Soil and soil-water relationships W Anderson Murfreesboro Master

Soil and soil-water relationships W. Anderson Murfreesboro Master Gardener Feb 20, 2009

From UTK Extension Publications Planning the Vegetable Garden SP 291 -M Soil Preparation for Vegetable Gardens SP 291 -C Care of the Vegetable Garden SP 291 -D Organic Vegetable Gardening PB 1391

Definitions • Natural medium composed of solids, liquids, and gases that occurs on land surfaces • Supports plant and animal life • Upper limit, lower limit, plant roots • Does not cover all the Earth land surface • It is not tracked in on the house carpet

Soil Components • General rule, a soil is about one-half solids and one-half pores • Water and air fills the pore space • Soil air is lower in O 2 and higher in CO 2 than surface air – Plant roots – Biological organisms

Soil Components • Solids – Soil texture, relative proportion sands, silts, clays sized materials, separates • Sand • Silts • Clays 2. 0 mm to. 05 mm to. 002 mm less than. 002 mm – Clay soils, large surface area; small pores – Sandy soils, small surface area, large pores – Clay and Sand differ in ability to provide plants with water, nutrients, aeration and physical support – Sands are drier, less fertile but better aerated & able to support plants

Soil Texture • Twelve textural classes • 3 clay textures, 3 clay loam textures, 3 loam textures • 0 to 100 % sand, silt and clay by weight • Example: Clays, > 35% clay sized particles • Textural class Possible percentage – Clay loam – Loam 20% sand, 20% silt, 60% clay 30% sand, 35% silt, 35% clay 40% sand, 40% silt, 20% clay

Soil Components • Solids – Aggregate glue sand, silt and clay sized particles together • Granular – glue organic matter and calcium • Destroy soil aggregates – adding sodium – Density- mass per volume-pore space – Texture lbs/cu ft % pore space • Loam 84 • Clay loam 79 • Clay 74 49 53 56

http: //soils. usda. gov/education/reso urces/k_12/lessons/texture/

Soil Water Classification for Water Management Think of a soil as a sponge lift the saturated sponge up does water drip. • Saturation – Gravitational water - drainable • Field Capacity [FC] – Maximum Plant available water • Permanent wilting point [WP] – Plant unavailable water • Air dry – Unavailable water • Oven dry

Volumetric Soil Water Content Ranges Textural class Θv @ FC Θv @ WP Sand. 07 -. 17. 02 -. 07 Loam. 20 -. 30. 07 -. 17 Silt loam. 22 -. 36. 09 -. 21 Clay. 32 -. 40. 20 -. 24 Available Water = Θv @ FC - Θv @ WP Θv * inches of soil = inches of water in soil

http: //www. mt. nrcs. usda. gov/technical/ecs/agrono my/soilmoisture/clay. html • • Clay, Clay Loam, and Silty Clay Loam Soils Appearance of Clay, Clay Loam, and Silty Clay Loam Soils at Various Soil Moisture Conditions 75 to 100 percent available 0. 6 to 0. 0 inches per foot depleted Wet, forms a ball, uneven medium to heavy soil/water coating on fingers, ribbons easily between thumb and forefinger.

Irrigation • Maximize production, vegetable require 1 to 2 ½ inches of water per week • 1 inch of water over 100 square feet = 8. 3 cubic feet or 520 lbs water • Less water early in growing season • More when plants are larger and setting fruit • Apply water slowly • Don’t do frequent shallow watering. Why? Shallow root growth you want deep roots

Irrigation (2) • Irrigate early to reduce incident and spread of disease • Cultivate prior to overhead irrigation to increase water infiltration • Trickle irrigation, reduce water use by up to 50 times – Reduces weed growth, weed problems, soil compaction – Expensive

Irrigation (3) • Irrigation system – Back flow preventer must be connected to water source – Screen or disk filter – 10 to 12 psi pressure regulator – Trickle tape – Pressure gauge

Irrigation (4) • Soaker hose – non engineered – Cheap – Not uniform water distribution • Trickle system can be purchased at garden centers for $100 to $200

Time Irrigation Properly • Water late in day – increase diseases • Trickle, drip, furrow – conserve water, avoid foliage diseases • Sprinkler irrigation – best done early morning – apply 1 to 1 ½ inches of water – wait several days before repeating • Less frequent irrigation – less foliage and root diseases

Use Mulches • Reduce some pest pressures but increase others • Reduce moisture stress • Reduce weed pressure

Maintaining or Increasing Soil Organic Matter • • • Improves structure Holds water Increase microbe activity Stored and releases nutrients Plants and animals (organic matter) decay to more stable organic matter called humus • Balance between lost and added

Maintaining or Increasing Soil Organic Matter (2) • • Sandy soils – less Soil organic matter Clayey soils – more soil organic matter More soil mixing – less soil organic matter Tennessee – warm moist climate – favors decomposition

Using Crop Residues • Residue source of organic matter • Left or composted • If left – may increase insect, disease and weed problems • Turning under – breaks down faster – releases some nutrients • Fewer insect, disease and weed survive

