Agricultural Terraces Research Articles

Identifying and estimating soil erosion and sedimentation in small karst watersheds using a composite fingerprint technique

The highly heterogeneous surface environment and subsurface conduit network in karst areas make estimating soil erosion extremely complicated. Sediment fingerprint techniques have been successfully applied in soil erosion research in karst areas as a new way to more effectively collect information on soil loss. However, few sediment fingerprint factors, most of which are based on radioactive fallout tracers, such as 137Cs and/or 210Pb, have been used in existing studies. The soil loss rate estimated by these fingerprint factors varies greatly among different watersheds. To clearly identify the sedimentary sequence, to estimate the changes in soil erosion in recent years, and to relate the soil erosion process to rocky desertification, a composite sediment fingerprint technique is used in this study. Two typical watersheds with peak clusters and depressions and with different degrees of rock desertification were selected, and sediment cores were extracted from the depressions to measure changes in 137Cs, magnetic susceptibility, soil organic carbon (SOC) and sediment particle composition at different depths. The results indicated that the soil loss rates in the Liaojiawodang (LJWD) and Dajutang (DJT) watersheds showed a fluctuating decrease from 1954 to July 2018. The severe soil erosion in the periods of 1954–1963，1963–1970 and 1976–1986 was mainly caused by large-scale reclamation and deforestation. In addition, heavy rainfall in 1983 and 1991 might have played a significant role in the soil loss in the DJT watershed in 1978–1986 and in the LJWD watershed in 1986–2000, respectively. The construction of agricultural terraces several decades ago and the implementation of the Closing Mountains for Forest Cultivation, Grain for Green and Poverty Alleviation projects in recent years to improve the ecological environment have effectively alleviated the soil erosion in the studied watersheds. Over the past 60 years, soil loss in the LJWD and DJT watersheds decreased by approximately 89 % and 87 %, respectively. In karst areas, rocky desertification and soil erosion do not exhibit identical trends. Because of severe rocky desertification, the soil erosion in the LJWD watershed was significantly less than that in the DJT watershed. This study provides important information on detailed sediment dating and demonstrates the potential of using 137Cs, magnetic susceptibility, SOC and sediment particle composition to identify changes in erosion in a watershed.

No-tillage system participatory quality index

ABSTRACT The no-tillage system participatory quality index aims to evaluate the quality and efficiency of soil management under no-tillage systems and consists of a weighted sum of eight indicators: intensity of crop rotation, diversity of crop rotation, persistence of crop residues in the soil surface, frequency of soil tillage, use of agricultural terraces, evaluation of soil conservation, balance of soil fertilization and time of adoption of the no-tillage system. The aim of this study was to assess the extent to which these indicators correlate with the no-tillage system participatory quality index and to characterize the farmers who participated in the research. The data used were provided by ITAIPU Binacional for the indicators of the no-tillage system participatory quality index II. Descriptive analyses were performed, and the Pearson correlation coefficient between the index and each indicator was calculated. To assess the relationship between the indicators and the farmers’ behavior toward the indicators, principal component analysis and cluster analysis were performed. Although all correlations are significant at p-value ≤ 0.05, some correlations are weak, indicating a need for improvement of the index. The principal component analysis identified three principal components, which explained 66% of the variability of the data, and the cluster analysis separated the 121 farmers into five groups. It was verified that the no-tillage system participatory quality index II has some limitations and should therefore be reevaluated to increase its efficiency as an indicator of the quality of the no-tillage system.

