* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Soil-Water-Plant Relationships Topics to be covered: Soil Definitions:
Survey
Document related concepts
Camelford water pollution incident wikipedia , lookup
Crop rotation wikipedia , lookup
Regenerative agriculture wikipedia , lookup
Irrigation in viticulture wikipedia , lookup
Soil compaction (agriculture) wikipedia , lookup
Surface runoff wikipedia , lookup
No-till farming wikipedia , lookup
Perovskia atriplicifolia wikipedia , lookup
Renewable resource wikipedia , lookup
Transcript
2/26/2015 Topics to be covered: •Soils and sustainable soil management •Water availability and conservation •Plant – water relationship •Irrigation methods and systems Soil-Water-Plant Relationships Jose F. De Soto UCCE - Ventura 1 Soil Definitions: • “The top layer of the earth’s surface suitable for the growth of plant life” American Heritage Dictionary • “ The weathered and fragmented layer of the earth’s terrestrial surface” Introduction to Soil Physics 3 1 2/26/2015 Main Soil Components: Sand Mineral Soil Particles •Largest particle in the soil •It feels gritty and rough •It does not hold nutrients •It rapidly loses water and dries out •Plenty of aeration for good plant growth •Easy to till 2 2/26/2015 Silt •Size is smaller than sand •Feels smooth and powdery •When wet it feels smooth but not sticky •Generally resemble sand particles •Has some of the physico-chemical attributes of clay Clay •Smallest of the particles •Particles fit tightly together •Does not let water and air go through easily •It’s smooth when dry and sticky when wet •Easily molds into a ribbon when wetted •Holds a lot of nutrients •Difficult to till 3 2/26/2015 Soil Texture •Qualitatively, it represents the “feel” of the soil material, whether coarse or fine and smooth. •Quantitatively, it denotes the measured distribution or the proportions of the various size ranges of particles that occur in a given soil. Texture Triangle Soil Texture •The percentage units (0-100%) of sand, silt, and clay are listed along the sides of the triangle. •It determines water intake rates, water storage, the ease of tillage, and the amount of aeration. •Soil texture refers only to the mineral fraction of the soil. http://www.public.iastate.edu/~aros si/texture%20triangle.jpg 15 4 2/26/2015 Soil Structure •It is the arrangement and organization of the particles in the soil •There are three broad categories: single grained, massive and aggregated Soil Structure •Soil structure affects retention and transmission of fluids in the soil •Affects germination, root growth, tillage and erosion •Preferred in a loose and highly porous and permeable condition 18 Sustainable Soil Management •Avoid compaction •Aerate compacted soils •Prevent erosion •Use: -organic matter, -compost and -mulches 5 2/26/2015 Organic Matter Compost •Energy source for soil microbes •Considered a soil amendment more than a fertilizer •Helps restore soil biology •Well decomposed compost is best: - reduces tie-up of Nitrogen - reduces potential for soil borne diseases •Stores nutrients for plant use •Humus = Organic portion of the soil remaining after prolonged microbial decomposition. It is the glue that binds soil particles together to prevent soil erosion Amending soil with compost •Helps form soil aggregates •Improves soil structure and soil tilth •Reduces surface crusting and soil erosion •Improves air and water movement Mulches •Prevent raindrops from splashing on the soil surface •↑ water penetration, ↓ erosion •Reduce annual weeds •Conserve soil moisture ↑ root growth •Insulate roots from temperature extremes •Protect plants from mechanical injury •Improve plant establishment 6 2/26/2015 Types of Mulch Mulch reduces Evaporation from soil but not transpiration •Wood Clips •Compost •Ground bark •Rice hulls •Straw or hay •Rocks •Artificial – plastic, ground tires etc., The golden rule of gardening: •“If you treat your soil well, it will treat your plants well.” Questions? 