Many states in the Mississippi River Basin are developing a statewide nutrient reduction strategy at the request of the Environmental Protection Agency. This initiative outlines strategies or management practices to reduce nutrient loading into the Mississippi River and, ultimately, in the Gulf of Mexico.
Each year, the gulf receives runoff nutrients, which help create a hypoxia zone. The nutrients feed aquatic plants that die and start to decay. As these plants decay, they use up available oxygen in the water until the area has a very low oxygen level and will not support most forms of aquatic life.
As fish leave the area of low oxygen and other aquatic life die from the lack of oxygen, the area is sometimes referred to as a “dead zone.” The hypoxia zone in the Gulf of Mexico varies in size each year but averages approximately 6,800 square miles (somewhere in size between Connecticut and New Jersey).
The loss of nutrients comes from many sources, but in agriculture the commercial fertilizer and livestock manure we put on our fields is a ready source of nutrient runoff. Each year, farms spend millions of dollars on fertilizer, and without some proper management, much of the nutrient value of that fertilizer can leave the fields and relocate itself in the Gulf of Mexico.
This is a fairly extensive journey for nitrogen and phosphorus when you consider that the Mississippi River Basin has part of 37 different states and is the third-largest drainage area in the world.
From an environmental concern, nutrients can cause major water quality issues, such as decreased water quality, habitat degradation, hypoxia and increased algae in rivers, streams and lakes. Aquatic plants respond to these higher levels of nutrients and grow just like well-fertilized corn or grass. But that generally isn’t the main concern for most farmers.
The loss of nutrients through runoff or leaching means a loss of plant food. Farmers who buy commercial fertilizer or livestock manure recognize the value of the product they buy, and if we aren’t properly applying the nutrients or taking measures to reduce runoff, we are not only creating an environmental concern but letting costly nutrients float on down the river.
Fertilizer is the single largest expense for most producers, whether that expense is producing a crop to sell or producing feed for livestock. The more nutrients we place on fields and pastures that aren’t utilized by the plant, the more money we are wasting.
As many of the states in the Mississippi River Basin look at developing nutrient management plans, the focus is not only on environmental protection but also on economic efficiency and the selection of management practices that are feasible for farming operations.
Missouri is developing a selection of practices that have been proven to reduce the potential for nutrient runoff and leaching. These practices, in many cases, are those the producer would want to implement.
The practices should be cost-effective and provide a level of environmental protection to the state’s waterways. The selection of practices is not limited to just a few but are practices that have been identified as workable with many farming operations.
Farmers can select to use individual practices or to use them in combination to achieve a greater benefit of nutrient runoff protection. These practices need to be approached and designed as tools used by farmers in the process to manage nutrients.
Missouri has built much of its nutrient strategy on the following:
- 4-R strategy – right fertilizer source, right rate, right time and right place
- Rotational grazing
- Alternative watering area/sources
- Even distribution of livestock manure
- Variable-rate/precision application of nutrients
- Cover crop application for nutrient management
It is necessary to understand soil properties, soil types and weather patterns, along with a series of other items. The practices combine plant nutrient needs and, in many cases, certain structural or mechanical practices that can help reduce nutrient loading into waterways. Selection of practices must be based on the specific characteristics of individual farms and fields and address efficiency and productivity.
Missouri is using the 4-R nutrient strategy as a key management practice. The 4-R strategy is based on right fertilizer source, at the right rate, at the right time and in the right place. Following this process helps to protect the environment while maximizing production.
Whether the source of nutrients is commercial fertilizers or manure, knowing the nutrient value is an important first step in making sure you maximize nutrients for plant growth without overapplying.
When performing any type of nutrient management, understanding the needs of the plant for proper growth and development helps us determine the right rate of nutrients needed and the right timing of those nutrients. If we provide a higher level of nutrients than the plants need, the part not needed for growth by the plant can either leach into the ground or run off with storm water.
Those nutrients aren’t doing the plants any good, and their economic value is lost. Variable-rate application of nutrients can provide more accurate distribution based on plant need and uptake and may reduce the overall amount of nutrients being applied.
Another component is implementing a suite of management practices that help to keep the nutrients in the right place. This would include a series of management practices such as set-back distances, type of application, variable-rate application and erosion control structures.
If the practices selected are aligned with the farming operation, farmers are more likely to implement and maintain the practices. This will not only reduce the potential for nutrient runoff but will reduce the economic input of lost fertility to crops and pasture.
Private companies, universities and commodity groups are developing tools to assist producers with managing nutrient loading. The University of Missouri Extension Commercial Agriculture program has developed a nutrient management homepage .
This website is a listing of tools designed to assist producers in proper application of nutrients. The recommendations can be based on either nitrogen or phosphorus use and uses plants’ nutrient needs for determining application.
The University of Missouri Nutrient Management Tracker web tool (found at the website listed above) allows the producer to delineate fields, incorporate soil survey information, establish weather pattern data and estimate set-back distances. With this information available, nutrient application and planning becomes much easier for the producer in properly utilizing nutrients and maximizing productivity.
Nutrient runoff isn’t just an environmental concern for farmers but is a waste of finances as expensive nutrients wash off the land. Producers who recognize the economic benefit of nutrient management planning also get the extra benefit of reducing environmental problems and protecting water quality. PD
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Bob Bronz
- Water Quality Specialist
- University of Missouri Extension
