Pesticides

#16: EU Directives on Nitrates and Pesticides

Welcome back everyone! The future of agricultural pollution is not all bleak as there are measures put in place to allow the environment to gradually revert back to a time where there was less pollution. In this post, we aim to summarise some of the directives and legislations that the EU has implemented, especially against the use of excess pesticides and nitrates in fertilisers.

The use of pesticides in agriculture can help to fight crop pests, therefore increasing quality and yield of the crop. However, in the past few decades, it is realised that pesticide overuse can lead to serious health and environmental impacts. Therefore, the EU Common Agricultural Policy (CAP) was introduced in 1962, which implements a series of agricultural subsidies and programmes that has been revised and revamped throughout the years. Embedded within the CAP, there are some policies that not only target the use of pesticides, but also promote the sustainable use of plant protection.

Here are some of the policies and measures stated within the CAP:

  • Direct payments are not given to farmers who can generate the highest yield, this minimises the need for farm owners to use excess pesticides just to garner greater yield
  • “Green” direct payments are disbursed to farm owners who adopt farming practices that help take a step towards achieving environmental and climate goals
  • Cross-compliance rules state that farm owners will receive a cut from their payments if they do not adhere to the EU laws associated to environment, climate change, good agricultural condition of land, human, animal and plant health standards and animal welfare
  • These cross-compliance rules include conditions for use of pesticides, especially with regards to fruits and vegetables, where a minimum 10% of spending in operational programmes must go towards environmental actions
  • Agri-environmental measures are geared towards minimising the risks of environmental degradation and improve the sustainability of agro-ecosystems

It is the responsibility of the farm advisory systems to alert farm owners about conditions under cross-compliance, green direct payments, water framework directive and the directive on sustainable pesticide use. With regards to organic farming, chemical pesticides, synthetic fertilisers, antibiotics and other substances are severely prohibited.

A summary of the EU Nitrates Directive

The use of inorganic nitrogen and phosphorus fertilisers to supply the crops with nutrients to grow quickly and in abundance helps to boost crop yield. However, it is not sustainable as they stimulate eutrophication upon reaching water bodies. Therefore, the EU’s Nitrates Directive was introduced in 1991. The directive aims to achieve reduction in water pollution by nitrates from agricultural sources and to promoting good farming practices.

This directive is enforced by the EU countries. These countries would need to ensure that agricultural water quality is regularly inspected, demarcate areas which could become heavily contaminated by nitrates once applied, as well as establish acts of good agricultural practices. With regards to the areas easily contaminated by nitrates, the directive restricts up to 170kg as the maximum annual limit of nitrogen from livestock manure (used as fertilisers) that can be applied per hectare. Acts of good agricultural practice include adhering to fertiliser application periods, fertiliser application areas, manure storage methods, manure spreading methods as well as certain land management measures. Every 4 years, member states are required to report on the nitrates concentrations in waters, presence of eutrophication, any revisions in the areas vulnerable to nitrate pollution as well as future trends in water quality.

At present, as with many other solutions or legislations implemented to curb pollution stemming from agriculture, there are limitations which hamper its environmental success. It is worthy to note that studies mention a hiccup in its intended success is due to a lack of governance-oriented debate. Only with this debate, the knowledge of the policy and directive performances can then be fully understood. To overcome this limitation, it is encouraged that member states be required to provide to EU Commission a thorough assessment of the governance dynamics that reinforce the policy and directive implementation, along with the 4-yearly environmental monitoring report.

References:

Musacchio, A., Re, V., Mas-Pla, J. and Sacchi, E., 2019. EU Nitrates Directive, from theory to practice: Environmental effectiveness and influence of regional governance on its performance. Ambio, 49(2), pp.504-516.

European Commission – European Commission. 2020. Pesticides In Agriculture. [online] Available at: <https://ec.europa.eu/info/food-farming-fisheries/sustainability/environmental-sustainability/low-input-farming/pesticides_en> [Accessed 24 July 2020].

European Commission – European Commission. 2020. Nitrates. [online] Available at: <https://ec.europa.eu/info/food-farming-fisheries/sustainability/environmental-sustainability/low-input-farming/nitrates_en> [Accessed 24 July 2020].

Ec.europa.eu. 2020. Nitrates – Water Pollution – Environment – European Commission. [online] Available at: <https://ec.europa.eu/environment/water/water-nitrates/index_en.html> [Accessed 24 July 2020].

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#15: Buffer Zones along Farm Boundaries

In many of the previous posts, there is a lot that is mentioned regarding water pollution as a result of intensified agriculture. This post will be focussed on a possible solution that could minimise the risk of water pollution.

One approach to solving the water pollution problem is the creation of buffer zones between the polluting farms and receiving waters. A buffer zone refers to a permanently vegetated area of land which is roughly 5-100m in width, preferably placed adjacent to a watercourse. The buffer zone works by providing a biochemical and physical barrier between the pollution source and the receiving water body.

