Presentation Transcript

1. Soils and FertilizerMaster Gardner Presentation25 January 2012

   Sam Doak sdoak@vt.edu
2. Functions of soil Is needed to grow YOUR plants Are the start of our food chain And your pay check Use CO2 and create O2 Why we are still here Home for macro and micro plants and animals Break down [decompose] plant and animal residues Releases nutrients so plants can use them
3. Why is Soil Important?? Soil Serves Four Functions for Plants Anchors the plant via roots Trees and wind Holds water available for plants Holds air [oxygen] for plant roots Respire & exchange More CO2 in soil air Holds nutrients for plants microbes YIELD OF YOUR CROPS IS LARGELY DEPENDANT OF QUAILTY OF SOIL
4. Ideal Soil 2 – 5 % Organic Matter 25 % Macropores [ Air] 25 % Micropores [Water] 48 – 45 % Mineral [solid]
5. Soil Forming Factors Parent material Water Organic matter On the east coast all these tend to drive the soil pH towards the acid side – -why we lime so often
6. Moisture and Temperature Effects on Soil Types Northern versus Southern USA Temperature Physical weathering Shorter growing seasons – less microbial activity Species differences - trees Eastern versus Western Rainfall Soil pH Accumulation of salts and Na Microbe activity Species differences trees vs. grasses Old mountains vs. “new”
7. INCEPTISOLS ARE IN BROWN MOLLISOLS ARE GREEN ULTISOLS ARE IN ORANGE
8. Organic O Dominated by organic material Soil Organized in to Horizons Topsoil A Mineral horizon showing organic enrichment Eluvial E Horizon showing depletion of OM, Clay Fe and Al Horizon showing enrichment of OM, Clay Fe and Al Maximum number of roots Subsoil B Parent Material C Horizon of loosened of unconsolidated parent material R Regolith Bedrock
9. Soil Horizons Ap A2 Bt1 Bt2 Bk
10. We visualize 3-Dimensional landscape segments Each may be made up of one or more soil series
11. Using and measuring the different characteristics of each horizon pH Texture Color Thickness Other The soil scientist can determine the SOIL SERIES [the smallest unit in soils] This is “CSI” soils
12. Virginia based on the STATSGO database PAMUNKEY SERIES Virginia has about 1,000 soil series
13. What is a published soil survey? A soil survey is a detailed report on the soils of an area. The soil survey has maps with soil boundaries and photos, descriptions, and tables of soil properties and features. Soil surveys are used by farmers, real estate agents, land use planners, engineers and others who desire information about the soil resource.
14. The major parts of a soil survey publication... Table of Contents Detailed soil map units Use and management and interpretive tables Classification of soils References Glossary Index to map sheets Soil maps
15. Using the soil survey... Obtain a printed soil survey from the NRCS, USDA office, or local conservation office or access a Web version at: http://soils.usda.gov/survey/ Published Soil Surveys for Virginia Published soil surveys are available without a fee, to walk-in customers, at the NRCS office located in each county. Each local office has only the published soil survey for their area. See the Virginia NRCS Contacts web page to help locate the office nearest you. http://soils.usda.gov/survey/printed_surveys/virginia.html
16. Using the soil survey continued... The lines on the image separate different soil types. Your area of interest may include one or more types. The small letters or numbers that are within the same polygon as your area of interest, such as ScC, or KnC, or LaC designate a map unit. Note this map unit symbol. It is the key to finding information. Turn to the Index to Map Units which shows the page where these map units are described. Also go to the various tables or reports which are organized by map unit symbol.
