|Long Distance Water Transfer: A Chinese Case Study and International Experiences (UNU, 1983)|
Guo Huancheng and Xu Zhikang
Institute of Geography, Academia Sinica, Beijing, China
CHARACTERISTICS OF LAND USE AND CROP DISTRIBUTION
THE DENSELY populated region of the proposed water transfer has a long history of agriculture. Its cultivation index is the highest in China-over 60 per cent of the land in most parts of the plain and up to 30 to 40 per cent in the hilly areas. It has the largest sown area for wheat, cotton, peanuts, sesame and tobacco. The production of dry and fresh fruits such as apples, pears, persimmon, dates and Chinese chestnuts leads the country. On the other hand, forestry and animal husbandry are extremely underdeveloped. Forest coverage is only 7 to 8 per cent, one of the lowest percentages in China.
The main characteristics of land use and crop distribution in the region are as follows (Institute of Geography, 1980):
(1) The land is predominantly devoted to farming with only a very small portion in forest or pasture. In 1979, the region's cultivated land accounted for 38.9 per cent of the national total but forest and pasture land were less than 13 per cent. The output value of the different branches of agriculture reflects the structure of land use: farming, 67 per cent; animal husbandry, 11 per cent; fishery, 1.1 per cent; and others, including industry and sidelines, 19.6 per cent. The proportion of forest and pasture land is higher in general in the vicinity of mountains and hilly areas, in the south and in the west. Over 80 per cent of the cultivated land is concentrated on the plain.
(2) Grain predominates in agriculture but cotton, peanuts, sesame and tobacco are also important. Among the region's grain crops, wheat has the largest area, the highest output and the most rapid growth; maize, tuber crops and rice have also developed greatly; and the growing area and output of millet and soybeans have both fallen.
In 1979 wheat accounted for 35.9 per cent of the region's grain sown area and 33.2 per cent of its grain output. The sown area for wheat is 45.8 per cent and its output is 51.2 per cent of the national totals. The region's wheat acreage has increased by 29 per cent and output by 374 per cent since 1949. Wheat is rather widely distributed and concentrated mostly in south-central Hebei, north-central and eastern Henan, the piedmont plain of central Henan, the lakeshore area of southwest Shandong and the Huaibei Plain (north of the Huai He) in Jiangsu and Anhui. This is China's largest winter wheat producing area. Wheat production makes possible the extension of the multiple-cropping area.
The region has 54.3 per cent of the nation's cotton area and 50.4 per cent of its output. The cotton fields are concentrated mainly in south-central Hebei, western Henan and western and northwest Shandong. In recent years, however, undue emphasis was placed on "taking grain as the key link". The area devoted to cotton diminished by about one-third compared with the 1950s and the fields became more scattered with lower yields.
In addition, this is one of the country's major oil-bearing crop areas. Over 60 per cent of China's peanuts and sesame were produced here in 1979. Peanuts are distributed in the main on the Shandong peninsula, along the lower reaches of the Luan He in eastern Hebei, in the sandy-gravel soil of the hill slopes in the area of eastern Henan inundated by the Huang He and in the areas of alluvial sandy soil or eolian sandy soil along the rivers and the ocean. Sesame is mainly distributed along the banks of the Huai He and in southeastern Henan west of Hongze Lake as well as in the Huaibei Plain of northern Anhui. Production is especially concentrated in the Hong and Nanbu He basins. This region is also the largest tobacco producing base in the country, with 45 per cent of the national output in 1979. The crop is mainly produced in Henan's Xuchang County, Shandong's Yidu and Linqu Counties and Anhui's Fengyang, Dingynan and Jiashan Counties. The tobacco acreage in 1979 was about 20 per cent greater than in the 1950s and total output was up around 60 per cent, making this a rapidly developing cash crop.
(3) Three crops in two years has consistently prevailed and is adopted on 60 to 70 per cent of the cultivated area, mainly on the Huang-Huai-Hai Plain. The main rotation pattern is wheat(r)summer soybeans (or summer sweet potato or summer millet)(r)winter fallow(r)spring maize (or spring sorghum or spring sweet potato).
