Fertilizer Use Overview

Fertilizers play a vital role in agriculture andalso are commonly used in urban areas. Ferti-lizers increase crop production and improvelawns and gardens dramatically. However,commercial fertilizer is a major source ofnitrate, which can contaminate ground water.The nitrate-nitrogen maximum contaminantlevel (MCL—or level beyond which humanhealth problems can occur) in federal and statedrinking water standards is 10 milligrams perliter (mg/l; equivalent to 10 parts per million).Nitrogen levels above the MCL have beenfound in many water wells in Texas. Othermajor components of commercial fertilizer,such as phosphorus and potassium, are notgenerally a ground water contamination con-cern.

Elevated nitrate levels in drinking water canpose serious risk to infants. Infants under 6months of age are particularly susceptible tohealth problems, including the conditionknown as methemoglobinemia (blue baby syn-drome), which is caused by drinking waterwith elevated nitrate content. Nitrates also canaffect adults, but the evidence is less certain.

Young livestock also are susceptible to healthproblems from high nitrate-nitrogen levels.While livestock may be able to tolerate severaltimes the 10 mg/l nitrate-nitrogen level, 20 to40 mg/l may prove harmful, especially in com-bination with high levels (1,000 mg/l) ofnitrate-nitrogen from feed sources.

Improper handling of fertilizers can affectground water by allowing nitrogen to seepthrough the soil and down into the water.Other potential sources of nitrate are septicsystems, livestock yards, livestock waste stor-age facilities, and silage storage. This bulletincovers the following topics:

1) Building a new storage facility

2) Modifying an existing facility

3) Mixing and loading practices

4) Spills and container disposal

5) Other management factors

6) Evaluation table

Building a New Storage Facility

While a new facility just for fertilizer storagemay be expensive, it may be safer than trying

to adapt areas designed for other purposes.When planning or building a new storage facil-ity, keep these simple principles in mind:

★ The dry storage building or liquid sec-ondary containment structure should belocated downslope and at least 100 feetaway from the water well. Separationfrom the water well should be greater inareas of sand or fractured bedrock.

★ In the event of a fire, contaminated sur-face water should drain to a confinedarea.

★ The mixing and loading area should beclose to your storage facility to minimizethe distance that chemicals are carried.

★ The building foundation or secondary con-tainment floor should be well drained andlocated above the water table. The fin-ished soil grade should be 3 inches belowthe floor of the storage area and slopedaway from the building to provide surfacedrainage. The subsoil should have a lowpermeability.

★ Bags should be stored on pallets, and dryproducts stored separately from liquids toprevent wetting from spills.

★ If you plan to store large bulk tanks, pro-vide a containment area large enough toconfine 125 percent of the contents of thelargest bulk container, plus the displacedvolume of any other storage tanks.

★ A locked storage cabinet or building pro-vides security. Preventing unauthorizeduse of fertilizer reduces the chance ofaccidental spills or theft. Post signs orlabels indicating that the cabinet or build-ing is a fertilizer storage area. Labels onthe outside of the building give firefightersimportant information about fertilizersduring an emergency response for a fireor spill.

★ Provide adequate road access for deliver-ies and emergency equipment.

For information on factors to consider in thedesign of a storage facility, such as ventilation,water access, temperature control and workersafety, contact your county Extension office orthe Texas A&M University Department ofAgricultural Engineering.

Modifying an Existing Facility

Modifying an existing facility can be expen-sive and difficult, but compared to the cost of amajor accident or even a lawsuit, storageimprovements are a bargain. Also, spilled liq-uid fertilizer captured by the secondary con-tainment can be recovered; thus, the product isnot lost. The last four items in the list aboveare also important for existing storage manage-ment.

The cheapest alternative you may have is tocut back on the amounts stored. If that optionis not practical, consider how you can protectthe fertilizers you keep in storage (Fig. 1).