17. Soil Survey / Maps The JCC map
18. Brief explanation of JCC soils – environmentally sensitive Bob Winter to do more detail later
19. Soil structure Granular – Small, rounded, high in Organic Matter - common in top soil Blocky – about as high as long – common in subsoils Platy – flat – limits water and air movement, near compacted layers Prismatic – long on the vertical axis – mainly in subsoils Prismatic – No structure or shape – sand-like
20. Platy Granular Prismatic Blocky
21. Soil Pedon A PEDON SOIL HORIZONS
22. LOTS OF OM AVERAGE TILTH
23. Review Functions of soil Holds water, nutrients, air & holds plants Soil has solids, OM and space Soils have horizons – CSI Soil maps – id soil series Soil structure – granular to prismatic
24. Soil Texture Is the percentage of Sand Clay Silt The three classes are based mainly on particle size
25. Soil Texture Is the distribution of different particle sizes and types in the soil By chemical analysis In Lab Burn off organic matter, mix soil with water in cylinder Or measure using a hydrometer By Feel – THE 3 COMPONENTS OF TEXTURE ARE: Sand - Gritty Silt - Smooth ( like talcum powder) Clay - Sticky
26. LARGE COARSE SAND 2.0 TO 0.05 MM diameter By feel = Gritty MEDIUM MIXED SILT 0.05 TO 0.002 MM diameter By feel = smooth and slick SMALL FINE CLAY LESS THAN 0.002 diameter By feel = smooth and sticky
27. Relative Soil Particle Size Particle Size = moisture holding capacity [size does matter] SOIL PARTICLES DIAMETER (mm)RELATIVE SIZE Gravel > 2 Very coarse sand 1 – 2 soccer ball Coarse sand 0.5 – 1 tennis ball Medium sand 0.25 – 0.5 golf ball Fine sand 0.1 – 0.25 marble Very fine sand 0.05 – 0.1 match head Silt 0.002 – 0.05 sesame seeds Clay < 0.002 table salt basketball and bb’s
28. Surface Area (SA) Smaller size = more surface area = more reaction [THIS IS THE KEY] Surface area of one gram Sand = three lines in textbook Silt = four pages in textbook Clay = large wall plus internal SA = walls, floors and ceilings of a house (10,000 + times Sand) Organic Matter = almost as much as clay
29. CLAY (large SA) Large nutrient and water holding capacity Less fertilizer and less frequent watering Less chance of leaching Little resistant to compaction Less traffic tolerant More aeration needed SAND (small SA) Little nutrient and water holding capacity More frequent applications of fertilizer and water are needed Leaching is a big concern Big resistance to compaction More traffic tolerant Properties of Soil Types
30. TWELVE MAJOR TYPES OF SOIL TEXTURES
31. Soil texture triangle problems 60% sand 20% silt 15% clay = ??? Sandy Loam
32. SAND CLAY
33. Monitor Soil MoistureSAND 25-50% 50-75% 75-100%
34. Monitor Soil MoistureLOAM 25-50% 50-75% 75-100%
35. Monitor Soil Moisture 50-75%
36. The Ideal Soil Has Holes in IT 2 – 5 % Organic Matter 25 % Macropores [ Air] 25 % Micropores [Water]  48 – 45 % Mineral [solid] A 50 / 50 mix of macro and micro is generally preferred
37.   SOIL GETTING DRIER    Soil Macro and Micropores
38. Why care about pore space ?? The roots tend to follow the macropores Path of least resistance Less macro = more resistance = less rooting This is compaction!!! Macropores allow easier exchange of gasses Roots need oxygen, they give off CO2 Exchange with atmosphere Prevents build up of toxic gasses
39. Why care about pore space ?? Micropores hold water Smaller particles = more water held Water allows nutrient to move to plants REMEMBER WE WANT A GOOD MIX OF PARTICLES TO GET THAT 50 % PORE SPACE with ½ macro-pores and ½ micro-pores
40. SOIL PORES MICROPORES OR CAPILLARY PORES WATER FILLED SPACES MACROPORES OR NONCAPILLARY PORES -AIR FILLED SPACES
41. The Ideal Soil Has Holes in IT SPACE in Soil 2 – 5 % Organic Matter 25 % Macropores [ Air] 25 % Micropores [Water]  48 – 45 % Mineral [solid] A 50 / 50 mix of macro and micro is generally preferred
42. Micropores (Water filled) Macropores (Air filled)
43. Soil Moisture Balance Balance of Air&Water Saturated Field Capacity Permanent Wilting
44. Saturated soil Macropores filled with water –all space is filled with water Gravitational Water Water removed from soil by gravity [usually after 24 hours] Field capacity Macropores filled with air Permanent Wilting point Water removed from soil particles until permanent plant wilting occurs Equals dead plants Hygroscopic Water Water held on soil colloids to tight for plant uptake SOIL WATER Saturated Soil minus Gravitational Water = Field Capacity
45. WATER HOLDING AND NUTRIENT HOLDING CAPACITY SURFACE AREA AND WATER HOLDING SAND VERSUS CLAY Clay Has smallest particle size Has the most surface area = holds the most water Sand Has the largest particle size Has the least = smallest amount of water held
46. SILTY CLAY LOAM 1.6 2.2 1.8 2.5 2.65 1.0
47. The water holding capacity of various soils and Available Water (AW) is determined by porosity Values are for the top 12 inch soil layer
48. These diagrams illustrate the effects of “deep and infrequent” irrigation on root density, depth, and health
49. A summer bentgrass green example of deep, infrequent watering Effective rooting depth = 4 inches Sand = 1” AW/ft = 0.25” AW Summer ET demand is 0.15”/day; so in less than 2 days all rootzone moisture depleted Irrigate with about 0.2” every 2 days to refill rootzone
50. Different soils Same WATER amountSoil particle size is the difference
51. Implications for Irrigation and fertilizer Applications How much per application How often [how many times] THIS APPLIES TO LEACHING ALSO !!
