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Distr. GENERAL

WP.16 26 April 2010 ENGLISH ONLY

UNITED NATIONS ECONOMIC COMMISSION FOR EUROPE (UNECE) CONFERENCE OF EUROPEAN STATISTICIANS

EUROPEAN COMMISSION STATISTICAL OFFICE OF THE EUROPEAN UNION (EUROSTAT)

ORGANISATION FOR ECONOMIC COOPERATION AND DEVELOPMENT (OECD) STATISTICS DIRECTORATE

Meeting on the Management of Statistical Information Systems (MSIS 2010) (Daejeon, Republic of Korea, 26-29 April 2010) Topic (iii): Issues for Asian statistical organizations and ways to increase international cooperation

APPLICATION OF REMOTE SENSING TECHNOLOGY IN CROP ACREAGE AND YIELD

STATISTICAL SURVEY IN CHINA*

Zhang Fumina, Zhu Zaichunb, Pan Yaozhongb,**, Hu Tangaob, Zhang Jinshuib

a Data Management Center of National Bureau of Statistics of China, Beijing 100826, China;

State Key Laboratory of Earth Surface Processes and Resource Ecology, College of Resources Science & Technology,Beijing Normal University, Beijing 100875, China

ABSTRACT 1. Crop acreage and yield is of great significance to develop food policies and economic plans for the countries. Current agricultural statistical survey system in China is developed accompany by the development of China, and investigation methods were advancing all the time to meet the needs of business departments. The development of remote sensing makes it possible to achieve the revolutionary development from traditional approach to spatial statistical methods for national statistics. In this paper, we describe the development process of China's crop acreage and yield statistical survey and the international research development in this field. Then, we introduce the application status of crop acreage and yield estimation using remote sensing in China. Finally, we put forward the prospects of the application of remote sensing technology in agricultural survey in China after analyzing deficiencies of current survey system.

* Foundation: The National High-tech Research and Development Program (863 Program) (No.2006AA120101) and National Natural Science Foundation of China(No.40871194) ** Correspondence author, E-mail: pyz@ires.cn

Keywords: crop, statistical survey, planting area measurement, growth monitoring and yield estimation

2. China is a big agricultural production, agricultural product consumption and trading country, the abundance of crops have long been paid much attention by society and government. A variety of agricultural information, especially the cultivated area, growth and yield of major crops, is an important basis to make food policy and economic planning for a country (Chen et al., 2005). At present, crop acreage, production and other agricultural information released by National Bureau of Statistics of China are mainly obtained in two ways: the traditional overall report (summary of several administrative levels) and the directory sampling based on classical statistics. Agricultural production is different from other industries, which have large area, large spatial variability, flat area-efficient, large inter-annual and seasonal variation characteristics. Because of these characteristics, regular survey and monitoring methods are difficult to offer accurate, low cost agricultural information in time to meet agricultural production and management needs. And the existing sample survey methods based on traditional overall report and directory sampling are easily impact by people and lack of spatial distribution, which can’t meet the requirements of information society any more. Remote sensing can obtain surface information macroscopically, periodicity and economically. It has many advantages in agricultural monitoring and survey. Governments has long been paid much attention to survey crop acreage and yield using remote sensing, and great success has been achieved (Narasimhan R L and Chandra H, 2000; Dadhwal V K and Ray S S, 2000; Bastiaanssen W G M and Ali S,2003; Prasad et al., 2006). In order to occupy the active position in world grain market, The United States not only use remote sensing in its own crop yield estimation, but also set up a special body in the Ministry of Agriculture to monitor food production of the world's major grain production areas and consuming countries, and tremendous gains were made (Liu, 1997; Sun, 1996; Mac Donald R B and Hall F G, 1980). European Union established crop yield estimation operating system for the implementation of common agricultural policy (Liu, 1999; T. A. Tsiligirides, 1998). Over the past 10 years, France, Germany, the former Soviet Union, Canada, Japan, India, Argentina, Brazil, Australia and Thailand have also been studied on wheat, rice, corn, soybeans, cotton, and sugar beet yield estimation by remote sensing (Wu, 2000). As a vast country with varied topography, small-scale farmers, complex crop planting structure, crops survey using remote sensing in China is now basically stuck in the initial stage of surveying typical sample areas using high-resolution data (TM, SPOT, ALOS and other data sources), and then calculate large administrative unit crop area and average yield using statistical methods. At the same time, a series of key issues about "acquisition of remote sensing data and accuracy verification of measurement results" has not been effectively addressed yet. Data published by these systems remain in research, which is not approved by national sector. On the other hand, these systems can only be research systems, it is difficult to promote operational. Therefore, select the main crops and study the key issues of the system that measure crop area and yield using remote sensing as soon as possible, and establish a wide range of agricultural statistical survey system is particularly important without delay. This paper describes the development process of China’s crop area and yield sample survey and research process of crop area and yield estimation by remote sensing measurement, summarizes the problems combine with the present status of agricultural survey by remote sensing in China, and prospects the application foreground of remote sensing technology in China's agricultural survey.