Double cropping, which has developed rapidly, and three crop systems are mainly found in areas with a high population-land ratio, good water and fertilizer conditions, a high degree of mechanization and a tradition of intensive farming. These are the region's high yielding grain and cotton areas and are located mainly on piedmont alluvial fans west of the Beijing-Guangzhou rail line, in the suburbs of cities and towns and on the valley plains of eastern Shandong Province. The main crop rotations are wheat(r)summer maize (or summer soybeans, summer sweet potato or summer millet) for double cropping; wheat intercropped with spring maize(r)summer maize (or summer soybeans) intercropping after the wheat harvest for three crops; and spring maize (or spring sweet potato or spring sorghum)(r)wheat(r)summer soybeans (or summer sweet potato)(r)wheat(r)summer soybeans for five crops in three years.
Double crop rotations of wheat(r)rice, oil-bearing crops(r)rice, or green manure(r)rice are adopted in the paddy districts south of the Huai He, as are triple crop rotations of wheat(r)rice(r)rice, oil-bearing crops(r)rice(r)rice or green manure(r) rice(r) rice. Single cropping is mainly found where the population-land ratio is low; where the soil is thin and suffers from salinization, alkalization or windblown sand; where it is low-lying and prone to flooding; in hilly areas where the soil is thin and susceptible to drought; in districts with a short frost-free period; and in cotton-producing areas. The principal rotation patterns adopted in these areas are the following: wheat(r) sunning the upturned soil; sweet potato(r)winter fallow; maize intercropped with soybeans(r)winter fallow; and peanuts(r)winter fallow.
For the most part, one crop of cotton is grown each year with a continuous monoculture. In recent years the system of interplanting wheat with cotton has been somewhat popularized.
Improvements in the conditions of agricultural production have brought with them widespread changes in the cropping systems of the region. In particular the multiple-cropping index has increased and there has been a switchover to highyield crops. The multiple cropping index increased from 132 in 1952 to 156.7 in 1979 and on grain land it went up to 170-180. This has played an important role in making full use of light and heat conditions and land resources to develop agricultural output in the region.
Although the grain cultivated area has declined by 40 per cent in the region since 1952, total output has increased by 252.4 per cent. Of this,87.1 per cent has been due to the extension of multiple cropping, intercropping and interplanting. At the same time, these have produced many new contradictions. These include the conflicts between the increase in the multiple cropping index on the one hand and the farming seasons and soil, fertilizer and water conditions on the other; those among various interplanted crops; and those between mechanization and the forms of interplanting. All of these need to be studied further before they can be resolved.
(4) The level of agricultural production is low but the potential is quite high. The region is one of China's most important producers of grain, cotton, oil-bearing crops and tobacco, yet the present level of production is only middling for the country. The area on which grain yields are low and unstable is still quite large. For instance, the 1979 grain yield averaged around 3.75 t/ha on the 21.3 x 106 ha in the region. Of this about 2.7 x 106 ha yielded less than 2.25 t/ha and on 670,000 ha yields averaged less than 1.5 t. Cotton yields are also only 62 per cent of the national average.
Numerous model instances of high yields over extensive areas have demonstrated the existence of a great potential in increasing production, however. For example, 135 counties attained grain yields over 6 t/ha in 1979. Of these,51 had yields exceeding 7.5 t/ha. In addition there were many models of high cotton yields in excess of 0.75 t/ha.
(5) Regional differences in natural conditions such as heat, moisture, landforms and soil as well as in socioeconomic conditions express themselves in marked differences in the regional distribution of production in agriculture, forestry and animal husbandry as well as in the crop structure and in production levels. To sum up, agricultural land use can be divided roughly into the following five types (Editing Group, 1980):
(a) The type in the piedmont plain of the Yan and Taihang Shan with high agricultural yields. Starting from Shanhaiguan in the east and bordering the Huang He in the south, this region embraces the piedmont plain along the Yan Shan and the Taihang Shan as well as part of the hilly and mountainous area. It consists of 97 counties and county-level municipalities with 3.7 x 106 ha of cultivated land. Consisting in the most part of flat piedmont plains which are diluvial and alluvial fans, this region has the most favourable soil and water conditions in the north. It has a thick, fertile soil layer and welldeveloped irrigation. Crops are intensively cultivated and the standard of fertilizer application is high. This is one of the main areas in the north for cotton and high-yield wheat production.