52. Clay soil holds more and holds longer Can use more per application and fewer applications Sandy soils holds less and shorter time Must use more applications but less each application
53. If a plant needs 1 inch of water per week –it needs 1inch but the soil type influences HOW Clay soil may only need watering twice a week at ½ inch each time Sandy soil may need to be watered four times a week at ¼ inch each time. Clay holds nutrients better than Sand
54. The key is to keep water and nutrients in the plants root zone so the plant can use the materials before they move below the plants roots. Deep roots are key!! Turfgrass (cool season) roots reduce during the summer months.
55. Review Soil texture = % sand, % silt, % clay Sand = little water/ nutrient holding Clay = holds water/ nutrient - compacts Soil has spaces Marco = large spaces = air [roots follow] Micro = small spaces = water Soil Water = Field Capacity Clay loam = most Plant Available Water
56. Soil Organic Matter -SOM Leaf litter, clippings, roots, compost, bioproducts Influences Water/drainage – too wet = less SOM Temperature – too cold = less SOM Biomass – under trees= less, grass = more Tillage – more tillage = less SOM Soil texture – more in clayey soils
57. Soil Organic Matter Sources Type Examples of byproducts Agricultural • Livestock and poultry manures. • Rotten/unusable plant material such as feed, hay, silage, and forages. • Wood chips. • Slaughterhouse wastes and animal mortalities. Municipal • Wastewater sewage sludge/biosolids. • Water treatment residuals. • Landscape trimmings such as leaves, brush, and grass clippings. • Food waste. • Newspaper and other paper waste. Industrial • Paper mill sludge. • Food processing sludge such as poultry dissolved air flotation sludge, brewery waste, and peanut hulls. • Wood shavings, sawdust.
58. Soil Organic Matter - SOM Supports Microbes Warm, Moist, Well aerated, pH at neutral Microbes functions in soils Break down materials into nutrients Humus is fully decomposed + stable Nitrogen and Sulfur = bigger users of microbes
59. Soil Organic Matter - SOM Virginia Typical SOM levels Between 0.5 and 2.5 % Garden soils are about 5% Organic Soil Material = 12 – 20% Provides nutrients and soil structure
60. Drainage THE KEY is knowing where the water will end up. Neighborhood Watershed – storm drains
61. Leaching water movement Nitrogen Moves with water unless WIN Phosphorus Generally does not leach – unless in very high concentrations. Soil test !! Moves with soil particles – sediment Therefore control erosion
62. SOIL EROSION AND CONTROL SOIL EROSION BY WATER DETACHMENT Pick up of soil colloids loosened by freeze/thaw, wet/dry, raindrops, etc TRANSPORTATION Movement of soil FASTER WATER TRANSPORTS MORE SOIL LARGER VOLUME TRANSPORTS MORE SOIL BARE SOIL VERSUS A VEGETATED SOIL
63. FORMS OF EROSION BY WATER SHEET erosion Removal of thin layers of soil RILL erosion Washing away soil in shallow channels GULLY erosion Washing away soil in deep channels LANDSLIDES Sliding of whole masses of soil Sheet and rill remove over 100 times the soil of gully and landslides. WHY IS THIS IMPORTANT?
64. FACTORS THAT INFLUENCE WATER SPEED AFFECTS EROSION CLIMATE Rainfall, temperature [hot & cold] SOIL PROPERTIES Stable aggregates, clay, etc Resist detachment and transportation SLOPE Steepness, length, shape SURFACE COVER & LAND USE Fallow, row crops, legumes, grasses Clean tillage, no-till, conservation tillage
65. Losses in the USA 1966 = 5 BILLION TONS 1995 = 3 BILLION TONS THIS EQUAL OVER 3 MILLION ACRES AN AREA THE SIZE OF CONNECTICUT 1000 TON OF SOIL PER ACRE @ 7 INCHES DEEP SEDIMENTATION SOIL CARRIED FROM IT’S ORIGINAL LOCATION AND DEPOSITED IN ANOTHER PLACE
66. Functions of Erosion Control Prevent detachment and movement of soil particles Adsorbs and spreads the energy of rain drops Dissipate the forces of flowing water Protect seedlings from the above forces
67. Erosion control blankets [ECB] – EC2 Temporary control of erosion forces Vegetation will provide permanent control Mild slopes and ditch lines Turf reinforcement mats [TRM] – EC3 Permanent control of mowing water Vegetation provides cover TRM provide the majority of the soil stabilization Moderate to steep slopes and where intermittent flowing water is present
68. Finding the most cost effective solution Steeper slopes require more durable and sturdy RECPs The higher the expected rainfall [or water flow], the higher the strength of the RECP’s. Varies with application Slopes versus ditch lines
69. REMEMBER THE SOIL TESTING AND PREPARATION [CREATING A GOOD SEEDBED] IS STILL THE KEY TO SUCCESSFUL ESTABLISHMENT OF VEGETATION
70. Geotextiles Types Woven Non woven Applications Underlayment for roadbeds, riprap, silt fence
71. Stone materials Benefits Permanent Controls the highest flow rates Control continuous flow situations Drawbacks Creates a hazard to people traffic Requires maintenance to control vegetation intrusion Can damage equipment Collects trash
72. SOIL EROSION AND CONTROL BARE SOIL VERSUS A VEGETATED SOIL Turfgrass is very effective at EC Many plants per square foot Fibrous root system Trees, shrubs or mulch
73. Review Soil Organic Matter- Important Provides nutrients and structure Leaching – based on soil type Erosion – control the small first Especially Phosphorus
