Soil biological pollution can trigger a series of chain reactions, and its degree of harm often exceeds surface phenomena. The survival time of pathogenic microorganisms in soil far exceeds expectations. For example, typhoid bacilli can survive for 3 months in moist soil, and anthrax spores can even survive for decades. These pathogens pose a threat to human health through crop absorption or direct contact. The outbreak of leptospirosis in a certain area in 2019 was traced back to the spread of pathogens in farmland soil through the rainy season. The more hidden harm lies in the imbalance of soil microbial communities. When exogenous microorganisms invade, beneficial bacterial communities that originally undertake functions such as nitrogen cycling and organic matter decomposition will be inhibited, leading to a decrease in soil self-healing ability. Experimental data shows that the number of nitrogen fixing bacteria in contaminated soil can be reduced by more than 70%, directly affecting crop yields.

This type of pollution has a persistent characteristic of damaging ecosystems. Invasive species such as nematodes and soil borne pathogens can form "hotspots" of biological pollution under suitable conditions. There have been cases in the United States where soybean cyst nematodes invaded and caused complete crop failure in farmland. The horizontal transfer of antibiotic resistance genes in soil environment is even more concerning. The detection rate of common E. coli resistance genes in the soil around aquaculture farms is as high as 60%. These genes may enter the human body through crops, exacerbating the public health crisis. The soil animal community has also been impacted, with key species such as earthworms experiencing a sharp decline in population numbers in polluted environments. Long term monitoring data from the UK shows that after an 80% decrease in earthworm density in biologically polluted soil, soil porosity decreases, leading to a 45% decrease in rainwater permeability.

The economic losses are equally alarming. The reduction in crop yields caused by biological pollution is usually between 20-50%, resulting in direct economic losses of approximately $50 billion annually worldwide. The cost of treatment is even more astonishing. Using fumigation to treat 1 hectare of farmland contaminated with nematodes requires an investment of 30000 yuan, and the effect can only last for 1-2 planting seasons. The more profound impact lies in the depreciation of land value. After the relocation of an industrial zone in a certain province, the land price is only 30% of the surrounding area due to continuous biological pollution. These hazards have intergenerational transmission characteristics, and the dormant bodies of certain soil pathogens can survive for decades and may be reactivated at any time by activities such as plowing, forming long-term ecological hazards.