Resource management, soil fertility and sustainable

crop production: Experiences of China

H.S. Yang *

Department of Agronomy and Horticulture, University of Nebraska, Lincoln,

P.O. Box 830915, Lincoln, NE 68583-0915, USA

Available online 16 May 2006

Abstract

China is unique for its long history of permanent arable farming, large population, low per capita natural resources, and at the same time,

having largely achieved food self-sufficiency. Some of the experiences of Chinese farming may provide clues or alternatives to other resource-

poor countries in their strive for optimizing utilization of natural resources, improving soil fertility, and increasing food production. China’s

experiences are summarized into five attributes: (1) farmer’s strong awareness of the importance of organic manuring in soil fertility and

productivity, (2) exploration of all possible organic resources for recycling, (3) maximization of resource use efficiency, (4) crop rotation and

cropping intensification, and (5) irrigation and use of chemical fertilizers. Chinese farmers regard almost all forms of organic wastes as

‘organic treasures’, and recycle them into organic fertilizers through animal digestion and/or composting. Biogas generation using organic

wastes is explored as an extra step in this process. Recycling of organic wastes through animals and biogas generation utilizes effectively the

part of organic carbon that can be converted directly to food and useful energy, which would otherwise be quickly lost in the early phase of

decomposition in soil or compost. Crop rotation with legumes helps restore and balance soil nutrient supply. Multiple cropping is effective in

boosting crop production from limited arable land. Cropping intensification, however, requires external nutrient inputs from chemical

fertilizers, and in many places, also irrigation. Government support proved critical in the development of agricultural infrastructure as well as

in overall crop production.

# 2006 Elsevier B.V. All rights reserved.

Keywords: China; Manuring; Resource management; Soil fertility; Sustainable crop production

www.elsevier.com/locate/agee

Agriculture, Ecosystems and Environment 116 (2006) 27–33

1. Introduction

Maintaining soil fertility is vital for sustainable soil

productivity, especially in resource-poor countries. While

food shortage and malnutrition are still seen in many parts of

the world (FAO, 2003a), tackling the problem requires not

only short-term remedies, but also long-term solutions that

are ecologically sound and compatible with local natural and

socio-economic configurations (Rosegrant et al., 2001).

China is unique for its long history of permanent arable

farming, large population, low per capita natural resources,

and at the same time, is an example of having largely

achieved food self-sufficiency (FAO, 2000).

* Tel.: +1 402 472 1566; fax: +1 402 472 7904.

E-mail address: hyang2@unl.ed.

0167-8809/$ – see front matter # 2006 Elsevier B.V. All rights reserved.

doi:10.1016/j.agee.2006.03.017

China’s permanent arable farming of cereal crops began

at least 3000 years ago along the middle and lower reaches of

the Yangtze River and Yellow River (King, 1911; Xu and

Peel, 1991; Li, 2001). The land has been cultivated

continuously for centuries in some places (Li and Sun,

1990; Ellis and Wang, 1997). Cereal crops, including rice

(Oryza sativa L.), wheat (Triticum aestivum L.), maize (Zea

mays L.), sorghum (Sorghum bicolor L.) and millet

(Pennisetum glaucum L.), have traditionally been the major

foodstuff for Chinese. On the other hand, the long history of

arable farming and ever increasing population have resulted

in depletion of arable land reserve (Li and Sun, 1990). While

the population has more than doubled since the 1950s to its

current 1.3 billion, the total arable land has expanded only

29% to the current 136 million ha (FAO, 2002). In a global

perspective, China’s population accounts for 21% of the

H.S. Yang / Agriculture, Ecosystems and Environment 116 (2006) 27–3328

Table 1

China’s population, arable land area (including permanent crop land) and per capita share in 1961 and 2000 in comparison with the developing countries

(excluding China) and the world

1961 2000

Population

(million)

Arable land

(million ha)

Arable land

per capita (ha)

Population

(million)

Arable land

(million ha)

Arable land per

capita (ha)

China 669 105 0.16 1275 136 0.11

Developing countries 1427 571 0.40 3467 721 0.21

World 3079 1347 0.44 6057 1497 0.25

Source: FAO (2002).

world, while its share of arable land is only 9%. At present,

China’s per capita arable land is 0.1 ha, which is 45% of the

world average and half of the rest of the developing

countries (Table 1).