74. Questions ??
75. Soil Acidity Acids Substances that burn Substances that donate a Hydrogen ion to another substance Soil pH A numerical measure of the acidity or number of hydrogen ions of a soil
76. Soil Acidity Active vs. Reserve Acidity H H H H H H H Clay (-) Clay (-) H H H H H H H This is what is measured in a pH test Reserve Acidity (soil bound) Active Acidity (in soil solution)
77. pH is a measure of soil acidity Lime juice = 1.9 Pepsi = 3 OJ = 4 Beer / coffee = 4.5 Milk = 6.5 Pure water = 7.0 Eggs = 8 Bleach = 11 SCALE 0 Acid 7 Neutral 14 Alkaline
78. pH value defines relative acidity or basicity Strong 9.0 Basicity Medium 8.0 Moderate Most productive soils Slight Neutrality 7.0 Slight Moderate 6.0 Medium Acidity Strong 5.0 Very Strong 4.0
79. pH Scale pH Scale is a logarithmic scale This means that each number is 10 times the amount of the adjacent number The difference between 6 and 7 is ten fold. The difference between 6 and 8 is a hundred fold Soil pH is measure of the ACTIVE acidity or the acidity of the soil moisture.
80. A Soil’s pH Is Affectedby Several Factors: Parent material Precipitation Decomposition of organic matter Native vegetation Crops grown Soil depth Nitrogen fertilization Flooding
81. Soil pH of Virginia Ranges from 4 - 8 5.1 - 5.3 most common in unlimedsoils Direct Effects of Acidity Burning of plant roots Occurs at pH 4.0 or less
82. Indirect Effects of Acidity Affects nutrient availability < 7 Acid low availability of major (3) and secondary (3) nutrients > 7 Alkaline low availability of trace elements (except Mo) Critical pH Level Sandy : 5.0 or less Piedmont / Mountain : 5.5 or less Optimum pH Level 6.2 - 6. 3 (NOT 7.0)
83. pH Influences on Nutrient Availability
84. On Andisols, lime requirement should be based on site-specific field trials
85. Soil Acidity /pH How to change soil pH Lime Sulfur Leaves Wood ash Pine needles sulfates
86. Charge it Soil has a NEGATIVE charge Influences: OM, Clay Climate, fertilizers
87. MOST CHEMICALLY ACTIVE Clay and Organic Matter [OM] SOIL HAS A NEGATIVE CHARGE CATION EXCHANGE CAPACITY Measure of the charge that soil has CATIONS ARE ( + ) CHARGED Like magnets they are attracted to the negatively charged soil
88. Base saturation Ca2+,Mg2+, K2+ and Na+ are base The % of CEC that is occupied by the above cations is the base saturation. Above 50% is high - 70+% is very good
89. Urban soils Urban soils do not contain the natural sequence of intact soil horizons. Horizons mixed by large soil disturbance, movement and mixing. Exposed subsoils, filled and compacted No top soil, building materials embedded pH and nutrient outside plant requirements Low SOM and nutrients
90. Urban Soils Fixes: Soil Test, Add SOM, Nutrients, Lime Gypsum, tillage to increase aeration Best to incorporate vs. surface application Improve drainage
91. Urban soils Heavy Clay SOM – improves tilth / structure High Sand SOM– improves water / nutrient holding
92. C:N ratios Adding high C:N ratio materials like Sawdust, stubble, non composted material Microbes explode [growth] Steal / use most of the soil nitrogen Plants suffer – lack of nitrogen Until microbes fully decompose the material
93. C:N ratios FIXES – before planting Wait until fully decomposed Add additional nitrogen Use better planning
94. Review Soil pH Key to plant nutrient availability 6.3 - 6.5 best Soil has a negative charge Holds cations better than anions Urban soils Disturbed – turned upside down
95. break
96. Nutrients / Fertilizers Why do we fertilize? Actively growing plants can use more nutrients than an average soil can provide. Nutrient Groups Macro = plants use these the most Intermediate = in between usage Micro = used in small amounts = PPM
97. Nutrients MARCO C, H, O supplied by water and air N, P, K supplied by the soil On a bag of fertilizer N-P-K % of plant available nutrient
98. PLANTS [GENERAL] 80% Water 14% Carbohydrates & Fat 4% Protein 2% Minerals Corn plant % dry wt 44.5% Oxygen 43.6 % Carbon 6.3% Hydrogen 1.25% Nitrogen 1.20% K 1.20% Si 0.40% Cl 0.20% P, Ca & P PLANT GROWTH AND NUTRITION C H O = OVER 94% OF TOTAL
