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CHAPTER 9. RICE-BASED CROPPING SYSTEMS AND THEIR DEVELOPMENT IN CHINA

CHAPTER 9. RICE-BASED CROPPING SYSTEMS AND THEIR DEVELOPMENT IN CHINA

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340



GUO YI XIAN AND FEI HUAI LIN



I. INTRODUCTION

The history of rice cultivation in China, according to records found in

ancient literatures and relics, can be traced back to as early as 5000 B.c., and

during the twelfth century B.C. it was already generally practiced in the

Yellow River Valley. Evidently China has one of the oldest histories of rice

culture in the world. Rice is now grown throughout the country. China's vast

rice cropping area extends from the south end of Hai-nan Island (18" 9")to

the northern part of Hei-long-jiang Providence (more than 50"N)and from

tide-flooded lowland fields along the eastern shore to the lake fields and

polder fields in Central China and the terrace fields in the southwest. Rice is

cultivated even on the Yun-Guei Plateau, about 2600 m above sea level. As a

result, varied cropping systems have been developed throughout the country.

The national land area of paddy fields in 1983 was 22.2 million ha, and the

cropping area of rice amounted to 33.3 million ha. Rice occupies more than

20% of the total area of grain crops and contributes more than 40% of the

total grain production.



II. ENVIRONMENTAL FACTORS

Rice is grown in the tropic, subtropic, temperate, and subtemperate zones

in China, and on plains, basins, hilly regions, and plateaus. Consequently, the

environmental factors affecting rice-based cropping systems are very complex. Temperature, rainfall, day length, soil, and population are the major

factors influencing crop production.



A. TEMPERATURE

Temperature is the most important environmental factor which affects

rice-based cropping systems in China. The mean temperature in January

averages 24°C in southern Hai-nan Island and - 30°C in northern Hei-longjiang Province. Because of the influence of the sea and continent, the

differences in mean temperatures in July are not so great between the north

and the south. The highest July temperature occurs in the Sichuan Basin and

averages 30°C; the lowest one occurs in the northern part of Hei-long-jiang

Province and averages about 20°C. Thus, there is a 10°C difference.

Due to the large variations in temperature, the length of the growing

period for rice varies considerably from region to region. The period is

shortest (less than 110 days) in Hei-long-jiang Province and longest (290 days



RICE-BASED CROPPING SYSTEMS



341



FIG.1. Growing period of rice in different areas of China.



or more) in Guangdong Province (Fig. 1). The rice-growing period increases

from north to south and from west to east with close relation to the latitude

and altitude. But in the eastern coastal regions, which are affected by the

ocean climate, the period for rice is shorter than that in the inland regions at

the same latitude.

B. PRECIPITATION



The annual precipitation in China is irregularly distributed. Generally, it

diminishes from the southeast to the northwest and from the areas along the

coast to the inland regions (Fig. 2). Along the western slope of the Da-Xingan-ling Mountains and running southward, the isohyet of 500 mm annual

precipitation passes through the upper reaches of the Liaohe River and the

fringes of the Yanshan and Tai-hang-shan Mountains to the north slope of

the Chin-ling Mountains. Areas west of this isohyet have an annual precipitation of less than 500 mm. The isohyet drawn through the Huaihe River in the

east and through Chin-Ling Mountains in the west represents an annual

precipitation of 750 mm, while that along the Yangtze River represents an

annual precipitation of 1000mm. The annual precipitation in areas south of

the Yangtze River is more than 1000 mm.

Under the influence of the monsoons, the annual precipitation is highest in

summer and lowest in winter in all localities. The rainfall concentration in

summer is more apparent in higher latitudes. In Beijing in North China, the

summer rainfall is 75.1 % of the annual precipitation, while the winter rainfall



342



GUO YI XIAN AND FEI HUAI LIN



FIG.2. Distribution of annual precipitation in different areas of China.



is only 1.7%; in Guangdong Province, South China, the summer rainfall is

46.5%of the annual precipitation, while that in winter is 9.0% (Fig. 3). The

characteristic of more rainfall and higher temperatures occurring in the same

period is very favorable for agricultural production.

C. DAYLENGTH

Differences in latitudes and growing seasons cause the differences in day

length under which rice is grown. In Heihe County (50'13") of Hei-longjiang Province, the day length during the whole growing period (MaySeptember) for rice is longer than 14 h. In Beijing Municipality (39"48'N),the

day length during the major growing period for rice is more than 14 h. In

Shaoxing County (30"N) of Zhejiang Province, the day length is more than

14 h only in the period of mid-June to early July. In Hai-kou County

(20"02'N), Hai-nan Island, the day length during the whole growing period

for rice is less than 13.5 h (Fig. 4). Moreover, the trend in day length as it



RICE-BASED CROPPING SYSTEMS



343



Rainfall

(rnrn) (days)



2801 I41



t



L



n



I\



FIG.3. Distribution of seasonal rainfall in Beijing and Guangzhou, China.



increases or decreases during the growing season differs from location to

location. Differences in day length and whether the day length is decreasing

or increasing generate different responses to photoperiodism of rice varieties

in the different cropping systems.

