Wednesday, July 1, 2020

2nd Pollution Census Shows China's Agriculture is a Big Polluter

Celebrating the results of China's second pollution census in early June, an agricultural official bragged that the agricultural sector produced more grain and meat while simultaneously reducing its discharge of pollution, a sign of progress in the greening of the country's farms, so he said. An environmental official also lauded the progress, but acknowledged that "green agricultural development" is still in its infancy. Data showing a boom in fertilizer application during the years when runoff supposedly fell 55 percent cast doubt on the pollution census data.

A communique announcing results of China's second pollution census was issued June 8, 2020. The census estimated discharges of pollutants of water, air, and soil as of December 2017, ten years after the first pollution census revealed that agriculture was a major source of pollution. A 2014 survey of soil found that 19 percent of cultivated land was contaminated with heavy metals and other pollutants.

It took several years after the first pollution census was published before Chinese officials got busy addressing farm-sourced pollution:
In 2017, a Ministry of Agriculture researcher ascertained that agriculture could be the country's largest polluter if accurate numbers were collected.
A facility to produce methane gas from pig manure. No smoking!
The 2nd pollution census indicates that great progress has been made--if the data are accurate--but agriculture has made less progress than industrial, residential and commercial entities in reducing emissions of pollutants. Farming is the chief culprit for several types of emission; farms are responsible for half of chemical oxygen demand (COD), half of total nitrogen discharged, and 69 percent of phosphorus discharges, according to the 2017 census data. Agriculture's share of COD and phosphorus discharges was up from the first census ten years earlier, while its share of nitrogen emissions were down 5 percentage points. The census found that air pollutants are emitted mainly by industrial sources. The census found agriculture only emits marginal amounts of air pollutants through burning straw and operating farm machinery.
Calculated from China's first and second censuses of pollution sources.
Comparison of the two censuses appears to show great improvement in controlling pollutants. COD, a measure of oxygen-sucking organic pollutants in bodies of water, declined dramatically from 2007 to 2017. COD from livestock and aquaculture farms declined 19 percent over ten years. This reflects mainly animal manure that washes into streams, creeks and lakes. Agricultural officials attribute the decline in livestock COD to demonstration farms that disseminated environmentally-friendly methods and other policies, but it's more likely that aggressive closure of hundreds of thousands of livestock farms during 2013-17 did the trick. The improvements by livestock farms are modest in comparison with the reduced COD emissions by industrial, residential, and commercial sources (including hotels, restaurants, laundries, hair salons, repair shops, etc.) that declined by 37 percent. 
Source: China's first and second censuses of pollution sources.
Total nitrogen discharge declined 42 percent between 2007 and 2017, according to the census results. Nitrogen runoff from crop production declined by 55 percent and nitrogen emitted by livestock declined 42 percent. Nitrogen discharged by aquaculture went up 20 percent, but fish farming still accounts for a small share of nitrogen emissions. Industrial/residential/commercial nitrogen discharges declined 35 percent. 
Source: China's first and second censuses of pollution sources.
Phosphorus discharge went down 25 percent between 2007 and 2017. Crop production's phosphorus emissions went up 10 percent and aquaculture's phosphorus emissions went up 3 percent, but livestock's phosphorus emissions fell 50 percent, according to the census. 
Source: China's first and second censuses of pollution sources.
Mining and metalworking industries discharged 182 metric tons of heavy metal during 2017. The 2007 census reported a rounded-off number of 900 metric tons, so this appears to be a big improvement. Heavy metals such as lead, mercury, cadmium, and arsenic can be absorbed from the soil by food crops like rice and vegetables. 

Residential and food service sources discharged 309,000 metric tons of animal fats and vegetable oils, according to the census. This seems like an implausibly small amount considering China's Ministry of Agriculture estimates that 26 million metric tons of edible oils are used annually, and a large portion of that must be disposed of after cooking is finished. 
Tanks for transporting organic fertilizer to greenhouses
The very brief description of methodology in the very brief communique sounds different from the methodology described in the first pollution census, and it sounds like only a fraction of livestock farms were surveyed. The first census estimated that livestock and poultry produced just over 400 million metric tons of manure and urine, but the Ministry of Agriculture put the livestock waste amount at 3.8 billion tons (no estimate was given in the second pollution census).  The second pollution census reported that 805 million metric tons of crop straw and stalks are produced annually, slightly less than the 900 million metric tons estimated by the Ministry of Agriculture. The pollution census says nothing about the Ministry of Agriculture's estimate of 60 million carcasses of diseased animals and poultry produced annually.

A commentary on the pollution census by China Environmental Protection News celebrates the reduction in emissions over the last 10 years, but warns that residential and agricultural sources are still the short legs of the stool in pollution control. The author commented that agricultural "green development" is still in its infancy and there is great pressure to "gradually repay old accounts" (clean up existing pollution) while avoiding new environmental damage. The commentator warns that agriculture accounts for over 60 percent of annual water use, a very large proportion of agricultural wastewater is untreated, and even more wastewater will be produced due to stricter requirements to clean up and sanitize livestock farms. He/she warns that residential sewage plants are often beyond capacity, and many communities have "secret discharges" into streams and rivers, notes that many neglect construction of pipe networks, and newly urbanized districts often ignore requirements to build sewage treatment facilities. It's not hard to imagine such neglect and subterfuge in agricultural waste collection and treatment.

The agriculture ministry's story about increases in grain output with reductions in fertilizer runoff smells fishy. Official data indicate that output of cereal grains increased 34 percent between 2007 and 2017. Most of the increase in grain output reflects a 67-percent increase in output of corn--the most fertilizer-hungry grain--and the corn-planting boom displaced nitrogen-fixing crops like soybeans and alfalfa.
Note: total fertilizer used = crop area x fertilizer used per unit of land.
Source: National Development and Reform Commission and National Bureau of Statistics.
China's official cost of production survey shows that chemical fertilizer application per unit of land used in wheat, rice, and corn production increased 16 percent between 2007 and 2017 (the pollution census years). The application rate appears to have plateaued at the end of the period, in 2016-17. Multiplying these application rates by the area planted in grain crops indicates that total fertilizer applied to cereal grain crops increased 29 percent over ten years. Officials claim that runoff was reduced by increasing the efficiency of fertilizer application so that more was absorbed by crops. However, the 55-percent reduction in nitrogen emissions from crop production between the 2007 and 2017 pollution censuses seems quite hard to believe if the total fertilizer applied rose 29 percent. Officials did not even introduce their sustainable development plans until 2014-15.

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