During the process of sowing, nurturing, harvesting and processing agricultural products, farmers often turn to pesticides and fertilizers to combat pest infestations, replenish spent soils, increase yields and reduce farm labour. Unfortunately, the overuse of pesticides, the application of especially toxic pesticides, and pesticide spills have serious negative consequences for the environment, farm workers, and wildlife. Indiscriminate pesticide use can also disrupt food webs and natural pest-control mechanisms, and place farmers on a treadmill of escalating chemical use that is neither environmentally nor economically sound. The overuse of fertilizers can lead to the build-up of nitrates, phosphates and other nutrients in downstream water bodies, causing algal blooms and mass die-offs of fish and other aquatic life, while the underuse of fertilizers can lead to poor yields. Soil erosion – or the wearing away of topsoil – is a separate but related problem. While wind and rainfall are often drivers of soil erosion, the problem is made worse when farmers over-till or plant crops on streambanks, or when foresters log trees on steep slopes.
Soil erosion and the overuse of pesticides and fertilizers are taking a measurable toll:
Pesticides have been linked to declines in bees and pollinators, insects, birds, mammals, aquatic animals and non-target plants. Pesticide run-off contaminates ground and surface water. Soil microorganisms are affected, which in turn impacts soil fertility. The toll on human health is also vast: The World Health Organisation (WHO) estimates that over 350,000 people in developing countries die every year from acute pesticide poisoning. In addition, the WHO estimates that another 750,000 people in developing countries are suffering from specific chronic defects and cancers each year from pesticide exposure.
Nearly all sustainability standards, certification and related supply chain tools in the agriculture sector promote practices that aim to reduce soil erosion and prevent the overuse of pesticides and fertilizers. Some programmes prohibit synthetic pesticides altogether, while others prohibit only the most toxic pesticides and those that are illegal or not officially registered for use. Most standards that permit pesticide use require safeguards to minimize the risk of pesticide spills and other forms of contamination or runoff.
In place of synthetic pesticides, many programmes promote integrated pest management (IPM) – a scientifically based process to manage pests effectively through careful monitoring, prevention, non-chemical pest-control measures, and the judicious application of pesticides when it is technically and economically warranted, and in a manner that minimizes risks to human health and the environment.
The overuse (and underuse) of fertilizers can be addressed by ensuring that the application rates are guided by current soil nutrient levels, as determined by soil tests. In addition, standards and related tools often promote the use of organic fertilizers – such as compost and manure – that deliver nutrients to the soil over a longer period. Non-synthetic fertilizers also provide structure to the soil and increase its ability to hold water, which reduces soil erosion. Other measures that programmes often mandate to reduce soil erosion include the use of mulches, terraces, windbreaks and vegetated buffer strips beside streams.
Some resources that examine the impact of standards and related tools on pesticides, fertilizers and soils are as follows:
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