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.
Fertilization is a very important component of plant health care in the landscape. Fertilization is necessary to supplement naturally occurring essential mineral elements in the soil and to maintain an optimum supply for plant growth. Soil analysis (testing), combined with observations of plant growth, are the keys for the home gardener to develop the most effective nutrition program for the landscape. The mineral elements critical for optimum growth and development of landscape plants must be present in the soil and plant at proper levels.
The objective of this fact sheet is to help the gardening public make informed decisions regarding the nutrition of their landscape plants. Included is a brief review of soil analysis, soils, pH, essential elements, fertilizers and fertilizer rates, timing, and methods of application.
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.
The copper sulfate foot bath is an excellent tool in the dairyman's toolbox as far as hoof health for their dairy cows. Over the past years the used foot bath material has been recycled with the manure. Copper is one of the sixteen essential nutrients for crop growth, however copper is a micronutrient which means it is only required in small amounts for crop growth. 200 bushel of corn will remove 0.15 lbs Cu/acre, 100 bushel of wheat will remove 0.11 lbs Cu/acre and one of the most common crops grown for the dairy cows alfalfa will only remove 0.30 lbs Cu/acre. One of the best ways to monitor copper levels is with soil testing, and that is where we can help you. This article goes into detail explaining copper in the soil and also how the use of copper (in the diluted form with manure) should be managed on agricultural land. Although it was written with Pennsylvania growers in mind, the same basic principles and practices hold true for other areas of the country. Exceptions to this would be areas which contain sandy soils which do not have a high nutrient holding capacity. Muck soils which contain a high amount of organic matter also should be managed differently. As good stewards of the land, be sure to check with your local state specialists to help you better manage the use of copper materials or give us a call at Spectrum Analytic.
This article was written by Rick Stehouwer, Environmental Soil Science and Greg Roth, Corn Management, Crop and Soil Sciences at Pennsylvania State University. Although their work and observations were made in Pennsylvania the observations and recommendations that they have made can be used in other areas of the country. Two areas which would need different considerations are those soils that are either sands or those that contain a high level or organic matter.
“Copper sulfate hoof baths are used on many dairies in Pennsylvania as part of their overall hoof hygiene program. On most dairies spent hoof baths are dumped into the manure pit or lagoon so the copper ultimately gets spread on production ground with the manure. Recently there have been several reports in the dairy press regarding copper accumulation in soils from this practice. It is possible that after several years copper could accumulate in soil to levels that become toxic to soil microbes and crops. This could slow organic matter decomposition and nutrient cycling in soil (especially conversion of organic nitrogen to plant available nitrogen) and crop production could be reduced because of direct toxic effects of copper on the plants as well as reduced soil fertility. Copper accumulation in soil and forage could become toxic to sheep, whose tolerance for copper is much lower than that of dairy cattle.
The potential for accumulation of toxic levels of copper in soil is a critical issue because there is no practical way to reverse the problem if it occurs. On the other hand it is a problem that will take many, many years to develop and can easily be avoided. Copper is an essential element for all living organisms so plants and microbes need a constant small supply. All soils naturally contain some copper and it is only when the availability of soil copper becomes too large that toxicity could result. Thus two important questions for dairies that use copper sulfate hoof baths are: (1) How much copper can be added to soil before it reaches the toxic threshold, and (2) How long will it take to reach that threshold? Unfortunately there are no simple or clear answers to those questions. In this article we will look at factors that affect copper availability in soil and provide some guidance for dairies on how to deal with this issue.
