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Published byBarnard Carroll Modified over 7 years ago
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Nutrients and Soil Organic Matter for Crops: Care for these RESOURCES
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Starting with The Basics!
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What is soil Naturally deposited MIXTURE of: Rock particles
“Organic” materials Air Water
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Soil Components
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Soil Components Air= Mixture of atmospheric gases
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(more on these in a little while…)
Soil Components MINERAL= Solid compound of known composition: NaCl, SiO2, Al2Si2O5(OH)4 ROCK= Mixture of minerals (more on these in a little while…)
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Soil Components WATER= H2O Every living thing needs water
Water shapes the planet
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Soil Components Organic Matter= Solid material originating from living organisms
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A deeper look at Soil Organic Matter
WHERE does it come from?
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Plants ARE Organic Matter!
Well, WHERE do plants come from? AIR ~ WATER ~ LIGHT
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AIR
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WATER
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LIGHT
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PHOTOSYNTHESIS- conversion of Light Energy into Chemical Energy
Creates carbon-based plant life- “FIXED CARBON” or “REDUCED CARBON” -from CO2 Water Light Energy GLUCOSE
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SO: Plants produce their own food (ENERGY)!!
Glucose=Basic Sugar Immediate energy for plant Building Block of: Starch- energy storage Cellulose- structural carbohydrate Fats, oils, waxes
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Microorganisms can digest it!!!
Cellulose: basic structural unit of plant cell walls Most abundant organic polymer on Earth Makes up: 90% of Cotton fiber 40-50% of Wood Microorganisms can digest it!!!
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Plants=Food Food=Energy Energy=Fuel Fuel “BURNS” All life requires Fuel
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About ENERGY… The CARBON Cycle
CO2 PHOTOSYNTHESIS RESPIRATION “Reduced Carbon” (GLUCOSE)
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Plant material is the ULTIMATE Source of SOIL ORGANIC MATTER and ENERGY
Plants and animals grow and die Residues enter the soil ecosystem …and are broken down and transformed by soil microbes and fauna Organisms mineralize nutrients Accumulation of organic matter Chemical Energy of organic matter is converted into new organisms Agricultural Production Systems sIMulator (APSIM)
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Energy feeds the Soil Food Web
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Plants SYNTHESIZE Biomolecules
Not all biomolecules are carbohydrates! Fats, Proteins, Vitamins, Cofactors, and Nucleic Acids all have CARBON backbones MORE INGREDIENTS REQUIRED FOR THESE…
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Plant Nutrients- Elements obtained from the SOIL
MACRONUTRIENTS MICRONUTRIENTS Phosphorus (P) Potassium (K) Calcium (Ca) Magnesium (Mg) Sulfur (S) Iron (Fe) Manganese (Mn) Zinc (Zn) Copper (Cu) Nickel (Ni) Molybdenum (Mo) Boron (B)
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One more… SUPER IMPORTANT
NITROGEN (N) acquired by plant roots BUT All N is ultimately derived from the air In nature: Bacteria are able to use atmospheric N, which then becomes available to plants In agriculture: Atmospheric N is converted to ammonium (NH4) by an industrial process called Haber-Bosch
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Q: Where do these elements come from?
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A: From the crust of the Earth
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So Rocks dissolve- SLOWLY!!
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Ionic forms of Plant Nutrients
NO3- PO4-3 NH4+ K+ Ca+2 Mg+2 SO4-2 Fe+2 Mn+2 Cu+2 Zn+2 BO3-3 Cl- MoO4-2 H+ Al+3
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Sources of Plant Nutrients
Weathering of soil minerals- very little Added fertilizers- VERY IMPORTANT Organic matter, including crop residues, manures, compost (more on this in a bit…)
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Q: Why are fertilizers necessary for CROP production?
Hint: What does the word “CROP” mean?
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Most added fertilizers are derived from rock deposits
Phosphate Rock, Potash Rock, Limestone, Gypsum, Talc, others
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Some fertilizer nutrients are applied as MANURES
Manure is an ORGANIC nutrient source- remember what we mean by ORGANIC… BUT- there aren’t enough manure nutrients to meet more than 10% of US cropland needs
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Why do manures have plant nutrients?
Livestock do not digest everything they eat Manure can have 10 to 40 lbs/ton of N and P Organic nutrient sources release slowly
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Nutrient Cycling through Organic matter
Agricultural Production Systems sIMulator (APSIM)
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All elements have cycles
Nitrogen Legumes!! Alflafa Clovers Trefoils
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All elements have cycles
Phosphorus
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Caring for these Resources
Nutrients: They are necessary for growing agricultural crop plants They are expensive They are in limited supply They can pollute ecosystems and groundwater if excessive
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Making the most of Nutrients
Some are removed with the crops Some can be cycled through crop residues and manures Losses should be minimized: a) for Cost Saving, b) for Water Resource Protection, c) for Ecosystem Protection
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Minimizing Nutrient Loss
Prevent soil erosion (loss of Phosphorus) Allow space for vegetated buffer zones between crop fields and water bodies Grow cover crops in fallow seasons to absorb excess soil nutrients Apply manure responsibly GROW LEGUME COVER CROPS FOR N
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Caring for these Resources
Soil Organic Matter: Provides a slow release supply of plant nutrients, especially N and P Has extremely important soil benefits, especially as FUEL for microorganisms
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Caring for these Resources
Conservation of Soil Organic Matter: Minimize soil disturbance- aeration helps the microorganisms to “burn” SOM Leave crop residues in the field Apply additional organic materials if they are available PLANT COVER CROPS
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Questions?
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