99. Jan Baptista Van Helmont(1577-1644) Willow tree 5 lbs Container and soil 200 lbs After five years Willow tree 169 lbs 3 oz Container and soil 199 lbs 14 oz WHERE DID THE TREE WEIGHT COME FROM? Van Helmont thought it was from water – Hmmm ? C H O [CO2, O2, H2O] Cells, woody material, flowers, etc Plants are mini factories: make food, energy to move materials, growth and development
100. Five Functions Needed by Plants 1) Absorption of water and nutrients from roots up to shoots 2) Transpiration Water to atmosphere [cooling and creates the force to move water into the plant and up to the leaves] 3) Making of organic compounds Simple to very complex – everything the plants needs to grow and develop [e.g. change from vegetative to reproductive]
101. Five Functions Needed by Plants 4) Photosynthesis Create [sugars or carbohydrates] from chemical combination of CO2 and H2O using light to supply the energy and give off O2 as a byproduct. 6CO2 + 6H2O –energy-> C6H12O6 + 6O2 6 C + 12 H + 18 O = the same amount Chloroplasts in the chlorophyll cells convert light to energy Why is chlorophyll green??
102. Five Functions Needed by Plants 5) Respiration Uses “food” and O2 to create or releaseenergy and give off CO2 C6H12O6 + 6O2–release energy-> 6CO2 + 6H2O Roots respire, people respire Soil air is higher in what gas than regular atmosphere?
103. MARCO - Nutrients NutrientSymbol TypeConc. In PlantNatural Primary Source Source in Production Carbon C Major 45% Air Air Hydrogen H Major 6% Water Water Oxygen O Major 43% Air,WaterAir, Water Nitrogen N Major 1-3% Soil, Air Fertilizer Phosphorus P Major 0.5-1% Soil Fertilizer Potassium K Major 0.3- 6% Soil Fertilizer
104. Natural SECONDARY -NUTRIENTS Source Added Calcium Ca Secondary 0.1-4% Soil Lime Magnesium Mg Secondary 0.05-1% Soil Lime Sulfur S Secondary 0.5-1% Soil Soil TRACE / Micro ELEMENTS Zinc Zn Trace 5-100 PPM Soil Soil Manganese Mn Trace 5-5000 PPM Soil Soil Copper Cu Trace 2-50 PPM Soil Soil Iron Fe Trace 10-1000 PPM Soil Soil Molybdenum Mo Trace 0.1-10 PPM Soil Soil Boron B Trace 2-75 PPM Soil Soil Chlorine Cl Trace 0.05 – 3% Soil Soil
105. NUTRIENTS MAJOR = macro plus secondary C, H, O, + N, P, K + Ca, Mg, S MACRO N, P, K SECONDARY OR INTERMEDIATE Ca, Mg, S TRACE OR MINOR Fe, B, Mn, Cu, Cl, Mo, Zn
106. Nutrient Levels and Maximum Yield Too much = more inputs [$$] for less output
107. __________________________ Brady and Weil 1996
108. VON LIEBIG’S LAW OR THE LAW OF THE MINIMUM The plant will only reach it’s maximum genetic potential yield if there are no limiting factors. --- WILL GROW ONLY TO THE MOST LIMITING FACTOR – FIX IT, THEN IT WILL GROW TO THE NEXT LIMITING FACTOR UNTIL ALL LIMITING FACTORS ARE ELIMINATED
109. Review Nitrogen, Phosphorus, Potassium Macro - supplied by soil – in fertilizer Used in large quantities Remember C H O Trace or micro nutrients – used in PPM Von Liebig’s Law WILL GROW ONLY TO THE MOST LIMITING FACTOR – FIX IT, THEN IT WILL GROW TO THE NEXT LIMITING FACTOR
110. General Crop Nutrient Deficiency Symptoms NutrientDeficiency Symptom* Nitrogen (N)Restricted growth of tops and roots; growth upright and spindly; leaves pale yellowish-green in early stages, more yellow and even orange or red in later stages; deficiency shows up first on younger leaves. Phosphorus (P)Restricted growth of tops and roots; growth is upright and spindly; leaves bluish-green in early stages with green color sometimes darker than plants supplied with adequate phosphorus; more purplish in later stages with occasional browning of leaf margins; defoliation is premature, starting at the older leaves. Potassium (K) Browning of leaf tips; marginal scorching of leaf edges; development of brown or light colored spots in some species which is usually more numerous near the margins; deficiency shows up first on younger foliage. Calcium (Ca) Deficiency occurs mainly in younger leaves near the growing point;younger leaves distorted with tips hooked back and margins curled backward or forward; leaf margins may be irregular and display brown scorching or spotting. Magnesium (Mg) Interveinal chlorosis with chlorotic areas separated by green tissue in earlier stages giving a beaded streaking effect; deficiency occurs first on lower foliage. Sulfur (S) Younger foliage is pale yellowish-green, similar to nitrogen deficiency; shoot growth somewhat restricted.