Sensitivity of source apportionment predicted by a Bayesian tracer mixing model to the inclusion of a sediment connectivity index as an informative prior: Illustration using the Kharka catchment (Nepal)

Long-chain saturated fatty acid (LCSFA) isotopic composition in tandem with Bayesian isotope mixing models (BIMM) can provide insight into land use-based sediment sources in catchment systems. Apportioning sediment sources robustly, however, requires careful consideration of how additional factors including topography, surface cover and land use practices interact to influence contributions from individual sources. Prior knowledge can be used in BIMM; however, the full capacity of this functionality has not been thoroughly exploited yet in conjunction with sediment fingerprinting. In response, we propose an approach for applying a state-of-the-art BIMM incorporating a sediment connectivity index (SCI) as an informative prior for sediment source apportionment in a highly hydrodynamic catchment in Nepal. A library of LCSFA carbon isotopic composition was constructed for surface soils collected from mixed forest, upland and lowland terraces in the Kharka micro-catchment. δ13C values of LCSFA of time-integrated suspended bulk (<2 mm) sediment were depleted by 4‰ compared to the fine (<0.063 mm) sediment fraction. Conventional source apportionment for fine sediment samples without the SCI informative prior suggested that 66% of the sediment is derived from forest soils followed by lowland (19%) and upland (15%) terraces. Incorporation of the SCI as an informative prior in BIMM, however, modified the original source apportionment estimates to 90%, 9% and 1% respectively. The lower contributions from agricultural terraces are explained by landscape complexity comprising small levelled terraces that reduce hillslope-to-channel sediment connectivity. This study demonstrates the sensitivity of BIMM posterior distributions to incorporation of an informative prior based on a SCI. Inclusion of SCI linked to land use and management can provide a more physically-grounded approach to estimating sediment source contributions from biogeochemical tracers, and critically one which generates results better reflecting what makes good environmental sense in the context of land management and visual evidence of sediment mobilisation and delivery.

Earthen Terrace Technologies and Environmental Adaptation in the Montane Forests of Pre-Columbian Northeastern Peru

ABSTRACTThe pre-Columbian Andes are renowned for agricultural terrace systems in areas of steep terrain. Most studies have concentrated on regions characterized by seasonally-variable limited precipitation, yet research in high-precipitation and cloud-forest regions of the North and Eastern Andes demonstrates the diversity of terrace technologies adapted to different landscapes. This paper presents research from survey, excavation, and digital modeling of three types of well-preserved agricultural terraces found in a 50 km2 area in central Chachapoyas, northeastern Peru. These terrace types—which we refer to as linear segmented, contour, and sinkhole—were all comprised entirely of earth, not stone. Results from digital modeling using ArcGIS hydrology tools indicate different manners through which each terrace type structured the movement of water over the ground surface, supporting previous arguments that similar earthen terrace infrastructure in Colombia, Ecuador, and eastern Peru were likewise designed to manage runoff drainage rather than support irrigation.

Terrace agriculture in a mountainous arid environment – A study of soil quality and regolith provenance: Jabal Akhdar (Oman)

In the Sultanate of Oman remnants of deteriorating terrace agricultural systems offer important insights into long-term human adaptation in the arid tropics. Irrigation and terrace agriculture in the mountainous Jabal Akhdar region reveal historic agricultural practices in a rugged, high elevation context. The present study examines soil quality and regolith provenance in abandoned agricultural soil terraces. Three soil profiles in each of the Villages of Hadash and Wijma were excavated and analyzed. Physical, chemical and mineralogical analyses were conducted for all soil horizons. In addition, six other soils, 3 possible soil parent rocks (regolith) and soil’s bedrock were collected. Soil ages were constrained by 14C assays and stable isotope, (13C and 18O) on the bulk carbonates in the calcrete (caliche). The results demonstrate that both sites display poor soil quality with very low average total organic carbon (TOC) (6.2–5.0 g kg−1) and mean weight diameter (MWD; 0.27–0.48 mm), with low water stable aggregate content (<42%). All the geochemical, mineralogical and the thin section analyses show that the soils exhibit unique characteristics that differ from those of other sediments (possible parent regolith) and soils in the vicinity. The finding of ostracod shells in the soil terraces in both areas and 14C dating of calcrete (10.193 ± 30–13.887 ± 40 a BP) indicate that regolith was human-transported to terraces to create soil. The 14C ages of the bulk carbonates match well with a dry period of high calcite precipitation contemporaneous to the Younger Dryas. The Hadash and Wijma soil terraces are located ~45 km away from each other, but still display significant similarities in terms of regolith provenance and soil development and were likely filled with regolith from the same source. These results offer new perspective on agricultural terrace development and oasis agriculture in a rugged, high-elevation, arid environment.

