Expansion Of Paddy Fields Research Articles

Farmland-atmosphere feedbacks amplify decreases in diffuse nitrogen pollution in a freeze-thaw agricultural area under climate warming conditions.

Although climate warming and agricultural land use changes are two of the primary instigators of increased diffuse pollution, they are usually considered separately or additively. This likely lead to poor decisions regarding climate adaptation. Climate warming and farmland responses have synergistic consequences for diffuse nitrogen pollution, which are hypothesized to present different spatio-temporal patterns. In this study, we propose a modeling framework to simulate the synergistic impacts of climate warming and warming-induced farmland shifts on diffuse pollution. Active accumulated temperature response for latitudinal and altitudinal directions was predicted based on a simple agro-climate model under different temperature increments (△T0 is from 0.8°C to 1.4°C at an interval of 0.2°C). Spatial distributions of dryland shift to paddy land were determined by considering accumulated temperature. Different temperature increments and crop distributions were inserted into Soil and Water Assessment Tool model, which quantified the spatio-temporal changes of nitrogen. Warming led to a decrease of the annual total nitrogen loading (2.6%-14.2%) in the low latitudes compared with baseline, which was larger than the decrease (0.8%-6.2%) in the high latitudes. The synergistic impacts amplified the decrease of the loading in the low and high latitudes at the sub-basin scale. Warming led to a decrease of the loading at a rate of 0.35kg/ha/°C, which was lower than the synergistic impacts (3.67kg/ha/°C) at the watershed level. However, warming led to the slight increase of the annual averaged NO3 (LAT) (0.16kg/ha/°C), which was amplified by the synergistic impacts (0.22kg/ha/°C). Expansion of paddy fields led to a decrease in the monthly total nitrogen loading throughout the year, but amplified an increase in the loading in August and September. The decreased response in spatio-temporal nitrogen patterns is substantially amplified by farmland-atmosphere feedbacks associated with farmland shifts in response to warming.

A population genetic study on the relationship between medaka fish and the spread of wet-rice cultivation across the Japanese archipelago

It has been generally thought that a tiny freshwater fish, medaka (Oryzias latipes), has expanded its habitat into the Japanese archipelago as wet-rice cultivation spread across the region, and hence the distribution of medaka should be a matter of anthropological interest. However, there has been no study to verify this popular belief. To address the issue, we sampled wild medaka, and undertook genetic analyses of its populations. We collected 976 individual medaka from 13 local wild sites, which included 11 paddy-field irrigation channels and two ponds. The gene tree constructed based on nucleotide sequences of mitochondrial genome D-loop region showed no discrepancy in the topology, which is presumed to reflect the northern Kyushu origin of the southern Japanese medaka. Population genetic statistics indicated that the medaka populations in west Japan have greater genetic diversity (heterozygosity) than those in east Japan, supporting the hypothesis that the medaka originate from northern Kyushu. Hence, we argue that the current medaka distribution can be attributed to their past migration event(s) following the expansion of paddy fields from northern Kyushu to the eastern part of the Japanese archipelago.

Climate warming and land use change in Heilongjiang Province, Northeast China

This study explores the relationship between climate warming and rice paddy expansion in Heilongjiang Province of China. It is found that paddy fields more than quadrupled from 3479 km2 in 1958 to 14 564 km2 in 1980, and increased further to 21,940 km2 in 2000. The newly gained paddy fields originated chiefly from dry fields (46.35%), swamps (30.22%), and primary forest (nearly 10%) during 1958–1980. During 1980–2000 paddy fields expanded at the expense of dry fields (70.50%), swamp (16.59%), and grassland (10.13%). Analysis of climate data shows a warming of over 2 °C from the 1960s to the 2000s in most places. All 28 meteorological stations except one experienced a warming trend. Spatially, the expansion of paddy fields coincided closely with the spatial distribution of annual temperature. These fields were located mostly between the isolines of 2–3 °C. Sowing area of grain increased at a modest rate during the 1970s and the 1980s when >0 °C area expanded rapidly. However, sowing area of rice rose in the 1990s and 2000s at a rate twice higher than that for sowing area of grain in the preceding decades. Thus, the expansion of paddy fields at the expense of other land covers was made possible owing to climate warming in the preceding decade. On average, it takes about 20 years for agricultural practices to adapt to the warmer climate.

