1. Soil Testing and Analysis Nutrient Management Basics
Sustainable Small Acreage Farming and Ranching
Slides adapted from the Living on the Land curriculum,
University of Nevada-Reno, Sue Donaldson, et al. 2001

2. How do I know what to add to my soil???

3. Test your soil!
Soil testing is important to determine the fertility of a soil. Farmers routinely test their soils to determine the nutrient status. For both economic and environmental reasons, the farmer does not want to apply any more than is needed for healthy crop development. Based on soil test results from across their fields, farmers can vary the rate of application depending on soil conditions.
UNCE, Rno, NV

4. What Information Does a Soil Test Provide?
Soil textural analysis
pH and salts
Soil nutrient content
Fertilization recommendations
Be sure the test that you request is for the question you want answered. Nutrients are not the only factor for good crop production. Before sending samples, contact the laboratory first. They may have special requirements for packing etc. Contact your local extension office for a list of analytical laboratories that serve your area.
The results of a soil test can be used to make a fertilizer recommendation for certain crops and pastures. Soil testing laboratories use different test methods that may influence results and sufficiency ranges. Because lab may use different methods of analyses, and different analyses are appropriate for different soil types, it is advisable to send a soil sample to a lab in the same region from where the soil sample is from. A lab in your region may be more likely to use procedures suited for your soil type and they may have data correlating the results to plant responses on similar soils.

5. A Fertile Soil Has:
The right kinds and amount of nutrients to grow pasture or crops
Low salinity and sodium
Close to a neutral pH (about 7)
Plenty of organic matter
Soil fertility refers to the quality of a soil that enables it to provide essential chemical elements in quantities and proportions for the growth of plants. The major nutrients that plants use are Nitrogen (N), Phosphorus (P), Potassium (K) and Sulfur (S). These are macro nutrients.
The pH of the soil will influences how much nutrient is available to plants. Also, the amount of organic matter your soil has is very important for growing crops.
USDA NRCS Photo Gallery

6. How Often Should I Take a Soil Sample?
Prior to seeding a crop in new ground
At least every three years for established perennial crops
Frequently enough to make good decisions on fertilization
When it is cost effective
The frequency of sampling is a management decision based on economics, the environment, and personal interest. If one is not as concerned about maximizing productivity, then the frequency of testing can be reduced. However, it is useful to know if the correct amount of fertilizer is being applied. Applying too much fertilizer is costly, does not benefit the crop, and can result in surface and groundwater pollution, especially by nitrates. Applying too little will decrease productivity.

7. How to take a sample
First select the site. Your soil sample should represent only one soil type or soil condition.
When taking a soil sample, choose areas of the field that have a similar condition as shown in this slide. Avoid areas where you know fertilizer has been place recently and sample unusual areas, such as low spots, separately. If areas are very different, you will need to collect separate samples. Be sure to use clean equipment to avoid contamination.
OSU Extension Service

8. How to take a sample
Each sample should consist of sub-samples taken from about 15 locations within the same soil type or sampling area.
The accuracy of the soil test is a reflection of the sample taken, so make sure you have a good sample! Start by selecting about 15 locations randomly. Avoid sampling near gravel, manure or compost, septic leach fields, brush piles, or under eaves.
OSU Extension Service

9. How to take a sample
Use the “slice” method for a representative sample.
Dig a hole 6 to 12 inches deep. Slide your shovel or trowel down the side of the hole from top to bottom, removing a “slice” of soil. Place all of the samples together in a clean pail and mix them thoroughly. Remove pebbles and debris. Let the sample dry. When dry, place about 1 to 2 cups of soil in a ziplock bag, label and date the bag, and send the sample to the lab. The lab may have other shipping requirements, so check with them first.
Note: Soil testing is done for a particular use – you tell them what crop you are going to grow ( lawn, forage, mixed vegetables, potatoes, etc.) and the tests results have recommended amounts of nutrients (mainly Nitrogen, Phosphorus, Potassium and Sulfur) needed.
UNCE, Reno, NV

