Terraced Fields Research Articles

High Temperature Water Vapor Corrosion Behavior of Titanium Aluminate (Al2TiO5)

Water vapor corrosion resistance of titanium aluminate (Al 2 TiO 5 ) was examined at 1500°C in 30 wt% H 2 O flow. The weight loss rate of this substance was 8.6×10 -6 g/cm 2 .h during a 100-h test. No phase change occurred during the corrosion test, but anisotropic corrosion behavior was observed. In the X-ray diffraction patterns of the sample surface following the corrosion test, the relative intensities of 230 and 420 peaks were drastically decreased compared with that of the sample prior to corrosion. Geometrical patterns as like to sand ripples or terraced fields were observed on the sample surface after testing corresponding to the anisotropic water vapor corrosion.

Assessment of soil losses on cultivated land by using the [formula omitted] technique in the Upper Yangtze River Basin of China

This paper presents the results of using the 137 Cs technique to assess soil erosion rates of both sloping cultivated land and flat terraces in the Upper Yangtze River Basin, China. The study was carried out on eighteen sloping cultivated fields and four flat terrace fields in eight counties and cities over the eastern part of the basin. The 137 Cs -reference inventory ranged from 620.5 to 2573.2 Bq/m 2. For the 18 sloping cultivated fields, the average 137 Cs inventory over a field ranged from 204.9 to 1847.7 Bq/m 2, which accounts for 15–77% of the local 137 Cs reference inventory, and the average water erosion rate ranged from 758 to 9854 t/km 2 per year, with erosion rates of <1000 t/km 2 per year in two fields; 1000–5000 t/km 2 per year in eight fields; and >5000 t/km 2 per year in eight fields. It is apparent that most of the sloping cultivated fields suffer severe or very severe soil erosion. For the four terrace fields under this study, the average 137 Cs inventory over a field ranged between 915.8 and 2675.4 Bq/m 2, which accounts for 97–104% of the local 137 Cs reference inventory. However, water erosion is very slight on the terrace fields and little soil is lost from the terraces. The study also indicated that the severity of soil erosion is strongly related to soil texture and slope gradient.

Discharge water quality models of storm runoff in a catchment

The relationships between the water qualities of nitrogen and phosphorous contents in the discharge water and the discharge of storm runoff of an experimental catchment including terraced paddy field are analyzed based on experiment results of the catchment. By summarizing the currently related research on water quality models, the water quality models of different components of storm runoff of the catchment are presented and verified with the experiment data of water quality analyses and the corresponding discharge of the storm runoffs during 3 storms. Through estimating the specific discharge of storm runoff, the specific load of different components of nitrogen and phosphorus in the discharge water of the catchment can be forecasted by the models. It is found that the mathematical methods of linear regression are very useful for analysis of the relationship between the concentrations of nitrogen and phosphorus and the water discharge of storm runoff. It is also found that the most content of the nitrogen (75%) in the discharge water is organic, while half of the content (49%) of phosphorus in the discharge water is inorganic.

137Cs DEPTH DISTRIBUTION IN HAPLIC-UDIC FERROSOLS OF SOUTHERN CHINA AND ITS IMPLICATION FOR SOIL EROSION

The depth distribution of 137Cs (cesium-137) and its relationship with organic carbon and different particle size fractions in Haplic-Udic Ferrosols in Yujiang, Southern China, are described in this paper. Compared with other sites, the lower 137Cs inventories associated with uncultivated soils on or close to the crests indicate the relatively low 137Cs in situ retention ability of the soil. Therefore, the use of 137Cs techniques in erosion studies on uncultivated Haplic-Udic Ferrosols may create some significant difficulties and limitations, including identifying the suitable 137Cs reference site and its validity on and near the crests. The impact of the soil erosion process to a depth of more than 4 to 6 cm on the sloping dry farmland and dry terrace farmland indicates that the widely accepted assumption of uniform 137Cs depth distribution within the plough layer may not apply in these soils, although it does basically hold true for the paddy terrace field, in the area dominated by Haplic-Udic Ferrosols. For uncultivated Haplic-Udic Ferrosols, the organic matter may not control the downward migration of 137Cs because no significant relationship was found between the depth distribution of 137Cs and that of organic matter. It was also demonstrated that the 137Cs fallout is associated mainly with the clay fraction, whereas the organic matter is associated mainly with the silt fraction. For Haplic-Udic Ferrosols, the waterinduced erosion removes preferentially the clay associated with the relatively high concentration of 137Cs and low content of organic matter.