The working mechanism of the buffer zone is relatively simple. The buffer zone spreads and separates the incoming flow of pollutants, minimising its fluid velocity. This increases infiltration and subsequently reduces the water depth on the surface. Huge particles fall to the bottom as sediments while suspended particles get filtered through leaf litter and soil. The remaining pollutants get trapped in the soil of the buffer zone, which allows for decay and subsequent absorption by plant roots or adsorption onto soil particles. The removal of pollutants transported in particulate form varies according to the buffer zone’s capacity of reducing energy of the incoming flow to allow pollutant particle settling. On the contrary, the removal of pollutants transported in dissolved form depends on the ability of the buffer zone to stall the runoff long enough to facilitate the pollutants breaking down, for subsequent absorption by plants.

The effectiveness of a buffer zone is determined by a number of factors. We must consider its physical structure, the type of pollutants it must handle and the closeness of the buffer zone to the pollution source. As for agricultural catchments, they are usually located in areas of low slope where the uplands were already cleared without any buffer. Such runoff from the uplands gets channelled away in the upper catchment and could flow out of the catchment without passing through the buffer downstream. This results in a huge loss of nutrients, which in this case are pollutants, that ultimately enters water bodies and causes water pollution.

In order to ensure the effectiveness of buffering for agricultural catchments, the buffer zones should ideally extend along tributary streams, so that none of the polluting sources will be left out and allowed to channel away. Hence, all polluting sources have to pass through buffer zones to trap the pollutants, as represented in the figure below.

Ideal agricultural catchment buffer zone

Regarding the effectiveness of buffer zones towards pesticides in agriculture, it has shown commendable results. In a study conducted by Asmussen et al. (1997), it was reported that herbicide 2,4-D were reduced along a buffer zone by 77% and 69% in wet and dry conditions. In a similar study by Rohde et al. (1980), there was evidence of trifluralin loss of 96% and 86% in wet and dry conditions. The large reduction of pesticide loss can be attributed to water infiltration, sediment deposition and attachment on vegetative and organic matter.

References:

Muscutt, A., Harris, G., Bailey, S. and Davies, D., 1993. Buffer zones to improve water quality: a review of their potential use in UK agriculture. Agriculture, Ecosystems & Environment, 45(1-2), pp.59-77.

Norris, V., 1993. The use of buffer zones to protect water quality: A review. Water Resources Management, 7(4), pp.257-272.

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#10: Bee Vectoring

Instead of using conventional pesticides to kill pests, there are other ways to protect the health of plants. We can harness the power of our natural pollinators, which are bees! These bees can be recruited to help transport beneficial fungi to plants, so that there is less reliance on pesticides. This is known as bee vectoring.

The addition of fungi would enable the plant to be more resistant to a certain type of pest, just like how an antibiotic increases the human body’s resistance to a type of illness. One such fungi advantageous to plants is Clonostrachys rosea, a naturally occurring fungi which is especially good at combating plant diseases like mould growth on plant fruits. As of now, this bee vectoring technique is commercialised and has been practised on blueberry, strawberry, tomato, almonds and sunflower plants. Many other microbes are being tested to see if they can work well against various kind of pests.

To recruit the bees to carry the right fungus, one can place a box of inoculant-dosed powder right at the entrance of the commercially reared beehive. In order to exit, the bees have to pass through the box of power before leaving. When doing so, the bees will coincidentally dip their legs and bodies into the powder, ultimately delivering them straight to the plant (flower) during pollination.

U.S. EPA approves bee-delivered fungicide | Good Fruit Grower

Bee dipping legs and body in powder fungicide

These fungi works well in protecting the plant health, minimising the use of pesticides. Usually, spraying pesticides in traditional farming is over used and non-target specific, where excess pesticides lead to bioaccumulation and biomagnification when it enters the food chain. Comparing it with bee vectoring, the usage of chemical agents is less wasteful and has a potential in completely replacing pesticide use in the future, if results are positive.

References:

Evans Ogden, L., 2020. Sustainable Farming: Can We Use Less Pesticides For More Environmentally Friendly Agriculture. [online] Bbc.com. Available at: <https://www.bbc.com/future/bespoke/follow-the-food/the-clean-farming-revolution/?referer=https%3A%2F%2Fwww.google.com%2F> [Accessed 17 July 2020].

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#8: Pesticide Case Study: Brazil

Hello everyone! Previously on this blog, much has been mentioned of why farmers choose to use toxic chemicals as well as why they hang around for so long in our environment. Today, we explore more on how pesticides, in this case DDT, is so detrimental to human health, which ultimately led to their ban in the 1970’s in almost all developed countries.

DDT is good for me.” An advertisement for widespread farm, home ...

A poster encouraging the widespread use of DDT

DDT is considered as an endocrine disruptor. Studies have shown that there was reduced sperm count and reduced breastfeeding period. DDT is also suspected of causing spontaneous abortion and premature delivery. DDT’s breakdown product, DDE has also significant evidence for liver cancer mortality. The major source of DDT intake for the general population is through food. Since DDT has a high lipophilicity, food substances like eggs, meat and milk should be most considered when performing studies on DDT intake and its effects.

