In this paper

the need of implementing sampling network for crop type proportion is analyzed and the strategy to implement the sampling network on regional division

sampling contents

team

frequency and date for different division as well as the quality control was also discussed. The entire country is divided into 7 regions for field sampling by 7 institutes of CAS in 1999

and then 9 regions was optimized in 2002 for better scheduling and meeting the crop calendar. The sampling was to get the crop type proportion for every growing season. According to the crop calendar

different regions have different sampling frequency

for example

north-east region only need to sample once a year

whereas in south China

three times are needed for sameplaces. For each region

the deadlines are settled. The sampling works should be completed and the results have to be delivered before the deadline. Crop type proportions for sampling lines

counties

strata and province were calculated. Guideline and operational criteria are formulated to ensure the quality

and intensive training was made every year for the sampling operators. There are many factors affecting the sampling works. The costs is very high

including wages

vehicles

equipments

training

technical support

etc. The sampling efficiency needs to be improved. Sometimes

proportion data of only a few crop types were collected with many times

consuming a large amount of energy and people resources. How to manage and supervise the sampling team always is a difficult question

and the sampling frequency and schedule should be exactly followed. The quality control is also a problem. It is mostly rely on the sampling team themselves. There are 6 steps to implement it every year. The first step is training and planning at the beginning of the year. The second one is the supervision and technical assistance before and during the sampling procession. Third is the sampling in the field

and then is the calculation in house

and then is the quality control and delivery

and the last step is the summarizing to evaluate the sampling work at the end of the year. The sampling network has been used for 6 years. It shows the sampling network is efficiency.