Changing Grain Production in China: Perspective on Changing Grain Acreage

JIN Tao, FANG Zhou Agriculture College of Yangzhou University

Yangzhou ，China

Abstract—The consecutive growth in China’s grain output over the past decade has partly depended on the expansion in grain sown area. The paper examines spatiotemporal patterns of China’s grain sown area by using a complete decomposition approach. The results show that changing grain sown area during 1978-2012 is the product of augmenting multiple cropping index (MCI), shrinking share of grain crops and loss of cultivated land on the whole. Owing much to augmenting MCI, grain acreage has expanded mainly in the high latitude areas since the mid-1990s, while it has shrunk in the eastern and central parts of China. A shift in growing grain crops from south to north can thus be discerned, affecting China’s grain production pattern. Pattern change in grain sown area, associated with declining cultivated land and regional variability in changing MCI, is then discussed for the sake of China’s grain supply security.

Keywords—grain production; grain sown area; spatiotemporal pattern; decomposition analysis; China

I. INTRODUCTION Changes in grain production can either originate from

changes in grain sown area or from changes in grain production level per unit area (grain yield) [1]. Advancing grain yield has long been a major mission for grain supply security in China due to the scarcity of cultivated area compared to its large population. Besides much discussion on the fluctuating grain yields [2，3] , China’s land use change and its impact on grain production have been extensively explored in the literature [1，4-6]. Land changes may relate to grain sown area but can not fully represent its change. Grain sown area, as one component of grain production, has seldom been specifically investigated in the light of its impact on grain security. In several China’s case studies [7-9], the connection between grain sown area and grain output has been examined and the parameters for changes in grain sown area have also been traced, yet these links may not be clearly identified due to the lack of a proper measurement. In this study, we employ a complete decomposition approach to evaluate the effect on grain production by changing grain sown area, and then to quantify the factors for changing grain sown area temporally and spatially, in an attempt to give some implications for enhancing China’s grain security from a perspective of grain sown area.

II. METHOD AND DATA

A. Decomposition approach Changes in grain production can be divided into changes in

grain sown area and changes in grain yield (i.e. grain production per unit sown area). Changes in grain sown area can be subdivided into three components: cultivated land area, multi-cropping index (MCI), grain cropping share, which is derived from the following equation: Grain sown area=cultivated land area × (total sown area/cultivated land area) × (Grain sown area/total sown area).

A decomposition approach is then raised to quantify the contributions from changes in these factors on the equation’s right side to changes in output on the equation’s left side. For a certain observed subject A, assume A can be decomposed into k factors, and kxxxA 21= , then, the change from time 0=t to t for the subject A can be estimated by the summation of the factors’ effects.

We have ,, 21

002

010

tk

tttk xxxAxxxA ==

We then have

)ln()ln()ln()ln( 002

201

1

0 k

tk

ttt

xx

xx

xx

AA

+++=

)ln()ln()ln()ln()ln()ln(10

00

02

2

001

1

AA

xx

AA

xx

AA

xx t

k

tkt

tt

t

+++=

Where the term )ln()ln(0

0 AA

xx t

k

tk equals weight value of

factor k(Wk). Hence, the decomposed effect of the factor k is given by

)ln()ln()(0

00 AA

xx

AAAwx t

k

tk

tkeffectk −=Δ=−

Decomposition can thus be conducted with China’s case for changing grain production or changing grain sown area temporally or spatially.

B. Data Annual data for grain production, grain sown area, total sown area at the national and provincial levels for the period 1978-2008 are from the statistical data of New China Agriculture for 1949-2008 (Ministry of Agriculture of the People’s Republic of China 2009) and Annual Report on China’s Agricultural Statistics (2009-2012).

The data series of China’s cultivated land need to be collated according to the most recent report from the second

This research was funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.

National Land Resource Survey finished in 2009, in which 135.385 million hectares (Mha) of the country was identified as arable, yet 9.963 Mha of them were either in converted forest and grassland in the north, or in ecologically fragile flood zone, or high in the mountains in the southeast. Deducting such land area planned for land set-aside programs from the overall arable figure, we estimate the available land for cultivation. Based on the previous underreporting statistics and the latest figures, by offsetting the discrepancy in between, we reconstructed the annual data of cultivated land for the period 1996-2009, and then for 1980-1996 based on revised results from previous study [10]. The land area in the early 1980s measured in such way is around 137Mha, approximate to 137.82Mha assumed by Institute of Remote Sensing Application Chinese Academy of Science[10].