Despite of the limited land resources, cereal production in

China has seen markedly growth in the last four decades

(FAO, 2000). Annual cereal production raised from around

110 million Mg in early 1960s to an average of 421 million

Mg during the 1990s. The growth is attributed mainly to the

near four-fold increase in crop yields per land area (Fig. 1).

Fig. 1. Yield of cereal crops (A), per capita cereal production (B) and per

capita calorie supply (C) of China in comparison with the developing

countries (excluding China) and the world in the last four decades. Data

source: FAO (2002).

Per capita calorie supply, an important index of basic living

standard, has increased to over 3000 kcal per day, almost

doubled in four decades even with the double increase in

population.

The objective of this paper is to review some of the

agricultural experiences in China that have contributed

greatly to the significant improvement in China’s food

security. The experiences can be summarized into five

attributes: (1) farmer’s strong awareness of the importance

of organic manuring in soil fertility and productivity, (2)

exploration of all possible organic resources for recycling,

(3) maximization of resource use efficiency, (4) crop rotation

and cropping intensification, and (5) irrigation and use of

chemical fertilizers. The experiences may provide clues or

alternatives to other resource-poor countries in their strive

for optimizing utilization of natural resources, improving

soil fertility and food security.

2. China’s experiences

2.1. Manuring as a tradition of farming

Traditional Chinese farming emphasizes organic manur-

ing, which is understood by modern soil science to be

essential for maintaining soil organic matter, soil fertility

and productivity. One of the Chinese farming proverbs says

‘Farming is a joke without manuring’. Many ancient Chinese

articles have the mention of applying human and animal

excreta to the field. For example, Han Feizi (280–233 B.C.)

wrote in ‘Lao Jie’ that human excreta must be applied in

order to restore and improve soil ‘strength’ (a Chinese term

for soil fertility). Throughout the farming history, farmers

are taught from one generation to another that manures are

both the food for crops and the remedies for soil problems

(Yu et al., 1980). Farmers also regard organic manuring as a

short-term investment (i.e., for the current crops) as well as a

long-term investment (i.e., for soil fertility). Before the era

of chemical fertilizers, farmers relied solely on organic

manuring to maintain soil fertility and to support permanent

arable farming (Li and Sun, 1990; Ellis and Wang, 1997).

Farmers usually apply manures in the beginning of a

growing season prior to plowing. They also know the

importance of placing manures close to crop stands. For

instance, when manures are insufficient for the whole field,

H.S. Yang / Agriculture, Ecosystems and Environment 116 (2006) 27–33 29

Fig. 2. Application rates of organic and chemical fertilizers in China since

the 1950s. The rates are based on N for nitrogen, P2O5 for phosphorous, and

K2O for potassium. Data source: IIASA (2002).

farmers usually place manures directly into planting rows or

pits. In addition, farmers have traditionally used manuring as

an effective means to improve soil workability, tilth and

water holding capacity (Li and Sun, 1990). Organic

manuring is probably the key practice that has supported

permanent arable farming in China for centuries (Chen,

1990). Use of manures remained an important farming

practice even after chemical fertilizers became widely

available (Fig. 2). However, the proportion of manures in

overall nutrient supply has declined significantly in recent

years, as a results of increase in use of chemical fertilizers

(Gao et al., 2000) and the decline in use of manures. For

instance, He and Xie (2000) report decline in use of manure

in many areas in Guangxi (southwest) in the last decade,

while Chen and Liu (2003) report similar observations in

Liaoning (Northeast).

2.2. Exploration of resources for manuring

Unlike chemical fertilizers which have definitive forms

and composition, manures can virtually be any organic

wastes that contain crop nutrients and are decomposable. In

the eyes of Chinese farmers, organic wastes are ‘organic

treasures’ that have the magic to turn their hard work into a

good harvest. The way Chinese farmers value organic wastes

is described as ‘religious’ by early western visitors to China

(Sanders, 2000). Exploring resources for manuring is more

like a treasure hunting. Collecting animal and human wastes

and composting them are an important part of farm work. In

rural areas, almost all household wastes, human and animal

wastes are eventually collected and recycled to the field (Yu

et al., 1980). In urban areas, most of the human and

household wastes are collected by farmers in surrounding

rural areas. In recent years, however, the practice of

recycling household wastes for field use, especially from

urban areas, has become unpopular, due partly to the

growing presence of indecomposable solid materials

(mainly plastic and glass) in the wastes and increasing

labor costs.