Assessment of Soil Loss in the Mirabah Basin: An Overview of the Potential of Agricultural Terraces as Ancestral Practices (Saudi Arabia)

Water erosion remains the major problem in many countries, especially those with an extension in the arid and semi-arid area and those marked by a long dry season. The intensification of land degradation which is a result of the strong erosive dynamics on a global scale has stimulated the initiative of multidisciplinary researchers investigate the issue of water erosion from its various facets [1] [2]. The goal is to preserve water and soil, two resources threatened. Multiple attempts were made to diagnose and implement empirical and experimental methods for quantitative estimation of soil loss caused by diffuse erosion. Indeed, the Eastern slope of the high mountains of Asir (Saudi Arabia), formerly worn and cut by the depression of rivers and undeniable branching of the river system, deserves to be studied in detail given the release of a huge erosive potential that is responsible for soil losses that are increasing gradually and continuously. The purpose of this paper was to validate the suitability of agricultural terraces in terms of soil preservation, using the results of the soil loss application as an indicator of the state of function of these latter. Many studies have addressed the agricultural terraces, however, only a few of them have focused on the relationship between erosion and agricultural terraces through an experimental approach. Previous work has concentrated mainly on their socio-economic impact; whilst the knowledge of their environmental impact remained scarce. In terms of the climate change context, soil erosion is becoming a central problem in Asir region. Thus, in this way, the application of the universal equation of soil loss was very helpful to explain and predict the role of each factor. Nevertheless, extreme caution and great care must be taken because of the application of this model outside its frame.

Ethno archaeological Clues to Stone Exploitation in Ancient Dangme-land, Greater Accra Region, Ghana

Dangme-land is naturally replete with abundant stone resources whose exploitation facilitated the peoples’ adaptation to their environment. The objective of the researcher in this paper was to investigate for what purposes the ancient indigenous Dangme populations that occupied Sega Hill, Kpone, Shai and Prampram exploited and used stones in the remote past. It also documented the techniques and methodologies utilized by the people to exploit this resource. Data for the study were derived from ethnographic and archaeological investigations and from early European sources relating to the area. The combined evidence revealed that the people of the aforementioned settlements exploited stone for a variety of purposes, such as for the construction of agricultural terraces and protective enclosures against slavers. The ethno archaeological evidence also indicated that the four principal early vocations of the people namely; fishing, crop farming, hunting and trapping were facilitated greatly by the use of a variety of tools manufactured from stone.

How did that get there? Understanding sediment transport and accumulation rates in agricultural landscapes using the ESTTraP agent-based model

The 15th–18th century CE site of Engaruka in Tanzania is often described as primarily comprising drystone agricultural terraces, but it is now known that many of these former farming plots are not terraces per se, but are instead sediment traps. Stratigraphic excavations of these traps show that they were built by constructing low drystone walls adjacent to either natural or artificial water courses in order to capture fine alluvial sediments entrained within water flows. In the northern area of the site sediments were accumulated to a depth of up to 700 mm, while in one area in the south of the site over 2 m of deposits were accumulated over at least a 300 year period. The presence of sediment traps on archaeological sites allows investigations of the efficacy and sustainability of these structures over decadal to centennial timescales, since stratigraphic excavations can define the process of construction, and geoarchaeological analyses can explore changes within accumulated sediments over time. Although a combination of stratigraphy and absolute dating can discern the broad sequence and timing of sediment capture they cannot determine sediment-accumulation rates, and these techniques are too time consuming to be used to map the development of over 9 km2 of sediment traps. The ESTTraP agent-based model provides these data by simulating sediment accumulation under different hydrological conditions. Four scenarios were simulated for a period of 100 years: constant water availability (SIM-01), seasonal variability (SIM-02), long-term climate variability (SIM- 03), and vegetation-cover impact (SIM-04). The model results suggest that the fields can be constructed over a short period of time, approximately 1–3 months per 6 × 6 m field, and that to construct a block of 90 fields covering 3,000 m2 it would take between 8 and 13 years in periods of high water availability, and up to 27 years during prolonged dry periods. The results define the amount of time needed to construct individual fields, and suggest that farmers constructed blocks of fields concurrently rather than sequentially expanding across the landscape, and that the c. 10 km2 area of sediment traps at Engaruka could have been constructed by a number of households working independently. The ESTTraP model presents an important resource in the assessment of sediment dynamics and patterns of field development, is relevant to a range of archaeological sites worldwide that include intentional or unintentional alluvial deposition, and has applications for modern landscape management.

