1. Soil and Water Kelly Young UA Cooperative Extension

2. Objectives: Discuss soil components, texture, chemistry Consider relationships between soil, water, plants and air Learn about the properties of water Compare and contrast fertilizers Suggest soil amendments 2

3. How long have you lived in Arizona? 3 1.Less than 1 year 2.1-5 years 3.5+ years 4.Born and raised here (or nearly so)

4. 4 Ideal Soil Composition Desert soils have significantly less than 5% organic matter. Why?

5. 5

6. Maricopa County soils: –Mineral –Alkaline –Arid –Probably some caliche –May be rocky and shallow, particularly in foothills –May be saline –May be heavy 6

7. Are Maricopa County Soils Bad? 7 1.Yes 2.No

8. Soil Texture 8 beachball frisbee dime

9. Soil texture affects water movement 9

10. Which soil texture warrants the greatest number of drip emitters to wet an area? 10 1.Sandy 2.Loam 3.Clay

11. Determine your soil texture 11

12. Soil Texture Triangle 12

13. 13

14. Soil Compaction Compaction reduces pore space: –Restricts H 2 O and O 2 –Poor root development 14

17. Capillary Action Cohesion – “like sticking to like” –Water molecules stick together Adhesion – “sticking to unlike” –Water molecules stick to certain surfaces Capillary action – drawing of water in a narrow tube

19. Soil-Plant-Air Continuum

20. Stomata Factors affecting opening and closing: Light, especially blue light Water Temperature CO 2

21. Water moves down its concentration gradient Concentration of water is –Highest in soil –High in plant –Low in air

22. When transpiration > water uptake by roots, wilting occurs.

23. Water loss Evaporation – change of water phase from liquid to gas Transpiration – evaporation of water from leaves Evapotranspiration (Et) – combined loss of water directly from soil evaporation and transpiration

24. Factors that affect Et Temperature Relative humidity Wind speed Light intensity Type of plant

25. Terry’s 1-2-3 Rule Watering depth 1.1 ft - Flowers, vegetables and other small annuals 2.2 ft – Shrubs 3.3 ft – Trees

26. Root volume V = ½( 4/3 π r 3 ) Π ≈ 3.14 r = ½ diameter If a tree has a 12’ diameter: r = 6’ The root volume would occupy approximately 452 cubic feet.

27. Root volume V = ½( 4/3 π r 3 ) V = ½( 4/3 π r 3 ) Π ≈ 3.14 r = ½ diameter Assume 5 years later the tree has a 20’ canopy: r = 10’ Now, the root volume would occupy approximately 2093 cubic feet!

28. Larger trees require more water than smaller trees of the same species. 28 1.True 2.False

29. Soil Chemistry 29 atom

30. Cations: –NH 4 +, K +, Fe ++, Ca ++ Anions: –NO 3 -, SO4 2- 30 Cation Exchange Capacity Clay particle Organic matter and clay carry a negative charge

31. Plant Nutrients Macronutrients C H O N P K Ca Mg S Micronutrients Fe Zn Mn B Mo Cu 31

32. 32 Nitrogen deficiency

33. 33 Phosphorus deficiency

34. pH is a measure of acidity/alkalinity 34

35. 35

36. 36 Zn deficiency Fe deficiency

37. Add nutrients to the soil Organic and inorganic forms Usually salts Can burn plants Must be watered in 37 Fertilizers

38. Fertilizer analysis N-P 2 O 5 -K 2 O (nitrogen-phosphate-potash) Complete fertilizer Incomplete fertilizer Slow release fertilizers 38

39. “Organic” versus “Chemical” fertilizers Organic Manure, compost, fish emulsion, etc. Sometimes recycles waste May be resource intensive Can be bulky, heavy Micronutrients Pathogens, weeds Salt Chemical Ammonium nitrate, urea, superphosphate, etc. Can be energy intensive to make Lighter weight Salt Must be purchased Salt 39

40. Do plants prefer organic over chemical fertilzers? 40 1.Yes 2.No

41. Salinity Na, Ca, K and other salts accumulate in soils 41

42. How does soil become saline? Shallow watering Fertilizers Irrigation water quality Application of other salty substances to soil.

43. Soil Amendments Used to modify soil chemistry –Gypsum (Calcium sulfate) – temporarily removes Na from soil –Soil sulfur – may eventually reduce pH after many yearly applications –Organic matter 43

44. What should be added to the native soil when planting trees and shrubs in the landscape? 44 1.Organic matter 2.Fertilizer 3.Organic matter and fertilizer 4.Nothing, only native soil should be backfilled into the planting hole.

45. Possible causes of “unthriftiness” High soil salinity Root diseases Root parasitic nematodes

46. How did you like using the clicker system? 46 1.I loved it! 2.It was okay. 3.Neutral 4.I’d rather not. 5.I hated it!

47. Questions? Contact me at kyoung@arizona.edu. 47