Periodical clearing of shallow water bodies, such as

ponds, lakes or seasonal rivers, not only helps in flood

control and improve irrigation, the mud is also an excellent

soil amendment and fertilizer (Li, 2001). In northern

China where winter is a long off-season, organized

clearing of seasonal rivers and cannels used to be common

during the commune era (from late 1950s to early 1980s),

and the mud benefited greatly nearby farmland. Mud

from fishing ponds is especially seen as one of the best

organic fertilizers.

Domestic animals, including pig, cattle, poultries and

even fish, have long played a big role in turning organic

materials to precious fertilizers while producing useful

products including farm power. Through the animals, a wide

range of plant materials, including crop residues, weeds and

grasses from non-farm land, are recycled eventually as

fertilizers into farmland. This is an important source of

external nutrient inputs to farmland (Li et al., 1988).

2.3. Maximization of resource utilization

Maximum utilization of available resources is vital for

farming systems that do not have significant external

material and energy inputs. The hardship of making a living

has taught Chinese farmers that every piece of natural

resources must be utilized with high efficiency. To achieve

that, the usable energy and nutrients in the primary resources

(i.e., plant materials) must be converted as much as possible

into useful products as food, fuel and working power before

those materials arrive in the field as fertilizers. For instance,

farmers typically keep two or three kinds of animals in their

households: cattle or horse for consuming cellulose-rice

materials such as crop residues, and poultries for tender

weeds and waste food. Pig and fish are typically fed on

almost everything, including waste food, weeds, and even

wastes from other animals.

Energy shortage in rural areas of China has been one of

the key factors that hinder rural development (Deng, 1995).

The traditional reliance on crop residues for domestic fuel in

many rural areas has the drawback of competing with the

soil for nutrients as well as for organic matter. Since the

1970s, in particular during the 1980s and 1990s, biogas

generation from crop residues and organic wastes has

received widespread attention (Marchaim, 1992; Wang and

Gao, 2003). Li (2001) estimates that approximately five

million farm households in China had anaerobic digesters by

the late 1990s, with the majority in the south where the

climate is warmer and raw materials are abundant. Yang

(2001) reports that 9.5% of the rural households in Jiangxi

Province in southeast have anaerobic digesters. In the wave

of rapid development of intensive animal production and fast

pace of urbanization, biogas generation could become an

effective means to achieve integrated use of animal and

domestic wastes while easing the energy shortage and

improving sanitation in many rural areas (Zeng, 2000; Wang

and Ren, 2002).

H.S. Yang / Agriculture, Ecosystems and Environment 116 (2006) 27–3330

Fig. 3. Mineralization of typical green manure, cereal straw and farmyard

manure (FYM) in soil under field conditions. Data source: Janssen (1992).

Fig. 4. Multiple cropping index in China as of 1993. Data source: FAO

(2002).

Biogas generation makes efficient use of the energy in the

raw materials while preserving most nutrients that are usable

to crops. It also greatly improves energy use efficiency as

much as six fold compared with direct burning (The United

Nations University, 1979). In contrast, when plant materials

are retuned directly to the soil, 60–80% of the carbon is lost

in the first year along with the energy they carry in the

process of decomposition (Fig. 3). In farming systems where

natural resources are limited, such an integrated exploration

of energy and nutrients is more attractive and sustainable

than direct return of crop resides. Implementing such a

scheme, however, requires extra labor as well as knowledge

and skills. In addition, extension education and govern-

mental support often play a critical role in making it viable

(Deng, 1995; Zhang, 2000).

2.4. Cropping intensification and crop rotation

The limited land resources for arable farming is one of the

struggles China has faced for centuries (Zhao, 1989).

Farmers’ solution to this problem is to grow more than one

crop in the same field each year, known as multiple

cropping. Depending on local conditions, including climate

and irrigation, either relay (or inlaid) cropping or sequential

(or successive) cropping is practiced (Liu and Mu, 1988). In

a relay cropping system, a second crop is planted before

harvesting the first crop; in a sequential cropping system, a

second crop is planted immediately after harvesting the first

crop. Two sequential crops a year is the dominant form in the

last two decades (Fig. 4), especially in the south where

winter is short and mild (Liu and Mu, 1988). Maize followed

by winter wheat dominates in the north, whereas two crops

of rice or rice followed by an upland crop is more common in

the south. Three crops a year is currently practiced on one

fifth of China’s arable land along the coast in southeast and

south, where winter is very mild and rainfall is abundant.

