INTRODUCTION
Homeowners recognize the need for timely nutrient applications to promote vigorous
plant growth in landscapes and gardens. These nutrients may be supplied by either organic or inorganic fertilizers, or a combination of materials. Many nursery and garden supply stores now stock a wide variety of organic fertilizers. In addition, many organic materials are produced around the home, or can be obtained at little or no cost from livestock operations, municipal green waste collection centers, and local landfills. Virtually any organic material can be used as a fertilizer; however, materials vary considerably in the concentration of plant nutrients they contain and the rate at which these nutrients are released for plant use. Therefore, some organic fertilizers are better for certain situations than others, and different materials need to be applied at different rates to supply the correct amount of plant nutrients.A common misconception is that organic fertilizers are safer for plants and the environment than inorganic (chemical) products. Improper organic fertilizer application can also contribute to surface and ground water pollution, may induce a plant nutrient deficiency or toxicity, or cause salt burn. Properly used, both organic and inorganic fertilizers are safe for plants and the environment. The purpose of this guide is to provide general selection and use information for organic fertilizers.
DETERMINING NUTRIENT NEEDS
Nutrient needs vary widely depending on soil conditions, previous fertilizer and organic matter additions, and the type of plants grown. The best way to determine which nutrients are needed and in what amounts is to test the soil. A soil test (cost: $10.00 to $40.00 per sample) is recommended every two to three years for landscapes and gardens. Sample soils more frequently if you have problems. See your County Extension Agent for instructions on how to collect soil samples and where to send them for analyses.
A soil test report will be accompanied by interpretations and nutrient recommendations for your specific conditionS. Nitrogen is the most common nutrient needed in home landscapes and gardens. Vegetable nitrogen requirements are designed to produce optimum yields in a garden setting.
Plants General requirements Recommendation Ornamentals
Low:............xeriscapes, natural areas.....0 to 1 lb of nitrogen/1000 sq ft
Intermediate:...standard landscapes...........2 lbs of nitrogen/1000 sq ft
High:...........lower beds, new landscapes....2 -4 lbs of nitrogen / 1000 sq ft
Turf*...........low maintenance...............0-1 lbs of nitrogen /1000 sq ft
Intermediate maintenance......2-3 lbs of nitrogen /1000 sq ft
High maintenance....................4 to 6 lbs of nitrogen/1000 sq ft
Vegetables**
Low: peas, beans. 1 to 2 lbs of nitrogen / 1000 sq ft
Intermediate: asparagus, beet, carrot melon,
cauliflower, broccoli,
Brussels sprout, celery, 2 to 3 lbs of nitrogen /1000 sq ft
pepper,tomato,lettuce
radish,spinach,turnip,
squash,pumpkins
2 High: onion,sweet corn, potato 4 to 6 lbs of nitrogen /1000 sq ft
*Split the total amount of nitrogen into 2 or more separate applications made over the growing eason.To prevent burning do not apply more than 1 ½ pounds of nitrogen/1000 sq feet n a single application.
**For high nitrogen requirement vegetables, apply the intermediate recommendation before lanting, then broadcast or band additional nitrogen after plants are well established (seetext under fertilizer application methods).
SELECTING AN ORGANIC FERTILIZER
The numbers on an organic fertilizer label refer to the concentration (percent) of three major nutrients in the material:
nitrogen (or N),
phosphate (or P2O5),
potassium (potash, orK2O) .
For example, a 6-12-0 fertilizer (bone meal) contains:
6% nitrogen,
12% phosphate (P2O5), and 0% potash (K2O).
One-hundred pounds of this material would contain 6 lbs of nitrogen (100 x 0.06), 12 pounds of phosphate (100 x 0.12) and no potash.
Fertilizer labels on organic products have been standardized so that the concentration of nitrogen, phosphate and potash always appear in thesame order on the front of the package.
Othercommon organic fertilizers are listed below. Many organic fertilizers also contain other nutrients like sulfur, iron, and zinc; however, concentrations of these are usually not given on the label because levels are either too low or too variable to be specified. In addition to supplying nutrients, regular use of organic fertilizers also increases soil organic matter levels which improves soil physical properties like water holding capacity, drainage and tilth (the physical condition of soil related to structure and the ease of tillage).
FERTILIZER RATE CALCULATION
Fertilizer needed = X lbs of nutrient/1000 sq. ft × 1 lb fertilizer/ Y lb nutrient
× Z sq. feet area
.
FERTILIZER APPLICATION METHODS
Organic materials can be broadcast on the surface and tilled or watered into soil, or
applied in a narrow band on or beneath the surface. A common fertilizer spreader will often work well for applying small quantities of organic fertilizer. Two main types of broadcast applicators are available:
the drop spreader and the rotary spreader Most drop spreaders are capable of applying a wide range of rates. however, the path spread is limited to the width of the unit (normally 18 inches to (three feet) rotary spreader may
!!!CAUTION!!!