10. Soil test results What do my soil test results mean?
What nutrients do plants need?
How can I supply those nutrients?
Supplying nutrients to crops is very important. Supplying the right quantity at the right time will help the plants and reduce the unnecessary loss of fertilizer while protecting the environment. If a landowner wants to grow crops or a pasture, he or she should have a soil test done.
Soil test results are only indices of nutrient-supplying power of a soil. They don’t tell you the actual supplying power of your soil, because many nutrients may be locked up in organic material and biomass. It is best to think of soil test results as more qualitative than quantitative.
Most laboratory results will be returned to you with a fertilizer recommendation based on the kind of crop you want to grow. Also remember that the results of the soil test are only as good as the sample you provide!

11. What kind of information does my soil test report provide?
Particle size analysis (texture)
Soil organic matter content pH
Soluble salts
Nutrient content
Most soil tests will provide information on major nutrients, pH, and organic matter. You may need to specifically request other tests, such as micronutrient levels. Soil testing is not the answer to all problems in growing a crop or maintaining a healthy yard and garden. It is, however, a good place to start learning about the capability of your soil.
USDA NRCS

12. Particle size analysis
Provides the relative percentages of sand, silt, and clay
Allows determination of soil textural class
A loamy texture is generally best for most plants
Soil textural classes are determined by the proportions of sand, silt, and clay in the soil. Sand is the coarsest size particle, and clay the finest. Generally, as texture becomes finer, water-holding capacity increases, infiltration rate decreases, capacity to hold nutrients increases, and the amount of amendment needed to change pH increases. Soil textural classes are grouped into five categories:
1. Coarse (sands, loamy sands)
2. Moderately coarse (sandy loam, fine sandy loam)
3. Medium (very fine sandy loam, loam, silt loam, silt)
4. Moderately fine (clay loam, sandy clay loam, silty clay loam)
5. Fine (clay, sandy clay, silty clay)
NRCS, Bozeman, MT

13. Soil organic matter (OM)
Living or dead plant and animal residue
Measured in percent
OM content is highly variable
Generally, 3% to 8% OM content is good for plants
Organic matter refers to the organic portion of the soil that is composed of both living organisms and once-living residues in various stages of decomposition. The benefits of soil organic matter are many, and include rapid decomposition of crop residues, formation of stable soil aggregates, decreased crusting, improved water infiltration and drainage, and increased water and nutrient holding capacity. Soil organic matter is also a source of soil nutrients.
UNCE, Reno, NV

14. pH Indicates relative acidity or alkalinity
pH 7 = neutral; less than 7 = acid; more than 7 = alkaline or basic
The pH scale ranges from 0 to 14. It measures the acidity or alkalinity of a solution. A pH of 7 means it is a neutral solution. Pure water has a pH of 7. A pH of less than 7 means the solution is acidic. A pH of more than 7 means the solution is basic, also called alkaline. The lower the pH, the more acidic the solution is. The higher the pH, the more basic the solution is. Each change of number in either direction represents a tenfold change in acidity or alkalinity. Most soils lie in the range of 5.5 to 8.5.
Item pH
Most acid soils
Lemon juice
Vinegar
Clean rain water
Blood plasma
Mild soap solution
Adapted from library.thinkquest.org

15. Widest part of the bar indicates maximum availability
Soil pH and nutrients
Soil pH affects the availability of plant nutrients as well as the biological activity of soils. Most essential plant nutrients are available at or around a neutral pH of about 7. As soils become more acidic (< pH 7) or alkaline (> pH 7), nutrients become less available. Also, bacteria tend not to do well in more acidic environments.
Phosphorus is never readily soluble in the soil but is most available in soil with a pH range centered around 6.5. Extremely acidic soils (pH ) can have high concentrations of soluble aluminum, iron and manganese that may be toxic to the growth of some plants. A pH range of approximately 6 to 7 promotes the best nutrient availability.
Adapted from
Widest part of the bar indicates maximum availability

16. What makes soils acid? Acid soils: pH is below 7
Soils become acid because of heavy rainfall that weathers soils quickly
Basic cations such as calcium, magnesium, and potassium are leached from the soil profile
This natural weathering process makes soils acid
Soils tend to become acidic as a result of: (1) rainwater leaching away basic ions (calcium, magnesium, potassium and sodium); (2) carbon dioxide, formed as a result of decomposing organic matter and root respiration, dissolving in soil water to form a weak organic acid; (3) formation of strong organic and inorganic acids, such as nitric and sulfuric acid, from decaying organic matter and oxidation of ammonium and sulfur fertilizers. Strongly acid soils are usually the result of the action of these strong organic and inorganic acids.

