Managing Soil to Keep It Productive
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Transcript of Managing Soil to Keep It Productive
Managing Soil to Keep It Productive
Developed by: Hudson MinshewOregon State University Extension ServiceSusan DonaldsonUniversity of Nevada Cooperative Extension NRCS, Bozeman, Mont.
Part One: Fertilizing
What do my soil test results mean? What nutrients do plants need? How can I supply those nutrients?
pH Indicates relative acidity or alkalinity = pH 7 => neutral; < pH 7 => acid; > pH 7 => alkaline or basic
Adapted from library.thinkquest.org by A. Miller
CO Soils generally 7.0-7.8Western CO Valley Soils generally 7.5-8.5
Soil pH and nutrient availability
Adapted from www.soil.ncsu.edu by A. Miller
Widest part of the bar indicates maximum availability
What makes soils acid? Acid soils: pH is below 7 Soils become acid due to 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 Soils high in calcium Reduces solubility of all micronutrients
Adapted from library.thinkquest.org by A. Miller
http://ag.arizona.edu
Example of crop grown in alkaline soil
Adapted from ag.arizona.edu by A. Miller
Soluble salts A measure of inorganic
chemicals that are more soluble than gypsum, such as: ◦sodium, ◦calcium, ◦magnesium, ◦chloride, ◦sulfate,◦bicarbonate.
Salty soils are a problem in arid regions or in poorly drained soilsUSDA NRCS
Classifying salt-affected soils Electrical conductivity measurements
(EC) Exchangeable sodium percentage (ESP) Salt-affected soils are commonly
classified for management purposes into three groups based on EC and ESP: ◦saline, ◦sodic, and ◦saline-sodic
Grand Valley, CO
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 salt-affected soils In soils with good drainage, periodically
leach the salts below root zone with high quality irrigation water (avoid if high water table present)
Plant nutrients Substances necessary for plant growth Some, such as hydrogen, oxygen and
carbon, come from the air and water Others, such as nitrogen and phosphorus,
may need to be added Excess or improper use of fertilizers may
result in water pollution
Macronutrients
N = nitrogenP = phosphorusK = potassiumB
IG 3
More macronutrientsH = hydrogenO = oxygenC = carbon
Ca = calciumMg = magnesiumS = sulfur
MicronutrientsFe = iron Mn = manganeseZn = zincB = boronMb = molybdenum
Ni = nickelCu = copper Co = cobaltCl = chlorine
Six 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?6. Will I get a return on my
investment?
Types of fertilizers Chemical fertilizers Organic fertilizers (bone meal, compost,
manure, etc.)
www.farmphoto.com
What’s in the bag?
WAY TO GROWFERTILIZER
28 – 14 - 5GUARANTEED ANALYSIS
Total nitrogen 28% 6% Ammonium nitrogen 14% Urea nitrogenAvailable phosphoric acid 14%Soluble potash 5%
Derived from sulfur-coated urea,etc.
Product name NPK formula Nitrogen content Phosphorus content Potassium contentSpecific sources
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 1,000 square feet, or pounds per acre
Calculating fertilizer rates
X 100Pounds of nutrient recommended Percentage of nutrient in fertilizer
material
To convert a recommendation to pounds/acre of an actual fertilizer material, use the following formula:
Calculating land area Length x Width = Area If the area is oddly shaped or oval,
calculate using a regular shape that closely fits the shape of the land to be fertilized
100 ft
200 ft
150 ft
150 ft
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
Different sources of manure have different amounts of nutrients
UNCE, Reno, Nev.
Cautions for fertilizing with manures
Watch out for weeds and pathogens
Know the manure nutrient content
Consider the salt content
Univ. of Oregon
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, Nev.
USDA NRCS
Nutrient deficiencies
• Nitrogen• Phosphorus• Potassium• Calcium• Zinc• Manganese
What we’ve learned Use soil test results to guide you in
amending your soil Test results are only as good as the sample you collect Fertilize to meet plant needs, and avoid costly overuse that may pollute water
Web Soil Survey How to use a soil survey How to find a map unit Map unit descriptions
Soil ratings and capabilities
http://websoilsurvey.nrcs.usda.gov
Soil map units A map unit
describes a soil “type” in the soil survey
“Map-unit descriptions” are found at the beginning of the survey
Soil map unit example630 Fleischmann
gravelly clay loam
Soil textural class is part of map unit name
Number designation
Name given by soil scientists conducting survey
NRCS, Bozeman, Mont.
Soil limitations
Suitability ratings Freeze dates and growing season Productivity (tons/acre) Building site development Suitability for irrigation Physical and chemical properties
◦ (percent OM, pH, available water capacity)
Soil surveys can differ in the information they provide.
Other information
Restrictive features Cemented pan Droughty Erodes easily Flooding Low strength Restrictive layer Shrink-swell
potential
UNCE, Reno, Nev.
Capability classes I and II - good farmland with few to
moderate limitations III and IV - severe to very severe
limitations for growing crops V and VI - limitations that are impractical
to remove. VII and VIII - very severe, unsuited for
cultivation.
Classes
Capability classes
USDA NRCS
To wrap it up... Soil surveys are generated by NRCS scientists
Available in printed form or on the Web
Soil surveys are useful for determining capabilities and limitations of your soils at the large scale.