Agricultural non-point source pollution refers to the environmental pollution caused by nutrients such as nitrogen and phosphorus fertilizers, pesticides, and other organic or inorganic pollutants in agricultural production activities through surface runoff and leakage from farmland, mainly including fertilizer pollution, pesticide pollution, livestock manure pollution, straw burning pollution, etc. So the monitoring task of agricultural non-point sources is particularly important.

1. Fertilizer pollution

The utilization rate of chemical fertilizers in crops is not high, and the nutrients absorbed and utilized by crops are very few. The remaining nutrients enter the environment through various pathways, such as runoff, leaching, denitrification, adsorption, and erosion. These excessively applied fertilizers flow into the water, causing rapid growth and reproduction of algae in the water, consuming a large amount of dissolved oxygen, causing the water to lose its proper function and enter the soil, changing the structure and characteristics of the original soil, causing soil compaction and a decrease in organic matter. In addition, excessive heavy metal components in fertilizers accumulate in the environment, and if absorbed by crops, it can harm human health. The main monitoring indicators are COD, phosphate, pH, suspended solids, fluoride, and ammonia nitrogen

2. Pesticide pollution

Organic chlorine and organophosphorus pesticides are still commonly used in agricultural production. According to data, more than 95% of sprayed powder or liquid pesticides either adhere to the surface of plants, land on the ground, or float in the air. Due to the unreasonable use of pesticides, most of them are wasted. These pesticides flow into the water through various channels, causing the content of various pollutants in the water to exceed the standard and the water quality to deteriorate. The main monitoring indicators are COD, volatile phenols, sulfides, and suspended solids.

3. Poultry and livestock farm pollution

A large amount of organic pollutants and nitrogen, phosphorus, etc. are generated from livestock and poultry farms, and the daily flushing sewage flows into rivers and lakes, causing water pollution and serious environmental pollution. The main monitoring indicators are phosphorus and nitrogen.