. Current agricultural statistical survey system in China is developed from estimation consultation, report, yield per unit area to a sampling system of acreage and yield of wheat, rice, corn,

otton accompany by the development of China (National Bureau of Statistics of China, 2005).

the existing survey system can be divided into five phases: (1) the initial age in 50s, 20th century; (2) the stage of development in 60s, 20th century; (3) the early recovery period in

ey is the result of the development of statistical theory and ethods, which has made great contribution to the development of China. As social and economic developed,

survey organization and implementation methods in China should advance with e times in order to meet the needs of practice.

y results: reducing the impact of subjective factors, prove the objectivity of the results, enhance the timeliness of reports, and dynamically monitor the crops in

e critical period of growing season; (3) improve means of investigation: use the "3S" techniques to replace the

ENSING EASUREMENTS

. Since the 70's of 20th century, the United States and other developed countries take the lead to carry out

1. DEVELOPMENT PROCESS OF CROP AREA AND YIELD ESTIMATION SURVEY SYSTEM IN CHINA 3and investigation of grain c 1.1 Historical origin 4. The development process ofst80s, 20th century; (4) the full implementation phase after 1984; (5) sample rotation and multi-subject survey after 2000(Zeng and Zhang, 2004). 5. Crop acreage and yield sampling survmcrop acreage and yield sampleth 1.2 Development needs 6. The current survey system has following shortages: (1) foundation of sample survey is not solid; (2) sample survey objects are unstable; (3) sampling methods are backward; (4) the quality of investigation is lack of control. Therefore, we need to further improve the crop sampling system, carry out a crop survey using ground sampling, combined with the use of modern spatial information technologies, and improve the investigative capacity of the national crop statistics comprehensively from the methods, systems and mechanism. Mainly include following aspects: (1) improve the survey system: from the traditional catalog sample to space sample, and expand the connotation of the investigation targets, provide not only crop area and yield in digital form, but also with crop spatial distribution information and survey result that can be used for provincial, county and village; (2) improve the surveimthexisting tools such as ground measuring using the tape. 2. DEVELOPMENT OF CROP AREA AND YIELD ESTIMATION BY REMOTE SM 2.1 Construction progress of foreign major research programs and technical systems 7acreage and yield estimation of major food crops (wheat, corn, rice, etc.), implemented a series of major projects and eventually formed regular operation technology system and monitoring system.

. By using remote sensing technology, efficiency and accuracy of traditional agricultural statistics and

Large Area Crop Inventory Experiment, 974-1978), finish the experiment in measuring the area, yield and production of world’s major

become a practical operating system. MARS can onitor and forecast crop information in three levels: the Community level, regional level and the national level

large area; Russia use MODIS to stimate crop acreage in the south of Russia; South Africa estimate crop area with the support of remote sensing

azil using remote nsing data; In Asia, Japan, India, Thailand, Indonesia, Vietnam and other countries use remote sensing

emy of ciences, (Chinese Academy of Sciences and the People's University of China, etc.); (4)the " application and

