FERTILIZERS FOR 1LASKA

Transcription

1 Alaska Experiment Station Circular 10 GENERAL RECOMMENDATIONS FERTILIZERS FOR 1LASKA University of Alaska Alaska Agricultural Experiment Station Do>n It. Irwin, Director PALMER, ALASKA In cooperation with, the United States Department of Agriculture Agricultural Research Administration FEBRUARY, 1950

2 FIELD CROPS ON MINERAL SOILS Approximate quantities of plant nutrients in pounds per acre With 6 to 8 tons Without manure Oats and peas or vetch for hay or silage* Small grains for grain* Bromegrass (and small seeded grasses) for hay, silage, or pasture 80** Clover and grass (with grain nurse crop) Clover and grass for hay, pasture and silage Sweetclover for hay or silage green manure Potatoes of manure N P K D * For oats include 100 to 150 pounds of manganese sulfate 080 percent) if outs hfcve previously been damaged by Gray Speck (soil manganese deficiency),!* Half may be applied) as early as possible in the spring, the remainder in mid-july. : Manure can be used to a greater "advantage on other crops, ; Manure applied immediately.before >a potato crop may encourage scabbiness; a good practice is to apply manure to the crop preceding potatoes, TRUCK CROPS ON MINERAL SOIL Approximate quantities of plant nutrients in pounds per acre With 6 to 8 tons Without manure Root crops (turnips, beets, carrots, rutababas, etc,) 25** 100 Leaf crops (lettuce, cabbage, cauliflower, celery, brussels sprouts, mustard, chard, kale, rubarb, etc-). 50** 120 Beans, peas Potatoes i,., of manure N P K * For organic soils use".half the quantities of N and twice the water-soluble potash indicated for mineral soils. # Apply half at planting time, the remainder as side-dressings twice after plants emerge, at -about 2-week intervals, : Manure applied immediately before potatoes may encourage seabbiness; a good practice is apply manure the year before planting potatoes.

3 GARDEN CROPS ON MINERAL SOILS Approximate quantities in ounces per 100 Without manure Root crops (turnips, beets, parsnips, radishes, carrots, rutabagas, etc.) iy2** 7 3 Leaf crops (lettuce, cabbage, cauliflower, celery, brussels sprouts, rhubarb, mustard, chard, kale, etc,) 3** 8 3 Beans, peas Potatoes Cane fruits : Strawberries :: New beds Old beds Flowers (annuals and perrenials)...,!1^ 7 3 of plant nutrients square feet With 50 pounds cow manure per 100 square feet* * #* * Or 25 pounds ol sheep, goat, hog, rabbit, <or poultry manure,. ** Apply half <at planting time, the remainder as side-dressings twice.after the plants emerge, at about 2-week intervals. *** Manure applied' immediately before potatoes may encourage scabbiness. ; Apply a;bout the time growth starts in the spring. :: For new beds work into soil before setting plants. Top-dress in August with another 2 ounces of N for each 100 square feet of toed. Apply fertilizer to old 'beds after the harvest. Manure is not recommended because it encourages weediness. MISCELLANEOUS Tomatoes and cucumbers in greenhouses Approximate quantities of fertilizer 100 square feet per 50 to ao pounds of cow or hoarse manure, 8 ounces of. **' anc* ^ ounces of K worked in soil before setting plants. After third, cluster -of tomatoes or early setting of cucumbers, top-dlress with 1 to 1% ounces of N at intervals <of 10 days to 2 weeks. If manigianese deficiency occurs, apply 2 ounces of manganese sulfate with one top- dressing. Lawns on mineral soils,,,. 1 pound of complete fertilizer as soon as possible in the sn-ring after the snow disappears. Thereafter, apply y% pound of at intervals of 4 or 5 weeks. Clip* lawn at frequent intervals at a heig-ht of not less than iy2 -inches,..,... In these tables N means total nitrogen, P means available phosphoric acid (phosphate), and K means water-soluble potash as shown on fertilizer sack or container. Head instructions on the reverse side of this sheet to find out how to calculate how much of a particular grade of fertilizer you need to furnish the recommended quantities of each nutrient.

4 WHAT YOU SHOULD BUY Note that concentrated carriers in the last formula give a total bulk of 960 pounds. Compare this weight with the 2000 pounds of required to contain the desired quantities of nutrients. This is an important point for most Alaskan farmers because shipping costs are high, Buying concentrated carriers gives you more plant nutrients for your money. For this reason ammonium nitrate (31.5% N) is a better buy than ammonium sulfate (21% N), 42% treblesugerphosphate is better than 20% superphosphate. In many places, a farmer can save money by buying these concentrated carriers and mixing them in just the proportions he needs. It often happens, however, that a farmer doesn't have time to do his mixing in the spring, nor a suitable place to store fertilizers so they can be mixed earlier when his work is lighter. Many farmers don't have machinery that will spread concentrated materials unless they are diluted with sand. The problem of whether to mix concentrated carriers or to buy ready-mixed complete fertilizers has to be solved by each farmer, according to his own particular conditions of time, labor and facilities. REMEMBER Commercial fertilizers do not substitute for good soi I management. Fertilizers containing nitrogen or potash will injure seed of cultivated crops when in direct contact. If you don't have the right machinery for placing fertilizer, you can plow it under or disk it in. Different crops and soils require different fertilizers. The fertilizer formula on the sack or tag shows what is inside. Read it to find out what you're buying with your money. Buy fertilizers that give you the most plant food for your money. Materials containing less than a total of 20 percent nutrients are not recommended because too much of your money goes into shipping costs. Recommendations for specific crops listed in the accompanying table are based on limited research in Alaska. They will change from year to year as more experimental results are obtained.