Water management in the high mountain watersheds of the Sierra Nevada National Park (southern Spain). An example of ancestral Integrated Water Management

Sierra Nevada is the main mountain range in the southern Iberian Peninsula and has been catalogued as a Biosphere Reserve (1986), a Natural Park (1989) and a National Park (1999). Apart from its ecological, geomorphological and landscape singularities, there are other remarkable hydrological, historical and cultural features, such as the ancestral water management performed at the headwaters of the rivers. A dense network channels excavated in the ground, the so-called acequias de careo, allows the derivation of melt water from of the river water head towards the higher zone of the hillsides, where it infiltrates. It slowly flows down through the weathered zone of the metamorphic rocks, until reaching the rivers and springs used for supply and irrigation. This water management system, implemented since the Muslim conquest of southern Spain (VIII century), has led to a remarkable transformation of the landscape, where agricultural terraces and pastures coexist with ecosystems of high ecological value. This paper describes the careos water-management technique in a pilot basin, the Bérchules watershed, recently studied during 2014 and 2015 by the Geological Survey of Spain. Migration, the abandonment of cultivated lands and, consequently, of the acequias de careo are affecting the dynamics of the rivers, endangering the delicate balance reached between man and nature in the Sierra Nevada, after many centuries of harmonious coexistence.

Assessment of Agricultural Vulnerability to Flood in Ngaski, Kebbi State, Nigeria

The assessment of agricultural vulnerability to flood in Ngaski Local Government Area of Kebbi State, Nigeria was carried out. The study made use of ASTER data of 2017 with spatial resolution of 30m, topographical map at a scale of 1:50,000, monthly rainfall data for 35 covering the study area and soil map at a scale of 1:50,000. Thematic maps for soil, rainfall and elevation were produced converted to raster data in GIS environment. Each data set in a single map was given weight by pair-wise comparison; reclassification of each map was done based on the weights generated from the pair-wise comparison of each dataset. The results showed that the rainfall recorded in the study area ranges from 950mm to 1150mm and this is categorized between high and very high under the pair-wise comparison rating. The elevation is such that parts of the study area had high elevation that ranges between 226m and 255m and low elevation that ranged between 125m and 167m giving room to flooding. The soil types in the study area are such that encourage flooding coupled with high amount of rainfall on one hand and the high and low elevations experience across the study area. For the farmers to sustain agricultural activities as a result of flooding, they practiced mixed farming, shifting cultivation, terrace farming, fallow and arable farming. The above farming systems were practiced by the farmers to alternate, avoid or take advantage of the floods. In conclusion, the study recommends the use of more resistant seedlings and crops to flooding, channelization of the river should be carried out by the government to reduce the level of flooding across the study area among others.