(b) The type in the low-lying plains in Hebei, Shandong and Henan Provinces with low agricultural yields. This region covers south central Hebei, eastern Hebei, northwest Shandong, north and northeast Henan and most of Tianjin. It includes 105 counties and 5.7 x 106 ha of cultivated land. With its low-lying terrain and serious drought, flooding and salinization, this region has low and unstable grain yields but a very high potential for increasing grain and cotton production. The land surface has an extremely small gradient and a rolling microrelief with crisscrossing hillocks, slopes and depressions. Consequently, floods and flooding occur regularly during each summer and autumn rainstorm season due to inadequate surface drainage. Approximately 20 to 30 per cent of the cultivated land of an average county is subject to lowland flooding.
Poor surface drainage over a long period of time has led to a spread in saline soils due to a rise in the water table and the consequent accumulation of a large amount of salts in the soil. In many counties 20 to 30 per cent of the cultivated land is saline with low and unstable grain and cotton yields, generally only about 2.2 t/ha and 0.2 t/ha respectively. It is entirely possible, however, to change low yields to high through the comprehensive control of drought, flooding and salinity.
The region contains numerous depressions and shallow lakes which provide fairly good conditions for developing aquatic products. In addition there are 1 X 106 ha of saline and sandy wasteland which offer a vast area for planting trees and grass to develop forestry and livestock.
(c) The type in the Huang-Huai Plain with average agricultural yields. This region includes eastern Henan, northern Anhui, northern Jiangsu and southwest Shandong, a total of 116 counties and county-level municipalities with 8.7 x 106 ha of cultivated land. The original agricultural base in the region is fairly good. This is one of north China's main dry grain areas and an important producer of numerous varieties of cash crops. The wheat-growing area is one-sixth of the national total. Sesame and tobacco outputs lead the nation and the area sown to soybeans is in second place. New cotton-producing districts are in the process of being formed and in recent years there has been a new tendency to plant rape on winter fallow land.
However, the great reduction in soybeans and sorghum and expansion in maize and sweet potatoes which have taken place over the past twenty years have led to rural fuel shortages and a drop in soil fertility. The level of production is not high and there is a wide disparity between high and low yields. While the annual grain yield for a number of communes exceeds 6 t/ha, many communes are stuck at a level of 2.2 to 3.0 t/ha. High-yield communes produce as much as 1.1 to 1.5 t/ha of cotton while most average but 0.3 to 0.4 t/ha. This shows that there is still a great potential for improving production. This region also has a relatively good foundation and conditions for developing forestry, animal husbandry, sideline occupations and fisheries.
(d) The farm and forest type in the hills of Shandong. This region includes the Shandong peninsula south of the Huang He and east of the Grand Canal, with a total of 65 counties and county-level municipalities and 4.2 million ha of cultivated land. It has a high population-land ratio with intensive farming, high grain output and a developed diversified economy. This is Shandong's main commodity grain base.
Peanuts are the most important cash crop with one-fourth of the nation's total sown area and about one-third of its output. Tobacco production is second only to that of Xuchang Prefecture, Henan Province. This area is also an important producer of temperate zone fruits and tussah silk.
(e) The agricultural and forest type in the mountainous and hilly areas of western Henan Province. This mainly includes the area lying south of the Funiu Shan and the Huai He and north of the Tongbai and Dabie Shan, a total of 48 counties and county-level municipalities and 3.7 million ha of cultivated land. Half the region is occupied by hills while mountains and ridge plains each cover one-fourth. The ridge plains are the major agricultural areas, the hills more commonly combine cultivated land and economic forests and the mountains are mainly forest lands. Rice is the principal grain produced in the region with double-crop rice planted in most parts. Only in the Nanyang Basin is there a low proportion devoted to paddy fields. There dryland wheat predominates, but the basin is also an important producer of cotton, sesame and tobacco. Production levels are relatively high.
EXISTING PROBLEMS IN LAND USE AND CROP ALLOCATION AND MEANS FOR IMPROVEMENT
In general, the terrain in the proposed water transfer region is flat, the soil layer is thick, the climate is temperate and both light and heat conditions are beneficial to agricultural production. On the other hand, the topography and climate cause drought, flooding and salinization-alkalinization to remain major affecting the development of agricultural production in the region.
The worst problems are due to drought and excess surface water. This region is located in China's eastern monsoon area where atmospheric precipitation and surface runoff vary greatly and are distributed unevenly between seasons. During the spring there are droughts in nine years out of ten, seriously affecting the lateperiod growth and production of wheat and disrupting the timeliness of summer sowing. Rain is concentrated in the summer, mostly in storms, creating serious flooding damage because of inadequate drainage.
