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 waterWater shapes the planet

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

9 A deeper look at Soil Organic MatterWHERE 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 EnergyCreates 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 CycleCO2 PHOTOSYNTHESIS RESPIRATION “Reduced Carbon” (GLUCOSE)

19 Plant material is the ULTIMATE Source of SOIL ORGANIC MATTER and ENERGYPlants 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 BiomoleculesNot 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 SOILMACRONUTRIENTS 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 IMPORTANTNITROGEN (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 NutrientsNO3- 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 NutrientsWeathering 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 depositsPhosphate Rock, Potash Rock, Limestone, Gypsum, Talc, others

31 Some fertilizer nutrients are applied as MANURESManure 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 matterAgricultural Production Systems sIMulator (APSIM)

34 All elements have cyclesNitrogen Legumes!! Alflafa Clovers Trefoils

35 All elements have cyclesPhosphorus

36 Caring for these ResourcesNutrients: 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 NutrientsSome 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 LossPrevent 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 ResourcesSoil 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 ResourcesConservation 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?