TERRA: Terrain Extraction from elevation Rasters through Repetitive Anisotropic filtering

Over the past decades, several filters have been developed to derive a Digital Terrain Model (DTM) from a Digital Surface Model (DSM), by means of filtering out aboveground objects such as vegetation. In this filtering process, however, one of the major challenges remains to precisely distinguish sharp terrain features, e.g. ridges, agricultural terraces or other anthropogenic geomorphology such as open-pit mines, riverbanks or road ramps. Hence, loss of elevation data around terrain edges (and consequent smoothing) is very common with existing algorithms. In terraced landscapes, the preservation of precise geomorphology is of key importance in digital terrain analyses, such as hydrologic and erosion modelling, or automatic feature recognition and inventorying. In this work, we propose a new filtering method called TERRA (Terrain Extraction from elevation Rasters through Repetitive Anisotropic filtering). The novelty of the algorithm lies within its usage of terrain aspect to guide the anisotropic filtering direction, therefore maximising the preservation of terrain edges. We derived six DTMs from DSMs using UAV Structure from Motion (SfM) photogrammetry, laser altimetry and satellite sources (grid resolutions ranging from 0.1–1.0 m). The results indicated a close agreement of DTMs filtered using the TERRA algorithm and reference DTMs, while terrace risers were well preserved even under thick canopies of vines and trees. Compared to existing filtering approaches, TERRA performed well in minimising Type I errors (false ground removal), while Type II errors occurred locally where vegetation was covering the terrace edges. Given the promising filtering performance, and supported by the minimal requirements of parameterisation and computation, the TERRA algorithm could be a useful tool in DTM preparation for digital terrain analysis of agricultural terraces and similar hillslopes characterised by a complex mosaic of sharp terrain and non-terrain features.

The vitality of fruit trees in ancient Bedouin orchards in the Arid Negev Highlands (Israel): Implications of climatic change and environmental stability

Thirty-seven sites with fruit tree orchards were found in the arid Negev Highlands of southern Israel. A variety of domesticated fruit trees were planted in these orchards, including date palm, fig, olive, pomegranate, almond, carob, pistachio, grapevine and bitter orange. The orchards were irrigated only by runoff water accumulating in runoff-harvesting systems built during the Byzantine and Early Muslim eras, some 1000–1500 years ago, which, despite their antiquity, are still vivid and occasionally fruit bearing today. The oldest olive trees seem to be direct descendants of trees planted during Byzantine times, whereas the youngest trees were planted by the Bedouin population of the Negev Highlands in the last few decades. The fact that the Bedouin population, with very little experience in agriculture, has succeeded to cultivate a large variety of fruit trees in the present harsh arid climate utilizing the historical agricultural installations has important environmental implications. It indicates that the original builders of the desert agriculture systems were highly sophisticated in transforming desert soil into arable land. However, this was achieved through hard labor, involving the construction of a vast number of stone dams and agricultural terraces to divert channels, and the clearing of rocky surfaces. This huge effort indicates that the climate and environment prevailing during the Byzantine–Early Muslim eras was equally harsh and arid; otherwise, the invested labor would not have been justified. We conclude that the Byzantine farmers, with their greater agricultural experience and long heritage in dry land agriculture, have achieved greater success than today Bedouin population, at cultivating of fruit trees under the harsh conditions of the Negev Highlands. Therefore we deduce that the ancient desert agriculture was not the outcome of better climate; rather, the climate prevailing during the relevant historical times was probably dry and harsh, much like today. The fact that the Bedouin population in that geograghical area is cultivating orchards utilizing the same constructions, and technologies indicates that the present environmental and climatic conditions were are suitable for practicing desert agriculture and have hardly changed since the Byzantine era.

Leaf Wax δD and δ13C in Soils Record Hydrological and Environmental Information Across a Climatic Gradient in Israel