During the twenty-four years from 1949 to 1972, flooding was relatively serious in eight years and drought was relatively serious in seven. One main feature has been the alternation of drought and flooding, with drought in years of excess surface water and flooding in years of drought. In an average drought, output is reduced by about one-third. Losses due to flooding are always greater-about one-half and in some areas everything. Therefore the main path to developing the region's agricultural output is to prevent and combat drought and to provide sufficient drainage to avoid the accumulation of excess surface water.
Next is the problem of soil salinization. Currently there are approximately 2.7 million ha of saline soil in the region, accounting for about one-fifth of the cultivated land in the plains. This is roughly 40 per cent of the country's saline soil area. Within the region, 37 per cent of the saline soil is in Hebei, 28 per cent in Shandong, 22 per cent in Jiangsu, 12 per cent in Henan and 7 per cent in Anhui.
Slightly and moderately saline soils prevail on 73.7 per cent of the affected area. Here the salt concentration generally ranges between 0.1 per cent and 0.7 per cent and the seedling retention rate is at least 30 to 70 per cent, so it is still possible to grow crops. The remaining 26.3 per cent of the affected area has a salt concentration exceeding 1 per cent and a seedling retention rate below 30 per cent. This land is used mostly for livestock and forestry. The extensive saline area in the region is not only unfavourable to current agricultural production but also an important problem which must be taken into account in considering a south-tonorth water transfer.
Finally, the crop structure is too simple, the multiple cropping area is too large and soil fertility is constantly dropping due to the lack of proper soil utilization or nutrient maintenance. A long-term one-sided emphasis on high yielding grains and on increasing the multiple cropping index has led to a great expansion in the area devoted to maize, wheat and sweet potatoes at the cost of crops such as soybeans, sorghum and millet which are resistant to flooding and replenish the soil.
The multiple cropping index of grain land increased from 120-130 in the 1950s to the present 170-180. Although grain output thereby increasedto some degree, this strategy induced an improper distribution of crops in some areas. Water, fertilizer and labour force shortages resulted, which hampered intensive cultivation. Moreover, soil fertility dropped due to insufficient organic fertilizer, a result of the low number of livestock raised, the even more limited availability of green manure and the use of most straw for fuel. All this was aggravated by the overemphasis on land use to the neglect of maintaining soil fertility. Investigations indicate that the organic matter in the soil of most places is less than 1 per cent and in some instances is only 0.6 to 0.7 per cent. The total nitrogen content is 0.05 per cent and effective phosphorus is generally less than 20 ppm and may be as little as 10 ppm. In addition the soil structure has worsened due to the thin layer of cultivation. As a result, even though many areas have developed irrigation, agricultural production has not been able to increase. Thus the barrenness of the soil has become an important factor limiting the region's agricultural yields and their stability.
The following summarizes some suggestions for further rationalizing the utilization of land resources and readjusting crop distribution in the light of the region's characteristics:
(1) Control drought, flooding and salinization comprehensively. The dangers of flooding, waterlogging, drought and salinization have yet to be brought under complete control in many areas because for a long time drainage has not been integrated with irrigation into a complete system, the land has not been levelled and irrigation has been done irrationally. For this reason, it is necessary to make full and rational use of natural conditions in the region. First of all, overall plans should be drawn up for the comprehensive control of drought, flooding and salinization. Of course, this should be done in light of local conditions, using the following specific measures:
(a) Integrate regulation and control of surface and subsurface water and
correctly handle the relations between drainage, irrigation, storage and
recharge. At the same time that we can continue to raise the harnessing
standards of key projects we urgently need to build up field drainage and
irrigation works, so that excess water can be drained and drought-stricken land
can be irrigated. Irrigation and drainage should be integrated, with primary
emphasis on drainage.
(b) Fully utilize groundwater by developing well irrigation. In light of the different hydrogeological conditions in each locality, the placement of pump wells should be adjusted suitably so that there is both extraction and replenishment of the groundwater and so that the wells ensure a bumper harvest while the rivers replenish the water sources.
(c) Strengthen irrigation management by training personnel, improving the system of irrigation and using water scientifically. Irrigation should be done at the right time in keeping with local conditions according to differing crop water requirements.
(d) Divert the water of the Huang He in a planned way for irrigation of areas along the river. There should be strict control, however, over the quantity, frequency and timing of water so diverted. The area to be irrigated, quantity of water, time periods and management personnel should be fixed ahead of time so as to prevent blind water diversion which leads to secondary salinization.