Marsh terracing as a wetland restoration tool for creating fishery habitat

Terracing is a relatively new wetland-restoration technique used to convert shallow subtidal bottom to marsh. This method uses existing bottom sediments to form terraces or ridges at marsh elevation. A terrace field is constructed by arranging these ridges in some pattern that maximizes intertidal edge and minimizes fetch between ridges; the intertidal area is planted with marsh vegetation. We examined the habitat value of terracing for fishery species at Sabine National Wildlife Refuge, Louisiana (USA) in spring and fall 1999 by quantifying and comparing nekton densities in a 9-yr-old terrace field and nearby reference area using a 1-m2 drop sampler. Decapod crustaceans were more abundant than fishes, composing 62% and 95% of all organisms we collected in spring and fall, respectively. White shrimp Litopenaeus setiferus, daggerblade grass shrimp Palaemonetes pugio, blue crab Callinectes sapidus, and brown shrimp Farfantepenaeus aztecus accounted for 94% of all crustaceans, whereas 60% of all fishes were gulf menhaden Brevoortia patronus. Mean densities of white shrimp (fall), daggerblade grass shrimp, blue crab, and brown shrimp (spring) were significantly greater in terrace marsh than on non-vegetated bottom in the reference pond. Densities of most nekton on non-vegetated bottom were similar in the terrace field and the reference pond, but gulf menhaden and white shrimp had higher densities at terrace pond sites and brown shrimp (spring) were more abundant at reference pond sites. The pattern for biomass was similar to that for density in that the mean biomass of most species was significantly greater at terrace marsh sites than reference pond sites and similar at terrace and reference pond sites. Terrace marsh, however, was not functionally equivalent to natural marsh, as mean densities of daggerblade grass shrimp (fall), brown shrimp (spring), and blue crab and mean biomass of white shrimp (fall), striped mullet Mugil cephalus (spring), and spotted seatrout Cynoscion nebulosus (fall) were greater at reference marsh sites than terrace marsh sites. Using these density and biomass patterns and the percentage of marsh and pond area in the terrace field, we concluded that terrace fields support higher standing crops of most fishery species compared with shallow marsh ponds of similar size. Future restoration projects could include design changes to increase the proportion of marsh in a terrace field and enhance the habitat value of marsh terraces for fishery species.

Evaluating Soil Quality–Soil Redistribution Relationship on Terraces and Steep Hillslope

Soil redistribution from tillage and water erosion have the potential to modify the spatial patterns of soil quality on terraced and steep cultivated hillslopes. However, few studies have investigated this relationship. Our objectives were to quantify soil quality parameters along terraced and steep hillslopes and determine the relationship between soil redistribution from tillage erosion and water erosion on soil quality parameters in the Chinese Loess Plateau. Soil quality indicators, i.e., soil organic matter (OM), available P, N, bulk density (Db), and clay and silt contents were measured at 5‐m intervals on a terraced field and at 10‐m intervals on a steep cultivated hillslope in a down slope transect. Soil redistribution rates from tillage and overland flow were obtained by 137Cs technique integrated with a tillage erosion prediction model (TEP). Water erosion was the primary cause for the overall decline in soil quality on the steep cultivated hillslope while tillage erosion had a comparable contribution to overall level in soil quality on the terraced hillslope. Soil movement by tillage controlled the spatial patterns in OM, N, and P on both terraced and steep cultivated hillslopes. Selective removal of finer particles by water erosion caused a linear decrease in clay content of 0.02% m−1 and corresponding increase in silt content of 0.04% m−1 downslope on the steep cultivated hillslope. The impact of tillage erosion on OM, N, and P on the steep cultivated hillslope can be assessed using the change in adjacent slope gradients (X) through a soil quality‐topography regression model, Y = aX + b

