1. Nutrients and Soil Organic Matter for Crops: Care for these RESOURCES

2. Starting with The Basics!

3. What is soil Naturally deposited MIXTURE of: Rock particles
“Organic” materials
Air
Water

4. Soil Components

5. Soil Components
Air= Mixture of atmospheric gases

6. (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…)

7. Soil Components WATER= H2O Every living thing needs water
Water shapes the planet

8. Soil Components
Organic Matter= Solid material originating from living organisms

9. A deeper look at Soil Organic Matter
WHERE does it come from?

10. Plants ARE Organic Matter!
Well, WHERE do plants come from? AIR ~ WATER ~ LIGHT

11. AIR

12. WATER

13. LIGHT

14. PHOTOSYNTHESIS- conversion of Light Energy into Chemical Energy
Creates carbon-based plant life-
“FIXED CARBON” or
“REDUCED CARBON”
-from
CO2
Water
Light Energy
GLUCOSE

15. 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

16. 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!!!

17. Plants=Food Food=Energy Energy=Fuel Fuel “BURNS” All life requires Fuel

18. About ENERGY… The CARBON Cycle
CO2
PHOTOSYNTHESIS
RESPIRATION
“Reduced Carbon”
(GLUCOSE)

19. 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)

20. Energy feeds the Soil Food Web

21. Plants SYNTHESIZE Biomolecules
Not all biomolecules are carbohydrates! Fats, Proteins, Vitamins, Cofactors, and Nucleic Acids all have CARBON backbones MORE INGREDIENTS REQUIRED FOR THESE…

22. 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)

23. 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

24. Q: Where do these elements come from?

25. A: From the crust of the Earth

26. So Rocks dissolve- SLOWLY!!

27. 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

28. 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…)

29. Q: Why are fertilizers necessary for CROP production?
Hint: What does the word “CROP” mean?

30. Most added fertilizers are derived from rock deposits
Phosphate Rock, Potash Rock, Limestone, Gypsum, Talc, others

31. 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

32. 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

33. Nutrient Cycling through Organic matter
Agricultural Production Systems sIMulator (APSIM)

34. All elements have cycles
Nitrogen
Legumes!!
Alflafa
Clovers
Trefoils

35. All elements have cycles
Phosphorus

36. 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

37. 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

38. 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

39. 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

40. 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

41. Questions?