(2) Adjust the distribution of crops, improving the cropping systems and combining land utilization with replenishing the soil. Given the region's severe spring drought, summer flooding, late autumn drought and salinization, the area devoted to wheat and maize should henceforth be reduced in favour of soybeans, sorghum and millet. Although wheat is a water-resistant crop sown in the autumn and harvested in the summer which can provide high and stable yields, it is grown over too extensive an area. This is bound to cause water shortages in the spring, intensifying the drought conditions and reducing yields. In addition, summer planting and field management are also affected by the labour shortage created by the three summer tasks of planting, harvesting and field management.
Maize, a summer crop, cannot withstand either drought or excess water. so its yields are unstable. On the other hand, soybeans are water resistant and can replenish the soil. Hence the summer crop area sown to soybeans should be suitably increased.
Sorghum is resistant to flooding and salinity and is an important fuel and construction material in the rural areas. Its sown area should be suitably expanded in low-lying areas in order to stabilize yields there and guarantee harvests. Millet not only serves to adjust grain varieties but also provides high-quality livestock feeds, so we must revive its development.
This is an important cotton area in China because of its favourable natural, historical and technical conditions. It is thus necessary to stabilize the growing area and to focus on raising cotton yields.
Green manure crops must be promoted to replenish the soil. The main cropping patterns for this in grain areas are the "one grain/one manure", where green manure (e.g., alfalfa, Chinese trumpet creeper, sesbania) is planted after the wheat harvest; "two grains/one manure", where maize is interplanted prior to the wheat and green manure is planted following the wheat; and "two grains/two manures", where autumn wheat is intercropped with Chinese trumpet creeper and corn is ploughed under the following year, while green manure is planted following the wheat harvest. In cotton areas, "intercropping of cotton and maize" and "one cotton/one manure" are adopted.
A survey carried out in the Eyapo Brigade, Yanggu County, Shandong Province, showed a 43 per cent average increase in the total nitrogen content of fields where green manure was planted for one to two years over that of fields without green manure. Total phosphorous increased by 15.9 per cent, with quickacting phosphorous up 81.6 per cent. Organic matter increased by 33.2 per cent. Wheat yields increased by an average of 0.94 t/ha, or 68 per cent.
(3) Consider problems of irrigation development and the proposed south north water transfer. There has been a great development of irrigation in the proposed water transfer region over the past thirty years, but water sources are still inadequate in some areas. This is because of great seasonal contradictions between when the rains come and when water is used in agriculture. In addition to the serious threat posed by spring drought, industrial-municipal water use has increased continuously. The problem of water sources has become particularly pronounced in Tianjin Municipality and Hebei Province.
The latest field research and data analysis show that there are two main
avenues to solving the present problem of water sources. The first is to improve
secondary and on-farm development and to raise the rate of water utilization as
much as possible. Investigations indicate water utilization rates of 72.5 per
cent in well irrigation districts, 32.5 per cent in medium-sized canal
irrigation districts and only 23 per cent in large-scale canal irrigation
districts. This demonstrates a great potential for further increases in the rate
Secondly, we should develop and utilize the groundwater by stressing the development of well irrigation. At the same time we can block and store river water in the rainy season for use in the dry season.
Our position on the matter of south-north water transfer is that at present we should focus on carrying out further research and explore some of the major questions related to the proposed transfer. Firstly, we must make a thorough investigation of the existing water sources within the region so as to determine how much water is actually there and how large is the deficit. Secondly, we should do research on the distribution of saline and alkaline soils and the laws governing their development and change in order to investigate the possible trends of soil salinization subsequent to a south-north water transfer. Thirdly, we should improve our overall analysis to prove the possibility and rationality of south-north water transfer from the natural, economic, technical and environmental aspects. In sum, in developing irrigation in this region we should first of all make full use of the available water resources and at the same time continue to develop investigations, studies and planning of south-north water transfer in order to solve rationally future problems of water sources and to open up new paths which promote industrial and agricultural production.
Editing Group, National Comprehensive Agricultural Regionalization, 1980, National Commission of Agricultural Resources Survey and Agricultural Regionalization, Report on national comprehensive agricultural regionalization, Agricultural Press.
Institute of Geography, Chinese Academy of Sciences, 1980, Agricultural Geography of China, Science Press, Beijing.