AbstractThe hydrogen (δDwax) and carbon (δ13Cwax) isotope compositions of long‐chain alkanes derived from plant waxes record hydrological and environmental conditions. However, the integration of plant n‐alkanes into the sedimentary cycle, the variability of δDwax and δ13Cwax in soils, and the paleoclimate applicability in paleosols and archaeological sediments are poorly constrained. We sampled plants and soils across a steep climate transect in Israel to understand how plant type and environmental parameters shape δ13Cwax and δDwax. This transect has three advantages: existence of long‐term precipitation isotopic composition (δDr) records, a single wet season potentially reduces variability due to seasonality, and abandoned Byzantine period (~300–600 AD) agricultural terraces that reduce modern and ancient soil mixing and provide age constraints. We find that soil δ13Cwax is constant (0.4‰, 1σ) across a 500‐ to 1,300‐mm/year rainfall gradient and appears insensitive to rainfall amount, unlike bulk plant δ13C. The absence of a rainfall effect suggests that δ13Cwax may be better suited to reconstructing C3/C4 plant ratios than bulk δ13C. Homologue average soil δDwax significantly correlate with δDr, and the offset between δDr and soil δDwax (εapp) correlates with growing season relative humidity. The seasonality of leaf production accounted for at most ~10% of total plant δDwax variability. Lastly, soil δDwax and δ13Cwax variability is reduced by ~80% relative to plant δDwax and δ13Cwax variability. Our results show that soil δDwax and δ13Cwax faithfully record δDr and landscape C3‐C4 plant contributions and thus support the utility of these proxy data in paleosols and archaeological sites.

Integrated edge detection and terrain analysis for agricultural terrace delineation from remote sensing images

ABSTRACTAgricultural terraces are important for agricultural production and soil-and-water conservation. They comprise treads and risers that require manual construction and maintenance. If managed improperly, risers will collapse, causing soil loss, gully erosion, and cultivation threats. However, mapping terrace risers remains a challenge. This study presents a novel approach to automatically map terrace risers by combining remote sensing images and digital elevation models (DEMs). First, a terraced hillslope was extracted via a hill-shading method and edges in the image were detected using a Canny edge detector. Next, the DEM was used to generate the contour direction, and edges along this direction were searched and coded as candidate terrace risers via directional detection. Finally, the results of directional detection and the edge image obtained from the Canny detector were overlaid to backtrack complete terrace risers. The approach was validated using four study areas with different topographic characteristics in the Loess Plateau, China. The results verify that the approach achieves outstanding performance and robustness in mapping terrace risers. The precision, recall, and F-measure were 90.81%–97.57%, 88.53%–94.10%, and 90.13%–95.80%, respectively. This approach is flexible and applicable with freely available images and DEM sources.

RECONSTRUCTING THE LANDSCAPE OF THE PAST IN THE AGRICULTURAL TERRACES OF THE CITY OF AVDAT

Abstract. Large areas in the arid Southern Levant are dotted with ancient agricultural terraces and runoff harvesting installations. In the Negev Highlands, Israel, they were constructed in the 3rd–4th centuries CE, maintained for 6–7 centuries, and then abandoned after the 10th century. Their design pattern and foundations provide a rare insight to the prevailing environmental conditions during the middle Holocene, while their 600–700 years cultivation tells the story of their maitainance and desert agriculture in these regions. From their abandonment onwards, they documented more than 1000 years of land degradation and soil erosion till present time. In this paper, we follow a complete cycle of desert agriculture of two sites near the UNESCO world-heritage town of Avdat. We reconstruct the landscape at the period pre-dating the first anthropogenic intervention, through the centuries of cultivation, and into a millennium of abandonment until the present erosion phase. We use high-resolution 3-D data to document the erosion and environmental dynamics during these two millennia, and to compute rates of siltation and erosion. Long-term measures of such kind are unique, as it is rare to find a millennium-scale documentation of soil erosion processes. Their study improves our understanding of the long-term environmental change mechanism acting in arid environments. The detailed analysis of these installations also offers insights into methods for soil conservation, for sustainable desert inhabitation, and for strategies to protect world-heritage installations. As the globe-wide struggle to combat soil erosion becomes urgent, this case study becomes even more relevant.