111. General Crop Nutrient Deficiency Symptoms Zinc (Zn)Interveinal chlorosis followed by die back of chlorotic areas. Manganese (Mn) Light green to yellow leaves with distinctly green veins; in severe cases, brown spots appear on the leaves and the leaves are shed; usually begins with younger leaves. Boron (B)Growing points severely affected; stems and leaves may show considerable distortion; upper leaves are often yellowish red and may be scorched or curled. Copper (Cu) Younger leaves become pale green with some marginal chlorosis. Iron (Fe) Interveinal chlorosis of younger leaves. Molybdenum (Mo) Leaves become chlorotic, developing rolled or cupped margins; plants deficient in this element often become nitrogen deficient. Deficiency symptoms for a particular crop may vary widely depending on the crop being investigated. For this reason, the deficiency symptoms that are listed should be used only as a guide.
112. Reddish-purple, especially on YOUNG leaves Firing or drying along the edges of lowest [older leaves] Yellowing at tip then down middle of blade Whiteish stripes along veins Leaf curl and grayish-green color
113. Why Fertilize? Plants can outstrip soil resources Balance & recycle Know why YOU need fertilizer Deficiencies –unfavorable conditions Soil tests[use a good lab] Biological tests Indicator plants – lettuce or tomatoes – your crop Small scale Tissue or sap tests Compared tests
114. Plant Balance Sheet Approach To maintain – put in what the crop removes Larger yield removes more nutrients Different soils = different yields Plan for the whole cropping rotation What are the major elements /nutrients plants remove from the soil and must be replaced by the soil?
115. Goals of a “Balanced Fertilizer Program” Build to optimum fertility Is site specific May mean planting a crop to remove an excess nutrient [ex. Phosphorus] Be economically aware Replace what each crop uses [removes] Some crops ADD nutrients Avoid runoff [movement of sediment] Be environmentally aware
116. Soil testingis a BMP
117. Soil Tests ServeTwo Basic Functions Provide a starting point for developing fertilizer and lime program Monitor the production system to keep the fertilizer program on track
118. The greatest potentialfor error in soil testingis in taking the sample
119. The steps in soil sampling Specific problem areas? sample these areas separately. Avoid (or sample separately) areas: - frequented by pets. - contaminated by fertilizer and/or chemical spills. - contaminated by ashes from fireplaces or stoves.
120. Mix the soil samples Use clean tools Use plastic bucket not metal – could give off traces of metal - contaminate the sample Mix thoroughly labs use only several spoonfuls must represent the entire area
121. Sampling with a spade or garden trowel
122. Collecting the sample. Any implement (probe, trowel, shovel, or spade) that can take up to a 6 inch depth of soil will work. Remove any turf, thatch, or mulch from the surface of the sample.