DEVELOPMENT OF A MAJOR RICE CULTIVATION AREA IN THE KILOMBERO VALLEY, TANZANIA

After economic liberalisation in Tanzania, rice cultivation rapidly expanded as a source of income, and several production areas formed. The Kilombero Valley, located in central southern Tanzania, is a major rice production area. The people residing in the valley had already developed the original rice paddy cultivation system for subsistence farming by the mid nineteenth century. The system depends on run-off from a flooded tributary of the Kilombero River. Recently, production using the indigenous cultivation system has increased and has produced a surplus for sale. However, suitable lands for the flood cultivation system are limited to narrow riversides. One reason why rice production has successfully increased is the introduction of modern technologies, such as tractors and trucks, into the indigenous sys- tem. Tractors and trucks have enabled the expansion of paddy fields to remote areas, and as a result, rice production has increased. At the same time, abundant production has accelerated the trading of rice and has increased opportunities for trading. Thus, increased rice produc- tion in the Kilombero Valley based on the established indigenous cultivation system has led to activation of the rice market.

Dutch Colonial Rule and Development of Paddy Fields in Priangan, Java

This essay sketches the changing relationships among the Dutch Colonial Government and among native chiefs and their people in early 19th Century Priangan. This is a time when paddy fields were rapidly spreading to this area.Wet rice cultivation in Priangan started to spread in the middle of the 18th Century, and after the turn of the century, Dutch officials reported construction of various scale irrigation facilities. The Dutch Government began to construct large irrigation canals and dams, limiting its role to planning the works and supplying the necessary funds and goods for the projects. The native chiefs, who had been organizers of irrigation works throughout the 18th Century, undertook the projects. They organized their people's corvee labor, and arranged for native irrigation specialists to supervise the work. Besides these large facilities, many small scale irrigation facilities were constructed; some of them were planned by the chiefs, and others by the people. These small facilities seem to have contributed to the expansion of paddy fields far more than did the Govern ment's large facilities.Although irrigated paddy fields expanded with these facilities, the basic tax system in Priangan didn't change in these decades. Dutch sources show that most of the arable lands irrigated with these facilities were reclaimed by individual settlers who owned the lands. The poll-tax system survived as the main tax system in Priangan at least to the 1820s.During these decades the Government succeeded in expanding coffee cultivation with the people's corvee labor. This was not done by introducing land tax system, but by extending its patronage through the chiefs to the people. The chiefs obeyed the goverment because of their economic dependency. They could'nt manage their finances without the rights and interests given by the Government, which included funds for irrigation works and coffee plantations, concessions of coffee transport and trade, and a coffee production percentage. The people in turn obeyed their chiefs by producing coffee. The reason of their obedience partly because they could get far more profit from wet rice cultivation than from slash and burn. And partly, most of them couldn't run the rice cultivation without agricultural credits given by the chiefs, and part of them couldn't run the cultivation without the facilities constructed by the chiefs.Thus, the relationships between the chiefs and their people in early 19th Century Priangan seemed to be far different from M. C. Hoadley's “Feudal Mode of Production” (1994). On the other hand, this chief to people relationship shows some similar points to these depicted in Y. Breman's “patron-client relationships” (1978, 1982). However, the relationships in early 19th Century are not the same ones as the pre-colonial relationships, but are relationships transmuted under the influence of Dutch colonial rule.

On the Irrigation of Terraced Paddy Fields (or Rice Terraces) with Special Reference to the Wajima Region, the Obasute Region and the Hayakawa Valley

