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Home > Protecting Our Lands & Waters > Conservation > Conservation Practices > Nutrient Management

Conservation Practices
Minnesota Conservation Funding Guide


Nutrient Management

 

Taking soil samples for laboratory analysis. Photo Karl Hakanson.
Taking soil samples for laboratory analysis. Photo Karl Hakanson.

Using GPS maps for more precise nutrient application. Photo courtesy Univ of Wisconsin Extension.
Using GPS maps for more precise nutrient application. Photo courtesy Univ of Wisconsin Extension.

Nutrient management requires keeping and using good records. Photo Karl Hakanson.
Nutrient management requires keeping and using good records. Photo Karl Hakanson.

Nutrient management is using crop nutrients as efficiently as possible to improve productivity while protecting the environment. Nutrients that are not effectively utilized by crops have the potential to leach into groundwater or enter nearby surface waters via overland runoff or subsurface agricultural drainage systems. Too much nitrogen or phosphorus can impair water quality. Therefore, a major principle of crop nutrient management is to prevent the over-application of nutrients. This not only protects water quality but also benefits a farm's bottom line.

The keys to effective crop nutrient management are developing and following a yearly plan and conducting soil tests to determine the nutrient needs of crops. (Increasingly, soil nitrate testing before applying fertilizer and plant tissue testing are also used.) It is essential to keep good records on the rate, method and timing of all nutrient applications. It is also important to note the source of the nutrients, be they purchased fertilizers, manure or other bio-solids, legumes or irrigation water. Residual nutrients in the soil must also be accounted for. Keeping good records help farmers compare expenses and returns from year to year. In short, good records provide solid information that helps farmers and crop consultants decide whether and how to adjust nutrient application rates, methods and timing.

Another important element of nutrient management is to consider the application rates recommended by private or public sector specialists. In 2006, the University of Minnesota Extension estimated that 86% of Minnesota farmers could save more than $6/acre and 56% could save more than $10/acre in fertilizer costs by following UM recommended rates. This was based on calculations by roughly 700 Minnesota farmers who prepared their own nutrient management plans at Extension workshops.

There are many ways to fine-tune or modify nutrient application rates, methods and timing to ensure that nutrients are used as efficiently as possible. Below are some examples:

  • Banding, side-dressing and injection are examples of methods to place nutrients where they are most likely to be used by plants. Cover crops or green manures can be used to similar effect; they help nutrients stay in the soil where plants can use them.
  • GPS grid sampling and flow meters are used to tailor nutrient application rates to the needs of each soil type rather than using the same rate across an entire field. This is called variable-rate application; it is an important technique because farm fields (especially larger fields) typically contain several soil types.
  • Examples of strategies related to timing include (1) splitting the total amount of fertilizer into two or more applications during the growing season, rather than applying it all at once and (2) avoiding fall application of nitrogen altogether (i.e., applying it in the spring, closer to when crops need it). The latter is especially important in southeastern Minnesota where fractured bedrock (karst geology) increases the risk of nitrates leaching into groundwater.

For water quality purposes, nutrient management is especially important on slopes, on soils with high phosphorus levels and in environmentally sensitive areas. Sensitive areas include shoreland (land near rivers, stream, lakes and wetlands), areas around sinkholes, wells and surface drainage inlets, areas with sandy soil or shallow soil over bedrock (especially fractured bedrock) and wherever groundwater is close to the surface.

Why practice nutrient management on your farm?

  • Enhances profitability by significantly reducing purchased fertilizer costs
  • Protects surface water quality by minimizing nutrients, organic matter and pathogens in agricultural runoff
  • Protects groundwater in wellhead protection areas from nitrate contamination
  • Aids compliance with Minnesota feedlot regulations, which limit manure application rates
  • Improves soil quality and productivity by increasing nutrient retention and water holding capacity and enhancing soil structure
  • May improve air quality by reducing ammonia emissions
  • Helps protect public health when nutrient application occurs near municipal or domestic wells, residences, businesses, schools and public lands

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Similar & related practices

  • Crop nutrient management is an important component of comprehensive nutrient management planning for livestock operations. Crop nutrient management often includes manure management and is most effective together with upland erosion and runoff control practices such as conservation tillage, cover crops andconservation crop rotations.
  • Nutrient management should be coordinated with pest management so as to integrate both sets of management strategies into an agricultural production system.
  • Conservation buffers such as grass filter strips are important complementary practices. Whereas nutrient management helps minimize the amount of nutrients leaving farm fields, buffers provide a second defense against water pollution by trapping and filtering nutrients that do leave the field.
  • Nutrient management is often used in wellhead protection areas (areas that supply water to public wells and receive special attention from state and local agencies to prevent contamination of drinking water).
  • A related practice is the use of restored wetlands or constructed wetlands to receive and filter nutrients in agricultural runoff.

More information

Guidance from USDA Natural Resources Conservation Service (NRCS)

Other resources

Nitrogen

Phosphorus

Nutrient Management in General

Service providers

Also see Manure Management and Conservation Planning resources.

Contact

See contacts for specific programs that fund this practice in the side-by-side payment comparison or contact your local Soil and Water Conservation District