Sound containers are your first defenseagainst a spill or leak. If a bag is accidentallyripped, the fertilizer should be confined to theimmediate area and promptly recovered. Thatmeans having a solid floor and, for liquid fertil-izers, a curb. The secondary containment spaceshould be large enough to hold 125 percent ofthe contents of the largest container, plus thedisplaced volume of any other storage tanks inthe area.

Ideally, your fertilizer storage area should beseparated from other uses. If the building mustalso serve as a machine shed or as housing forlivestock, you may find it difficult to meet allthe requirements for safe storage.

Stored fertilizers can pose a danger to fire-fighters and to the environment. Reducing thefire risk in the storage area may be the firststep, but other things can be done.

You can reduce the damages by anticipatingsuch emergencies. If a fire should occur, con-sider where the water will go and where itmight collect. In making the storage areasecure, also make it accessible, thus allowingyou to get fertilizers out in a hurry.

If fertilizer containers are damaged, thestored nutrients may be carried away by waterand spread over a large area. A curb aroundthe floor can help confine contaminated water.

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MIXING AND CONTAINMENT SECURITY

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FERTILIZERSTORAGE

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Figure 1. Farm-sized fertilizer facility. Source: Modular Concrete Wash/Containment Pad for Agricultural Chemicals, by. R.T. Noyesand D.W. Kammel, American Society of Agricultural Engineers Paper Number 891613.

Mixing and Loading Practices

Contamination can result from small quanti-ties spilled regularly in the same place. Spills ofdry fertilizer should be promptly and complete-ly cleaned up and placed immediately into theapplication equipment. Cleaning up spills ofliquid fertilizers can be much more difficult.

Using a Liquid Fertilizer Mixing and Loading Pad

Containing liquid fertilizer spills and leaksrequires an impermeable surface (such as con-crete) for mixing and loading. A concrete padshould be large enough to accommodate yourequipment and to contain wash water andspills when transferring fertilizers to thesprayer.

Locate the pad adjacent to the storage area.Make sure that water moves away from thewell. At sites where runoff could reach thewell, construct a diversion to direct runoff toanother area.

The size of the pad depends on the equip-ment you use. Provide space around parkedequipment for washing and rinsing. The fertil-izers and rinse water should be kept in a con-fined area, such as a sump, for settling beforethey are transferred to rinsate storage tanks.Having several rinsate storage tanks allows youto keep rinse water from different fertilizermixes separate. That way, it can be used formixing water on subsequent loads.

If you are considering constructing a mix-ing/loading pad, more detailed information isavailable from county Extension office or theDepartment of Agricultural Engineering atTexas A&M University.

Better Management of your Existing Mixing and Loading Site

Take steps to minimize liquid fertilizer spillsand leaks and their effects. Even if you do nothave an impermeable mixing and loading pad,you can minimize contamination by followingsome basic guidelines:

★ Avoid mixing and loading fertilizers nearyour well. One way to do this is to use anurse tank to transport water to the mix-ing and loading site. Ideally, the mixingsite should be moved from year to yearwithin the field of application to avoidbuild-up of fertilizers in the soil.

★ Avoid mixing and loading on gravel drive-ways or other surfaces that allow spills tosink quickly through the soil. A clay sur-face is better than sand.

★ Install an anti-backsiphon device on thewell or hydrants. Never put the hose inthe application tank. Provide an air gap of6 inches between the hose and the top ofthe application tank.

★ Always supervise tank filling.

★ Consider using a closed handling system,in which the fertilizer is directly trans-ferred from the storage container to theapplicator equipment, such as by a hose.This will ensure that humans and theenvironment are never inadvertentlyexposed to the chemical.

★ Use rinsate for mixing subsequent loads.

Spill Cleanup

Promptly sweep up dry spills and reuse thefertilizer as it was intended. Dry spills are usu-ally very easy to clean up. Dry pesticideimpregnated fertilizer is considered a pesticideand, if spilled, should be recovered and appliedto the target crop as it was intended. For liquidspills, recover as much of the spill as possibleand reuse it as it was intended. It may be nec-essary to remove contaminated soil and applyit to fields. Have an emergency response planfor the site. Know where the runoff water willflow, how to handle your particular fertilizersand whom to call for help.

