Nutrient Management Measure and Irrigation Systems

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Nutrient Management Measure

Develop, implement, and periodically update a nutrient management plan to: (1) apply nutrients at rates necessary to achieve realistic crop yields, (2) improve the timing of nutrient application, and (3) use agronomic crop production technology to increase nutrient use efficiency. When the source of the nutrients is other than commercial fertilizer, determine the nutrient value and the rate of availability of the nutrients. Determine and credit the nitrogen contribution of any legume crop. Soil and plant tissue testing should be used routinely. Nutrient management plans contain the following core components:

* Farm and field maps showing acreage, crops, soils, and waterbodies.
* Realistic yield expectations for the crop(s) to be grown, based primarily on the producer’s actual yield history, State Land Grant University yield expectations for the soil series, or SCS Soils-5 information for the soil series.
* A summary of the nutrient resources available to the producer, which at a minimum include:
* Soil test results for pH, phosphorus, nitrogen, and potassium;
* Nutrient analysis of manure, sludge, mortality compost (birds, pigs, etc.), or effluent (if applicable);
* Nitrogen contribution to the soil from legumes grown in the rotation (if applicable); and
* Other significant nutrient sources (e.g., irrigation water).
* An evaluation of field limitations based on environmental hazards or concerns, such as:

* Sinkholes, shallow soils over fractured bedrock, and soils with high leaching potential,
* Lands near surface water,
* Highly erodible soils, and
* Shallow aquifers.
* Use of the limiting nutrient concept to establish the mix of nutrient sources and requirements for the crop based on a realistic yield expectation.
* Identification of timing and application methods for nutrients to: provide nutrients at rates necessary to achieve realistic crop yields; reduce losses to the environment; and avoid applications as much as possible to frozen soil and during periods of leaching or runoff.
* Provisions for the proper calibration and operation of nutrient application equipment.

1. Applicability

This management measure is intended to be applied by States to activities associated with the application of nutrients to agricultural lands. Under the Coastal Zone Act Reauthorization Amendments of 1990, States are subject to a number of requirements as they develop coastal nonpoint programs in conformity with this measure and will have some flexibility in doing so. The application of management measures by States is described more fully in Coastal Nonpoint Pollution Control Program: Program Development and Approval Guidance, published jointly by the U.S. Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA) of the U.S. Department of Commerce.

2. Description

The goal of this management measure is to minimize edge-of-field delivery of nutrients and minimize leaching of nutrients from the root zone. Nutrient management is pollution prevention achieved by developing a nutrient budget for the crop, applying nutrients at the proper time, applying only the types and amounts of nutrients necessary to produce a crop, and considering the environmental hazards of the site. In cases where manure is used as a nutrient source, manure holding areas may be needed to provide capability to avoid application to frozen soil.

This measure may result in some reduction in the amount of nutrients being applied to the land, thereby reducing the cost of production as well as protecting both ground water and surface water quality. However, application of the measure may in some cases cause more nutrients to be applied where there has not been a balanced use of nutrients in the past. This will usually allow all the nutrients to be used more efficiently, thereby reducing the amount of nutrients that will be available for transport from the field during the non-growing season. While the use of nutrient management should reduce the amount of nutrients lost with surface runoff to some degree, the primary control for the transport of nutrients that are attached to soil particles will be accomplished through the implementation of erosion and sediment control practices (Section II.A of this chapter). For information regarding the potential problems caused by nutrients see Section I.F.1 of this chapter.

Operation and Maintenance for Nutrient Management

The use of a nutrient management plan requires accurate information on the nutrient resources available to the producer. Management practices typically used to obtain this information include periodic soil testing for each field; soil and/or tissue testing during the early growth stages of the crop; and testing of manure, sludge, and irrigation water if they are used. The plan may call for multiple applications of nutrients that require more than one field operation to apply the total nutrients needed by the crop.

A nutrient management plan should be reviewed and updated at least once every 3 years, or whenever the crop rotation is changed or the nutrient source is changed. Application equipment should be calibrated and inspected for wear and damage periodically, and repaired when necessary. Records of nutrient use and sources should be maintained along with other management records for each field. This information will be useful when it is necessary to update or modify the management plan.