Marginal Lands and Erosion in Terraced Fields in the Mediterranean Mountains

Abstract Since the 1950s, the Spanish Mediterranean mountains have become a marginal territory, with few inhabitants and limited economic activity. As a consequence, significant land use changes (farmland abandonment, development of extensive cattle rearing, and reforestation) have taken place, resulting in landscape degradation and new hydromorphological processes. In this article, the process and impact of farmland abandonment in the Camero Viejo (northwestern Iberian System) are described. The authors also studied the geomorphological evolution of terraced fields after cultivation was given up. Runoff rates and sediment yield in abandoned and grazed terraces were measured using a rainfall simulator. Results show that the speed and intensity of the hydrological and erosional response increased if plots were grazed intensively. The study demonstrates that new land management systems in the Camero Viejo, in particular extensive cattle grazing, have generated additional source areas of sediments.

Bodendegradierung und Ernährungskrise bei den Ouldeme und Platha. Umwelt- und Ernährungsprobleme bei zwei Feldbauerngruppen in den Mandarabergen Nord- Kameruns: Eine Folge der Adaptation an Monetarisierung und Wandel traditioneller institutioneller Rahmenbedingungen

The Ouldeme and the Platha are two traditional farming communities of northern Cameroon. During the A.'s field work between 1990 and 1991, both groups in this semi-arid zone faced an environmental crisis and food shortages which cannot be explained by neo-Malthusian theory. He offers explanations that are influenced by the new institutional economics and anthropology and focuses on the various changes during colonial and post-colonial times. These include the monetarisation of social relationships as well as changes in traditional institutions of land use, traditional management of the harvest, and restricted beer production. There are also changes in rules concerning land use. Neglecting to maintain terraced fields under rent for one year and terraced fields in mortgage because of insecure land tenure seems to be one of the major changes leading to soil erosion. The A. explains how different gender and age-specific individual strategies of adaptation to monetarisation, that give short-term pay-offs, lead to environmental degradation and food insecurity in the long run, and change traditional institutions that once helped people to use the resources in a more sustainable way.

中山間地域の景観を活かした農村整備構想 岐阜県白鳥町白鳥東部地区

In this study, we proposed a rural consolidation method of planning making use of the traditional rural landscape of terrace fields in Shirotori town, a typical mountainous area of Gifu Prefecture. We examined the actual conditions of rice terraces and rural resources which formalize rural landscapes. we also conducted a survey on residents opinions in connection with this consolidation planning. As a conclusion, we presented three conceptual areas classified as “village area”, “field area” and “mountain area”. These areas were linked by farm roads and management roads along irrigation canal.

B26 棚田と平野部の水田における蚊幼虫発生様相の違い 第 2 報

B26 棚田と平野部の水田における蚊幼虫発生様相の違い 第 2 報

Holocene environments of the high plateau, Yemen. Recent geoarchaeological investigations

The late Pleistocene and Holocene sedimentary stratigraphy is described for part of the high plateau of Yemen (altitude 2000–3000 m A.S.L.), to the south of Sana'a. The presence of angular slope debris and dune sand in pre-Holocene contexts suggest cold and arid late Pleistocene conditions, followed, after a phase of indeterminate semiarid fluvial activity, by the development of humic palaeosol A horizons at a wide range of altitudes. Dated to between 7500 and 4350 B.P., this palaeosol includes a valley floor component related to marsh and lake development. Correlation with the humid Neolithic phase of southern Arabia is suggested for this palaeosol. Above the palaeosol thick sedimentary accumulations are associated with increased evidence of human activity and the construction of terraced fields after around 4300 B.P. © 1997 John Wiley & Sons, Inc.