Container Disposal

Bulk deliveries of anhydrous ammonia, liq-uid fertilizers and dry bulk fertilizers reducethe need to dispose of containers. Many peo-ple do, however, use bagged fertilizers. Burningfertilizer bags is illegal in Texas; therefore, bun-dle the bags and dispose of them in anapproved landfill.

Your drinking water is least likely to be cont-aminated by your disposal practices if you fol-low appropriate management procedures ordispose of wastes in an approved landfill.Proper offsite disposal practices are essential toprevent contamination that could affect thewater supplies and health of others.

Other Management Factors

Reducing fertilizer waste makes financial aswell as environmental sense, but it meansmore than just reducing spills. It also meansnot buying more than you need and keepingrecords of what you have on hand. Buying onlywhat you need makes long-term storage unnec-essary.

Keeping records may seem like a task unre-lated to contamination, but knowing what youhave used in the past and what you have onhand allows you to make better purchasingdecisions. Keep records of past field applicationrates and effectiveness. Purchase fertilizersonly after careful and complete soil testing todetermine your exact needs.

Evaluation Table

The following table can help agriculturalproducers and rural homeowners determinethe risk that drinking water on a given proper-ty will be contaminated because of the man-agement practices being used. For each catego-ry on the left that is appropriate, read across tothe right and circle the statement that bestdescribes conditions on your land. Allow 15 to30 minutes to complete the table, and skip anycategories that do not apply. Note any highrisk ratings and take appropriate actions toremedy them. Strive for all low or low-moder-ate risk ratings.

Drinking Water Well Condition: Assessing Drinking Water Contamination Risk

Low Risk Low-Moderate Risk Moderate-High Risk High Risk

Fertilizer Storage

Dry formulation:Amount stored None stored at any Less than 1 ton. Between 1 and 20 More than 20 tons.

time. tons.

Type of storage Covered on imper- Covered on clay soil. Partially covered on Not covered onmeable surface Spills are collected. loamy soils. Spills sandy soils. Spills(such as concrete or not collected. not collected.asphalt). Spills arecollected.

Liquid formulation:Amount stored None stored at any Less than 55 gallons. Between 55 and More than 1,500

time. 1,500 gallons. gallons.

Type of storage Concrete or other Clay-lined secondary Somewhat perme- Permeable soilimpermeable secon- containment. Most of able soils (loam). No (sand). No second-dary containment spill can be recovered. secondary contain- ary containment.does not allow spill ment. Most of spill Spills contaminateto contaminate soil. cannot be recovered. soil.

Containers Original containers Original containers Containers old but Containers haveclearly labeled. No old. Labels partially patched. Metal con- holes or tears thatholes, tears or weak missing or hard to tainers showing signs allow fertilizers toseams. Lids tight. read. of rusting. leak. No labels.

Security Fenced or locked Fenced area separate Open to activities Open access to theft,area separate from from most other that could damage vandalism and chil-all other activities, or activities. containers or spill dren.locks on valves. fertilizer.

Mixing and Loading Practices

Location of well in 100 feet or more 50 to 100 feet down- 10 to 50 feet down- Within 10 feet down-relation to mixing/ downslope from well. slope from well. slope or 100 to 500 slope or less thanloading area with feet upslope from 100 feet upslopeno curbed and well. from well.impermeable con-tainment area

Glossary

Air gap: An air space (open space) betweenthe hose or faucet and water level, repre-senting one way to prevent backflow of liq-uids into a well or water supply.

Anti-backflow (anti-backsiphoning) device:A check valve or other mechanical deviceto prevent the unwanted reverse flow of liq-uids back down a water supply pipe into awell.

Backflow: The unwanted reverse flow of liq-uids in a piping system.

Backflow prevention device: See anti-back-flow device.

Backsiphonage: Backflow caused by forma-tion of a vacuum in a water supply pipe.

Closed handling system: A system for trans-ferring pesticides or fertilizers directly fromstorage containers to application equipment(through a hose, for example), so thathumans and the environment are neverinadvertently exposed to the chemicals.