The toxicity of copper in soil depends more on the available concentration of copper than it does on the total concentration. Available means that the copper is in a form that can be taken up by plants, microbes, or animals. For example, copper pipes are almost pure copper but are not toxic because the copper is not in a form that is available to living organisms. When water flows through the pipes, tiny amounts of copper dissolve in the water and that copper is available. The same holds true for copper in hoof baths, manure pits, and soil. Copper sulfate hoof baths are normally made as a 10% solution so the water contains about 25,000 parts per million (ppm) of copper. All of this dissolved copper is available, and at this high concentration is toxic to fungi and bacteria (intentionally so). As soon as the bath is dumped into the manure pit its toxicity decreases dramatically for two reasons. First, there is a huge dilution as a bath of a few gallons is mixed into thousands of gallons of manure. We have analyzed liquid manure from dairies using copper sulfate and found copper concentrations of 20 - 60 ppm, or about a 1,000-fold dilution. Secondly, copper becomes strongly bound to the organic matter in the manure pit. We have found that in liquid dairy manure about 90 - 95% of the copper is held on organic matter. When copper is bound to organic matter its availability is vastly reduced. Nevertheless, hoof baths do add a lot of copper to the manure - up to 1,000 ppm on a dry weight basis (sewage sludge normally has 300 - 500 ppm copper on a dry weight basis).
Ultimately all the copper ends up in the soil. Surface soils in Pennsylvania normally have total copper concentrations in the range of 15 - 30 ppm (mg/kg), or 30 - 60 lb/acre. When high copper manure is spread on the soil, copper is added to this natural background level. In the soil copper is strongly bound to soil organic matter and to clay particles. A lot of the copper gets bound so tightly that it is not available to microbes or plants and thus has no effect on toxicity. Copper availability is lowest at near neutral soil pH (6.5 - 7.5), but as pH decreases copper availability increases. Thus when high copper manure is added to soil, we would expect a greater increase in copper availability in a light textured soil with low organic matter and somewhat low pH than in a heavier textured soil with moderate organic matter and near neutral pH. In all soils, however, almost all added copper stays right where it is placed. Thus spreading high copper manure in soil year after year will steadily increase the total amount of copper in the topsoil. At one PA dairy that used a lot of copper sulfate we found total copper in the soil was 3 - 5 times higher than the normal range for topsoil in Pennsylvania. But corn growth on that field was excellent and the silage contained normal levels of copper suggesting there had been little increase in copper availability.
Another indicator of copper availability is how much copper is taken up by crop plants. Most agronomic crop tissues (leaves and stems) normally contain copper in the range of 5 - 30 ppm. The average copper content of corn silage in Northeast US is 7 ppm. If crop tissues contain copper at the high end of this range or above, this is evidence of increased copper availability, though not of toxicity. The classic foliar symptom of copper toxicity is interveinal chlorosis (pale green striping in corn leaves). The problem of crop tissue analysis as an indicator of copper toxicity is that copper will also stunt root elongation and development and may never be taken up into the above ground part of the plant. Thus a copper problem in the soil may not be seen above ground.
So we come back now to the question of how much copper can be added to soil before toxicity problems might arise? While almost no research has been conducted with high copper dairy manure, investigations of high copper swine manure and sewage sludge provide some guidance. Based on this research, if copper is added gradually (< 10 lb of copper per acre each year) it appears that at least 150 lb of copper per acre could be added to light textured, low organic matter soils without causing crop toxicity. Heavier textured soils with moderate to high organic matter levels could likely receive at least 3 - 5 times as much copper without showing any crop toxicity. However, adverse effects on soil microbes might occur with smaller additions of copper. Unfortunately, no simple soil test has been developed that can reliably predict when copper toxicity might occur to plants or microbes. Thus, dairy farmers using copper sulfate hoof baths should determine how much copper they are adding to their fields each year, and should monitor their soils and crops for evidence of increased copper availability.
There are two ways to calculate how much copper is added to soil each year. One is based on the total pounds of copper sulfate used in a year for hoof baths. This total must be divided by 4 since the copper sulfate is 25% copper by weight. Now divide that result by the number of acres the manure is spread on to get pounds of copper per acre per year. This calculation will give a good estimate of how much copper is being added to a field. However, since there are other sources of copper in the manure (from feed and water) a more precise method is to have the manure analyzed for copper. Then multiply the concentration of copper in the manure (lbs/ton or lbs/1,000 gal) by the application rate used (tons/acre or 1,000 gal/acre) to get lb of copper added per acre with each manure application. We have done these calculations at 4 PA dairies and found copper additions ranging from 2 up to 11 lbs of copper per acre per year. If the amount of copper added is less than 2 lb per acre, the buildup in soil will be extremely gradual (crop harvest will likely remove about 0.5 lb of copper per acre) and unlikely to cause a problem. Farms with annual copper addition of more than 5 lbs per acre should analyze soils and crops for copper every 5 years or so to monitor for any increases. Soils should be analyzed for total copper (strong acid digestion). Soil and tissue analysis can be performed at many soil laboratories. Farms where annual copper addition is 10 or more lbs per acre should attempt to reduce the amount of copper being used. This can be done by reducing the frequency of hoof bath use to the minimum needed to control hoof diseases, decreasing the concentration of copper sulfate used in the baths from 10% to 5%, and by placing a water bath ahead of the copper sulfate bath so that the copper sulfate bath will not need be changed as often. Dairies could also investigate alternative treatments to copper sulfate. Zinc sulfate baths are one alternative, but with long-term use zinc could accumulate to toxic levels just like copper.”