3. Management Measure Selection

This management measure was selected as a method (1) to minimize the amount of nutrients entering ground water through root zone leaching and entering surface water from edge-of-field delivery and (2) to promote more efficient use of all sources of nutrients that are available to the producer. The practices and concepts that can be used to implement this measure on a given site are those commonly used and recommended by States and USDA for general use on agricultural lands. By implementing the measure using the necessary mix of practices for a given site there should not be a negative economic impact on the operator, and in most cases the impact will be positive. Many of the practices that can be used to implement this measure may already be required by Federal, State, or local rules (e.g., field borders along streams) or may otherwise be in use on agricultural fields. Since many producers may already be using systems that satisfy or partly satisfy the intent of this management measure, the only action that may be necessary will be to determine the effectiveness of the existing practices and add additional practices, if needed. Use of existing practices will reduce the time, effort, and cost of implementing this measure.

4. Effectiveness Information

Following is a summary of information regarding pollution reductions that can be expected from installation of nutrient management practices.

The State of Maryland estimates that average reductions of 34 pounds of nitrogen and 41 pounds of phosphorus per acre can be achieved through the implementation of nutrient management plans (Maryland Department of Agriculture, 1990). These average reductions may be high because they apply mostly to farms that use animal wastes; average reductions for farms that use only commercial fertilizer may be lower. The reduction in the loading of these nutrients to coastal waters is difficult to measure or predict. Field-scale and watershed models, however, can be used to estimate the reduction in nutrients moving to the edges of fields and to ground water.

As of July 1990, the Chesapeake Bay drainage basin States of Pennsylvania, Maryland, and Virginia reported that approximately 114,300 acres (1.4 percent of eligible cropland in the basin) had nutrient management plans in place (USEPA, 1991a). The average nutrient reductions of total nitrogen and total phosphorus were 31.5 and 37.5 pounds per acre, respectively. The States initially focused nutrient management efforts on animal waste utilization. Because initial planning was focused on animal wastes (which have a relatively high total nitrogen and phosphorus loading factor), estimates of nutrient reductions attributed to nutrient management may decrease as more cropland using only commercial fertilizer is enrolled in the program.

In Iowa, average corn yields remained constant while nitrogen use dropped from 145 pounds per acre in 1985 to less than 130 pounds per acre in 1989 and 1990 as a result of improved nutrient management (Iowa State University, 1991b). In addition, data supplied from nitrate soil tests indicated that at least 32 percent of the soils sampled did not need additional nitrogen for optimal yields (Iowa State University, 1991b).

In a pilot program in Butler County, Iowa, 48 farms operating 25,000 acres reduced fertilizer nitrogen use by 240,000 pounds through setting realistic yield goals by soils, giving appropriate crop rotation and manure credits, and some use of the pre-sidedress soil nitrate test (Hallberg et al., 1991). Other data from Iowa showed that in some areas fields have enough potassium and phosphorus to last for at least another decade (Iowa State University, 1991b).

In Garvin Brook, Minnesota, fertilizer management on corn resulted in nitrogen savings of 29 to 49 pounds per acre from 1985 to 1988 (Wall et al., 1989). In this Rural Clean Water Program (RCWP) project, fertilizer management consisted of split applications and rates based upon previous yields, manure application, previous crops, and soil test results.

Berry and Hargett (1984) showed a 40 percent reduction in statewide nitrogen use over 8 years following introduction of improved fertilizer recommendations in Pennsylvania. Findings from the RCWP project in Pennsylvania indicate that, for 340 nutrient management plans, overall recommended reductions (corn, hay, and other crops) were 27 percent for nitrogen, 14 percent for phosphorus, and 12 percent for potash (USDA-ASCS, 1992a). Producers achieved 79 percent of the recommended nitrogen reductions and 45 percent of the recommended phosphorus reductions.

In Vermont, research suggests that a newly introduced, late spring soil test results in about a 50 percent reduction in the nitrogen recommendation compared to conventional technologies (Magdoff et al., 1984). Research in New York and other areas of the Nation documents fertilizer use reductions of 30 to 50 percent for late spring versus preplant and fall applications, with yields comparable to those of the preplant and fall applications (Bouldin et al., 1971).