17. Raising the pH of acid soils
Add lime to raise the pH (making soil less acid)
Lime most often consists of calcium carbonate
Plant response will be relatively slow, taking weeks or months
Lime is usually added to acid soils to increase soil pH. The addition of lime not only replaces hydrogen ions and raises soil pH, thereby eliminating most major problems associated with acid soils, but it also provides two nutrients to the soil -- calcium and magnesium. Lime also makes phosphorus that is added to the soil more available for plant growth and increases the availability of nitrogen by hastening the decomposition of organic matter. Liming materials are relatively inexpensive, comparatively mild to handle and leave no objectionable residues in the soil.
Some common liming materials are: (1) Ground Limestone, which is CaCO3; (2) Ground Dolomite or Dolomitic Limestone, which is CaMg(CO3)2 or limestone high in magnesium, respectively; and (3) Miscellaneous sources, such as wood ashes. The amount of lime to apply to correct a soil acidity problem is affected by a number of factors, including soil pH, texture (amount of sand, silt and clay), structure, and amount of organic matter. In addition to soil variables, the crops or plants to be grown influence the amount of lime needed.

18. What makes soils alkaline?
Alkaline soils: pH is above 7
Soils that have not been greatly weathered or leached
Some alkaline soils are high in calcium
Reduces solubility of all micronutrients
In arid or semi-arid climates, soil pH may tend to be higher or what we call alkaline (pH > 7). This alkalinity is caused because the base forming ions mentioned above (calcium [Ca2+], magnesium [Mg2+], potassium [K+], and sodium [Na+]), tend to accumulate in the soil because of a greater amount of annual evaporation and low rainfall. Often times, these soils have a high quantity of calcium carbonate and are called calcareous soils. Higher Soil pH levels directly influences the availability of essential plant nutrients such as phosphorus, zinc and iron.
Micronutrients can be added to high pH soils by using water soluble chelates that are “stable.” If too much exchangeable sodium is present in the soil, it is usually removed by adding gypsum (calcium sulfate), followed by irrigation to leach the sodium ions.
Adapted from library.thinkquest.org

19. Example of crop in alkaline soil
The yellowish color of the sorghum grown in this field with calcareous soil conditions (soil high in calcium) is the result of iron deficiency. In this situation, the addition of sulfur and sulfur compounds may help to lower soil pH and increase the availability of micronutrient elements. In some situations, micronutrient deficiencies may also be remedied by foliar applications of fertilizer (applied to the leaves).
A better option might be to grow a different crop, as it is often difficult to lower pH.
ag.arizona.edu

20. Soluble salts
A measure of inorganic chemicals that are more soluble than gypsum, such as sodium, calcium, magnesium, chloride, sulfate and bicarbonate.
Salty soils are a problem in arid regions or in poorly drained soils
In arid regions, the accumulation of salts can be a problem. Soluble salts can cause harm to plants if they are in high enough concentration in water or soil. The salt effect pulls moisture out of roots and reduces the uptake of water and nutrients to affected plants. Tip and edge burn of leaves, slow growth, nutrient deficiencies, wilting and eventual death of the plant can occur if the salt level is excessive for the plant and the problem is not corrected. To avoid plant loss in salty sites, a soil test should be done to determine the soil salt level and plants selected based on their salt tolerance.
USDA NRCS

