar). Among the six zones of India, the average production loss occurred within a range of 10% (northern) to 24% (southern). At state level, the production loss ranged from 1.4% in Punjab and Haryana states located in alluvial Indo-Gangetic Plains to 41% in the erosion-prone northeastern Himalayan state of Nagaland. In terms of production loss among major groups of crops, cereals contributed 66% to the total loss, followed by oilseeds (21%) and pulses (13%). A similar trend was observed for the monetary losses amounting to 45% for cereals, 33% for oilseeds, and 22% for pulses. Paddy was the most affected among all the crops in terms of both production (4.3 million t [4.23 million tn]) and monetary ($0.56 billion [INR 24.4 billion]) losses. Since the losses are cumulative over time, it is imperative to undertake appropriate soil and water conservation measures for rehabilitation of rainfed areas to prevent huge declines in their productivity levels, which may escalate further due to population pressures.

Relationships between rock fragment cover and soil hydrological response in a Mediterranean environment

Abstract: Rock fragments are a key factor for determining erosion rates, particularly in arid and semiarid environments where vegetation cover is very low. However, the effect of rock fragments in non-cultivated bare soils is still not well understood. Currently, there is a need for quantitative information on the effects of rock fragments on hydrological soil processes, in order to improve soil erosion models. The main objective of the present research was to study the influence of rock fragment cover on run-off and interrill soil erosion under simulated rainfall in Mediterranean bare soils in south-western Spain. Thirty-six rainfall simulation experiments were carried out at an intensity of 26.8 mm h−1 over 60 min under three different classes of rock fragment cover ( 60%). Ponding and run-off flow were delayed in soils with high rock fragment cover. In addition, sediment yield and soil erosion rates were higher in soils with a low rock fragment cover. The relationship between soil loss ...

Analysis and modeling of soil conservation measures in the Three Gorges Reservoir Area in China

Abstract: Experimental plots were constructed in the Zhangjiachong Watershed of the Three Gorges Reservoir Area to evaluate soil erosion of traditional slope land farming and effects of soil conservation measures. Surface runoff and sediment from the watershed and each plot were collected and measured during 2004–2007. Field investigations indicated that hedgerows were the best for soil erosion control, followed by stone dike terraces and soil dike terraces. The Water Erosion Prediction Project (WEPP) model was used to simulate erosion of annual and rainfall events both at the watershed and plot levels. The low deviation, high coefficient of determination and model efficiency values for the simulations indicated that the WEPP model was a suitable model. The soil erosion rate distribution was modeled to determine where serious erosion would occur during rainfall events in the Zhangjiachong Watershed and so control measures can be taken.