understanding our garden’s soil. what does soil do? provides nutrients for the plants – npk...
TRANSCRIPT
Understanding our Garden’s Soil
What Does Soil Do?
• Provides nutrients for the plants– NPK
• Regulates water• Provides support for roots• Filters potential pollutants
SOIL COMPONENTS: Physical
• Mineral Particles–Sand–Silt–Clay–Organic Matter
• Air• Water
SOIL COMPONENTS: Living
• Microorganisms• Worms• Fungi• Bacteria
“It’s Alive!”In 1g of soil there are:
• >100,000,00 bacterial cells
• >11,000 species of bacteria
• Fungi and larger organisms
COMPOSITION OF SOIL BY VOLUME
Mineral Particles;
48%Water;
25%
Air; 25%
Organic Matter; 2%
SOIL FORMATION:ClORPT
•Climate
•Organisms
•Relief
•Parent Material
• Time
SOIL HORIZONS
1. O-Horizon1. Recognizable, recent2. Less recognizable3. Humus
2. A-Horizon– Mineral layer
3. E-Horizon– Elluviation layer
4. B-Horizon– Zone of Accumulation
5. C-Horizon– Clumps
6. Bed Rock
Physical Properties of Soil
• Color• Texture• Structure• Drainage• Depth
SOIL COLOR
• Light brown Low in organic matter• Dark brown High in organic matter• Black Very high organic matter• Red Weathered/nutrient poor• Red-brown Good drainage• Yellow Moderate drainage• Grey Poor drainage• White, light greySandy
SOIL TEXTURE
• Sand, Silt, Clay– Excludes organic matter
Water holding capacityIrrigation frequencyNutrient holding capacityFertilization frequency
CLAY LOAM SANDhigh medium lowlow medium highhigh medium lowlow medium high
Structure, Drainage, and Depth
• Structure is the shape soil takes based on its physical and chemical properties– Destroyed by over-tilling and traffic
• Soil drainage is improved by adding organic matter
• The deeper the soil, the greater the storage capacity for water and nutrients
SOIL pH
• pH is a measure of the acidity or the basicity of the soil
0 2 4 6 8 10 12 14
ACID BASIC
NEUTRAL
PLANT GROWTH
Effects of pH on Nutrient Availability
Reprinted from the Arizona Master Gardener Manual, Chapter 2, page 20.
IRON CHLOROSIS
Iron deficiency appears on the youngest leaves of plants growing in alkaline soils.
SOIL AMENDMENTS
• Complete fertilizers– NPK
• Incomplete fertilizers– Missing at least one of the
primary nutrients
• Organic fertilizers– Remains or by-products of
plants or animals– Release nutrients slowly
• Blood and bone meal• Fish emulsion• Manure
MANURES
% of N P KChicken manure 4.4 2.1
2.6Cow manure 1.9 0.7 2.0Pig manure 2.1 0.8 1.2Horse manure 1.4 0.4
1.0Sheep manure 3.5 0.6
1.0
NITROGEN
• Necessary for formation of chlorophyll, as well as building amino acids for proteins.
• Nitrogen deficiency symptoms– Yellowing leaves
beginning in oldest leaves– Leaf tips and margins
yellow and dies– Plants are stunted.
PHOSPHORUS
• Phosphorus is necessary for almost all aspects of plant growth and is essential for flower and fruit formation
• Phosphorus deficiency symptoms– Dark green foliage– Purplish foliage on stems– Reduced growth– Delayed maturity or reduced
flowering
POTASSIUM
• Potassium is necessary for the formation of sugars, starches, carbohydrates, protein synthesis and cell division in roots and other parts of the plant.
• Potassium deficiency symptoms– Leaf tips and margins burn– Affects oldest leaves first– Plants have weak stalks– Small fruit
Sources of NPKConventional Renewable
Nitrogen Synthesized from natural gas: Urea, anhydrous ammonia
Fixed from the air by rhizobacteria associated with legumes, Manure and compost; blood meal
Phosphorus Mined in Florida, CanadaRock phosphate
Manure, compost, bone meal; fish emulsion
Potassium Mined in Canada Green sand
Manure, compost
IMPROVING SOIL:Cover Cropping
• Mixing vegetable plants with other crops such as grasses and legumes.
• Add nutrients and organic matter to the soil
• Helps hold moisture• Improves soil texture• Prevents erosion
IMPROVING SOIL:Compost—Nature Recyles!
• Transformation of raw organic materials into biologically stable substances suitable for plants
• Improves soil structure, texture, and aeration.
• Increases water-holding capacity
• Increases nutrients
IMPROVING SOIL:Crop Rotation
• Planting crops in a prescribed rotation
• Builds soil nutrients• Crops help to fertilize
each other• “Tricks” pests• Adds diversity
IMPROVING SOIL:Reduced Tillage