One of the first questions many farmers ask about continuous corn is: Can I get the same corn yields with continuous corn that I can get in a rotation? The answer is yes, but only once in a great while. Research compared continuous corn to a corn/soybean rotation for 14 years at Lexington, Kentucky (see Table 1). During the 14 years of comparison, continuous corn yields beat corn/soybean only twice. Continuous corn did not do any better when compared with other crop rotations. Continuous corn yields beat corn/wheat/double-crop soybean once out of 11 years and corn/forage once out of five years tested. The two years that continuous corn beat corn/soybean had something in common. Both of those years were relatively dry and disease levels were very low but not sure why this would occur. Conversely, 1990, 1992, and 1997 were years with high levels of Diplodia. Those three years were some of the worst years for continuous corn yields when compared to corn yields in other rotations.
The study in Lexington is not the only place where continuous corn yielded less than corn in some type of crop rotation. Continuous corn yielded about 15 bushels per acre less than corn from a corn/soybean rotation at Princeton in 2002. There were no visual differences in disease levels in that experiment.
While the economics may favor continuous corn, the agronomics do not. So, what is a farmer to do? Pest management becomes very critical. The research at Lexington indicates that when disease is not a factor, continuous corn does very well. Farmers with continuous corn will need to be very good managers of weeds, insects and diseases. Other articles in this edition will focus more on pest management in continuous corn. Farmers will also need to factor the historically lower yields of continuous corn into their budgets. When looking at projected yields and contract marketing, the farmer should be aware that yields with continuous corn are historically 5 to 10% lower than corn yields in a rotation.
| Table 1. Crop Rotation Effect on Crop Yield in Lexington, Kentucky. | ||||
|---|---|---|---|---|
| Year | Continuous Corn | Corn/Soybean | Corn/Wheat/ DC Soybean |
Corn/Forage |
| Corn Yield (bu/A) | ||||
| 1984 | 116 | 122 +61) | – | – |
| 1985 | 145 | 175 +30 | – | – |
| 1986 | 98 | 103 +5 | – | – |
| 1987 | 130 | 116 -14 | 135 +5 | – |
| 1988 | 68 | 79 +11 | 97 +29 | – |
| 1989 | 141 | 155 +14 | 169 +28 | – |
| 1990 | 114 | 142 +28 | 141 +37 | – |
| 1991 | 94 | 107 +13 | 108 +14 | – |
| 1992 | 147 | 181 +34 | 190 +43 | 183 +36 |
| 1993 | 150 | 157 +7 | 169 +19 | 162 +12 |
| 1994 | 140 | 109 -31 | 135 -5 | 108 -32 |
| 1995 | 145 | 154 +9 | 166 +21 | 168 +23 |
| 1996 | 149 | 158 +9 | 173 +24 | 184 +35 |
| 1997 | 118 | 140 +22 | 151 +33 | 144 +26 |
| 1984-1997 | 125 ±252) | 136 ±30 | – | – |
| 1987-1997 | 127 ±26 | 136 ±30 | 149 ±29 | – |
| 1992-1997 | 141 ±12 | 150 ±24 | 164 ±19 | 158 ±29 |
ACID FORMING FERTILIZER- A fertilizer that is capable of lowering the pH (increasing the acidity) of the soil following application.
