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Fertilizers and Pesticides: Impacts of Fertilizers

Fertilizers and Pesticides: Impacts of Fertilizers

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Author: Sophia Tutorial
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Identify the positive and negative effects of fertilizers.

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Tutorial

what's covered
This tutorial will cover the topic of fertilizers and pesticides. We will discuss what fertilizers and pesticides are used for, what their impacts are, and how to mitigate those impacts.

Our discussion breaks down as follows:

  1. Fertilizers
  2. Addressing the Impact of Fertilizers
  3. Pesticides
  4. Addressing the Impact of Pesticides


1. Fertilizers

Agroecosystems remove nutrients from soils in order to grow crops. This is especially true with the practice of monoculture, which removes large amounts of nutrients from soil. Therefore, in order for more crops to grow, nutrients have to be added back in, which is where fertilizers enter the equation. The main nutrients that are needed by plants to grow, and therefore need to be replaced, are nitrogen and phosphorus, so most fertilizers focus on those two nutrients.

Fertilizer

Unfortunately, fertilizers with these nutrients tend to be expensive to produce, and they cause environmental problems through runoff. 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 the one shown below, to become polluted and dangerous. It can even sometimes leak into aquifers, contaminating where we source much of our safe drinking water, and then can cause disease.

Water Polluted By Runoff

IN CONTEXT

The Chesapeake Bay is a prime example of what can happen when fertilizer runoff occurs in high volumes. Phosphorus and nitrogen can cause what is called an algal bloom. Algae loves fertilizers, just like crops, and when large amounts of fertilizer drain into bodies of water like the Chesapeake Bay (shown below), huge communities of algae grow. Algal blooms consume much of the oxygen and can threaten fish populations, because there is not enough oxygen available.

Chesapeake Bay

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.

Dead Zone


2. Addressing the Impact of Fertilizers

There are ways to address the impacts of fertilizers.

Efforts to Address the Impact of Fertilizers Effect
Organic farming Organic farming does not use synthetic fertilizer and promotes soil health.
Manure Using natural fertilizers like manure can also reduce runoff problems.
Changing crops 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.


3. Pesticides

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 eliminate pests carrying disease
  • To eliminate pests that make a crop look less appetizing (crop aesthetic)
  • To eliminate pests that damage crop productivity
  • To reduce human labor needed to protect the crop

hint
The more effective a pesticide is, the more toxic it usually is as well, which means the more dangerous it is to our environment and our human health.

EXAMPLE

The pesticide DDT was a powerful pesticide that was eventually banned because it harmed many different animal species, especially baby birds.

There are a number of drawbacks to using pesticides.

  • Resistance: Over time, pests build up a resistance to a certain pesticide, which usually results in a different, stronger, and more toxic one being employed.
  • Human health: 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.
  • Harms other species: Pesticides can indirectly kill species not originally targeted, drain into the water systems, contaminate soil, and disrupt animals' hormonal systems.

did you know
Pesticides can also decrease ecological populations and reduce biodiversity!

IN CONTEXT

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 in 2004 when scientists discovered its presence in drinking water and the harmful effects it can have on animals.


4. Addressing the Impact of Pesticides

The impacts of pesticide can be decreased by using alternatives such as:

Pesticide Alternatives Effect
Insect Attractors Planting crops which attract pests away from the more valuable crop
Crop Rotation Rotating crops or planting a diversity of crops to disrupt insect cycles
Integrated Pest Management The practice of utilizing natural predators, parasites, and pheromones to disrupt insect cycles
Organic Farming Avoids or reduces synthetic pesticides
Biological Controls Disrupts pests from mating by utilizing substances like pheromones
GMOs Planting genetically modified crops, which have been engineered with pest repellent inside them

Integrated Pest Management


summary
Today we learned about fertilizers, which are chemicals used to add nutrients to the soil to improve crop productivity. We also learned about pesticides, which are chemicals used to kill and deter pests from interfering with crop productivity. We explored the various negative environmental impacts of both, and the different ways to mitigate those impacts.

Source: Adapted from Sophia instructor Jensen Morgan, FERTILIZER CC HTTP://BIT.LY/1YV8EID RUN-OFF PD HTTP://BIT.LY/1UR6B6H CHESAPEAKE PD HTTP://BIT.LY/1CSUKH5 DEAD ZONE PD HTTP://BIT.LY/167KXKC PESTICIDES PD HTTP://BIT.LY/1K3FZYT PEST MANAGEMENT PD HTTP://BIT.LY/1BVMSFZ