21. Managing salt-affected soils
Select plants that can tolerate salinity
Avoid excess or salty forms of fertilizers
Incorporate organic matter
If appropriate, add sulfur to lower the pH
Managing these soils for growing crops can be difficult. In some cases, leaching with excess irrigation water to get rid of excess salts may be needed. If irrigation water is of low quality, the quantity of water applied should continually exceed the plant’s needs by 15 to 20 percent to provide enough water to maintain the root zone at safe salt levels. Make frequent, low volume irrigations to avoid plant stress.
Because of saline irrigation water, high water table, or low permeability of the soil, it may not be economically feasible or environmentally wise to maintain low salinity. In such instances, the judicious selection of crops that can produce satisfactory yields under saline conditions and the use of special management practices to minimize salinity may make the difference between success or failure. In cases of alkaline soil, the addition of elemental sulfur may lower pH..

22. Nutrient Management Meet crop nutrient needs Maintain soil quality
Conserve resources
Protect water quality -- reduce leaching and runoff risk
A faremer must manage the nutrient levels of the soil to meet the crops needs but also to maintain soil quality,conserve resources and protect water quality.

23. Plant Nutrients Major Nutrients Micronutrients Nitrogen Phosphorus
Potassium
Calcium
Magnesium
Sulfur
Micronutrients
Boron
Iron
Manganese
Zinc
Copper
Chloride
Molybdenum
All plants require many nutrients for proper growth and development. Macronutrients are nutrients needed in large quantities. Micronutrients are those needed in small quantities.
Carbon, hydrogen, and oxygen are supplied to plants through air and water. The other nutrients come from the soil. To get economic crop yields, farmers must often add extra nitrogen, phosphorus, and potassium (beyond what exists naturally in the soil) in the form of commercial or organic fertilizers, or other soil amendments.
The portion of these chemicals that is not used by crops may leach through the soil profile and into groundwater supplies used for drinking water. Phosphorus and potassium are not toxic, but nitrate levels in groundwater can reach toxic levels when certain soil types, weather conditions, and agricultural practices prevail.
For this reason, it is important to use the results of your soil test to determine the nutrient needs of your soil and plants.

24. Macronutrients N = nitrogen P = phosphorus K = potassium
The nine main nutrients are called macronutrients. The three nutrients that plants get from the soil that are required in relatively large amounts are nitrogen, phosphorus, and potassium.
Nitrogen (N) is the plant nutrient most universally deficient for high crop yields. Nitrogen is the key ingredient for grass leaf growth. Be cautious in using nitrogen fertilizers. Nitrates are completely soluble in water and are easily washed away or leached below the plant’s root zone by over-irrigation, especially in sandy soils. This pollutes groundwater supplies and can result in unacceptable drinking water quality.
Phosphorus is important for developing strong root systems, and for flowering and fruiting. In general, phosphorus does not leach through soils because it is tightly bound to soil particles and chemically reacts with other elements to form insoluble soil compounds. It can be lost via soil erosion.
Potassium is necessary for durability and disease resistance. It seldom causes water quality problems because it is not hazardous in drinking water and is not a limiting nutrient for growth of aquatic plants. It is usually very abundant in the soil in western states. Like phosphorus, it is tightly held by soil particles, and can be lost by erosion.

25. More macronutrients Ca = calcium Mg = magnesium S = sulfur
The remaining three macronutrients are calcium, magnesium, and sulfur.
Calcium is an essential part in all cell walls and membranes, and must be present for the formation of new cells. Sulfur is a constituent of three amino acids and is essential for protein synthesis and nodule formation on legume roots. Magnesium is essential for photosynthesis and serves as an activator for many plant enzymes required in growth processes.

26. Micronutrients Fe = iron Mn = manganese Zn = zinc B = boron
Mb = molybdenum
Ni = nickel
Cu = copper
Co = cobalt
Cl = chlorine
The nine micronutrients (iron, manganese, zinc, boron, molybdenum, nickel, copper, cobalt, and chlorine) are required in tiny amounts. Except for chlorine, the primary role of the micronutrients is as activators in numerous enzyme systems. You will need to specially request micronutrient analysis, and it will increase the cost of the soil test. An adjustment in soil pH usually corrects deficiencies of the micronutrients .