AGLIME- Also know as “agstone”. Calcitic or dolomitic limestone that is crushed and ground to a graduation of fineness that will allow it to neutralize soil acidity. Usually material is ground to pass sieves from 8- to 100- mesh range or finer.
AGRICULTURAL LIMING MATERIAL- Any material that contains calcium and magnesium in forms that are capable of reducing soil acidity.
BURNT LIME- See calcium oxide.
CALCITE- The crystalline (having the regular internal arrangement of atoms, ions or molecules characteristic of crystals) form of calcium carbonate. Pure calcite contains 100% calcium carbonate (40% calcium). Calcite occurs in nature, limestone is not available commercially of this purity. It may be colorless, but is usually tinted by impurities.
CALCITIC LIMESTONE- A widely used term that refers to agricultural limestone with a high calcium content. Contains mainly calcium carbonate, but may also contain small amounts of magnesium. There are no regulations or restrictions governing the calcium or magnesium content.
CALCIUM (Ca) - Occurs in nature only in combination with other elements, does not occur solely as calcium. One of the 16 essential plant nutrients. It along with magnesium is one of the two main ingredients in limestone. Calcium is an essential part of teeth, bone and shells.
CALCIUM CARBONATE (CaCO3) - A compound which contains calcium combined with carbonate. It occurs in nature as limestone, marble, chalk, marl, shells, and similar substances.
CALCIUM CARBONATE EQUIVALENT (CCE) - Expression of the acid-neutralizing capacity of a carbonate rock relative to that of pure calcium carbonate (e.g. calcite). It is expressed as a percentage. For pure calcite the value is 100%, pure dolomite the value is 108.5%. Actual CCE of most limestone will vary from these percentages due to impurities in the rock, and the fact that most commercially available limestones have a mixture of calcite and dolomite rather than either in its pure form.
CALCIUM OXIDE (Ca0) - Chemical compound containing calcium and oxygen. Calcium oxide does not occur in nature, it is the formed from calcium carbonate by heating limestone to drive off the carbon dioxide.
CALCIUM OXIDE EQUIVALENT- The percentage of calcium oxide in a liming material plus 1.39 times the magnesium oxide content. For pure calcite, the value is 56.0%, for pure dolomite the value is 60.8%. Used by some states as a measure of aglime quality.
CAUSTIC LIME- See calcium oxide.
DOLOMITE- Limestone that contains magnesium carbonate (MgCO3) in an amount approximately equivalent to the calcium carbonate content in the stone. Limestone containing magnesium carbonate in lesser proportions is referred to as magnesian limestone or dolomitic limestone. Pure dolomite is 54.3% CaCO3 and 45.7% MgCO3 or expressed another way, is composed of 30.4% CaO, 21.8% magnesia (MgO), and 47.3% CO3.
DOLOMITIC LIMESTONE- Limestone that contains from 10%, but less than, 50% dolomite, and from 50-90% calcite. The MgCO3 content of dolomitic limestone may range approximately from 4.4-22.6%.
EFFECTIVE CALCIUM CARBONATE EQUIVALENT- An expression of aglime effectiveness based on the combined effect of chemical purity (CCE) and fineness. It is required for labeling purposes in some states. Determined by multiplying CCE by a set of factors based on the fineness of grind of the limestone. Also referred to as effective neutralizing value (ENV), total neutralizing power (TNP), effective neutralizing material (ENM) and, in one state, as the “lime score”.
EFFECTIVE NEUTRALIZING POWER (ENP)- This is a term used in Ohio. It means the neutralizing value of liming material base on the ECCE (effective calcium carbonate equivalent expressed as a dry weight. It is used to take into account for the amount of moisture (water, etc) that maybe present in liming materials.
FINENESS INDEX- The percentage by weight of a liming material that will pass designated sieves. It is calculated to account for particle distribution by totaling the amounts of material that are held and /or passed through the various sieve screens as determined by various state liming regulations and guidelines.
FLUID-BED ASH- Byproduct of electrical utility companies from mixing limestone into ground coal in a fluidizing bed to control burning rates of coal. The ash remaining after burning the coal has a neutralizing value for correcting soil acidity. Ashes and dusts collected from smoke stacks also can neutralize soil acidity. The calcium carbonate equivalence can vary widely from these sources and should be determined by laboratory analysis. Application rates need to be adjusted for the relative neutralizing value of these materials.