Biomagnification of DDT in human milk has been observed in parts of Brazil. In the agricultural area of Sao Paulo State, levels of DDT found in human milk was 0.149 mg/kg, was compared with the WHO guidelines of 0.02 mg/kg for cow’s milk. Also, in the capital of Rio Grande do Sul State, 2.98 mg/kg of DDT in human milk was found. The DDT levels in both these studies were high, despite the fact that DDT was prohibited in agricultural use there since 1986.

There aren’t many studies which focus on the fate of DDT which describe the full extent of its harm. However, what we know is they can stay in the environment or in us for a very long time, resulting in bioaccumulation and biomagnification. There are chronic effects which follow from DDT exposure, including hormonal effects.

References:

D.R Vieria, E., P.M Torres, J. and Malm, O., 2001. DDT Environmental Persistence from Its Use in a Vector Control Program: A Case Study. Environmental Reseach, 86(2), pp.174-182.

Photo Credits:

https://www.researchgate.net/figure/DDT-is-good-for-me-An-advertisement-for-widespread-farm-home-and-food-processing-use_fig1_263740149

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#3: Why Pollution of Human Synthesised Chemicals are Widespread

Welcome back! Today we explore why pollution caused by human synthesised chemicals used in agriculture are so widespread.

The key property that these chemicals possess is their PERSISTENCE.

They are usually very stable organic compounds, especially since most of them are halogenated. They do not degrade easily, lasting in the environment for very long periods of time, even up to a few decades. This persistence is also determined by the surrounding environment and climate, where the pesticides persist 3-8 times longer in cold climates compared to temperate ones. Such chemicals contaminate the air, soil and groundwater.

Hence, when such pesticides are applied, they tend to have widespread and prolonged effect on all the humans, wildlife and organisms. At the target site, the pesticides may enter the surface waters or volatilise into air after being sprayed. The excess pesticides applied onto the crops may also leak into groundwater sources. From the surface waters, the pesticides may reach the aquatic organisms, including those in the sediments. From the air, the pesticides may also get deposited onto the soil.

Due to their persistence, the pesticides are able to see through many different stages of natural environment processes to contaminate and remain in air, soil and water sources.

This is a compressed summary, to find out more, head to this link https://www.who.int/ceh/capacity/Pesticides.pdf provided by the World Health Organization.

 

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#2: Why Human Synthesised Chemicals are so Attractive

Hi everyone!

Today we bring to you a short introduction about the usage of toxic chemicals in agriculture, highlighting the more prominent ones, which are so persistent in our environment.

The use of pesticides in agriculture is not something new, in fact it has been with us since 2000BC, where elemental sulfur was used. However, only in the past 100 years or so, did humans create the first man-made pesticides. There were so many advantages of using them.

One of the earliest and most heavily used pesticide was Dichloro-diphenyl-trichloride (DDT). It was first synthesised in 1874 by an Austrian chemist named Othmar Zeidler. After many years, in 1939, Swiss chemist Paul Muller found it to be very effective in killing insects. DDT came rapidly to the United States, with rampant usage of this newly found chemical. For discovering DDT’s unique insecticidal properties, Paul Muller received the Nobel Prize in 1948. Since this discovery was well received, approximately 1,350,000,000 pounds of DDT was used 30 years before its ban in the US. DDT wasn’t expensive yet extremely effective, giving lots of yield to farmers of cotton, soybean and peanut as compared to without the pesticide.

Decades later, DDT is still a ‘silent’ killer

Another really toxic man-made chemical used as herbicides was 2,4-Dichlorophenoxyacetic acid (2,4-D). It got widespread recognition in 1944 and from then on its usage quickly accelerated. 2,4-D was termed as the ‘wonder drug’, where it could kill more weeds than any amount that could possibly grow. Furthermore, the actual food crop (corn) was left untouched!

Amazon.com : Southern Ag Amine 24-D Weed Killer, White Bottle ...

Now we all know why such usage of chemicals in agriculture was so widespread and prevalent.

 

Photo credits:

https://www.sustainability-times.com/environmental-protection/decades-later-ddt-pesticide-is-still-a-silent-killer/

https://weedkillerguide.com/for-lawns/

References:

Archive.epa.gov. 1975. DDT Regulatory History: A Brief Survey (To 1975) | About EPA | US EPA. [online] Available at: <https://archive.epa.gov/epa/aboutepa/ddt-regulatory-history-brief-survey-1975.html> [Accessed 24 June 2020].

Ganzel, B., n.d. Herbicides Like 2,4-D Introduced During The 1940S. [online] Livinghistoryfarm.org. Available at: <https://livinghistoryfarm.org/farminginthe40s/pests_03.html> [Accessed 24 June 2020].

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