Organic Matter in the Soil

1. Organic Matter in the Soil

2. Waste is a human concept. In nature nothing is wasted, for everything is part of a continuous cycle. Even the death of a creature provides nutrients that will eventually be reincorporated in the chain of life. Denis Hayes

3. What is Organic Matter? • all plant and animal residues in the soil

4. What things make up soil organic matter? • Plant & animal residues • Barnyard manure • Green manure • Dead roots • Insect & worm carcasses & excrement • Dead soil micro-organisms (bacteria, fungi, protozoa)

5. What is Green Manure? • a crop grown for its organic matter • green manure crops are generally plowed under while they are still green • Examples = sweet clover, rye

6. What two things have greatly lowered the Organic Matter content of soil? • soil erosion • continuous cropping

7. How can organic matter be increased? • crop residues • barnyard manure • green manure

8. What is the difference between organic matter & humus? Organic matter is dead plant & animal life before it has been broken down Humus = relative stable product of the decomposition of organic matter

9. What is Mineralization? • organic matter is broken down into simple mineral compounds • Due to the action of bacteria & fungi

10. When organic matter breaks down, what is released for the crop's use? • Nutrients (sulfur, nitrogen, phosphorous, potassium, calcium, magnesium + micronutrients)

11. How does Organic Matter Improve Soil? 1) increase water holding capacity 2) nutrients attach to O.M. 3) O.M. improves tilth (aggregate) 4) The amount of humus in soil is directly proportional to the amount of nitrogen in soil

12. How does Organic Matter Improve Soil? 5) Soils high in O.M. are easily worked and may be described as having good tilth. 6) Improves soil structure 7) Improves aeration

13. Benefits of Organic Matter • Organic Matter promotes granulation of soil by binding soil particles into granules. • O.M. makes clay soils less sticky and improve tilth. • Deeper root growth and water entry and storage are improved as well as aeration of the soil.

14. Organic Matter & Sandy Soils • Sandy soils have good aeration but dry out quickly. Sandy soils increase water holding capacity and have less erosion as O.M. is added?

15. What is the largest source of O.M. in the soil? • plant roots

16. Which is the most preferred green manure, legumes or non-legumes? • legumes- added nitrogen

17. What is nitrogen tie-up? • microorganisms in the soil use the nitrogen in the soil to break down organic matter, thus it is temporarily "tied up" (used as food) • this is very important when considering re-cropping and not allowing the soil to have a year in fallow to allow for mineralization in order to reduce the nitrogen tie-up.

18. Is organic matter a good mulch? Yes • Reduces surface evaporation • Equalizes soil temperature • Increases soil animal life • Reduces soil erosion

19. Detrimental effects of soil organic matter • Energy source for many disease organisms – ensuring their survival in the soil • Excessive amounts of plant residues are difficult to incorporate into the soil and hinder some planting operations • Addition of organic matter into soil may temporarily increase the carbon:nitrogen ratio – thus limiting the available nitrogen to the current crop

20. How many square feet are in an acre? • 43,560

21. What is an acre-six inches? • six inches of soil over an acre

22. An acre-six inches weighs how many pounds? • 2 million

23. Soil Conservation A typical farmer is doing a "good job" of soil conservation if he loses less than 1/16" of topsoil each year. How many pounds of soil does he/she lose each year if he/she loses 1/16"? How many tons? (extra credit)

24. How long does it take to create soil? It takes 100 to 400 years to create 1" of topsoil.