For the provincial-scale analysis of changes, the data are used with 3 years of data (around the study year) averaged in order to remove the year-to-year volatility. We take the year of 1996 and 2010 for decomposition analysis for grain production, whereas the year 1996 and 2008 for decomposing grain sown area due to the lack of updated provincial cultivated land area. Included are 30 provincial units which the Centrally Administered Municipality of Chongqing is integrated into Sichuan province as it did before 1997.

III. RESULTS

A. Dynamic Change in Grain Production and Grain Sown Area 1) Effect of changing grain sown area on grain production

change China’s actual grain production has increased from 305

million ton (Mt) in 1978 to 590 Mt in 2012. For the grain increment of 285 Mt over the period 1978-2012, 320 Mt was contributed by the increasing grain yield (9.4 Mt per annum), yet 35 Mt was lowered by the shrinkage of grain sown area (-1.03 Mt per annum). Inter-annual variation of grain production, as depicted by Figure 1, is kind of similar to that of grain yield, indicating the determinant of grain yield but held down by factor of grain sown area at intervals. However, increasing grain sown area from 2003 onwards has been an indispensable support for the recent successive growth of grain production (Figure 1).

2) Temporal change of grain sown area and of its limiting factors

Four major phases of fluctuating grain sown area in China can be identified since reforms began in 1978 (Figure 2): declining (1978-1985), fluctuating slightly (1985-1998),

-60

-40

-20

0

20

40

60

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

2010

2012

106t

Interannual change Acreage effect Yield effect

Fig. 1. Decomposition of the interannual variation in China’s grain production

0.9

1.0

1.1

1.2

1.3

1.4

1.5

197819801982198419861988199019921994199619982000200220042006200820102012

Area (108hm2)

020

406080100

120140

Share and MCI(%)

Grain sowing area Cultivated land area

Grain cropping share Multiple crop index

Fig. 2. Trends in three contributors for changing grain sown area in China,1978-2012

dropping (1998-2003), and rising steadily (2003-2012). Variation of grain sown area, by definition, derives from

3 factors, whose tendencies are relatively simple (Figure 2). Cultivated land area has been on the decline, especially significant at the turn of the century. The same trend applied to grain cropping share, which contracted continuously from 80.3% in 1978 to 68.1% in 2012, touching a historic bottom of 65.2 % at 2003, whereas MCI has been on the rise in the same period.

3) To quantify the factors of changing grain sown area by phases

As viewed from changing grain sown area phase by phase, a first sharp drop in grain sown area over 1978-1985 was driven by simultaneous declines in grain cropping share, cultivated land, and MCI. Subsequently, a slight rise in grain sown area during 1985-1998 totally owed to augmenting MCI, which potentially left much scope for planting structural adjustment and for non-agricultural sectors. Then another sharper reduction in grain sown area over the short period 1998-2003 was largely ascribed to the alteration of planting structure, which was more than double the effect of reduced cultivated land. In the recent phase, gradual recovery in grain sown area was mainly due to augmenting MCI, followed by the upswing share of grain crops, with the former generating nearly double effect than the latter (Figure 3).

In sum, the total decrement of 9.38 million hectares (Mha) of China’s grain sown area for the whole period 1978-2012, was given by shrinking share of grain crops (19.2 Mha) and reduced cultivated land area (11.0 Mha), and augmenting MCI (20.9 Mha) (Table 1). Thereby, the augmenting MCI is the most important factor to stabilize grain sown area from dropping, especially since the mid-1980s, while apparently shrinking grain cropping share is the major factor lowering grain sown area.

TABLE I. DEOMPOSITION RESULTS FOR CHANGES IN CHINA’S GRAIN SOWN AREA (104hm2)

Phase Total Change

Land Area Effect

Structure Effect

MCI Effect

1978-1985 -1174.2 -211.7 -668.6 -293.9

1985-1998 494.2 -147.6 -404.6 1046.4

1998-2003 -1437.7 -510.9 -1210.4 283.5

2003-2012 1179.5 -163.6 446.3 896.8

1978-2012 -938.2 -1103.6 -1922.5 2087.9

-300

-200

-100

0

100

200

1978-1985 1985-1998 1998-2003 2003-2012 1978-2012

Yea

rly

chan

ge (

×104hm2)