The Status of Women in Subsistence Agriculture in the Garhwal Himalaya, India

The rural people of the Garhwal region are generally characterized as economically deprived. Their basic source of income is traditional agriculture on small terraced fields with low productivity. Animal husbandry is neither productive nor profitable yet excessive and uncontrolled grazing has led to large-scale soil erosion; the only economic benefit from livestock is the dung which provides fertilizer for agricultural fields. The daily requirements of the inhabitants for fuel, food, and fodder are a cause of great concern in any attempt to achieve or maintain sustainable development and a balanced ecosystem (Negi, 1992). In view of this, an integrated watershed management project has been developed in the Garhwal Himalaya to improve rural agriculture and, at the same time, to prevent overexploitation of the natural resources. A study was undertaken in the area south of the River Bhagirathi. Here, watersheds defined by natural boundaries in each drainage basin were designated as 'sub-watersheds' or 'mini-watersheds' and these units were used to classify information on the development of land, water, and plant resources to meet the subsistence needs of the hill farmers and farm women. The Henval, Hindolakhal, and Muni-Ki-Reti subwatersheds were selected for field study in the south Bhagirathi area in the Tehri Garhwal district. Within these, five mini-watersheds were selected: the Agar (about 280 ha) on the eastern banks of the Henval; the Lawa (336 ha) and Amani (358 ha) on the north and south banks of the Hindolakhal; and the Simswara (104 ha) and Byasi (575 ha) on the north and west banks of the Muni-KiReti.

An Ancient Maya Reservoir and Dam at Tamarindito, El Peten, Guatemala

We report a Prehispanic dam and remnants of a small reservoir at the ancient Maya site of Tamarindito in the Río de la Pasión region of Guatemala's Petén district. The remnants of the dam are on the Petexbatún escarpment, to the east of the main site in the midst of an area of residential groups and numerous and varied agricultural terracing. The dam was about 60 m long and would have held a reservoir of about 2,000 m3. This volume of water was sufficient to irrigate nearby terraced fields. The dam and reservoir probably date to the Late Classic period (A.D. 550-800), a period during which Tamarindito was involved in regional warfare. In addition to producing irrigation water, we hypothesize that the system was built to provide a supplemental, more defensible, residential water supply and to protect a spring located below the dam.

A12 棚田と平野部水田における蚊幼虫発生様相の違い

A12 棚田と平野部水田における蚊幼虫発生様相の違い

地方中規模都市における住民の定住意向と環境評価・生活環境整備課題への要望に関する研究 栃木県鹿沼市を対象として

Recently, the Problem of maintaining population level in local cities and surrounding areas has been a serious subject for regional planning. It is an especialy serious problem in underpopulated rural areas. The factor involved are both economic and social. In this paper we wish to look at this problem.The aim of this study is to look at the following Points:(1) Views of the inhabitants as to the habitabilities of the hamlets and cities.(2) Whether inhabitants intend to continue living at the hamlets and the cities.(3) The value put on the principal regional facilities by the inhabitants.(4) The value put on the principal conditions in the neighborhood by the inhabitants.(5) The requirments for improvements to the regional facilities.(6) The requirments of improvements for the conditions in the neighborhood.We chose Kanuma city as the object of this study, It has a population of 93, 000, and is in Totigi prefecture. Kanuma city is composed of ten districts, these are densely inhabited districts, unterraced rice field and hamlets, and terraced field and hamlets, narrow village in between small mountains and small villages in the mountains.In this study, we sent out questionnaires to 2, 000 inhabitants and received 803 replies. The results of questionnaire showed the following tendencies:(1) On the questions of the habitability, 68.8% of people answered their lives were comfortable and 21.3% of people answered their lives were uncomfortable.(2) Questions of intentions of remaining in the city, 76.1% of people answered they wished to live there.(3) It appears that the positive or negative impressions of the city are directly related to whether or not people intended to continue living in the area.(4) The reasons given for remaining were the existence of properties attachment tothe home town and natural surroundings in city.(5) Response to the questions at the value put on regional facilities, the highly valued items were infant schools, elementary and junior high schools.(6) The low-valued facilities were the hospitals social welfare facilities for the aged peoples and of the high schools, museums, athletic facilities, leisure facilities for inhabitants.(7) The requirments for new facilities were confined to the medical facilities, leisure facilities and parks.(8) Other areas identified in the questions in need of improvement were environmental ammenities such as the conditions of the roads, the drain systems, safe play yards for the children, small parks and the more street lamps.

