Soil Testing and AnalysisNutrient 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

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

Test your soil!

UNCE, Rno, NV

What Information Does a Soil Test Provide?

Soil textural analysis pH and salts Soil nutrient content Fertilization

recommendations

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 USDA NRCS Photo Gallery

Prior to seeding a crop in new groundAt least every three years for established perennial cropsFrequently enough to make good decisions on fertilizationWhen it is cost effective

How Often Should I Take a Soil Sample?

How to take a sample

First select the site. Your soil sample should represent only one soil type or soil condition.

OSU Extension Service

Each sample should consist of sub-samples taken from about 15 locations within the same soil type or sampling area.

OSU Extension Service

How to take a sample

Use the “slice” method for a representative sample.

UNCE, Reno, NV

How to take a sample

Soil test results

• What do my soil test results mean?

• What nutrients do plants need?• How can I supply those

nutrients?

What kind of information does my soil test report provide?

• Particle size analysis (texture)

• Soil organic matter content

• pH• Soluble salts• Nutrient content

USDA NRCS

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

NRCS, Bozeman, MT

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

UNCE, Reno, NV

pH• Indicates relative acidity or alkalinity• pH 7 = neutral; less than 7 = acid; more

than 7 = alkaline or basic

Adapted from library.thinkquest.org

Soil pH and

nutrients

Adapted from www.soil.ncsu.edu

Widest part of the bar indicates maximum availability

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

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

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

Adapted from library.thinkquest.org

ag.arizona.edu

Example of crop in alkaline soil

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

USDA NRCS

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

Nutrient Management

• Meet crop nutrient needs

• Maintain soil quality

• Conserve resources

• Protect water quality -- reduce leaching and runoff risk

Plant Nutrients

Major Nutrients• Nitrogen• Phosphorus• Potassium• Calcium• Magnesium• Sulfur

Micronutrients• Boron• Iron• Manganese• Zinc• Copper• Chloride• Molybdenum

Macronutrients

• N = nitrogen• P = phosphorus• K = potassium

More macronutrients

• Ca = calcium• Mg = magnesium• S = sulfur

Micronutrients

• Fe = iron • Mn = manganese• Zn = zinc• B = boron• Mb = molybdenum

• Ni = nickel• Cu = copper • Co = cobalt• Cl = chlorine

Questions to ask yourself before you add fertilizer:

1. Which elements do I need? (N, P, K, S, Ca)2. How much do I apply? 3. What type of material do I use?4. Which application method is best?5. When is the best time to apply it?

Types of fertilizers

• Chemical fertilizers• Organic fertilizers (bone meal, compost,

manure,etc.)

www.farmphoto.com

Organic Materials

• Little or no processing

• Low nutrient content

• Slow release of nutrients

• Plant, animal, or mineral sources

Nutrient uptake

• The forms of nutrients taken up by plants are the same for all types of fertilizer -- manufactured or organic.

Organic materials:Fertilizers vs. Soil amendments

• Fertilizer 1. High nutrient content and availability. 2. Main benefit is nutrients. 3. Relatively small amounts applied.

• Soil amendment 1. Low nutrient content and availability. 2. Main benefit is organic matter. 3. Large amounts applied.

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

Fertilizing with manures• Good source of

nutrients and organic matter

• Protects soil from raindrop impact and erosion

• Local supply often available at no cost

OSU Extension Service

• Poultry manure is high in nitrogen

• Beef and horse manure tends to be lower in nitrogen

• Sheep manure is high in potassium (K)

Different sources of manure have different amounts of nutrients

UNCE, Reno, NV

Cautions for fertilizing with manures

• Watch out for weeds and pathogens

• Know the manure nutrient content

• Consider the salt content N- P- K

OSU Extension Service

Cautions for fertilizing with manures

• Incorporate or apply evenly to avoid smothering plants

• Don’t apply on frozen slopes

• Avoid leaching nutrients into waterways

UNCE, Reno, NV

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.