Fertilizers and Pesticides: Impacts of Pesticides

Video Transcription

Hi, I'm Jensen Morgan. We're going to talk about some great concepts in environmental science. Today's topic is fertilizers and pesticides. So let's get started.

We're going to talk about what fertilizers and pesticides are used for, what their impacts are, and how to mitigate those impacts. We'll start with fertilizers. Aggro-ecosystems remove nutrients from soils in order to grow crops. Monoculture in particular sucks up large amounts. Therefore, in order for more crops to grow, nutrients have to be added back in.

That's where fertilizers come in. The main nutrients that are needed by plants to grow, and therefore, need to be replaced, are nitrogen and phosphorus, which is why most fertilizers focus on those two nutrients. Unfortunately, fertilizers with these nutrients tend to be expensive and to produce and cause environmental problems through run off. As croplands are irrigated, or if it rains, the fertilizer in the soil drains away into the local water system.

This can cause bodies of water, like this one here, to become polluted and dangerous. It can even sometimes leak into aquifers, contaminating where we source much of our safe drinking water and cause disease. The Chesapeake Bay is a prime example of what can happen when fertilizers run off in high volumes. Phosphorus and nitrogen can cause what is called an algal bloom. Algae loves fertilizers, just like crops.

And when all of it drains into bodies of water like the Chesapeake Bay, huge communities of algae grow, which consume much of the oxygen and can threaten fish populations, because there is not enough oxygen available. This phenomenon has also occurred in the gulf of Mexico, creating an algal bloom as big as some states where it is difficult for aquatic species to survive.

There are ways to address the impacts of fertilizers, like organic farming, which does not use synthetic fertilizer and promotes soil health. Using natural fertilizers like manure can also reduce runoff problems. When farmers change what crops they are planting from year to year, it makes different demands on the soil's mix of nutrients, which promotes soil health and usually requires less added nutrients.

Pesticides are chemicals, which kill undesirable plants, insects, animals, and fungi that hinder crop production. There are a wide variety of pesticides with an equally wide variation in negative environmental impacts. There are four main reasons why pesticides are used. To kill pests carrying disease, kill pests that make a crop look less appetizing, kill pests that damage crop productivity, and to reduce human labor needed to protect the crop. The trick is, the more effective a pesticide is, the more toxic it usually is as well, which means the more danger it is to our environment and our human health.

Take DDT for example, it was a powerful pesticide that was eventually banned because it harmed tons of different animal species, especially baby birds. There are a number of drawbacks to using pesticides. Over time, pests build up a resistance to a certain pesticide, which usually results in a different, stronger and more toxic one being employed. As one goes up the food chain, the process of consumption can concentrate certain pesticides into high quantities, making it dangerous for higher level consumers, especially humans, to eat.

Pesticides can indirectly kill species not originally targeted, drain into the water systems, contaminate soil, and mess up animals' hormonal systems. Atrazine is a prime example of a pesticide with dangerous effects. Atrazine is the number one used pesticide in the world. Yet, it was banned in the EU when scientists discovered its presence in drinking water and the harmful effects it can have on animals.

The impacts of pesticide can be decreased by using alternatives such as planting crops which attract pests away from the more valuable crop, by rotating crops or planting a diversity of crops to disrupt insect cycles, by using integrated pest management-- which is the practice of utilizing natural predators, parasites, and pheromones to disrupt insect cycles. Farmers can become organic, which avoids or reduces synthetic pesticides. They can use biological controls, which can disrupt pests mating through things like pheromones. And they can even plant GMO crops, which have been engineered with pest repellent inside them.

Now, let's have a recap. Today we talked about how fertilizers are chemicals used to add nutrients to the soil to improve crop productivity. We talked about how pesticides are chemicals used to kill and deter pests from interfering with crop productivity. We talked about the various negative environmental impacts of both, and the different ways to mitigate those impacts.

Well, that's all for this tutorial. I hope these concepts were helpful. I look forward to next time. Bye.