Mitigating Agricultural Water Pollution: Strategies For Sustainable Farming

Agriculture is a major contributor to water pollution, with agricultural practices responsible for 48% of water quality impairment in American surface waters. The main sources of agricultural water pollution include agrochemicals, organic matter, drug residues, sediments, and saline drainage. However, there are ways to reduce agricultural water pollution and mitigate its harmful impacts on water resources. This involves adopting more sustainable farming practices and implementing various techniques to prevent and manage nutrient runoff.

Reduce the use of agrochemicals

Agrochemicals are chemical products used in agriculture, including insecticides, herbicides, and chemical fertilizers, with the aim of increasing crop yield and protecting crops from pests. They are a major source of water pollution, and their use has been increasing massively since the 1960s. The best way to reduce the risk of water pollution from agrochemicals is to use fewer of them. Here are some ways to reduce the use of agrochemicals:

Integrated Pest Management (IPM)

IPM involves reducing pesticide applications by monitoring and identifying pests, taking preventative measures, such as good plant hygiene and soil health, harnessing naturally occurring pest control, and judiciously using targeted pesticides only when other methods have not worked. This method helps to reduce the overall use of pesticides by only using them when absolutely necessary.

Use narrow-action pesticides

When using pesticides, it is important to use ones that are specific to the pest or disease afflicting the crop. Broad-spectrum mixes can compromise natural enemies and the soil food web, which leads to a long-term decline in the ecosystem’s in-built defences against pests and diseases. Targeted applications to known pest hotspots can also help reduce overall pesticide use.

Apply correct application rates and spray-drift reduction methods

It is important to use the correct application rates for agrochemicals and to ensure that contractors are properly trained. This can help reduce overapplication and minimize the amount of chemicals ending up in the water. Additionally, using spray-drift reduction methods can help prevent the chemicals from drifting to nearby areas and water sources.

Best practice in handling agrochemicals

Significant pollution from agrochemicals can occur through drips, spills, and the washing out of sprayers and containers. To reduce this, agrochemicals should be transferred over an impermeable surface, and washings should be collected and treated before discharge. Proper handling and disposal of agrochemicals can help reduce their impact on water sources.

Create buffer zones

By creating buffer zones, such as planting trees or non-crop plants like evergreen trees around agricultural fields, farmers can prevent the drift of chemicals into other areas. These boundaries serve as a windbreak and help absorb agrochemicals, reducing their impact on the environment.

Promote organic and sustainable farming practices

Organic and sustainable farming practices use natural and low-cost alternatives to chemical agriculture systems. Farmers can fertilize soils and protect crops with organic and eco-friendly techniques that work with nature, reducing the need for agrochemicals. By assisting farmers in converting to ecological and sustainable farming systems, governments can play a crucial role in reducing agrochemical use.

Optimise fertiliser application

Optimising fertiliser application is a key way to reduce agricultural water pollution. When nutrients from fertilisers are not fully utilised by plants, they can be washed from fields into waterways, negatively impacting water quality. This excess of nutrients can cause eutrophication of water bodies, leading to hypoxia and harmful algal blooms, which can be fatal to fish and other aquatic life, as well as being toxic to humans.

To prevent this, farmers should adopt nutrient management techniques. This involves applying the right amount of fertiliser, at the right time of year, with the right method and placement. For example, slow-release nitrogen fertiliser can significantly reduce reactive nitrogen losses. The use of manure can also enhance the storage of fertiliser nitrogen in the soil for future use.

It is also important to avoid applying manure where it can come into direct contact with drinking water supplies. Manure should be kept away from wells and measures should be taken to restrict livestock access to water sources.

Improve soil health

Improving soil health is essential for reducing agricultural water pollution and promoting sustainable farming practices. Here are some strategies to achieve this:

Farmers can enhance nutrient management practices by applying the right amount of nutrients (fertilizer and manure) at the appropriate time of year, using suitable methods, and ensuring proper placement. This approach will reduce the amount of excess nitrogen and phosphorus, which can contaminate water bodies and negatively impact aquatic life.

Implement Conservation Tillage Practices

Reducing the frequency and intensity of tilling fields can improve soil health, decrease erosion, and minimize runoff and soil compaction. By adopting conservation tillage, farmers can reduce the risk of nutrients reaching waterways through runoff, thereby lessening the impact of agriculture on water pollution.