Using Lime and Organic Fertilizers • Increase Soil p. H – Ground limestone – How much? Soil test – Calcite, dolomite – Basic slag – Wood ashes – don’t dump in one spot

Adding Nutrients - Manure • Manure – N, P, K – Poultry manure highest in N, P, and K – Spread on garden before planting • 250 -500 lbs large animal manure per 1000 square feet • 100 to 200 lbs poultry manure per 1000 square feet – Irish potato and sweet potato develop scab and canker if manure is used

Adding Nutrients – non-manure • • Fertilizer Blood meal Bone meal Granite dust Greensand Wood ashes Guano %N %P 2 O 5 %K 2 O 8 -15 0 -3 --2 -4 12 -28 ------3. 5 --1 -1. 5 5 -6 --1 -2 3 -7. 5 -12 4 -8 1 -3

Questions • What is soil? • Why manage water? How can a soils field capacity be used to manage irrigation? • Why should fertilizer be used? Can fertilizer improve a plants water use efficiency?

Water • • Precious resource Lost water means lost dollars What is water use efficiency? Defined as equal to units of crop production from each available unit of water • Example: bushels of grain per inch of water

• A long term fertility experiment has been conduct in Illinois. The experiment is called the Morrow Plots. The plots are on the National Historic Registry.

The Morrow Plots to gauge WUE • Plots received only lime, manure, rock phosphate or bone meal from 1904 to 1955 • 1955 a portion of some plot received lime, and commercial fertilizer annually • Fertilized continuous corn used precipitation more efficiently • Better management and improved varieties have also increased crop yield

The Morrow Plots can gauge WUE • Yields of both fertilized and unfertilized corn are increasing. from 1955 -1984 Fertilized Not Fertilized 130 -150 bu/acre 40 -50 bu/acre

The Morrow Plots can gauge WUE • Dry weather and poor fertility can reduce WUE. Proper fertilization that builds high fertility can help the crop overcome drought stress. from 1955 -1984 Fertilized Not Fertilized 3. 3 bu/inch of water 1 bu/inch if water

Question • If plants are fed the proper amounts of N, P 2 O 5 & K 2 O will these plants: – Produce more dry matter/acre: T or F – Remove more CO 2 from atmosphere: T or F – Will decrease the amount of water percolation through the soil and regolith: T or F – Will increase the amount of chemicals percolation through the soil and regolith to the ground water: T or F – Will utilize water less efficiently: T or F

What a soil need to grow: 150 bu/ac of corn • • • • Ingredient Water Oxygen Carbon N P K Ca S Mg Fe Mn B Cu Mo pounds per acre 6 to 8 million 10, 200 7800 C or 28, 500 CO 2 310 52 205 58 33 50 3. 45. 10 trace supplied 30 to 36 inches of rain carbon in 6 tons of coal 675 lbs urea 115 lbs TSP 340 lbs KCl 150 lbs ground limestone

Question • Cost to remove 28, 000 CO 2/ac from atmosphere? {basis: cost of Nitrogen} • 675 lb Urea * 45 lb N/100 lb Urea =304 lb N • 28, 000 lb CO 2/304 lb N =93 lb CO 2/ 1 lb N • 93 lb CO 2 /lb N * lb N/ $ 0. 30 =310 lb CO 2 / $1. 00 of N

• Typical topsoil – approximate composition • • • Soil basis Solids % by vol 50 Inorganic % by vol 40 % by wt 95 liquids Gases 25 25 Organic 10 5

• INORGANIC Fraction • (decomposed things) • Sand Silt Clay Humus • • Primary Secondary Colloids • Minerals • Quartz layer silicate • Feldspar hydrous oxide • mica

Questions • What are primary minerals? • What are secondary minerals?

• • • Soil - Root System Rye plant in 1 cu ft of soil for 4 months Length –miles surface area – sq ft Roots 385 2550 Root hairs 6600 4320

Questions • Soil resources in the USA (TN) do not have enough available nonmetals and metals elements for normal growth and development of plants and animals. – – – – TN land area -1980 Cropland 5. 1 million ac Grassland 5. 5 million ac Woodland 11. 7 million ac Urban 1. 7 million ac Other 1 million ac Federal 1. 2 million ac Now 14 million ac

• • Non-metal elements N Se P human function protein antioxidant bones & teeth • • Metal Cobalt Zn Mn human function vitamin B 12 sexual maturity bone formation, Insulin Production red blood cell formation • Cu

Questions • Emphasize – There is a difference between plant available content and total elemental content – Soil testing; plant available content

Other topics • Soil Testing, PB 1061 by Dr. H. Savoy • Liming Acid Soils in Tennessee, PB 1096 by Dr H. Savoy

Additional topics • Landscape Irrigation by Dr. J Buchanan, CD in the extension office • Commercial WEB sites – Rain. Bird Irrigation at www. rainbird now look under landscape irrigation – Toro Irrigation at www. toro. com/sprinklers/index. html – Hunter Industries at www. hunterindustries. com • Book Source: Simplified Irrigation Design ISBM 0 -471 -28622 -22