D. SOIL



Because of the wide variation in climate, soil-forming materials, and

cropping systems, paddy soils in China range from heavy clays to sandy soils,

with pH values from lower than 6 to higher than 9. Paddy soils in the plains

of Central and South China formed from alluvial and sedimentary materials

of rivers and lakes are deeply layered, rich in mineral and organic matters,

and comparatively fertile.

The paddy soil in the hilly regions has developed from red loams, yellow

earths, and yellow-brown earths. They are generally acidic, contain comparatively little organic matter, and are lacking in mineral nutrients such as



GUO YI XIAN AND FEI HUAI LIN



344



Heihe



16



15



14



-c

5



- 12

2

0

If



11



I



I



3



4



5



I



6



,



I



7



8



9



\,

10



Month



FIG.4. Day length during rice-growing season in different places from south to north in

China.



calcium, magnesium, phosphorus, and potassium. But the “purple mud” soils

developed from purplish-brown loams have good moisture and fertilitypreserving capacities and are rich in mineral nutrients. They are the highyielding paddy soils in the hilly areas of Sichuan and Gueizhou Provinces.

There are some low-yielding paddy soils such as those called “rust water,”

“cold soaked,” “mashed mud,” and “duck-dropping mud.” The common

defects of these soils are poor drainage, heaviness and poor texture, and

strong reduction. The rust-water field soils contain toxic levels of ferrous

salts.

Paddy soils in the northern parts of China developed mostly from chestnut,

meadow, marshy, and saline-alkali soils. Most are found in the depressions.

Their pH values are usually higher than 8. They are rich in mineral nutrients

but their organic matter contents are rather low (0.5-1.0%),except for the

meadow soils.



E. POPULATION

AND CROPPING

SYSTEMS

Only about 100 million ha of China’s total land area of 960 million ha is

cultivated. With an 800 million rural population, the per capita arable land



RICE-BASED CROPPING SYSTEMS



345



averages less than 0.13 ha. Moreover, because of the concentration of

population in provinces along the southeastern coast, the per capita arable

land averages less than 0.07 ha in some areas in Jiangsu, Zhejiang, Fujian,

and Guangdong Provinces. Limited arable land and dense populations

generated the age-old traditional multiple-cropping systems in China. And,

the population density plays an important role in determining the rice-based

cropping systems in different parts of the country.



111. DIVISION OF RICE BELTS

Referring to natural conditions and specialities of rice production in

different localities, the late Director of the Chinese Academy of Agricultural

Sciences, Professor Dying-Ying (1957), divided the rice-cropping areas of

China into six belts (Fig. 5). Although 27 years have passed and the ricebased cropping systems have been greatly changed, this division of rice belts

still holds with only minor revisions.



FIG.5. Sketch of rice-cropping regions in China.



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GUO YI XIAN AND FEI HUAI LIN



A. SOUTHCHINADOUBLE-CROPPING

RICEBELT

The South China double-cropping rice belt consists of areas south of the

Nanling Mountains, including Taiwan, Fujian, and Guangdong Provinces

and the Guangxi Autonomous Region. This belt has the highest annual

accumulated temperature and the longest crop-growing period in China. The

total cropping area of rice is about 27% of the national rice areas (Taiwan

excluded).

The mean temperature, except in the moutainous areas in the northern

parts, is about 10°C which allows thermophilic plants to overwinter safely.

The annual accumulated “active” temperature (diurnal average temperature

higher than l 0 T ) amounted to 6000-9000°C. During the growing period of

rice (March-September), the average temperature is about 22-26“C, the

relative humidity is 80%, and the annual precipitation is 1500-2000 mm. In

most areas of this belt, the growing period of rice is longer than 290 days a

year. The cropping systems are chiefly double cropping of rice. And, in

localities where the water resources are scarce, upland crops such as sweet

potatos, peanuts, and soybeans are grown in combination with rice to make

up double-crossing systems. In the districts of Hai-nan Island and Zhan-jiang

of Guangdong, there is also a limited area of triple cropping of rice (Fig. 6).

The soils of most of the paddy fields in this belt have developed from alluvial,

lateritic, and yellow soil material after long periods of cultivation. Generally

they have an acid reaction, but there are also saline-alkali soil in the Pearl

River Delta and in the coastal areas.

B. CENTRAL CHINA SINGLE-



AND



DOUBLE-CROPPING

RICEBELT



The Central China single- and double-cropping rice belt consists of areas

north of the Nanling Mountains and south of Huaihe River and the Chinling

Mountains. Included are provinces along the Yangtze River, the Han-zhong

Basin of Shanxi Province, and the Xin-yang Prefecture of Henan Province.

The rice-cropping area of this belt, China’s most important rice belt, accounts

for more than 63% of the national area.

The mean temperature in January is 2-8°C; that in July is about 26-30°C.

During the rice-growing period (late March to October), the average

temperature is about 22-26°C and the annual accumulated “active” temperature is 4500-6000°C and higher. The relative humidity is about 80% and the

annual precipitation is generally more than 1000 mm. There is more rainfall

on the upper reaches of the Yangtze River in autumn and more on the lower

reaches in spring. The intermittent drizzles during late spring and early

summer, characteristic of the rainfall in this belt, are very favorable for rice

production.



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