The Effects of Fertilizer Runoff
Fertilizer Use Revolutionized Food Production
Have you ever wondered why so many people are concerned about the use of fertilizer in agriculture and the impact of field runoff on the environment? Let’s talk about it for a minute.
The use of fertilizer in agricultural practices revolutionized food production and helped to build modern society as we know it today. From the big, industrialized farms to the little organic plots, most producers improve the efficiency of their soil by adding sources of Nitrogen, Phosphorous, and Potassium (N, P, and K) to their cultivation practices. These traditions have been in place since the beginning of modern farming and make it possible to feed the world.
A field can only hold as much fertilizer as its soil can capture. Soil is made up of sand, silt, and clay. Each of these structures have different sizes and qualities. They mix together to form the soil’s texture. This texture informs how a soil behaves: how crop roots develop, how much water the soil can hold, how well the field drains, and how much fertilizer can the soil structure hold. Soil is only capable of holding a certain amount of nutrients based its structure. Fertilizer compounds that are not contained and held by the soil structures dissolve into the water of the field and are carried away as fertilizer runoff. It does not matter if the fertilizer is organic or not. All added nutrients to soil have the potential to become runoff.
Lost Nutrients Increase Costs
Fertilizer runoff is a concern for both farmers and environmentalists. Nutrients lost from fields are wasted resources for farmers. These inefficiencies created unnecessary operational costs and limit the profitability of a farm. The environmental impact of runoff is a concern for everyone in the community, including the farmer. When the nutrients in fertilizer flow into local bodies of water, they can have damaging effects on local wildlife and water quality.
The nutrients found in fertilizers are not just good for crop growth. They encourage natural biological growth as well. Normally, more growth from fertilizer would be a good thing. However, natural systems, like rivers and lakes, have a balanced ecosystem that keeps them healthy and clean. When fertilizer leaves a field and enters these systems, the balance is thrown off. N, P, and K nutrients are naturally present in these bodies of water in very small amounts. The concentrations found in field runoff are typically much higher than an ecosystem is used to. Bacteria and algae grow extremely quickly using fertilizer nutrients. As their population explodes, the quality of the water decreases. The water becomes too toxic for fish and other aquatic life to live in the system. Eventually, the water begins to stink, turn green, and become unsafe for humans to use.
Nutrients in Runoff Create Toxic Effects
The scary thing about this effect is that it does not stay in the local river. All rivers flow to bigger bodies of water, and those nutrients travel with them. As they flow downstream, more runoff from other fields is added to the river until it reached its end point. In the United States, this is typically an ocean or one of the Great Lakes. When all of the nutrients from all of the field runoff reach those big bodies of water, we see the same algae and bacteria growth we saw in the local river on a massive scale. This growth is what causes large algae blooms in the Gulf of Mexico and on the Great Lakes. The water surrounding these blooms becomes so toxic, so quickly that mass die offs of local fish and plants occur. The blooms also make the water unsafe for humans to use or even touch in some cases. This effect is commonly referred to as hypoxia. It can cause problems at home and even bigger ones downstream.
In case you were curious about why so many people are talking about the problems of agriculture runoff, these are some of the reasons why.
I have a bachelor’s and a master’s degree in agricultural engineering from Purdue University and am currently working on my doctorate. My research focuses on improving the productivity of small scale local producers and new farmers entering agriculture. I believe that strong and clear communication between educational bodies and agricultural producers can provide the tools and opportunities to build a better tomorrow.