Cross-connection: A link or channel betweenpipes, wells, fixtures or tanks carrying con-taminated water and those carrying potable(safe for drinking) water. Contaminatedwater, if at higher pressure, can enter thepotable water system.

Milligrams per liter (mg/l): The weight of asubstance measured in milligrams con-tained in 1 liter. It is equivalent to parts permillion in water measure.

Parts per million (ppm): A measurement ofconcentration of one unit of material dis-persed in 1 million units of another.

Drinking Water Well Condition: Assessing Drinking Water Contamination Risk

Low Risk Low-Moderate Risk Moderate-High Risk High Risk

Additional Mixing and Loading Practices for Liquid Fertilizer

Mixing and loading Concrete pad with Concrete pad with Concrete pad with No mixing/loadingpad (spill contain- curb keeps spills curb keeps spills con- some cracks keeps pad. Spills soak intoment) contained. Sump tained. No sump. some spills contained. ground.

allows collection and No curb or sump.transfer to storage.

Water source Separate water tank. Hydrant away from Hydrant near well. Obtained directlywell. from well.

Backflow preven- Anti-backflow device Anti-backflow device No anti-backflow No anti-backflowtion on water installed or 6-inch air installed. Hose in tank device. Hose in tank device. Hose in tanksupply gap maintained be- above waterline. above waterline. below water line.

tween hose andsprayer tank.

Filling supervision Constant Mostly constant Frequent Seldom or never

Handling system Closed system for Closed system for All liquids hand All liquids handall liquid product most liquids. Some poured. Sprayer fill poured. Sprayer filltransfers. liquids hand poured. port easy to reach. port hard to reach.

Sprayer fill port easyto reach.

Clean-up and Disposal Practices

Sprayer cleaning Sprayer washed out Sprayer washed out Sprayer washed out Sprayer washed outand rinsate (rinse in field. Rinsate used on pad. Rinsate used at homestead. Rinsate at homestead. Rin-water) disposal in next load and in next load and applied on nearby sate sprayed less

applied to crop. applied to crop. field. than 100 feet fromwell.

Rinsate: Rinse water from pesticide or fertiliz-er tank cleaning.

Secondary containment: Impermeable floorand walls around a chemical storage areathat minimize the amount of chemical seep-ing into the ground from a spill or leak.

Contact and References

For additional information, contact yourcounty Extension agent or:

★ Natural Resource Conservation Service,

★ Texas Agricultural Extension Service WaterQuality unit (409) 845-0887, or Agricul-tural Engineering unit (409) 845-7451,

★ Texas State Soil and Water ConservationBoard, (817) 773-2250.

Internet address: TEX*A*Syst bulletins andlinks to other water quality sites are containedin a homepage located on the World Wide Webat: http://waterhome.tamu.edu.

TEX*A*Syst is a series of publications to help rural residents assess the risk of ground water pollution, and to describeBest Management Practices (BMPs) that can help protect ground water. The TEX*A*Syst documents were developedfrom the national Farm*A*Syst ground water protection program. The TEX*A*Syst system is designed to help the userlearn more about the environment, existing environmental policies and regulations, and recommended managementpractices. Thus, the user can voluntarily reduce the pollution risks associated with water wells.

TEX*A* Syst materials were edited by Anna Schuster Kantor, and reviewed by M.C. Dozier and the personnel of theUSDA-Natural Resources Conservation Service, U.S. Environmental Protection Agency, Texas Department ofAgriculture, Texas Natural Resource Conservation Commission, Texas Water Development Board, Texas State Soil andWater Conservation Board, Texas Water Resources Institute, and Texas Farm Bureau. Editorial and formatting assis-tance were provided by the Department of Agricultural Communications, The Texas A&M University System.

The TEX*A*Syst program is sponsored by the U.S. EnvironmentalProtection Agency under Section 319(h) of the Clean Water Act.Funds for this program are administered by the Texas State Soil andWater Conservation Board’s Agricultural/Silvicultural NonpointSource Management Program.