8agricultural condition monitoring systems was significantly improved, and a huge of economic and social benefits was created. So far, crop area and yield estimation by remote sensing measurements of the United States and the European Union are the most important ones. 9. United States National Aeronautics and Space Administration, the National Oceanic and Atmospheric Administration, Ministry of Agriculture jointly developed LACIE plan (1wheat-producing area. This is the first work on agricultural monitor by remote sensing measurements, which has become a milestone (Jerry et al., 1979). After the LACIE program, the United States have launched AGRISTARS, Ag20/20 and other agricultural resources survey project. 10. The European Union launched the MARS program in 1989, which experiment on surveying crops by using remote sensing techniques in a large area, and finally m(F. J. Gallego, 1999). After the MARS program, the EU launched the LUCAS that investigate land use situation base on area sampling frame. LUCAS has implemented at the national scale, Member States scale and international scale (Delince J, 2001; F. J. GALLEGO, 2004). 11. Furthermore, since the 90s of 20th century, rapid development of application in crop area and yield estimation by remote sensing technology was achieved: Food and Agriculture Organization (FAO) established a global early warning food information system to monitor and forecast global crop yield; Canada use NOAA to realize crop water measurement, disaster warning, yield forecasting in edata and unmanned aerial vehicles; Brazil monitor crop acreage and yield in the south of Brsetechnique to measure crop, vary degrees of income was made (Wu, 2004). 2.2 Development progress of national major research projects and technical system 12. In 1979, Chinese scientists started to pay attention to the economic significance and political significance of crop yield estimation by remote sensing, and made lots of positive suggestions (Wu, 2004). After that, China launched a series of monitoring plan. In the period of “seventh five year-plan”, China Meteorological Administration lunched the program of crop monitoring by remote sensing. In the period of “eighth five year-plan”, the Chinese Academy of Sciences lunched the program of crop monitoring by remote sensing. In the period of “ninth five year-plan”, the Ministry of Agriculture carried out another program of crop monitoring by remote sensing. In the period of “tenth five year-plan”, with the support of the Ministry of Science and Technology, domestic universities, research institutes and the industrial sector begun to cooperate to establish business systems: (1) the agricultural condition monitoring system of Ministry of Agriculture (Academy of Agricultural Sciences and the Ministry of Agriculture); (2) GVG system (Chinese Academy of Sciences and the National Food Authority);(3)the "multi-user remote-sensing business operations sampling techniques and systems to achieve" of the Institute of Remote Sensing Applications Chinese AcadStechnology standards of crop area measurement by remote sensing" of National Bureau of Statistics(National

d and running agricultural investigation systems that rely on remote sensing technology in China basically use results of typical area as auxiliary information while investigating main crop’s area and yield. Moreover, there are still

y p l atistical system and the general public, such as the expansion of statistical indicators, further classification of

agricultural statistical rvey system. In 2006, the Ministry of Science and Technology established the first "National High

opment Program 863" key project in the field of "Earth Observation and avigation Technology": "Research and Application of Key Technologies of National Statistics and Remote

15. NSRCP system is designed to combine the advantages of the country's current survey system and "3S" technology comprehensively, which can expand current survey indicators comprehensively, provide relatively accurate and objective results, and gradually meet the growing demands of national statistics and the public, under the promise that the timeliness of statistical survey is ensured.

Bureau of Statistics and the Beijing Normal University, etc.). In the period of “eleventh five year-plan”, NSRCP start to operate in the main grain producing provinces of China. 13. Looking at the development of domestic and international remote sensing research, lots of work has be done to use remote sensing technology to measure crop area, monitor crop yield and growth and research yield estimation system, and good progress was made too. However, due to late start, there is still a wide gap in the usage of remote sensing technology and the needs of national agricultural statistics service. The establishe

man roblems for these systems to enter the national survey system to meet the growing needs of the nationaststatistical unit, timeliness and accuracy of the survey, as well as the objectivity of the survey results, etc.