Many organic materials contain high levels
of salts. These salts will burn plants if
organic materials are over-applied.
Broadcast organic materials in a 5 to 10 foot wide path but with less uniformity and rate control than drop spreaders. If necessary, screen the material before spreading to remove large particles. Spreaders are adjustable for different fertilizer materials and rates of application. The spreader manufacturer will list calibration settings for various inorganic fertilizers. The gardener must calibrate these spreaders for organic fertilizer materials. Adjust the spreader to a relatively high setting. Place two or three pounds of organic material in the hopper and proceed to spread this amount in a continuous straight path. Note the width of the spread path and the distance traveled to broadcast all of the material. Calculate the rate of application and compare this to the rate needed. For example, if your spreader broadcasts a five foot wide path and you traveled 20 feet to empty three pounds of compost, the rate of application would be three pounds per 100 square feet (5 ft by 20 ft), or approximately 30 pounds of compost per 1000 square feet. Compare this to the rate of compost needed and if necessary adjust the spreader and calibrate again.
Because of their relatively low nutrient content, organic fertilizers are applied at much higher rates than inorganic fertilizers. Therefore, even at the highest spreader settings you may have to make two or more passes over an area to apply the required amount of material. Once a spreader is calibrated for a specific nutrient rate and organic fertilizer keep a record of the setting for future use with this material. Avoid streaking caused by skips and overlap by applying one-half of the fertilizer while traveling in one direction and the remaining one-half while traveling in a perpendicular direction. This method of application is especially important for turf fertilization where streaking is
common.
An alternative method of broadcasting large quantities of organic material is to space piles of the material throughout the area and spread the piles out uniformly using a garden or leaf rake.
Banding is a convenient way to make in-season fertilizer applications to high nitrogen requiring vegetables like corn . Use an organic fertilizer with rapid nutrient availability when banding. To band an organic fertilizer, first calculate the amount of material needed for the area as if you were going to broadcast the material. Divide this amount by the number of plant rows in the area to determine the amount of organic fertilizer to apply for each row. Make narrow furrows six to eight inches away from the base of the plants, two to three inches deep. Distribute the organic material evenly in the furrow and cover with soil. Liquid and foliar fertilizer applications can be made with water soluble products like fish emulsion or seaweed extract. There is a potential for leaf burning with liquid applications, so follow product label instructions carefully. Manure or compost tea can also be used as a source of liquid fertilizer. Partially fill a burlap or cloth bag with manure or compost and submerge for several days in a bucket of warm water. The resulting “tea” can be applied directly to the soil or foliage of plants.
Average nutrient concentrations and rates of availability for various organic materials.
Material %Nitrogen %Phosphate %Potash Availability* Notes**
Alfalfa hay 2-3 0.5-1 1-2 slow/mod.
Bone meal 1-6 11-30 0 moderate alkaline
Blood meal 12 1-2 0-1 rapid acidic
Cottonseed meal 6 3 1 slow acidic
Composts 1-3 1-2 1-2 moderate alkaline
Feather meal 12 0 0 moderate
Fish meal 6-12 3-7 2-5 rapid acidic Grass clippings 1-2 0-0.5 1-2 moderate
Hoof/horn meal 12-14 1.5-2 0 moderate alkaline
Kelp 1-1.5 0.5-1 5-10 moderate zinc, iron
Leaves 1 0-0.5 0-0.5 slow
Legumes 2-4 0-0.5 2-3 moderate
Manures: Cattle 2-3 0.5-1 1-2 moderate weed seed
Horse 1-2 0.5-1 1-2 slow weed seed
Swine 2-3 0.5-1 1-2 rapid
Poultry 3-4 1-2 1-2 rapid
Sheep 3-4 0.5-1 2-3 moderate weed seed
Pine needles 0.5 0 1 slow acidic
Sawdust 0-1 0-0.5 0-1 very slow
Sewage sludge 2-6 1-4 0-1 moderate zinc, iron
Seaweed extract 1 2 5 rapid zinc, iron
Straw/corn stalks 0-0.5 0-0.5 1 very slow
Wood ashes 0 1-2 3-7 rapid
*Approximate rate of nutrient release from the material.
**Special properties or characteristics of the material.
Utah State University Extension is an affirmative action/equal employment opportunity employer and educational organization. We offer our programs to persons regardless of race, color, national origin, sex,religion, age or disability. Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30,1914, in cooperation with the U.S. Department of Agriculture, Robert L. Gilliland, Vice-President and Director,Cooperative Extension Service, Utah State University, Logan, Utah.
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