In discussing agricultural pollution, and the story of agriculture, we begin with soil, as from the soil springs the basis for the biodiversity of all land-based life on this planet. Soil is the first part of an evolutionary process that begins when bare rocks are colonized by certain species that scientists refer to as pioneer species (for example, lichens and mosses). As lichens and mosses live and die, they decay, and then get replaced by new generations of lichens and mosses.
This is how the process begins. The decay just keeps building up, bit by bit, and over time it builds up into the first layer of what we call humus,- which is the first step in the creation of soil. As these humus layers continue to build up, herbaceous vegetation finally comes along, then shrubs, and then finally trees. .
This is a process that can take hundreds, or even thousands of years. It is the process of how soil becomes the basis for an entire ecosystem,- contributing to plant, animal, and microbial diversity. The health of our soil is a large indicator of the health of our environment. It is important for us to take care of it.
Referred to as soil degradation, there are a number of ways that mismanaged agricultural practices can deplete the soil, and cause a loss of organic material. An important example is when pesticides, herbicides, and fertilizers are applied to agricultural land, and, then accumulate in the soil over time.
This accumulation in the soil can be harmful because it can alter microbial processes, and be toxic to the organisms that normally live there. These same pesticides can be ingested, not only by the insects that are being targeted as pests, but also by random insects and animals that are not being targeted, simply because of the way the chemicals are applied in a blanketed fashion across entire agricultural fields.
The effects are far reaching. With these all-inclusive, blanketing losses, also comes a great loss in biological diversity. This loss impacts the microbial communities as well as all the different kinds of insects and animals that live in the soil, and also results in the disappearance of many different stages and types of vegetation.
All of these impact areas are frequently cited as major causes of soil degradation. A final outcome of soil depletion is often soil erosion. With the population of the world now exceeding over 7 billion people, scientists today estimate that half of the top soil available on the planet has already been lost.
Another important way that agriculture can impact the environment occurs when excessive amounts of rainfall washes the chemicals and residues underground, where it contaminates groundwater, or carries them into streams and rivers. When they eventually reach the ocean, they can create oxygen-deprived “dead zones” in the aquatic environment.
A very similar challenge is posed by agricultural animal waste. Today, industrial and intensive farming dominates livestock production. Nearly all the meat, poultry and dairy products come from large-scale industrial operations where thousands of cattle, pigs and chickens are kept in cramped, confined conditions, and they produce huge volumes of waste.
Similarly to the situation involving the pesticides and fertilizers mentioned, if they are not carefully controlled, toxic contaminants from these animal waste systems can find their way into groundwater and waterways, polluting drinking water and killing aquatic life. And just like fertilizer and pesticide runoff, toxic manure effluent is a major contributor of pollutants to lakes and rivers, as well as contributing to creating oxygen-deprived dead zones along the coast.
“Worldwide demand for palm and soy are among the most significant agricultural drivers of deforestation threatening tropical rainforests.”
In addition to the loss of soil, biodiversity, and vegetation that can occur in association with agriculture, the loss of trees has a significant impact on the environment, and importantly, a direct relationship with the issue of global warming. Deforestation is what occurs when large strands of trees are cut down to make room for urban development, industrial development, or to make room for agricultural needs, such as the grazing of cattle or the growing of crops. How does deforestation, and the loss of trees, contribute to global warming? The answer is that trees absorb carbon dioxide, mitigating and partially offsetting the greenhouse gas emissions produced by burning fossil fuels.
Scientists refer to this process as “carbon sequestration,” and it is defined as the capture and storage of excess carbon dioxide. Since trees play an important role in carbon sequestration, we refer to our forests as “carbon sinks” because they remove and store harmful carbon dioxide. Of all trees around the world, tropical trees alone are estimated to provide a large share of the climate mitigation that’s needed to offset climate change.
But the process of removing trees to create farmland, whether it is for growing crops, or for grazing cattle, not only removes the vegetation we need to offset climate change, it actually contributes to it. This is because sometimes instead of being clear-cut, forest land is sometimes cleared by controlled burning. During this process, the act of clearing forests by burning them actually has the opposite effect of storing carbon,- by releasing stored carbon. That’s right,- the smoke from burning trees contains all of the carbon that has been stored inside the trees for all of the years that they’ve been growing. As a combination of these reasons, the Food and Agriculture Organization of the United Nations tells us that deforestation is the overall second-leading cause of climate change.
The causes of deforestation are varied and many, but the needs of the agricultural sector provide the primary incentive to cut down trees, with the most significant drivers being soy beans, palm oil, and cattle ranching. And while this deforestation is occurring on a ongoing basis, there are a number of ways that modern agricultural practices additionally contribute to the global warming equation.
For example, the fertilizers used on crops emit the greenhouse gas, methane. Furthermore, according to the Food and Agriculture Organization of the United Nations, the animal agriculture sector, which includes the production of feed crops for animals, the manufacturing of fertilizer, as well as the shipment of meat, eggs, and milk, is a primary contributor of green house gas emissions.
These green house gas emissions come from a broad spectrum of sources related to animal agriculture, including methane emissions directly from the livestock, carbon emissions resulting from their transport, as well as emissions from the decay of their organic waste, including manure used as fertilizer on crops.
By contributing green house gases, animal agriculture is literally choking the life out of our planet, slowly, and the longer we ignore it, the deeper in we get, and the more we limit our ability to protect our health and save the environment. Raising livestock for meat, eggs and milk generates a significant percentage of global greenhouse gas emissions, and is a major contributing factor to global warming.
“When trees are burned to make room for animals to graze, carbon dioxide is released into the atmosphere, and methane, another greenhouse gas, is released with the animal waste.”
References and Resources:
The Food and Agriculture Organization of the United Nations is a specialized agency of the United Nations that leads international efforts to defeat hunger and improve nutrition and food security.
From the U.S. Environmental Protection Agency. Farmers apply nutrients on their fields in the form of chemical fertilizers and animal manure, which provide crops with the nitrogen and phosphorus necessary to grow and produce the food we eat. However, when nitrogen and phosphorus are not fully utilized by the growing plants, they can be lost from the farm fields and negatively impact air and downstream water quality.
The European Network for the Durable Exploitation of Crop Protection Strategies aims to develop science-based sustainable, innovative pest control strategies to reduce pesticide use in agriculture.
Collection of indicators, reports, links, data sets and targets on topics related to European agriculture and the environment.
Mission is to create environmentally and economically sustainable rural communities and regions through sound agriculture and trade policy. Supporting sustainable agriculture, reduced pesticide use, and related practices.
LADSS is an agricultural research tool being developed to assist in the investigation of policy and environmental change impacts such as CAP reform and climate change.
Research in natural systems agriculture featuring perennial grain polycultures using nature as its measure.
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