3. APPLICATION STATUS OF AGRICULTURE SURVEY BY REMOTE SENSING IN CHINA 14. In 2003, base on full study of the research progress of using "3S" technology to monitor agriculture at home and abroad, National Bureau of Statistics discussed the possibility of the combination of national agriculture statistical survey system and remote sensing technology with many well-known colleges, universities and research institutes. They tested the system in Henan, Hebei, Anhui, Shandong and Jiangsu provinces, and released the result of summer grain crops using remote sensing technology and traditional statistical methods, which marks the beginning of "3S" technology enter the nationalsuTechnology Research and DevelNSensing Service System". And "National Statistics and Remote Sensing System of Crop Production" (referred to as: NSRCP) is the core of the national statistics and remote sensing operation system. 3.1 Framework of NSRCP

Figure 1 Framework of NSRCP

3.2 Survey System of NSRCP 16. According to the needs of national statistics, combined with the identify ability of remote sensing technology, NSRCP system choose planting area and yield of major crops (wheat, corn and rice) at provincial level and county level as the survey targets. Accuracy of planting area and yield at county-level should better than 95% under the confidence level of 95%. The planting area of wheat, corn and rice should be annually report, and the yield should be report three times: preliminary report, pre-production and actual production. 3.3 Key technology system of NSRCP 17. Key technology of NSRCP includes geo-spatial framework, ground-support network, planting area measurement, and growth monitoring and yield estimation. Geo-spatial framework is the prerequisite and data protection for various remote-sensing measurements, planting area measurement and growth monitoring and yield estimation are the core measurements of NSRCP, and ground-support network provide true value of field measurements for measurement models, so the above four aspects make up the key technologies of NSRCP. (1) Geo-spatial framework 18. Geo-spatial framework is the basis of NSRCP. NSRCP establish a multi-scale, multi-resolution, multi-types of geo-spatial framework database, which can provide the basic spatial statistical units and high-quality space-based statistical services to meet the needs of various types of basic geographic information data, agricultural statistics thematic data, multi-source remote sensing base images during the business operation. A unified space-based statistics and remote sensing information platform was build to provide base information for high-precision space positioning, and then sustainable national spatial statistical system is build. Geo-spatial framework mainly includes: theoretical framework construction, database system design and application demonstration of space-based statistics and remote sensing and so on.

Figure 2 Geo-spatial framework of NSRCP

(2) Ground-support network 19. Ground-support network comprehensively combines advantages of remote sensing and ground sampling methods, achieve associated ground survey information of planting area and production of main crops timely and accurately. To establish ground-support network for crop acreage surveys, crop yields investigation, bio-meteorology survey and agricultural investigation, GPS, remote sensing and geographic information system techniques were used, sampling village, block and typical areas were specialized. The main survey content includes: sampling plot survey, high resolution area survey, typical area survey, county-level bio-meteorology survey and cropping structure of sampling village survey.

Figure 3 Ground survey organization chart (3) Planting area measurement 20. In support of mass to-ground sampling data by National Bureau of Statistics, select a number of pilot areas (technical approach experimental area, the typical county, a typical province) to research in the major grain-producing province according to district characteristics. NSRCP break through key technical issues for regular measurement operation with incomplete remote sensing data, and finally establish the major crops (wheat, rice and corn) acreage measurement methodology based on multi-source remote sensing data and sample survey data, which integrate research results at home and abroad, take variety of future data sources into account, and can make full use of existing remote sensing data at home and abroad. Crop acreage measurement methodology mainly includes: technologies and methodologies of regionalization of crop acreage measurement, measurement techniques and methods at regional/county level (remote sensing), measurement techniques and methods at the county level (remote sensing and sampling), measurement techniques and methods at the provincial level (remote sensing and sampling) and analysis and evaluation techniques and methods and so on.

Figure 4 Planting area measurement system of NSRCP

(4) Growth monitoring and yield estimation 21. After fully drawing on research results at home and abroad, aiming at operation of crop measurement, NSRCP establish the major crop growth and yield monitor program based on sample survey and multi-source remote sensing data, which is under support of relevant technical methods, a wealth of data and detailed statistical data of agricultural investigation by National Bureau of Statistics. The program mainly includes: techniques and methods of regionalization of crop yield estimation, growth monitoring techniques and methods, techniques and methods of crop yield estimation using weather information, techniques and methods of crop yield estimation based on historical statistical data at county-level and remote sensing technology, techniques and methods of crop yield estimation based on real measured yield data and remote sensing technology, techniques and methods of crop yield estimation based on crop growth model and remote sensing technology and so on.

