How grain output data is compiled and released

In July in Ningxia, the scent of wheat is everywhere, and the joy of the summer grain harvest is written on every farmer's face. A reporter learned from the autonomous region's Grain Bureau that the region's summer grain output this year is expected to reach 386,000 tonnes. Autumn grain is growing normally, and the seedling stage is doing better than last year. Recent rainfall has been favourable for grain growth in the southern mountainous area, and the preliminary judgment is that this year will be a bumper harvest year; as of last year, Ningxia's total grain output had maintained consecutive years of bumper harvests. So how is the grain output data behind all this produced? On the morning of the 9th, the reporter followed staff from the Qingtongxia Survey Team of the National Bureau of Statistics to the fields to experience grain output survey work.

Step one: Field-by-field yield estimation and registration

According to the introduction, grain output refers to the total production of cereals, pulses and tubers in a given area in a given year, usually also called total grain output. As an important indicator bearing on the national economy and people's livelihood, grain output data must also follow scientific and rigorous rules and methods in its statistical survey process.

In the Ningxia irrigation district, the main grain crops are wheat, maize and rice. At present, the grain output survey samples drawn across the region are distributed across 20 cities (counties and districts), 129 townships and 198 administrative villages.

At around 9 a.m. on the 9th, the reporter went with staff from the Qingtongxia Survey Team to the farmland of Wang Jianfu in the tenth villager group of Zhongzhuang Village, Daba Town, to carry out actual cutting and measurement of wheat yield. Looking out, there was a stretch of golden wheat fields; the ripe wheat swayed gently in the breeze, and the heavy grains weighed the ears down so they could not lift their heads. “The wheat ears are especially uniform, so the per-mu yield is bound to be high.” Before measurement even began, the experienced surveyor Xiao Bai said so.

In fact, half a month earlier, an auxiliary survey squad made up of village officials, surveyors and experienced farmers had already estimated the yield of all crops in Qingtongxia's 12 grain output sample villages, including plots with no harvest at all due to disasters and other reasons, all of which had to have their per-mu yield estimated plot by plot. Then, according to the estimated per-mu yield levels, a large sample frame was compiled by ranking from high to low, and 3 survey plots were drawn at random. Wang Jianfu's wheat field was one of the survey plots drawn at random. “Field-by-field yield estimation is the first step in the data survey.” Xiao Bai said.

The core of the survey: actual cutting and measurement

The second step is actual cutting and measurement. So-called actual cutting and measurement means on-site measurement and sampling.

In one of Wang Jianfu's wheat fields next to a maize field, the survey team members first used a tape measure to measure the length and width of the wheat plot, then used the tape measure to stretch a diagonal line between the two farthest opposite corners of the field. Another staff member, holding a T-shaped distance-measuring ruler, came to the diagonal line, randomly chose a centre point within the first one-third of the distance along the diagonal, and inserted the distance-measuring ruler into the field; under the direction of the measuring staff, Wang Jianfu cut the rice.

The staff then, according to the rules, chose three equally spaced points on the diagonal and likewise cut the rice within the circles marked by the distance-measuring ruler. “This circle is strictly specified as within 10 square chi, and 3 areas of 10 square chi each must be cut in one plot. When harvesting, not a single ear within the area is missed, and not a single ear outside the area is cut extra; the wheat in the yield-measurement area is cleaned up completely.” explained Ma Zibao, head of the Qingtongxia Survey Team. Because rice in one field receives different amounts of light, its growth may be uneven, so 3 points must be chosen for measurement.

More than 40 minutes later, the survey team members bundled the 3 bundles of wheat they had cut, bagged them and affixed sample labels, and this actual cutting and measurement work was considered complete.

Threshing, weighing and calculating moisture before measurement

Afterwards, the cut wheat samples were threshed, and then two surveyors used a standard scale to weigh out the total weight of each sample plot sample (weighing had to be accurate to 0.005 kg), and recorded the weighing results.

After the samples were weighed, moisture measurement was carried out, and according to the national standard for moisture and impurity rates (the Ningxia grain standard moisture content for wheat is 13.0%), the standard moisture and impurity rate of the crop actually cut and measured in each survey plot was calculated. The next step was to estimate losses of the surveyed crop during harvesting, transport and threshing.

The sum of the above losses is the average deduction per mu; only after deducting the losses is the actual per-mu yield of the crop obtained. The final grain output is the result of multiplying the per-mu grain yield obtained from actual cutting and measurement by the grain sown area calculated from actual measurement.

“It is precisely through this strictly regulated working process that first-hand data from farmers and from the actual harvesting of grain plots is obtained.” Wang Xuming, press spokesperson for the Ningxia Survey General Team of the National Bureau of Statistics, told the reporter that on this basis, through strict review, entry and verification, the sample survey data that passes review is finally reported to the Ningxia Survey General Team of the National Bureau of Statistics and the National Bureau of Statistics; the higher-level statistical agencies directly process and calculate the front-line actual measurement survey results according to procedure, so as to ensure the objectivity and authenticity of the grain output data.