Yearly change of grain sown area Land area effectStructure effectMCI effect

Fig. 3. Factors analyses of yearly change of China’s grain sown area

B. Regional Variability in Changing Grain Sown Area Since the Mid-1990s 1) Relationship between provincial changes in grain

production and grain sown area Regional differences in grain production change from

1996-2010 are presented in Figure 4, showing a notable fall in most coastal eastern provinces whereas a rise in northern China. 12 out of the 30 provinces with decreased grain production have more adverse grain acreage effect than positive yield effect, indicating the decreased grain production was entirely caused by shrinkage of grain sown area. Moreover, a lower advance in grain yield can also be observed in coastal southern provinces. On the other hand, some northern provinces saw paired increases in grain sown area and grain output, especially in Heilongjiang and Jilin, with approximately 70% of grain increment generated by rising grain sown area.

A correlation analysis is then conducted with a sample of 30 provincial units. As expected, grain production change is positively correlated with the two effects, respectively, yet showing a higher correlation coefficient (0.868) with the acreage effect than with the yield effect (0.647). That indicates the provincial variance in grain production over the research period is more attributable to provincial variations in grain sown area.

2) Regional variability in changing grain sown area

Fig. 4. The contribution of acreage effect and yield effect to grain production change, 1996-2010

Fig. 5. Factors analyses of yearly change of China’s grain sown area

In contrast with previous results showing a nation-wide reduction in grain sown area over the years 1978-1992[7], spatial disparity occurred from 1996 to 2010 among 30 provincial units, 12 expansions while 18 shrinkages. Most northern regions have experienced huge and rapid expansion in grain sown area, with the most conspicuous case of Heilongjiang (3.69Mha, a 47.6% increase), followed by Inner Mongolia, Jilin, Xinjiang with a more than 20% increase. On the contrary, eastern coastal China and some central provinces have seen a downward trend over the period 1996-2010, most distinctly in Sichuan, Shandong and Zhejiang in terms of absolute decrement. In terms of decreasing ratio, in the front rank were Zhejiang (with the sharpest drop of 55.4%), Fujian and 3 municipalities: Beijing, Tianjin and Shanghai (all with a drop of more than 30%).

Pattern change in grain production can be differentiated by the balance of acreage effect (Ea) over yield effect (Ey). As shown in Figure 5, three types of region (I-1, I-2, I-3) can be identified among 18 provinces with increased grain production. 5 of them (I-1) with acreage effect over yield effect includes Heilongjiang, Jilin in northeast China, Yunnan, Guizhou in the southwest and Anhui, where rising grain sown area dominates the output growth. In the I-2 cases with yield effect higher than acreage effect, mostly in high latitude such as Liaolin, Inner Mongolia and Xinjiang, rising grain sown area comes to aid in promoting grain output. For the I-3 provinces such as Henan, Shandong and Shannxi with negative acreage effect, higher yield effect holds sole responsibility for increased grain output. On the other hand, the provinces with decreased grain production can be classified as D-1 and D-2 by the adverse degree of acreage effect. D-2 region with negative acreage effect twice yield effect, undoubtedly locates on the eastern coastal China, where dwindling grain acreage shapes the decline of grain output.

3) Sources of changing grain sown area across regions Varied features in three limiting factors for changing grain

sown area over the period 1996-2008 are illustrated in Figure 6 based on the decomposition results.

Fig. 6. Decomposition of grain sown area change, 1996-2008

First, regional disparity in changing MCI can obviously be discerned. Augmenting MCI in North China, along with Yunnan, Guizhou and Sichuan in the southwest, appears to be the largest contributor to rising grain sown area. On the contrary, whittling MCI contributes much to the cutback of grain sown area mainly in subtropical zones such as Zhejiang, Fujian and Jiangxi.

Second, declined cultivated area has occurred in the vast majority of provinces, particularly in the following two regions. One is the central regions across the upper and middle reaches of major rivers, like Sichuan, Shaanxi, which experienced the cropland conversion to natural land under the “Grain for Green” program since 1998. The other is at or neighboring the heart of China’s growth with most remarkable urban expansion, such as Guangdong, Jiangsu, Hebei.

Third, food-grain crops have been widely substituted for non-staple crops, mainly in eastern coastal China, and the middle reaches of Yangtze River like Hubei, Hunan, Sichuan, which used to be called the “rice-bowl” of China, but now are hot spots with densely populated and higher developed levels. In contrast, few cases in remote regions (Heilongjiang), or in neighboring areas of coastal China (Anhui and Jiangxi) have seen a rising share of grain crops.