123. Take 10-20 samples per lawn unit to a depth of 4 inches (where > 90% of roots reside)
124. Organic Matter = 3.8% Estimated Nitrogen Release = 114 lbs/A Determined using acid digestion or burning off organic matter from soil sample Do not include thatch or shoots as this will greatly overestimate SOIL OM OM important as a N reservoir, for holding P, S, and micronutrients Handy estimate: about 30 lbs N/A/yr will be mineralized (released) from every 1% OM 3.8% x 30 lb/A = 114 lb/A or 2.6 lb/M/yr = ENR
125. Review Deficiency symptoms Mobile in plant if in older / lower leaves Not mobile if in new growth Fertilize because plants can grow faster than the soil can provide Take a GOOD soil sample – random Soil tests = pH nutrients – NO NITROGEN
126. Fertilizer bag labels Fertilizer labels all have 3 numbers on the label. They are important !! The sequence [order of the numbers] is important. N - P - K –other plant available nutrients not the ELEMENTAL form of the nutrients P2O5 = plant available Phosphorus (P) K2O = plant available Potassium (K)
127. Fertilizer labels ORDER is important –First 3 # are the same order on EVERY bagit’s the law NITROGEN - PHOSPHORUS - POTASSIUM NP K
128. NUMBERS ON A FERTILIZER BAG ARE A PERCENTAGE 46-0-0 = 46% NITROGEN - 0% PHOSPHORUS - 0% POTASSIUM 0-46-0 = 0% NITROGEN - 46% PHOSPHORUS - 0% POTASSIUM 0-0-60 = 0% NITROGEN - 0% PHOSPHORUS - 60% POTASSIUM 25-5-15 = 25% NITROGEN - 5% PHOSPHORUS - 15% POTASSIUM 15-30-15 = __% NITROGEN -__% PHOSPHORUS - __% POTASSIUM
129. To find amount of fertilizer = division To find amount of nutrient = multiplication
130. A 100 lb bag of 46-0-0 has 100 lb * 0.46 = 46 lbs on Nitrogen A 100 lb bag of 6-0-0 has 100 lb * 0.06 = 6 lbs on Nitrogen SO A 50 lb bag has ½ of a 100 lb bag = 23 lb N 50 lb * 0.46 = 23 lbs of N How much is in a 50 lb bag of 6-0-0 ?
131. Using a %: A 50 lb bag has a label of 28-0-0. How much nitrogen is in the bag? -bag method = 100 lb = 28 lb N so ½ of 28 = 14 lb N Remember percentages? Math way = ? 50 lb /bag * 0.28 = 14 lb N /bag This the method to determine how much nutrient is in a given amount of fertilizer How much potassium?
132. A 50 lb Bag of 26-8-16 Has ____________ lb Nitrogen? Has ____________ lb Phosphorus? Has ____________ lb Potassium?
133. If one acre = 43,560 ft2then there are 43.56 blocks of 1,000ft2 each in one acre 1 acre = 43.56 @ 1,000 ft2 plots 10% = 0.10 5% = 0.05 1,000 ft2 = M
134. How much fertilizer do you need to apply?How do you know?
135. WANT = NEED Rate __ HAVE Fertilizer % in decimal You want 1.5 lb N /1,000 ft2 [M] using 20-10-10. How much fertilizer is needed? WANT >> 1.5 lb. N/1,000ft2 >> 1.5 HAVE >> 20 % N fertilizer >> 0.20 = 7.5 lb of Product[20-10-10] per 1,000 ft2
136. YOU WANT TO APPLY 35 LB OF NITROGEN PER ACRE YOU HAVE 46 - 0 – 0 WANT35 LB N /A= 76 .09 LB PRODUCT / ACRE HAVE 0.46 YOU WANT TO APPLY 0.75 LB OF NITROGEN PER 1,000 FT2 YOU HAVE 21 – 0 – 0 WANT0.75 LB N /A = 3.57 LB PRODUCT / 1,000 FT2 HAVE 0.21 #2 100% = 4.76 SO THE FACTOR * RATE = 21% 4.76* 0.75 = 3.57 LB PRODUCT / 1,000 FT2
137. Your boss wants to apply 1.5 lb. N /M and you have some 25-5-15 in the shed. How much per M ? 1.5 / 0.25 = 6.0 lb fertilizer / 1,000ft2 or 100/ 25 = 4.0 * 1.5 lb = 6.0 lb / 1,000ft2 How much per Acre ? 6.0 lb/M * 43.56 M/A = 261.36 lb fertilizer/A How much area will a 50 # bag cover ? 50 lb \ 6 lb per M = 50 lb will cover 8.33 M or 8,333 sq ft
138. NITROGEN In all living cells – plant and animal Part of proteins , including enzymes In plants – part of chlorophyll Of all nutrients used from soil only H is present in greater numbers
139. Nitrogen Atmosphere is 78% N, but this is only 2% of earth’s total The remaining 98% is in soil, rocks and organic matter, but 90% in unavailable to plants At any one time less than 1% is plant available
140. General Aspects of N Plant N requirement Greatest plant need, percentage-wise Geographic area of deficiency Widely deficient – soil “runs out” Especially in areas that inhibit [slows down] decomposition
141. General Aspects of N N as a limiting nutrient IS THE MOST LIMITING nutrient Must be replaced frequently Plant responses are - Great - dark green - lush top growth Soil reactions Complex : many inputs, losses, storage mechanisms
142. Fertilizer forms Natural Manures, residues Organic Contains C [carbon] inc.Ureas Synthetic Most commercial fertilizers Am. Nitrate, Na nitrate, IBDU
143. Nitrogen inputs Fertilizer Manure Atmospheric deposition Crop residues Biological fixation Bacteria on some plant roots Tend to be very plant specific Algae blue-green [cynobacteria]
