Best Management Practices (BMPs) are farming methods that assure optimum plant growth and minimize adverse environmental effects. The BMPs presented here are for nutrient management on a wide variety of agricultural lands.
1. Have your soil tested – Nutrients should be applied to soils only as necessary. To know the soil’s nutrient-supplying capacity, you must have it analyzed by a soil test laboratory. Contact the laboratory to find out how to obtain a sample that is representative of the area to be fertilized.
2. Follow Soil Test Recommendations – A soil test report indicates the amount of nutrients that the soil can supply and recommends the amount needed from other sources. All of the recommendations should be followed completely because a deficiency of one nutrient or an undesirable soil pH will limit crop response to the other nutrients.
3. Set realistic yield goals – All fertilizer recommendations assume a certain yield goal for the crop to be grown. The yield history of a field is the best guide to realistic expectations. Do not over apply nutrients in the quest for unrealistic yields. Excessive amounts waste money and can contribute to water pollution.
4. Choose the Most Suitable Nitrogen Sources – It is important that nitrogen remain in the root zone long enough for it to be used by the growing crop. Regardless of its source, once nitrogen is in the plant it will not be lost and will not become a pollutant. Ammonium-nitrogen (NH4) is more likely to be held in the soil than nitrate nitrogen (NO3), which is more readily dissolved in runoff water.
5. Apply nitrogen and phosphorus correctly – Nitrogen and phosphorus are less likely to be lost by erosion or runoff if they are banded directly into the soil or applied to the soil surface and promptly mixed into the soil by disking, plowing, or rotary tilling. Subsurface banding also makes it possible for nutrients to be placed directly where the crop can make the best use of them. Do not broadcast fertilizer when it is windy.
6. Timely Nitrogen Application – The timing of application is more important with nitrogen than with any other nutrient because nitrogen is applied in large amounts to many crops and is very mobile. Phosphorus is very stable once it is mixed into the soil and can be applied when most convenient. Nitrogen should be applied frequently in small amounts that are tailored to the plants immediate needs. For most crops, nitrogen should be applied in split applications that coincide as closely as possible with the uptake pattern of the crop.
7. Use manure as a nutrient source – Manure and other waste or by-product materials can be excellent sources of nutrients if managed properly. The basic procedure is to collect and analyze the material to determine the nutrient content and then apply it in a recommended manner at rates based on a soil test report.
Improper amounts or placement of this material can lead to water pollution and poor crop growth.
8. Control Erosion – All nutrients can be lost when soil is eroded, but phosphorus is especially vulnerable.
A conservation farm plan providing for erosion control should be developed. Some specific practices are:
• Maintain a soil cover – Leave crop residues on the soil surface during winter. Do not till too early in the spring. Where feasible, use no-till methods.
On soils that are subject to erosion or leaching, use a winter cover crop to reduce erosion, to take up nutrients, and thereby reduce leaching.
A cover crop used in this way is called a “trap crop” since it “traps” and recycles nutrients for use by later crops
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• Manage the soil for maximum water infiltration and storage – Maintain crop residues on the soil surface. If there is little crop residue left in the fall, establish a winter cover crop, but leave the soil surface rough enough to help trap rainfall.
Increase the soil’s water-holding capacity by adding organic matter and maintaining good soil porosity.
• Maintain vegetation on ditch banks and in drainage channels – Try not to disturb vegetation in drainage channels such as ditches and sod waterways. If necessary, construct ditches larger than needed so the bottoms can be left vegetated to trap sediment and other possible pollutants.
• Use windbreaks and conservation tillage to control wind erosion – Wind erosion can be minimized by leaving the soil surface rough, maintaining crop residue on the soil surface, bedding to trap wind-blown sediments, keeping the soil wet, or maintaining a cover crop.
BMPs are designed to reduce harmful effects. In some sensitive areas, there may be no acceptable level of added nutrients; in these cases fertilizers should not be used. In other places they can be used along with BMPs. However, Fertilizers and other nutrient sources should never be applied haphazardly.
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