In short, causes for rising grain sown area, either in northern China or in southwest China, are relatively simple—largely from augmenting MCI. Yet reduced grain sown area in eastern or central parts of China is generally the product of shrinking grain cropping share, accompanied by loss of farmland, or even by whittling MCI in some cases of South China.

IV. DISCUSSION

A. Impact of Declining Cultivated Land Area on Stable Grain Output Declining cultivated area does not appear to be the

foremost factor to lower grain sown area either at the national level or in most provinces, yet it is vital for food security to curb the encroachment of competing land uses on prime

agricultural land since the available land is the ultimate constraining variable for agricultural output. Decreased cultivated area in China from the mid-1990s onwards was mainly driven by two development events: conservation set-aside programs and widespread construction activities. The former may have favorable effect on grain productivity. With large, upland areas out of cultivation, agricultural production can be confined to remaining premium land that respond better to additional inputs[11], thus leading to compensating increase in grain yield. Of particular concern are the latter cases with high-quality cultivated land lost to urbanized development. With an increasingly scarce land resource, it frequently induces the marginal and lower-grade alternatives to be reclaimed in order to retain a minimum of 120 million hectares of arable land—the ‘red line’ for food security that the central government has pledged to protect. Grain productivity impairment as a consequence of high-productive land encroachment by urban uses and agricultural expansion on less-productive hinterlands, is considered as a major concern in food security and needs additional investigation.

B. Increasing Grain Output has Depended on Augmenting MCI in North China Augmenting MCI in inland China, especially in North

China, plays a key role in expanding grain sown area and then in driving up China’s grain output in recent years, and in this regard, it generates concerns about the stability of growing grain output. North China has experienced climate change into a relative warming phase with more precipitation and moderate temperature [12], allowing for possible shortening of the fallow cycle, land-augmenting inputs or introduction of higher adaptability varieties which can facilitate cropland expansion and intensive cultivation. However, even the fertile humus land in Northeast Plain, where huge agricultural expansion took place, is not able to sustain yields for prolonged periods without nutrient inputs or through sufficient fallow periods that allow for soil recuperation. Therefore, land degradation and exhaustion of soils, latent environmental risks induced by arable intensification, and uncertainty in climate change pose challenges for new grain cropping regions, where the sustainability of higher grain yielding and of land use systems needs to be assessed.

C. Grain Productivity Restoration by Retaining Grain Sown Area in South China South China is generally rich in climatic resources but

sparse in land reserves, while North China is just the reverse. Declined grain crops in the south consequentially increase grain imports from the north, suggesting resource product transportation from the north poor in water resource and productive land to the south abundant in rainfall and alluvial soil. Caution is needed for the abating MCI in the central subtropical zones which have widely experienced the shift to one rice cropping system from double rice cropping system [13], inferring the low efficiency of climate resource use. It deserves attention to retain grain crops in South China, which has greater potential to increase grain productivity at a lower cost both environmentally and economically.

V. CONCLUSION Changing grain production in China during 1978-2012 was

largely dominated by rising grain yield but slightly curtailed by shrinking grain sown area, yet its consecutive increase since 2003 was guaranteed by a decade of successive growth in grain sown area. Fluctuating grain sown area over the whole research period was largely attributed to the two contradicting effects by augmenting MCI and by contracting grain cropping share. The declined cultivated land area is not the primary factor to lower grain sown area and then to measurable loss of grain output, yet it remains to be crucial for the nation with vast population since the limited land reserves define the ability of China’s food self-sufficiency.

Spatial variance in provincial grain production from 1996 to 2010 is more correlated with difference in provincial grain sown area than with that in grain yield. Rising grain sown area occurred evidently in northern China and some southwest provinces, while most eastern coastal China and some central provinces have seen great cutback in grain sown area. The spatial disparity in changing grain sown area confirms a shift of growing grain crops from China’s warm and humid south to the less suitable cold and water-limited north.

To compensate for the loss of grain crops in highly urbanized regions with favorable biophysical conditions, inland rural China with less endowed land has to yield much more grains by cropland expansion on natural lands, or by intensive use of water and fertilizers, which generates concerns for stability of grain output increase, as well as environmental impacts of land-augmenting activities. These challenges induced by pattern change of grain sown area need to be further explored.

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