27. Questions to ask yourself before you add fertilizer:
Which elements do I need? (N, P, K, S, Ca)
How much do I apply?
What type of material do I use?
Which application method is best?
When is the best time to apply it?
To answer the questions in this slide, you must have an idea of what you want to grow. The first step is to determine the existing nutrient content of your soil by taking a soil test. Which elements you need and how much is based on the test results and the requirement needs of the crop you are growing.
What type of material will depend in part on your goals. Are you interested in organic farming? What is your budget? Are the fertilizer materials you’d like to use readily available?
You want to 1) make the nutrient available when the crop needs it; 2) avoid adding excess nutrients (especially nitrogen) that the plant can’t use either before the plant grows or after harvesting; 3) make the nutrients available when they strengthen, not weaken, the plant; and 4) be able to apply when field conditions make it possible to get into the field.

28. Types of fertilizers Chemical fertilizers
Organic fertilizers (bone meal, compost, manure,etc.)
Organic fertilizers are derived from living materials. Animal manures, compost, bone meal and blood meal are organic fertilizers. Organic fertilizers are not immediately available to plants. Before the plants can use them, they must be broken down by soil micro-organisms into simpler, inorganic molecules and ions.
Chemical fertilizers are manufactured synthetic compounds or processed forms of non-living materials. Rock phosphate for example, is a common source of phosphorus in chemical fertilizers. The nutrients in chemical fertilizers are already in inorganic form and can be immediately used by the plants.

29. Organic Materials Little or no processing Low nutrient content
Slow release of nutrients
Plant, animal, or mineral sources
There are advantages and disadvantages to use of both organic and synthetic fertilizers. The above slide points out characteristics of organic materials.
Plants can only take up nutrients that are in available form (simple, soluble ions). Most nutrients in organic materials are in complex organic molecules or minerals, and are not immediately available to plants.
Biological processes slowly release the nutrients in organic amendment into available forms. Rate of nutrient release depends on the nature of the amendment and environmental conditions.

30. Nutrient uptake
The forms of nutrients taken up by plants are the same for all types of fertilizer -- manufactured or organic.
It is important to understand that there is no fundamental difference in nutritional quality between organic and inorganic fertilizers. It makes no difference to the beet root if the atoms of potassium it absorbs are from an organic fertilizer such as wood ash or an inorganic one such as muriate of potash.
However, there are specific reasons why sustainable and organic growers favor organic fertilizers. Sustainable growers are not limited and use both types but judicious use of high nitrogen fertilizers is important for many reasons.

31. Organic materials: Fertilizers vs. Soil amendments
Fertilizer 1. High nutrient content and availability Main benefit is nutrients. 3. Relatively small amounts applied.
Soil amendment 1. Low nutrient content and availability Main benefit is organic matter Large amounts applied.
Use of chemically synthesized (inorganic) fertilizers raise several concerns: 1)They are subject to leaching, which occurs when the fertilizers are washed by rain or irrigation water down below the level of the plant roots. Nitrogen is particularly susceptible to leaching. 2) Heavy applications of chemical fertilizers can "burn" seedlings and young plants. Fresh manure applied to plants can also have the same affect. 3) Overly heavy applications can build up toxic concentrations of salts in the soil and create chemical imbalances, 4) Repeated applications of some chemical fertilizers can acidify the soil also creating an imbalance of available nutrients, 5) Effects of chemical fertilization also has an effect on the balance of the living soil organisms as well.

32. How much fertilizer do I need to apply?
Estimate the amount of fertilizer needed based on soil test results, crop needs and area to receive fertilizer
Most fertilizer recommendations are in pounds per 1000 square feet, or pounds per acre
Estimate amount of fertilizer needed based on soil test results, crop needs and area to receive fertilizer. Then compare the recommendations given by the lab results to those recommended in crop fact sheets to determine the quantity and type of fertilizer or soil amendment.

