1. Soil Composition & Ferterlizers Northridge Garden Guild June 29, 2010 Materials are a condensed version of information provided by the USU extension service
4. Why is soil important? Like humans, plants thrive in a healthy environment Good soil provides nutrients, oxygen and water to plants without stress Weak plants are more susceptible to disease and insects
5. Components of Soil (by volume) (Transpiration and nutrient transport) (Primary soil particles and nutrients for plants) (Soil structure and nutrients for plants) (Oxygen to roots)
13. The Effect of Particle Size Sand particles Clay particles Air flow Water flow
14. Determining Soil Texture By feel Soil test jar method Fill a 1-quart jar ¼ full of soil Fill the jar ¾ full of water Shake very well to suspend soil Place on a flat surface and allow soil to settle
18. Treating Soil Texture “Problems” Too much sand? You are lucky Adjust irrigation accordingly Select drought tolerant plants Too much clay? Good luck! Select plants tolerant of poor drainage, lack of oxygen Either case: induce soil structure
19. Introduction of Organic Matter The combination of sand, silt and clay combined with organic matter creates secondary particles called aggregates
20. Compaction Destroys soil structure Seals off soil surface Water runs off instead of into soil – drought results Air can’t enter or escape soil - suffocation Roots can’t penetrate the soil Stress – plants die
26. Poor Drainage Problem Prevent compaction? Add organic matter Install subsurface drainage system Provide drainage ditches Develop raised beds Use precise water management
27. Excessive Drainage Problem Very sandy soil Consider sunken beds Add extra organic matter Precise water management
28. Amending Soil with Organic Matter Benefits: Improves drainage Improves water-holding capacity Reduces compaction Provides nutrients to plants Improves soil “tilth” (ease of tillage, working with a soil) Lowers soil pH
29. How much organic matter should I add? How much is already there? Native Utah soils ~ 0.25 to 2.0% Ideal soils 5-10% Are you satisfied with the current condition of your soil? Add some organic matter to maintain soil conditions Should I add sand to my clay soil?
30. Adding/Preserving Organic Matter Grow plants Mulch around perennials Add extra organic matter to gardens and other annual planting areas
31.
32. Summary Understand what you have Figure out what you need Texture Compaction Drainage
35. Sources of nutrients Inorganic/Synthetic fertilizers Organic Fertilizers Manures composts, and other organic materials Green manures (legumes and others)
36. Fertilizer label Three numbers always appear on the label 1. % Nitrogen (N) 2. % Phosphorus (P) 3. % Potassium (K)
37. Just A few N-P-K labels out there 34-0-0 21-0-0 29-3-4 26-3-3 28-4-4 25-3-5 20-2-4 26-3-3 25-3-5 32-3-5 24-6-12 16-4-8 16-16-16 12-12-12 22-4-11 22-4-14 20-27-5 18-5-9 5-10-10 9-17-9
38. Selecting a fertilizer What nutrients are needed? Soil test What ratio of nutrients are needed? Nitrogen alone or a “complete” fertilizer? Established landscapes need nitrogen annually; few landscapes need other nutrients Are extras needed? cost factor: extras increase cost
40. Soil testing… …prior to planting: ensures good success – especially in new landscapes …diagnose problems …every 2 to 3 years to monitor soil environment
41. Soil sampling Sample areas with different soils 6-inch depth in turf 12-inch depth around woody vegetation and in gardens Combine 4 to 6 sub-samples from the area for each sample submitted
43. Methods of application Broadcast – evenly distributed on surface Banding – applied in a narrow band on surface or in furrow opened adjacent to plant row Foliar – applied in liquid form
45. Organic nutrient sources Much lower concentration of nutrients Example: 2-2-2 for composts Good sources of organic matter May need to supplement with inorganic nitrogen fertilizer
46. Green manures Plants grown for the sole purpose of “storing” nutrients or producing nutrients (nitrogen) and organic matter for later use in the garden Examples: Legumes (peas, beans, vetch, alfalfa) Small grains (rye, oats, barley, wheat)
47. Other considerations Combine inorganic and organic nutrients Practice crop rotation in garden Return as much organic matter as possible to annual planting areas
49. Soil pH Soil pH: the degree of acidity or alkalinity of soil The pH scale: 2 4 6 8 10 12 Neutral (7.0) acidic alkaline
50. Causes of iron chlorosis High lime soils Buffer pH in 7.8-8.0+ range Planting acid-loving plants in Utah “Aggravating factors” Cold soils Over-irrigation Soil compaction Over-fertilization Other stresses
57. Sources of salts Residual salts in new development areas Irrigation water natural sources water softeners Deicing salts (road throw and sidewalks) Over-application of fertilizers and/or manures and composts
58. Solutions to salt problems Control the source: water, fertilizer, manure runoff, other? Clean up the problem: Remove salts by leaching with water
