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Reducing Fertilizer Pollution with Biological Control Technologies to Safeguard Water Quality

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To reduce nutrient pollution in water bodies, the EPA has developed homegrown biological control technologies, such as microbial agents, biochar and bio-fertilizers, which are effective in fixing nitrogen, dissolving phosphorus, improving soil environment and increasing nutrient uptake efficiencies of plants. Farmers participating in the program have come forward to share the results, showing that the technologies not only can reduce the loss of nitrogen and phosphorus nutrients by 20-70%, but can also save 16% to 41% of fertilizer expenses. As a result, production can be increased by 7% to 24%, and a triple-win scenario of improving water quality, the economy and agricultural products’ quality can be accomplished.

The EPA pointed out that the world is facing the pollution of water sources caused by excess nitrogen and phosphorus in the soil, a result of over fertilization. Aiming to protect water quality, the EPA has been carrying out measures such as on-site treatment, constructed wetland, grass belts and grass ditches to prevent pollution from affecting water sources. And now its measures are focusing on the source of the problem by promoting changes in fertilization methods, use of biological control technologies or other measures related to rational use of fertilizer in the agriculture industry. These measures will help to reduce the use of fertilizer, improve the nutrient uptake efficiency of plants, and decrease pollution.

The EPA indicated that the use of biological control technologies to promote eco-friendly agriculture is now an international trend as countries in Europe, North America and Asia have successively introduced relevant policies. Combined with the measures of the Council of Agriculture to promote rational use of fertilizer, the use of biological control technologies can greatly reduce nutrient pollution in water bodies while improving the quality of farm products and creating enjoyable water environments.

In an effort to reduce the impact of agricultural fertilizers on the water quality in the catchment areas of reservoirs, the EPA has selected the catchment areas of Feitsui Reservoir and Shihmen Reservoir as targets for future promotion. Measures promoted in these areas, where the tea plantations in Pinglin and Shiding Districts of New Taipei City and peach farms in Fuhsing District of Taoyuan City are located, are expected to help reduce about 850 metric tons of fertilizer utilization, or 15% of the current usage, making farming more eco-friendly.

The EPA stated that due to excessive fertilization in some farming activities, nitrogen and phosphorus nutrients that cannot be absorbed by crops often enter water bodies and cause pollution. Studies have shown that in conventional fertilization, only 20% to 50% of the fertilizer is absorbed by crops, and the remaining excess chemical fertilizer infiltrates and pollutes water bodies, affecting the normal uses of river water.

From 2019 to 2021, the EPA conducted farmland experimentation and promotion of biological control technologies with National Taiwan University, using microbial agents, biochar and biological fertilizers to reduce the use of fertilizers. Scholars culled microbial agents from Taiwan's domestic soil and water sources and gave them to farmers to use in trials. They then searched the most effective ways of using these agents from repeated trials and continued record keeping.

Six crops including Lactuca sativa (lettuce), Brassica oleracea, Prunus salicina (Chinese plum), bamboo shoots, pitaya, and Allium tuberosum (Chinese leek) were put to onsite trials in six farms including the National Taiwan University experimental farm. The results showed that the use of biological control technologies to replace 50% of fertilizer use caused the decrease of the total nitrogen and phosphorus nutrient loss in run-off and infiltration together by 20% to 70%, compared with the full amount of fertilizer use. At the same time, the technologies saved around 16% to 41% of fertilizer expenses and increased the yield by 7% to 24%.

"I hope that friends who grow peaches on Lala Mountain will be willing to use them," said Chin Ming-Da, a farmer who grows peaches in Fuhsing District, Taoyuan City. He said that when he first started using the new method, he was very doubtful and afraid of losses, and only dared try them on roughly 2,000 square meters of land, which accounted for just 1/5 of the planting area. After prolonged observation and record keeping, he found that the yield and quality of his fruits had grown by 20%, and the revenues had also gone up by 20% to 30%. He is therefore pleased to recommend the practice to other peach farmers.

Excerpt from Major Environmental Policies, April 2022

Ministry of Environment