33. Fertilizing with manures
Good source of nutrients and organic matter
Protects soil from raindrop impact and erosion
Local supply often available at no cost
Before chemical fertilizers were available, animal manures were the primary source of plant nutrients for agriculture. Manure has several advantages and disadvantages compared to chemical fertilizers. The advantages are that it improves the soil health by adding organic matter and increasing the numbers of soil organisms that are beneficial to crops. It also can reduce water and wind erosion by improving soil structure. The disadvantages are that it is bulky, and more difficult to transport and apply on large areas compared to chemicals. Also, manures may contain weeds and pathogens.
If over-applied, manure can be harmful to crops, soil surface and ground water quality. In some cases (usually with fresh poultry manure), manure with high nitrogen content can burn crops.
OSU Extension Service

34. Different sources of manure have different amounts of nutrients
Poultry manure is high in nitrogen
Beef and horse manure tends to be lower in nitrogen
Sheep manure is high in potassium (K)
It is a good idea to have your organic fertilizer such as manure or compost tested for nutrient content. The nutrient content will be determined not only by the source, but also by the manure handling system, climate, and soil characteristics. Follow tables that show approximate nutrient values for a range of manure types at wet and dry rates. Manures from different livestock have different N, P, and K contents.
Wet vs. dry manure
Remember that a wet manure (one that was flushed out of the barn with water) is going to weigh more and have a lower nutrient content on a per weight basis than the same manure when dry. Manure test results generally list nutrient values on a dry weight basis, but when manure is picked up, delivered and applied, it is at least 60-80% water. It is therefore necessary to know the nutrient values on a wet weight basis.
For an example calculation, see:
Reference: From End to Beginning: A Manure Resource Guide for Farmers and Gardeners in Western Washington. King Conservation District, 935 Powell Ave. SW, Renton, WA 98055; (206) Available on the web:
UNCE, Reno, NV

35. Cautions for fertilizing with manures
Watch out for weeds and pathogens
Know the manure nutrient content
Consider the salt content
Tips for safe manure/compost application:
Compost manure, if possible, before applying
Composting manure before application will reduce pathogens and weeds.
Weed seed concerns if composting not complete
Complete composting is fairly hot (160 degrees) and will kill most weed seeds. If composting is not complete, there may be viable weed seeds left – weed seeds you have now incorporated (reincorporated?) in your landscape somewhere.
Know the nutrient and salt content
Care must be taken when using and fertilizing with manures. When manure applications are based on nitrogen (N) need, long term application of manure can lead to excess phosphorus (P) and potassium (K) levels. Excess P levels may increase the amount of P in runoff, which will contaminate surface water. Many crops can thrive in soil with high levels of K, but livestock may be harmed if they consume diet of forages with high K levels. Also, after repeated manure application, less will be needed as the long term nutrient pool increases.
N- P- K
OSU Extension Service

36. Cautions for fertilizing with manures
Incorporate or apply evenly to avoid smothering plants
Don’t apply on frozen slopes
Avoid leaching nutrients into waterways
Incorporate or apply evenly and do not smother plants
Incorporate as soon as possible. This reduces runoff of nutrients and odor – if the ground is flat, there is less likelihood of runoff.
Seasonal considerations – winter, wet conditions, etc.
Most chemical reactions occur faster under “warm” conditions – composting and decomposition work fastest when the ground is not frozen. Manure or compost may be applied to frozen ground if the ground is flat. When the ground is saturated with water, there is a greater potential for run off. In the Pacific Northwest, manures shouldn’t be applied during the rainy season when crops are not growing, and composted manure or manure piles should be covered and protected from the rain.
Maintain a minimum of 100 feet from water source (if flat ground)
This includes well heads, artificial ponds and irrigation ditches
Away from natural drainages
Manure or compost needs to be kept out of ephemeral drainages (those with water only part of the year or that contain water only after storm activity).
Monitor soil’s Nitrogen content to avoid over application
As stated before, too much manure will burn existing vegetation.
UNCE, Reno, NV

37. What we’ve learned:
Use soil test results to guide you in amending your soil
Nutrient management is more than just adding fertilizers to meet plant needs
Chemical fertilizers and natural or organic soil amendments both have advantages and disadvantages and must be managed based on each farms particular cropping system.