Figure 5 Crops growth monitoring and yield estimation technology system of NSRCP

3.4 Applications of NSRCP 22. Since the establishment of NSRCP, Beijing Normal University, Chinese Academy of Agricultural Sciences and local coordination institutions, supported by the National Bureau of Statistics, have tested run the system in Jilin, Henan, Jiangsu, Hunan and Beijing and other demonstration provinces, and gradually extended to 13 major grain-producing provinces in China. Jiangsu is a typical agriculture province in the 13 major grain-producing provinces, because it has the following characteristics: cultivation of the two main crops (wheat and rice) is concentrated, planting area is big, blocks are broken and farming in mountains as well as plain. So test the system of crop acreage and yield estimation by remote sensing in Jiangsu Province is a good representation, which can also lay the foundation for measurement in other provinces. Survey of winter wheat at provincial level is divided into three times according to the institution of the statistics and remote sensing survey system. We choose the measurement in May as an example in this paper. (1) Winter wheat acreage measurement in Jiangsu province in 2009 23. From May 21 until June 20, the National Bureau of Statistics, Beijing Normal University and other research institutes took 30 days to complete the winter wheat acreage measurement in Jiangsu province in 2009. Data used in the measurement includes: present HJ and ALOS, history SPOT as base map, high precision block maps, administrative division maps, traffic information, phenological calendar, planting structure and meteorological data. With multi-level multi-scale sampling and field survey, winter wheat planted area in Jiangsu province in 2009 is 3225.0 mu is calculated out by sampling back stepping, and spatial distribution of the winter wheat is shown in Figure 7. 24. Measurements of winter wheat area at county level and township level(for consult) are also carried out according to statistics and remote sensing system to meet the needs of different administrative units.

Figure 6 Multi-level multi-scale sampling

plots at province level Figure 7 Spatial distribution of the winter

wheat in Jiangsu province in 2009

County Results

Town Results（Reference）

(2) Winter wheat yield measurement in Jiangsu province in 2009

Figure 8 Yield of winter wheat in Jiangsu in 2009

25. From May 15 until June 31, the National Bureau of Statistics and Beijing Normal University took 15 days to complete the winter wheat yield measurement in Jiangsu province in 2009. 26. Data used in the measurement includes: MODIS in the growing season of winter wheat, present HJ and ALOS, regionalization map of yield estimation, administrative division maps, real measured yield data, historical statistical data at county-level and meteorological data. Using methods such as crop yield estimation using weather information, crop yield estimation using remote sensing technology and crop yield estimation based on crop growth model and remote sensing technology, combine with the spatial distribution map of winter wheat in Jiangsu province in 2009 provide by geo-spatial framework of NSRCP, we predict that yield of winter wheat in Jiangsu province in 2009 is 5334.12 kg / ha, which is a little lower than in 2008, decrease degree is about 0.79%. 27. Measurements of winter wheat yield at county level and township level(for consult) are also carried out according to statistics and remote sensing system to meet the needs of different administrative units.

4. SUMMARY AND OUTLOOK 28. Comprehensively analyze international major research programs and technology system, we can find that the main research methods are sampling combined with remote sensing to obtain large-scale crop acreage and yield, which cannot provide results for all levels of government departments to meet the requirement of

national statistical offices. On the other hand, there are many problems in these systems, such as indicator, statistical unit classification, survey system, survey accuracy and so on. It is difficult for these systems to enter the national survey system. NSRCP solve these problems to a certain extent. 29. The system combine the advantages of the country's current survey system and "3S" technology comprehensively, expand current survey indicators comprehensively, provide relatively accurate and objective results, and gradually meet the growing demands of national statistics and the public, under the promise that the timeliness of statistical survey is ensured. Since its inception, NSRCP has been tested run in demonstration provinces such as Jilin, Henan, Jiangsu, Hunan and Beijing. 30. Through testing run in these provinces, we found that the system still needs a major breakthrough at the following two points: (1) Improve the ground-support network: Set up a wireless sensor network in crop measurement area to monitor crop conditions at real time, provide accurate real-time parameters for crop acreage and yield measurement models, which can reduce the cost of field investigation and exclude the interference of man-made factors. (2) Increase the accuracy of crop acreage and yield estimation: Improve remote sensing measurement methods by using multi-source multi-scale remote sensing data and real-time crop growth information provided by wireless sensor network. Improve measurement accuracy of sampling plots to improve the reliability of the result of multi administrative level. References

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