Chemical Modification of Surface Steps on SI(111) Vicinal Wafers: a Bonding Model for Phase Changes in Second Harmonic Generation

ABSTRACTThere have been several studies of second harmonic generation (SHG) from chemically-modified vicinal Si(111) wafers. The SH fields contain one-fold (ψ) and three-fold (3ψ) symmetry contributions, which originate respectively from the terrace and surface step atoms. The phase of these contributions are different for native oxides, and are a function of the frequency of the incident radiation, ω. To identify the origin of these different phases for the terrace and step SH fields, we use a classical anharmonic oscillator model based on two assumptions: (a) a significant fraction of Si atoms at the steps have dangling bonds when oxides are formed below ∼850°C, and (b) these step atoms are linked to atoms at the bottom of the steps by O-Si-O groups following annealing at &gt;900°C.

From "City Terrace Field Manual"

From "City Terrace Field Manual"

Weed population dynamics under ‘jhum’ (slash and burn agriculture) and terrace cultivation in northeast India

The pattern of emergence, survival and mortality of six weed species and the dynamics of total weed population were studied for 2 years in potato fields under slash and burn (‘jhum’) and terrace cultivation in Meghalaya, northeast India. The composition of the weed flora in ‘jhum’ and terrace fields was similar, however, the population density was generally higher in the former. Weed seedlings appeared at three different times during both autumn and summer cropping seasons, giving rise to three distinct cohorts. The overall pattern of weed seedling emergence differed among cohorts and from species to species. The effect of cropping season on mortality patterns of seedling cohorts was not significant. For all weed species early cohorts showed high mortality during the 45 days after emergence, but in the third cohort mortality rate was almost constant throughout life. During the cropping period, seedling recruitment rate ( K) and fecundity rate ( F) were higher in terrace than in ‘jhum’, but the survivorship ( P) was greater in the latter. High annual rate of increase in weed seeds (λ) in soil and low seedling recruitment rate appear to be the main causes of larger weed-seed populations in ‘jhum’ fields compared with the terraces. The larger soil seed bank in ‘jhum’ than in terrace eventually contributed to a larger weed population in the former.

Rice Cultivars in Northern Pakistan.

An IBPGR exploration for collecting cereal germplasm was carried out over a wide area of Pakistan in 1989. The result suggested that a large number of local varieties are grown in northern Pakistan. In 1991, we focused our survey on rice germplasm in northern Pakistan. T. he present status of rice growing and information on local varieties in the north-ern mountainous area are as follows; 1) In the Chitral District, rice plants are cultivated in terraced fields located at elevations ranging from 1, 000m to 2, 250m. Two kinds of varieties, Nali (transplanting) and Byene or Beyan (direct sowing), are adapted to these areas. These varieties are similar to the Japonica type varieties . They differed in the phenol reaction of the hull, , There were some differences in the color of the apiculus, awn and hull of Nali among the locations. Due to the higher productivity, the farmers prefer to cultivate Nali, although the grain quality of Byene is superior to that of Nali.

A Folk Expert System: Soils Classification in the Colca Valley, Peru

The agropastoralists of the Colca Valley, Peru, have achieved an enviable record of maintenance of soil fertility in their terraced fields over more than a millennium. This paper concerns the native classification of soils in that region, part of a larger team study that examined the indigenous knowledge of land use and management in the Quechua-speaking community of Lari. Soils classifications were obtained from ten primary informants. This study employed ethnoscienceprocedures, such as controlled elicitation, general sorting tasks, and triadic sorting tasks. These data were then used, in consultation with native farmers, to prepare two models of a Folk Expert System of the indigenous knowledge of soils classification. The FAI/SOILS models comprise the first Folk Expert System to be reported. Construction ofthe Folk Expert System led to a simple class~fication ofsoils byfertility which, with soil quality categories and other considerations, is useful in predicting crop and field management strategies. Further, thefolk classification may be compared with some aspects of the Western scientific classification. [expert systems, folk classification, knowledge acquisition, soil classification, Quechua]