Nationwide the average multiple cropping index is around

156% (Fig. 4).

Crop rotation is another measure farmers have long used

to sustain and improve soil fertility and productivity.

Rotation of cereals with legumes such as soybean or mung

bean used to be a common practice before chemical

fertilizers were widely available (Liu and Mu, 1988). Crop

rotation has several positive effects, including controlling

diseases, insects and pests, balancing nutrients, improving

soil physical properties, and restoring and improving overall

soil fertility (Xing et al., 1991; Torbert et al., 1996; Zhu

et al., 2000; Huang et al., 2003). Rotation with legumes also

provides diverse foodstuff for farmers and increases farm

income due to higher market values of the beans.

2.5. Use of chemical fertilizers and irrigation, and

support from pro-farming industries

In any ecosystems, the primary productivity is ultimately

limited by the resources that are available, including water,

nutrients and time (i.e., the length of growing season). Not

only must those needs be met, but also at times they are

needed. The later is particularly true for water. As monsoon

climate dominates in most part of China, the annual rainfall

typically concentrates in summer’s 3–4 months, while

severe spring drought is common, especially in the north.

Meanwhile, the long-time high cropping intensity has put a

great pressure on soil fertility and nutrient supply. Organic

matter content in top soil (0 to 15–20 cm) of arable fields is

typically around 10 g kg�1 in the north where upland crops

dominate, and 15–25 g kg�1 in the south where rice is the

major crop (Li and Sun, 1990; Yang and Janssen, 1997; Zhou

et al., 2003). Such a level of basic soil fertility is regarded

inadequate to sustain crop production at high intensity and to

meet China’s increasing demand for crop production (Gao

et al., 2000; Wang et al., 2002).

As a result, irrigation has been an important part of

farming in many parts of China, not only in the north but in

the south as well. Some large irrigation systems, including

reservoirs and cannels, were built centuries ago and are still

in operation (FAO, 2003b). For example, the renowned

Dujiangyan irrigation system in southeast was built around

256–151 B.C. and is still serving more than half million

hectares of farmland. During early 1960s to early 1980s,

agricultural investment to irrigation infrastructure was one

H.S. Yang / Agriculture, Ecosystems and Environment 116 (2006) 27–33 31

Fig. 5. Proportion of irrigated area in total cropland in China in comparison

with the developing countries (excluding China) and the world. Data source:

FAO (2002).

Fig. 6. Rate of chemical fertilizer use in arable land (including permanent

crop land) in China in comparison with the rest of developing countries,

Europe, North America and the world. The rates are based on N for nitrogen,

P2O5 for phosphorous, and K2O for potassium. Data source: FAO (2002).

of the priorities in government policy (Fig. 5). During the

1990s, however, the investment declined significantly, due

largely to the change from commune system to household

management and other policy changes in agriculture. To a

certain extent, the vast national investment in irrigation

during the 1960s to early 1980s built a solid foundation for

boosting China’s crop production in the last two decades,

and contributed enormously to the success of China’s

agriculture (Hu, 1997; Zhu, 2004).

Chemical fertilizers, especially of nitrogen (N), are seen by

farmers as a modern miracle for boosting crop growth, and

were quickly adopted in the 1960s and 1970s. But production

and supply had been a bottleneck until mid 1980s (Institute of

Sci-Tech Information, 1992; Mao, 2000). In the 1960s, the

government adopted the strategy of manufacturing in small

scales at local levels with simple technologies. As a result,

more than 1200 small fertilizer plants were put into operation

by early 1980s, producing 30 million Mg of NH4HCO3

(or approximately 5 million Mg of N). In late 1970s, the

government imported 13 fertilizer production plants from US,

Japan and Europe with a total annual production capacity of

0.6 million Mg of urea (Xu and Peel, 1991). By late 1990s,

China produced annually 28.7 million Mg (effective nutri-

ents) of chemical fertilizers with 76% as N fertilizers (Mao,

2000). With such an increase in production, use of chemical

fertilizers in crops has seen steep increase, reaching a national

average of 260 kg ha�1 year�1 in late 1990s (Fig. 6). Use of

chemical fertilizers is one of the most important modern

technologies that have helped boost China’s crop production.