USDA reports that improved nutrient management has resulted in nitrogen application reductions of 33.1 pounds/acre treated for surface water protection, 28.4 pounds/acre treated for ground water protection, and 62.1 pounds of phosphorus per acre treated for water quality protection in its 16 Water Quality Demonstration Projects and 74 Hydrologic Unit Areas (USDA, 1992). The Hydrologic Unit Areas begun in 1990 show the greatest reductions in fertilizer use per acre (Table 2-13).

A summary of the effectiveness of nutrient management in controlling nitrogen and phosphorus is given in Table 2-14. This summary is based on an extensive search of the published literature.

5. Nutrient Management Practices

As discussed more fully at the beginning of this chapter and in Chapter 1, the following practices are described for illustrative purposes only. State programs need not require implementation of these practices. However, as a practical matter, EPA anticipates that the management measure set forth above generally will be implemented by applying one or more management practices appropriate to the source, location, and climate. The practices set forth below have been found by EPA to be representative of the types of practices that can be applied successfully to achieve the management measure described above.

Following are practices, components, and sources of information that should be considered in the development of a nutrient management plan:

1. Use of soil surveys in determining soil productivity and identifying environmentally sensitive sites.
2. Use of producer-documented yield history and other relevant information to determine realistic crop yield expectations. Appropriate methods include averaging the three highest yields in five consecutive crop years for the planning site, or other methods based on criteria used in developing the State Land Grant University’s nutrient recommendations. In lieu of producer yield histories, university recommendations based on interpretation of SCS Soils-5 data may be used. Increased yields due to the use of new and improved varieties and hybrids should be considered when yield goals are set for a specific site.
3. Soil testing for pH, phosphorus (Figure 2-11), potassium, and nitrogen (Figure 2-12).
4. Plant tissue testing.
5. Manure (Figure 2-13), sludge, mortality compost, and effluent testing.
6. Use of proper timing, formulation, and application methods for nutrients that maximize plant utilization of nutrients and minimize the loss to the environment, including split applications and banding of the nutrients, use of nitrification inhibitors and slow-release fertilizers, and incorporation or injection of fertilizers, manures, and other organic sources.
7. Use of small grain cover crops to scavenge nutrients remaining in the soil after harvest of the principal crop, particularly on highly leachable soils. Consideration should be given to establishing a cover crop on land receiving sludge or animal waste if there is a high leaching potential. Sludge and animal waste should be incorporated.
8. Use of buffer areas or intensive nutrient management practices to manage field limitations based on environmentally high risk areas such as:

* Karst topographic areas containing sinkholes and shallow soils over fractured bedrock;
* Lands near surface water;
* High leaching index soils;
* Irrigated land in humid regions;
* Highly erodible soils;
* Lands prone to surface loss of nutrients; and
* Shallow aquifers.
* Control of phosphorus losses from fields through a combination of the Erosion and Sediment Control Measure (Section II.A of this chapter) and the Nutrient Management Measure. Limit manure and sludge applications to phosphorus crop needs when possible, supplying any additional nitrogen needs with nitrogen fertilizers or legumes. If this is not practical, route excess phosphorus in manures or sludge to fields that will be rotated into legumes, to other fields that will not receive manure applications the following year, or to sites with low runoff and low soil erosion potential.
* A narrative accounting of the nutrient management plan that explains the plan and its use.

6. Cost Information

In general, most of the costs are associated with providing additional technical assistance to landowners to develop nutrient management plans. In many instances landowners can actually save money by implementing nutrient management plans. For example, Maryland has estimated (based on the over 750 nutrient management plans that were completed prior to September 30, 1990) that if plan recommendations are followed, the landowners will save an average of $23 per acre per year (Maryland Dept. of Agriculture, 1990). The average savings may be high because most plans were for farms using animal waste. Future savings may be reduced as more farms using commercial fertilizer are included in the program.

In the South Dakota RCWP project, the total cost (1982-1991) for implementing fertilizer management on 46,571 acres was $50,109, or $1.08 per acre (USDA-ASCS, 1991a). In the Minnesota RCWP project, the average cost for fertilizer management for 1982-1988 was $20 per acre (Wall et al., 1989). Assuming a cost of $0.15 per pound of nitrogen, the savings in fertilizer cost due to improved nutrient management on Iowa corn was about $2.25 per acre as rates dropped from 145 pounds per acre in 1985 to about 130 pounds per acre in 1989 and 1990 (Iowa State University, 1991a).

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