5 FERTILIZER TERMS Nitrogen, phosphoric acid (sometimes called "phosphates"), and potash are the chief nutrients that must be purchased in large quantities. These nutrients are often indicated by symbols, like N f or nitrogen. Most fertilizer guarantee laws allow a manufacturer to omit even symbols from a statement of the "grade" of a mixed fertilizer which usually appears on a sack as , , and so forth, Unless otherwise indicated, the first number shows the percent of total N in the mixture; the second number shows the percent of available phosphoric acid; and the third, the percent of water-soluble potash, A mixture thus contains 5% N, 15% phosphoric acid, and 10% potash, Some fertilizers contain only one nutrient. Examples are ammonium sulfate which is about 21% N, or plain superphosphate which is 20% phosphoric acid; these materials are aften called "carriers" Other fertilizers, like ammonium phosphate (combining 11% N with 48% phosphoric acid), contain 2 nutrient elements. "Complete" fertilizers contain all three nutrients nitrogen, phosphoric acid, and potash, FERTILIZER ARITHMETIC. When the requirements of a crop are known, the amount of fertilizer needed per acre depends on the analysis of the particular fertilizers that can be purchased most cheaply. For example, suppose a recommendation for a certain crop is , This series of figures means that the farmer should apply 100 pounds per acre of N, 200 pounds per acre of phosphoric acid and 100 pounds per acre of potash to insure average yields of good quality produce. To obtain the desired quantities, he may need to mix several forms of these nutrients together. Here are some ways he might go about it: (1) 2000 pounds of complete fertilizer equals (2) 1000 pounds of complete fertilizer equals.,,, (3) 1000 pounds of complete fertilizer equals..., pounds of 31,5% ammonium nitrate equals., ^^^^ (160 times 31.5% N in ammonium nitrate) 1160 pounds of the above, mixed together, eontain,,.,lqo-200-lqo How do you figure the 160 pounds? Here's an easy way to think of it: A 100-pound sack of 31,5% ammonium nitrate contains 31,5 pounds of N. To supply 50 pounds of N you need 50/31,5 sacks, or sacks. Because each sack contains a total of 100 pounds, sacks equals 1,587 x 100, or pounds of ammonium nitrate. For convenience, you can round this figure off to 160 pounds the extra pound won't make much difference. (4) 320 pounds of 31,5% ammonium nitrate equals (320 times 31,5%) 475 pounds of 42% treblesuperphosphates equals.,, (475 times 42%) 165 pounds of 60% muriate of potash equals, (165 times 60%) 960 pounds of the above, mixed together, contain.,

6 ALASKAN SOILS Every crop demands a certain amount of each plant nutrient for the greatest economic returns per acre. Crops grown on different soils sometimes require different amounts of nutrients which must therefore be balanced for each field. Some farmers know from experience about what quantities of nitrogen, phosphoric acid, and potash their fields need in order to produce profitable yields. Soil samples may be studied to give an idea of how much fertilizer should be applied to a certain crop on a particular field. In Alaska, however, farm experience is generally limited to a few isolated areas while soil testing procedures have been too recently applied to yield trustworthy information, Alaskan farmers are therefore handicapped when faced with the problems of what kind and how much fertilizer to use. We know that many mineral soils now cultivated in Alaska are deficient in organic matter and nitrogen, and that they supply only a small fraction of the phosphates required by important crops. Mineral soils are generally well-supplied with basic elements such as potash, calcium and magnesium. Minor elements, including copper, zinc, iron and sulfur appear to be present in adequate quantities. In some Matanuska Valley fields manganese deficiency symptoms have been observed in oats and boron deficiency symptoms have been reported in cauliflower and lettuce. Manganese and boron applications are probably necessary for only a few crops, however, and these elements must be used cautiously even where needed because large quantities may do more damage than good. The average Alaskan farmer, then, is chiefly concerned with maintaining nitrogen and phosphates in his soil. This is best accomplished by returning plant residues and manure to all fields, supplementing these organic materials with commercial fertilizers high in nitrogen and phosphates. Potash is usually included in fertilizer programs to provide a balanced fertilizer mixture and to prevent potash from limiting yields when adequate supplies of the other two nutrients are readily available to the crop. The recommendations in the accompanying table are based on the best information available from experimental results with fertilizers in the field and from observations of field conditions and crop responses. They are also weighted by experimental results obtained from field trials in the north* central United States and parts of Canada where farming conditions somewhat resemble those in Alaska, The accompanying recommendations are made for average conditions of soil fertility, with the idea that in a favorable season about average yields will result. Many fields will produce larger yields when more fertilizer is applied while some fields will produce less. Successful farmers generally do a little experimenting to find out what each field needs. Commercial fertilizers used with manure and green manures in a rotation will assist in maintaining high production levels. Commercial fertilizers are no "cure all", however, and their use will seldom compensate for many faults of poor management.