Ensure Year-Round Ground Cover with Cover Crops

By planting cover crops or perennial species, farmers can prevent the exposure of bare ground on farm fields. This practice is especially crucial when the soil is most susceptible to erosion and nutrient loss into nearby waterways. Cover crops act as a protective barrier, preserving soil health and reducing pollution.

Plant Field Buffers to Absorb Excess Nutrients

Establishing buffers of trees, shrubs, and grasses along the edges of fields, particularly those bordering water bodies, is an effective strategy. These planted buffers act as natural filters, absorbing or trapping nutrients before they reach water bodies. This helps in reducing nutrient loss and mitigating the negative impacts on aquatic ecosystems.

Engage in Watershed Efforts and Collaborations

Farmers play a vital role in reducing nutrient pollution by actively engaging with various stakeholders, including state governments, farm organizations, conservation groups, educational institutions, and community groups. Collaboration across an entire watershed is essential to address the complex issue of water pollution resulting from agricultural activities.

By implementing these strategies, farmers can significantly improve soil health, minimize agricultural water pollution, and promote sustainable farming practices that benefit both the environment and human health.

Implement buffer zones

Buffer zones are vegetated areas of land that are managed separately from the rest of a field or catchment. They are designed to improve water quality by reducing the amount of agricultural pollutant runoff that reaches water bodies. The implementation of buffer zones is one strategy to reduce agricultural water pollution.

The effectiveness of buffer zones varies according to the mechanisms by which pollutants are transported. For example, the retention of nitrogen, phosphorus, and pesticides in buffer zones depends on factors such as the width, slope, vegetative cover, and soil type of the buffer zone. Research has shown that buffer zones can be particularly effective in reducing phosphorus and sediment loads in surface runoff and the nitrate content of diffuse subsurface flow.

Buffer zones are most successful in controlling water quality when positioned close to sources of surface water pollution. This means that for effective water quality control, a large proportion of the catchment area would need to be set aside for buffer zones.

One challenge with implementing buffer zones is that they require a significant amount of land to be set aside, which can be difficult to achieve, especially in large catchments with diverse land uses. In the case of agriculture, this may involve convincing landowners to take some of their land out of production for the sake of environmental protection.

Despite this challenge, buffer zones have been shown to have a positive impact on water quality. For example, in Oregon, rehabilitation projects that included the implementation of buffer zones have helped to clean up pollution and improve fish habitat in the Willamette River.

Reduce agricultural water demand

Agriculture accounts for 70% of water withdrawals worldwide and is a major contributor to water pollution. To reduce agricultural water demand and, in turn, water pollution, there are several measures that can be implemented:

Conservation Buffers

Trees, shrubs, and grasses can be planted along the edges of fields, especially those bordering water bodies. These buffers help absorb nutrients that may run off and act as a filter, preventing nutrients from reaching the water.

Nutrient Management Techniques

Farmers can improve their nutrient management practices by applying fertilizers and manure in the correct amounts, at the right time of year, using the appropriate method, and placing them in the right spot. This accuracy helps prevent runoff from farm fields that could impact other farms, livestock, or water supply.

Livestock Management

Controlling livestock access to waterways is crucial. Installing fences along streams, rivers, or lakes can help restore stream banks and prevent livestock from bringing nutrients or other agricultural pollutants into the water. It is essential to provide livestock with alternative sources of fresh water.

Conservation Tillage

Reducing the frequency and intensity of tilling fields can improve soil health, reduce erosion, runoff, and soil compaction. This, in turn, lowers the likelihood of nutrients reaching waterways through runoff. Minimal tilling also improves soil quality and reduces crop establishment time and energy use.

Efficient Irrigation Schemes

Implementing efficient irrigation schemes can significantly reduce the migration of fertilizers and pesticides to water bodies. By reducing water return flows, farmers can minimize the amount of chemicals that enter nearby water sources.

By adopting these practices, farmers can play a crucial role in reducing agricultural water demand and mitigating the negative impacts of water pollution on aquatic ecosystems, human health, and productive activities.

Frequently asked questions