When making paddy fields on a slope, the paddies, each with a level surface, must be made one by one in the form of a series of shelves or terraces. Paddy fields made in this manner are called “terraced paddy fields” or “shelf paddies” “tanada” in Japanese. Such paddy fields are found in various parts of the mountainous regions of Japan, and may roughly be divided into two categories, depending on the nature of the place where they are found. The first category includes terraced paddy fields that stretch in long, narrow lines along the bottom of small valley among the mountains. To the second category belong those that are found stretching on wide slopes. Terraced paddy fields belonging to the first category are found everywhere in mountainous regions. They are easy to make and their irrigation presents no problems. In the case of terraced paddy fields of the second category, however, because of the general complexity of the relief of the slopes where they are found, their making in such places requires great labor, and their irrigation is a difficult matter.The present writer conducted a study of 26 of the main terraced paddy fields belonging to the second category, and in each case, was convinced of the great pains and resourcefulness required to ensure the supply of irrigation water.In Japan, rice has been the main food crop since ancient times ; and until the Meiji period, it was the practice among farmers to pay their taxes in rice. Rice was the all-important element of economy, both for the central and local feudal lords until the Meiji period. This was the reason that, throughout the nation, the development and expansion of paddy fields were the two main concerns of the rulers as well as the farmers. This state of affairs continued until recent times. The present writer believes that it is possible to consider the existence of terraced paddy fields as one of the manifestations of the history of this type of rice-centered policy in the form of cultural landscapes seen in the land.In the present paper, the writer has chosen three typical regions, and he purposes to describe the development of the irrigation of the terraced paddy fields found in each of these regions.(1) The Wajima Region in the northern part of the Noto Peninsula.This region is the location of “Shirayone no Senmaida” (or “Numerous Small Terraced Paddy Fields of Shirayone”), which in recent years have come to attract the attention of tourists. There are monographs and books which state that the terraced paddy fields in this region are supplied with irrigation water by springs and rain water. The writer, however, has made clear in the present paper the fallacy of these claims. In the Edo period, in order to irrigate the terraced paddy fields in this region, long irrigation canals were dug to draw irrigation water from the upper reaches of rivers among the mountains, while irrigation reservoirs were made among the mountains to provide irrigation water. Examples of these irrigation systems are shown in Figures 1 and 2. The terraced paddy fields in this region are developed on slopes formed as a result of landslides.(2) The Obasute Region in Nagano Prefecture.This region is the location of terraced paddy fields widely reputed as “Tagoto no Tsuki” (or “The Moon Reflected in Each of Many Paddy Fields”). In this region, too, are found terraced paddy fields on slopes formed as a result of landslides. Concerning the terraced paddy fields in this region, there are books which state that they were supplied with irrigation water by springs and rain water, but the irrigation system in this region is not such a simple matter.

ON THE DISTRIBUTION OF “SHIMA-BATAKE” (ISLAND-LIKE OR MICRO-BUTTE-LIKE UPLAND FIELD) LANDSCAPE

By “shima-batake” landscape is meant landscape in which upland fields of various shapes, approximately 50-80 cm. above the ground of paddy-fields, are distributed among paddy-Melds, much as micro-buttes are scattered over a plain, or numerous small flat islands are scattered over the sea. In regions where “shima-batake” are densely distributed, there are cases in which the area of upland fields is larger than that of paddy-fields. The purpose of the present paper is to clarify in which regions such landscapes are found. In the first place, after making a detailed inquiry into the relationship between the distribution of “shima-batake” and micro-land forms as well as irrigation in the Hamana and Iwata Plains in the downstream region of the Tenryu River, consideration was given to the origin of “shima-batake.” By a similar method of investigation, inquiry was made into the downstream plains of the Kiso River, the Yahagi River, the Toyo River, the Sagami River, the Kuji River, the Naka River, the Shinano River, the Agano River, the Kariyata River, etc., and also the coastal plains of the Tone River, the Kinu River, and the Naka River, as well as the downstream plains of the Yoro River, the Obitsu River, and the Koito River, on the west coast of the Boso Peninsula, the Kujukuri coastal plain, and two other regions. Approximately 40 years ago, Prof. Glenn T. Trewartha expressed his opinion concerning the “shima-batake” in the downstream plain of the Tenryu River (Annals of American Geographers, Vol. 18, 1928, pp. 127-257). In a recent work, he has expressed the same opinion as before (Japan, a Geography, 1965, p. 652). His opinion is as follows: As a result of the flooding of the Tenryu River, large deposits of detritus were made in the paddy-fields, and the irrigation canals were buried. In their work of restoration following the disaster, the farmers removed the detritus from the paddy-fields and irrigation canals, and piled it up in one part of the paddy-fields, which they later leveled out to make upland fields. These up-land fields formed the “shima-batake.” The present writer, however, cannot agree with this opinion in view of the fact that “shima-batake” are distributed even in diluvial tablelands that are entirely free from any danger of flooding, as well as for other reasons. The present writer holds the following view: In regions where “shima-batake” are distributed, the slope of the land surface is extremely gentle, and the surface abounds in micro-relief. (In general, the difference in height between the high parts and the low parts is less than about 80cm.) Again, the water-level of the irrigation canals in such regions is approximately the same as the height of the lowest part. Moreover, the source of irrigation water is far from abundant. In such a region, in the days before pumps could be used, the farmers had no choice but to level down the high parts and make paddy-fields in order to expand their paddy-fields. The present writer thinks that it was as a result of the expansion of paddy-fields in these regions by individual farmers that the complex distribution pattern of paddy-fields and upland fields was formed. Recently, in regions where plentiful irrigation water has been made available by the use of pumps, “shima-batake” have been leveled out, and the whole region has been made into paddy-fields. Again, in regions where the area of paddy-fields cannot be expanded because of the limitation of irrigation water, and in other places where it was felt desirable that the upland fields should be left as they were, numerous small “shima-batake” have been combined to form upland fields with large areas.