144. Legumes Know since roman times that legumes will increase a fields fertility Bacteria family called Rhizobium form nodules on the roots The plant supplies bacteria with photosynthate [food] and the bacteria supplies the plant with Carbon and Nitrogen
145. Role of Phosphorus -- P - Necessary for the formation of proteins Enzymes Takes part in energy storage and transfer ATP Promotes early root formation and growth Starter fertilizer ratio 1-2-1 [NPK] Aids in seed formation
146. An early sign of P hunger is overall stunting of plant growth
147. Deficiency Remember soil P has little relationship to plant available P – low soil moisture and low temp = low plant available P Symptoms: Purple coloration in leaves Lack of P slows respiration = more Ps = more sugar accumulation = more purple color [anthocyon pigment] Stunted growth Reduced flowering Loss of older leaves IS MOBILE IN PLANTS - OLDER / LOWER LEAVES SHOW DEFICIENCIES FIRST
148. Phosphorus Major losses occurs from movement of sediment = soil erosion No till can reduce soil movement [erosion] Binds to soil particles High pH soils binds with Ca [ is fixed by] Low pH soil binds with Fe, Mg + Al In high P soils, some P forms will move in soil solution Also in high sand soils P will move faster
149. Eutrophication General: In a a body of water, nutrients are added which reduce water O2 This favors plant life over animal life Destroys the balance Levels of > 10 ppb Major nutrients that can cause eutrophication are Nitrogen and Phosphorus
150. Potassium - K+ K and Ca two most abundant plant elements in the top layer of the earth Potassium accounts for 2.6% of the earth’s crust Exist as exchangeable K+ ions Released and adsorbed by minerals
151. Potassium – Role in plants All roles are not clear cut – how it works Regulates water content in plant - key Improves winter hardiness Reduces lodging Increases disease resistance Required for photosynthesis Required for protein manufacture E.g. enzymes Encourages rooting in tap rooted crops, alfalfa
152. Potassium - K+ Available in soil As exchangeable K+ In soil solution Movement in soil Silt loam soil 1 – 2” per year Sandy soils – leaching a problem Erosion – movement of sediment = losses Some vermiculitic clays can fix K Plant uptake 70+% diffusion, 20% M Flow
153. Potassium – K+ Ca++ and Mg++ both compete with K+ for entry into plants Therefore if the soil is high in CA and Mg [both are in lime], the higher levels of K will be needed to supply the needs of the plant. A reduction brings the reverse effect
154. Why Bother to Calibrate Money, Money, Money Time, Time, Time Your Money and Your Time Your reputation Too much = wasted money Bad for the environment Too little = not effective, so do it again
155. CALIBRATION How much material is spread over a specified area Need to know how much material is dropped per minute [unit of time] How much area is covered per minute Distance covered times width of spread Speed traveling 1-2 MPH can change rate by 50% or more Effective spread width
156. Two methods to measure the amount of product being applied Area method apply the product on a measured paved surface or plastic sheet then sweep and collect the product into a dustpan Catch pan method attach a plastic or cardboard “pan” under the hopper to catch the product being applied
157. Spreader Examples Covered Drop spreader Area method Catch method Rotary spreader Catch method Finding effective spread width Motorized spreaders Finding the speed
158. Drop Spreader Fixed spread width Most accurate distribution of material Skips or overlaps very noticeable Best to apply ½ of the amount, then cover same area again but from right angles to the original direction with the remaining ½ Takes more time than rotary spreaders
159. Careful where you spread!! Not on impervious surfaces Storm drain – pipeline to water Not next to water or tidal area
160. Fertilizer timing Cool season – Tall Fescue, Ryegrass = 75 – 90% in Fall Time of maximum root growth Warm season – Bermuda, Zoysia = 80 – 90% in Summer Time of maximum root growth
161. Leaching / runoff prevention Leaves A source of Phosphorus More is chopped Caution -- runoff into storm drains Turf vs trees / shrubs mulch
162. Soil is the key Key to long term success Foundation Soil type, space, water, air, nutrients, OM Leaching, erosion Plant nutrients – pH, N, P, K Soil Tests Calibration Planning !!
163. THANK YOU !! Sam Doak sdoak@vt.edu Urban Nutrient Management Handbook Mid-Atlantic Nutrient Management Manual