WHAT ARE FERTILIZERS?
Fertilizers are generally defined as "any material, organic or inorganic, natural
or synthetic, which supplies one or more of the chemical elements required for the
plant growth". Most fertilizers that are commonly used in agriculture contain the
three basic plant nutrients: nitrogen, phosphorus, and potassium. Some fertilizers
also contain certain "micronutrients," such as zinc and other metals, that are necessary
for plant growth. Fertilizers are applied to replace the essential nutrients for plant
growth to the soil after they have been depleted.
Excess amounts of fertilizers may enter streams creating sources of nonpoint pollution. Fertilizers most commonly enter water sources by surface runoff and leaching from agricultural lands. Large amounts of nitrogen and phosphorous are present in the runoff. Increased amounts of nitrogen, phosphorous, and other micronutrients can have negative impacts on public health and aquatic ecosystems.
- Follow label directions
- Lock or otherwise secure storage container valves when not in use
- Storage buildings should have impermeable floors (impermeable secondary containment dikes can be used)
- DO NOT store fertilizer underground in containers or pits
- Mix and load fertilizers at the application place when possible
- Handle and store fertilizer away from wellheads and surface water
- Immediately recover and reuse or properly dispose of fertilizer spills
- Always store fertilizers in their original containers
APPLICATION OF FERTILIZER
Fertilizers with nitrogen present should be applied as closely as possible to the period of maximum crop uptake. Partial application of fertilizer in the spring with small additions as needed can reduce leaching and improve nitrogen uptake. Fertilizing in the fall has been shown to cause groundwater degradation.
It is necessary to sample soil every year to determine crop nutrient needs for accurate fertilizer recommendations. To calculate the optimal rate of application other sources that contribute nitrogen and phosphorous to the soil should be considered. Organic matter and manure contribute phosphorous. Crops can quickly take up nitrate forms of nitrogen, but are subject to leaching loss. Fertilizer with nitrogen should be limited when leaching potential is moderate to high. If the leaching potential is moderate to high, ammonium nitrogen fertilizers should be used because they are not subject to leach immediately. However, in warm moist conditions ammonium quickly turns into nitrate. More slowly available nitrogen fertilizers should be used in these situations. Although phosphorous is less prone to leach, loss through surface runoff is common so phosphorous should only be applied as needed and at recommended rates.
*Fertilizer application equipment should be checked and calibrated annually.
*Fertilizer should never be applied when the ground is frozen.
*Fertilizer application should be limited on slopes and areas with high runoff.
Irrigated crop production has the highest potential for water contamination because of the large quantity of water that is applied. When excess water is applied nitrogen and phosphorous can leach into groundwater or runoff into surface water. Using systems such as sprinklers, low energy precision applications, surges and drips help producers apply water efficiently and uniformly. Delivery systems such as lined ditches and gated pipes as well as reuse systems such as field drainage recovery ponds are efficient.
WHY IS IT IMPORTANT TO MANAGE FERTILIZER USE?
|Nitrate Level, ppm (parts per million)||Interpretation|
|0 to 10||
Safe for humans and livestock. However, concentrations of more than 4 ppm are an indicator of possible pollution sources and could cause environmental problems.
|11 to 20||Generally safe for human adults and livestock. Not safe for infants because their digestive systems cannot absorb and excrete nitrate.|
|21 to 40||Should not be used as a drinking water source but short-term use is acceptable for adults and all livestock unless food or feed sources are very high in nitrates.|
|41 to 100||Risky for adults and young livestock. Probably acceptable for mature livestock if feed is low in nitrates.|
|Over 100||Should not be used as drinking water for humans or livestock.|
- Utah Fertilizer Guide
- How to Protect Your Water from Fertilizer Contamination
- Landowner's Survey: How to Protect Your Water from Fertilizer Contamination
- Fertilizers Made from Domestic Septage and Sewage Sludge (Biosolids)
- Fertilizers Made from Wastes
- Selecting and Using Organic Fertilizers
- Selecting and Using Inorganic Fertilizers
- Fertilizer Management for Grass and Grass-Legume Mixtures
- Managing Agricultural Fertilizer Application to Prevent Contamination of Drinking Water
- Best Management Practices for Nitrogen Fertilization to Protect Water Quality