FLUID LIME- Also known as “liquid lime”. This product is made by mixing very finely ground limestone (100% passing a 100 mesh sieve and 89-90% passing a 200 mesh sieve) with either water or liquid nitrogen fertilizer along with a suspending agent (attapulgite clay) and applying with a liquid fertilizer applicator.
GYPSUM- A hydrated form of calcium sulfate (CaSO4). It supplies calcium to the soil, but it is a neutral substance and does not correct soil acidity; therefore it is not a liming material.
HYDRATED LIME- Produced by adding water to burned lime or by absorption of moisture from the air. It has the same characteristics and limitations as burned lime.
LIME- Chemically it is calcium and magnesium oxide. Produced by high temperature heating calcitic or dolomitic limestone, which will replace the carbonate ion (CO3–) of the limestone with oxygen. However, the term is broadly applied in agriculture to any material containing calcium and magnesium in forms capable of correcting soil acidity.
LIME REQUIREMENT- The amount of agricultural limestone required to move the soil acidity to reach another degree of acidity or pH. The desired pH range will depend on if the crop is an acid loving or more alkaline loving crop. It is usually expressed in pounds per acre of CaCO3 needed to bring the soil to the desired pH under field conditions.
LIME SLUDGES- Some water softening plants have lime sludge containing fine lime particles that are precipitated in the softening process. Lime sludges vary in calcium carbonate equivalent (CCE) and water content, both of which would influence the amount of sludge, needed to equal dry aglime.
MAGNESIAN LIMESTONE- Limestone that contains 5-10% pure dolomite, and 90 - 95% calcite. The MgCO3 content of magnesian limestone range from 2.3-4.4%.
MAGNESIUM CARBONATE- A compound consisting of magnesium combined with carbonate. It occurs in nature as the mineral magnesite and as an essential part of dolomitic limestone and dolomite.
MAGNESIUM OXIDE (MgO) - The chemical compound composed of magnesium and oxygen. It is formed from MgCO3 by heating to drive off the carbon dioxide, or in mixture with CaO by heating magnesian limestone or dolomite. Also known as magnesia, it occurs in nature as periclase.
MARBLE- A compact, hard, polishable form of limestone.
MARL- A granular or loosely consolidated, earthly material composed largely of calcium carbonate as seashell fragments. It contains varying amounts of silt and organic matter.
MECHANICAL ANALYSIS- Also referred to as screen or sieve analysis. Indicates the percentages of a material that fall within predetermined particle size limits and between certain mesh sizes. State laws governing aglime quality standards are all based on particle size distribution guidelines established by mechanical analysis.
PELLETIZED LIME- Limestone which is granulated into a pellet. The original product is a finally ground limestone (usually 100-mesh or smaller) in size that is put into a granulation drum and bound together with a highly water-soluble substance. This process improves the easy of handling and application of liming materials. In regards to correcting soil acidity, it takes the same amount of effective calcium carbonate equivalent pelletized lime as it does any other liming material to achieve correction of soil acidity.
QUICKLIME- See calcium oxide.
SLACKE LIME- See hydrated lime.
SLAGS- One of the steel industry byproducts is magnesium silicate or slag. Air-cooled slags must be ground the same as limestone. Water cooled slag is a porous granular material produced when water is applied to the hot slag. Because of the large particles associated with this material, it usually requires screening.
SOIL pH- An expression of the degree of acidity or alkalinity of a soil, measured on scale of 1 to 14. Readings from 1.0 to 6.9 indicate that a soil is acid (sour); from 7.1 to 14.0 that it is alkaline (sweet). A reading of 7.0 is neutral. The term “pH”; refers to negative logarithm (p) of the hydrogen ion (H) concentration in soil solution.
SOIL REACTION- The acidity or alkalinity status of a soil. Soils that are acid are said to have an acid reaction; those that are alkaline, an alkaline reaction.
STACK DUST- See fluid-bed ash.
UNSLAKED LIME- See Calcium oxide.