Conservation agriculture practices adopted in southern Brazil

ABSTRACTThe adoption of conservation agriculture (CA) practices are essential for soil and water conservation. In CA, farmers must adopt no-tillage (NT) with crop rotation to maintain a permanent soil cover. In Brazil, mainly in the South region, for CA to be more efficient, practices such as contour farming and agricultural terraces should also be adopted. Thus, the objective of this study is to determine the extent to which NT has been adopted with crop rotation and others soil and water conservation practices. Data from the Agricultural Census in Paraná State, southern Brazil, were used. For the data analysis, the relationship between the level of adoption of NT and the use of crop rotation, contour farming and agricultural terraces was analyzed. A factor and cluster analysis were performed to distinguish regions in terms of soil and water conservation practices. The results show good overall soil and water conservation practices, although heterogeneity has been observed in the adoption practices between regions. Adoption of NT is high in almost all the studied regions. The conservation practice most widely used with NT is contour farming, whereas the least used is agricultural terraces. Conservation practices for runoff control are being neglected by farmers.

Assessment of soil erosion rates in a Mediterranean cultivated and uncultivated soils using fallout 137Cs

Fallout radionuclides, such as 137Cs, have been recognized as a valuable means for studying soil erosion processes. In this study, the 137Cs technique was used to assess soil erosion magnitude and to investigate the effectiveness of terrace cultivations in the High Atlas of Morocco, particularly, the Ourika watershed. 137Cs depth distribution profiles were established along slope gradients associated with land use considering cereal crop, arboriculture and native forests.Along the slope gradient, depth distribution profiles highlight dissimilarities reflecting differences in land use, topographic roughness, soil particle distribution and stoniness. 137Cs inventory decreases exponentially with depth and its penetration increases along the slope. It becomes higher at the bottom of the slope, with penetration reaching 30 cm.137Cs mass activity and inventory significantly decrease in cultivated terraces, compared to native forest. Although the pattern of 137Cs gain/loss varied according to topography, soil properties and vegetation cover, showing eroding and aggrading profiles, most samples had 137Cs values lower than the reference value, suggesting net-loss of soil as a consequence of erosion processes.The net erosion rates were estimated about 8.5 and 6.0 t ha−1 yr−1 in cereal crop and arboriculture agrosystems, respectively, whereas in the forest, the net erosion rate was lower at about 4.2 t ha−1 yr−1.Soil loss on agricultural terraces is not significantly above tolerable erosion rates for Morocco (<7 t ha−1 yr−1), particularly for arboriculture terraces. A strong correlation was observed between 137Cs and both soil organic carbon and slope gradient, in uncultivated area, whereas, there was no correlation for cultivated terraces.Terraced arboriculture systems should be encouraged for better soil preservation against water erosion in the Ourika watershed.

Soil Quality of Abandoned Agricultural Terraces Managed with Prescribed Fires and Livestock in the Municipality of Capafonts, Catalonia, Spain (2000–2017)

The abandonment of the economic activities of agriculture, livestock, and forestry since the second half of the 20th century, in conjunction with the exodus of inhabitants from rural areas, has resulted in an increase in the forest mass as well as an expansion of forest areas. This, in turn, has led to a greater risk of forest fires and an increase in the intensity and severity of these fires. Moreover, these forest masses represent a fire hazard to adjacent urban areas, which is a problem illustrated here by the village of Capafonts, whose former agricultural terraces have been invaded by shrubs, and which in the event of fire runs the risk of aiding the propagation of the flames from the forest to the village’s homes. One of the tools available to reduce the amount of fuel in zones adjoining inhabited areas is prescribed burns. The local authorities have also promoted measures to convert these terraces into pasture; in this way, the grazing of livestock (in this particular instance, goats) aims to keep fuel levels low and thus reduce the risk of fire. The use of prescribed fires is controversial, as they are believed to be highly aggressive for the soil, and little is known about their long-term effects. The alternation of the two strategies is more acceptable—that is, the use of prescribed burning followed by the grazing of livestock. Yet, similarly little is known about the effects of this management sequence on the soil. As such, this study seeks to examine the impact of the management of the abandoned terraces of Capafonts by means of two prescribed fires (2000 and 2002), which were designed specifically to prevent forest fires from reaching the village. Following these two prescribed burns, a herd of goats began to graze these terraces in 2005. Here, we report the results of soil analyses conducted during this period of years up to and including 2017. A plot comprising 30 sampling points was established on one of the terraces and used to monitor its main soil quality properties. The data were subject to statistical tests to determine whether the recorded changes were significant. The results show modifications to the concentration of soil elements, and since the first prescribed burn, these changes have all been statistically significant. We compare our results with those reported in other studies that evaluate optimum soil concentrations for the adequate growth of grazing to feed goats, and conclude that the soil conditions on the terrace after 17 years are optimum for livestock use.