It compensates nutrient removals and losses, as well as helps

maintain soil fertility by increasing crop yields and thus

crop residues left in the fields (mainly root stubbles and

belowground biomass) (Yang and Janssen, 1997).

3. The test of sustainability

The unprecedented scale and intensity of modern arable

farming in China mean extensive external inputs of energy

and materials. This has generated some severe adverse

impacts on the environment, people’s health, and overall

social-economic development (Wen et al., 1992; Rozella

et al., 1997; Zhu and Chen, 2002; Tong et al., 2003). Those

impacts, along with the transitional nature of China’s social,

political and economic systems in the last two decades, have

sparked heated debate about sustainability of China’s

agriculture and even the health of China’ overall economic

development (Wen and Pimentel, 1992; Cai and Smit, 1994;

Brown, 1995; Alexandratos, 1997; Ellis and Wang, 1997;

Paarlberg, 1997; Rozelle and Rosegrant, 1997). Two issues

that are direct results of arable farming and occur in a large

scale, are discussed below. They serve as a reminder to other

resource-poor developing countries for more comprehensive

and balanced strategies when striving for food security and

improvement in quality of life.

The first issue is the sever soil and water erosion in the

Loess Plateau and many mountainous areas in southern

China. This is largely the consequence of over-expansion

of arable land into marginal land and grassland, as well as

deforestation (Huang, 2000; Cheng, 2001). This has

caused a large scale of environmental damage to water

bodies, air and overall ecosystems (Smil and Mao, 1998;

Wang, 2004). Solving this problem may require funda-

mental measures, including regional agricultural restruc-

turing (Zhang, 2001; Yang et al., 2003; Jiang, 2004), and

restoration of the erosion-prone arable land to grassland or

forest (Cheng, 2001; Xu et al., 2003). Other measures

include adoption of technologies that conserve soil and

water, e.g., organic manuring to improve soil physical

properties, fallow crops to cover soil surface, terracing and

no-till (Wen et al., 1992; Lal, 2000; Wu et al., 2004; Feng

et al., 2005).

The second pressing issue is the excessive accumulation

of NO3-N in soil profile below rooting depth and its pollution

to groundwater and surface water. This is due largely to

unbalanced and excessive use of N fertilizers (Zhang et al.,

1996; Zhu and Chen, 2002; Cassman et al., 2003; Gu et al.,

2003; Zhang et al., 2004a,b). Chen et al. (2004) report that

H.S. Yang / Agriculture, Ecosystems and Environment 116 (2006) 27–3332

many fields for cash crops received N rates as much as five

times the crops require, and Zhang et al. (1996) report N

rates of 500 to 1900 kg ha�1 year�1 in many places. This

concurs while organic manuring becomes less popular (Hu,

1997; Gao et al., 2000; Cao et al., 2002; Chen et al., 2003).

Soil organic matter content has seen declining in many

places and N use efficiency is typically below 40%. In

addition, potassium deficiency in arable land has become

common across the country (Gao et al., 2000; Sheldrick

et al., 2003; Chen et al., 2004; Dobermann et al., 2004).

There is an urgent need for extension education on rational

use of N fertilizers and the detrimental impacts of N loss on

the environment and human health (Gao et al., 2001), as well

as the indispensable role of organic manuring in improving

nutrient balance and overall nutrient use efficiency. At the

same time, practices of ecological agriculture should be

promoted for integrated resource utilization and sustainable

crop production (Wen and Pimentel, 1992; Liu, 2001; Huang

et al., 2002).

4. Conclusion

Traditional Chinese farming emphasizes integrated and

efficient utilization of natural resources based on local

conditions. The five attributes described above have made a

large contribution to China’s success in achieving food

security to one fifth of the world population using less than

one tenth of the global cropland resources. Other factors that

have contributed to the success include improvement of

transportation infrastructure, agricultural research and

extension, and overall socio-economic reform and devel-

opment (FAO, 2000). On the other hand, the success China

has achieved in food production also is facing a stringent test

of sustainability.

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