Spectrum Analytic Inc
1087 Jamison Rd
Washington Court House, OH 43160
(800) 321-1562
1087 Jamison Rd
Washington Court House, OH 43160
(800) 321-1562
Knowledge is key to using your analytic results to their fullest. The Spectrum Agronomic Library provides you with useful information that will help you to better understand the complex science of agronomy. Our agronomists will be continually adding original and reprinted articles, so check the library regularly for new information.
How Much Fertilizer Do I Need?
The first thing that needs to be done is to calculate how much area is in the place to be fertilized. The reader can do these simple calculations by going to our paper on how to calculate areas area_calculations.htm. This paper contains a variety of sizes and shapes that the average person will encounter when calculating how large of area to be fertilized .
Plant nutrient requirements can be supplied by a wide variety of fertilizers that are available in each area of the country. Spectrum Analytic serves a large number of states, and some foreign countries, and is not able to recommend specific fertilizers grades or brands that might be available in each area. For this reason, and to help explain proper fertilizer use, we have provided the following information.
It is common to hear people discuss fertilizer recommendations in terms of crop removal, plus or minus soil test buildup as if they were somehow disconnected from each other. In fact, they are two aspects of the same subject. Most of us fall into the habit of thinking that we are fertilizing plants. Except for foliar fertilizer or tree trunk injection, we do not fertilize plants… we fertilize soil. Because of this, soil chemistry will determine how much of the applied nutrients the plants will be able to take up. If a soil is low in phosphorus (P) or potassium (K), it will tie-up or “fix” much of the applied fertilizer P and K (P2O5 and K2O) into forms that are not available to the plants. This nutrient fixation is simply another way of saying that the soil is trying to build itself up in these nutrients… whether that is your intention or not. The soil is a reservoir for the nutrients that have been applied or generated by other means over the years. The nutrients that a plant gets in any one season are likely to be ones that have been in the soil for many years. Therefore you can think of fertilization as putting nutrients into one side of a reservoir while the plants are taking them out of another end. What happens inside of this nutrient reservoir is soil chemistry and microbiology. These processes, along with weather, determine how much access the plants have to the nutrients within the reservoir.
Soybean cyst nematodes (Heterodera glycines) have been an increasing problem for soybean producers over the past decade or more. H. glycines is the only cyst nematode known to attack soybeans in the U.S. Most of the major soybean producing areas of the U.S. now recognize that SCN is present in at least part of the area. SCN is and obligate parasite of higher plants, more than 1100 species of plants have been found to serve as hosts. Fortunately, most are weed and crop plants not commonly found in soybean fields or cropping rotations. Populations of the nematode increase rapidly under continuous soybeans, but decline drastically during the first year under non-host crops.
Severe infestations of SCN can have a devastating effect on yields. Yield losses can range from slight to as much as 90% depending upon the degree of infestation, soil fertility, cultivar susceptibility, environmental conditions, and race of the nematode. Root systems of heavily infected plants are drastically reduced, necrotic and practically devoid of Rhizobium nodules. In Iowa, susceptible varieties yielded about 40% less in infested fields than in non-infested fields. In Ohio on a fertile, dark colored soil, varieties resistant to SCN yielded over 50 bu/ac, whereas those susceptible to SCN yielded from 24-39 bu/ac (a yield loss of from 52% to 22%). Another study using aldicarb to control SCN found that high SCN populations may reduce yields by 30 bu/ac.