Evaluación de los servicios ecosistémicos proporcionados por las terrazas agrícolas

Las terrazas agrícolas son ampliamente utilizadas en todo el mundo desde la antigüedad. Su interés paisajístico es innegable y algunas de ellas forman parte del Patrimonio Mundial de la UNESCO. Son prácticas muy eficaces para la conservación del suelo y el agua a través del control de la escorrentía y la erosión, y proporcionan a los agricultores y a la sociedad importantes Servicios Ecosistémicos (SE). Presentamos un estudio basado en ejemplos de terrazas documentados en detalle en la base de datos WOCAT (World Overview of Conservation Approaches and Technologies), complementado con una revisión de la literatura científica sobre los impactos de las terrazas, con el objetivo de evaluar los múltiples SE que proporcionan. Los resultados muestran que los SE más importantes proporcionados por la construcción de terrazas están relacionados con servicios de regulación como el control de la erosión, escorrentía y otros riesgos naturales externos. Además, la presencia de terrazas favorece servicios de aprovisionamiento como el suministro de alimentos, fibras, y cantidad y calidad del agua. Se constatan las funciones ambientales, geomorfológicas e hidrológicas de las terrazas, así como la mejora de la calidad de vida de los habitantes. Sin embargo, los avances tecnológicos en la agricultura han llevado al abandono de este tipo de construcciones, con importantes riesgos de erosión y pérdida de SE. Nuestra evaluación destaca la importancia de preservar y restaurar las terrazas como parte de la agricultura regenerativa, con múltiples beneficios para el funcionamiento de los paisajes culturales y, en definitiva, para la sociedad.

Prospects of commercial horticulture placement of Dagestan

In the article, the complexity of the geomorphological conditions of the Republic of Dagestan, which necessitates the solution of issues of scientifically based placement and specialization of the horticulture is noted. The goal of study is the evaluation of approaches in placement of fruit crops in Dagestan in recent years. Economical and statistical, analytical, abstract and logical methods are applied. The card of placement of fruit crops on zones and subzones of the regions of Dagestan is given. The issues of horticulture development disclosed, taking into account the existing vertical zoning. The perspective directions of development of horticulture are determined taking into account the complex of natural and economic peculiarities of each fruit zone. The advantages of foothill and mountainous zone of the Republic in the development of industrial fruit-growing, which are expressed in high quality of fruit products and tree trees resistance to diseases are reflected. Among the main negative factors of placement of fruit crops in this zone, high costs for reclamation and agro-technical measures, as well as susceptibility to return spring frosts, the probability of which increases despite the fact that winters are becoming visibly warmer have been highlighted. The positive aspects of conducting terraced agriculture for the Republic, ensuring the involvement in the turnover of sloping lands, reduction of material and labor costs are given. The analysis of structure of varieties has revealed negative tendency in the spread of new foreign varieties, which are not adapted to local conditions that negatively influences on phytosanitary environment in the region. It was proposed to restore the functioning of variety plots in each natural-climatic zone. Calculations of the areas, outputs and productivity from 1990 to 2016 are given. The negative dynamics of areas and gross harvest of fruit crops in agricultural enterprises for the analyzed period is revealed, that is due to deep production and financial crisis situation in this sector of management, especially for horticultural enterprises of the mountain zone. It was noted that the key trend in Dagestan horticulture is the implementation of intensive technologies. The main directions of horticulture recovery in the republic are suggested: modernization of material and technical resources, creation of highly specialized horticultural farms, electronic maps for the gardens, development of a new plan of the placement of horticulture and fruit farming enterprises, as well as full state support.