7 2/26/2015 Supply Sources 2. Where is the water? Los Angeles Aqueduct Colorado River Aqueduct State Water Project Local Water Sources for Ventura County Water Limitations •Ground water •Santa Clara River (United Water) •Lake Casitas (Casitas) •State Water Project (Calleguas) 8 2/26/2015 Water Limitations Other water limitations Key Delta Risks 2000 • Population growth 1500 • Environmental issues 1000 Fishery Declines Delta smelt 500 0 1967 1973 1979 1985 1991 1997 2003 Seismic Risk Flooding Risk Bay Area Faults Jones Tract (2004) 9 2/26/2015 3. Plants and Water Questions? Why plants need water? 1 - Chemical reactions in cells Why plants need water? 2. Photosynthesis 10 2/26/2015 Why plants need water? 6CO2 + 6H2O + Energy ↔ C6H12O6 + 6O2 3. Transpiration: A plant must lose water in order to grow Which is a process similar to •Water lost through stomata is called TRANSPIRATION 11 2/26/2015 Evapotranspiration Values Crop Evapotranspiration Et crop = Eto x Kc Where: Et = Evapotranspiration Eto = Reference Evapotranspiration, or potential evapotranspiration referenced to grass, when grass Kc = 1.00 Kc = Crop Coefficient 12 2/26/2015 Crop Coefficients Alfalfa 0.94 Avocados 0.80 Chiles 0.59 Grass 0.85 – 0.95 Lemons 0.56 Lettuce 0.63 Strawberries 0.87 How many gallons is an inch? • One cubic foot contains 7.48 gallons Then, • 1 in/sqft = 7.48/12in = 0.62 gal • 1 inch/acre = 0.62 gal x 43,560 sqft = 27,007 gal/acre-inch What do I do with that? •Total Eto for VC in July was 5.80 inches •Total precipitation was 0.01 inches •Avocado Kc is 0.80 How much do I need to irrigate in July? (5.80 – 0.01) x 0.80 = 4.63 inches Following with the example… •4.63 acre-inch x 27,007 gal/acre-inch = 125,042 gallons •125,042 gal/100 emitters/10 gal/hr = 125 hrs of irrigation needed to replace the water lost and recharge the soil profile to full capacity 13 2/26/2015 Landscape Evapotranspiration Landscape Example Et = Eto x KL • Large mature planting of Star Jazmine in full sun and little wind exposure: Where: Et = Evapotranspiration of Landscape Eto = Reference Evapotranspiration KL = Landscape Coefficient Species Factor Density Factor Microclimate Factor • Star jasmine is classified as moderate in the WUCOLS list (0.4 to 0.60) then ks (species) = 0.5 • Is a mature plant with full canopy, average density, then kd (density) = 1.0 • Microclimate is equal to Eto (full sun, open area, no winds) and classified as average then kmc = 1.0 (0.1 – 0.9) (0.5 – 1.3) (0.5 – 1.4) Then KL = 0.5 x 1.0 x 1.0 = 0.5 53 Factors that determine ET 54 VC Monthly Average Eto •Soil moisture •Plant type •Stage of plant development •Weather factors: - Solar radiation - Wind Speed - Humidity - Temperature 6 5 4 3 Ten yr avg 2 1 0 Jan Mar May Jul Sep Nov 55 14 2/26/2015 Watering Index Factors Affecting Frequency of Irrigation • Water infiltration rate 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Dec. Oct. Nov. Aug. Sept. July May June April March Jan. (inch/hr): Feb. Percent of July ET Monthly Irrigation Index without Rain Very slow < 0.06 Slow 0.06 – 0.2 Moderate 0.6 – 2.0 Rapid 6.0 – 20.0 Very rapid > 20.0 57 Factors Affecting Frequency of Irrigation • Soil water holding capacity: - Saturation ( 0 kPa) 58 Factors Affecting Frequency of Irrigation •Plant water use Gravitacional water - Field capacity (-33 kPa) Available for plant use •Depth of rooting - Wilting point (-1500 kPa) Capillary water - Oven dry •Irrigation method and output 15 2/26/2015 Monitor Soil Moisture Use the ‘Feel’ Test Dry Medium Soil probe Wet Soil sampling tube 61 General principles for watering •Irrigate established plants deeply and infrequently •Avoid watering everyday •Water below the current root system during each watering to encourage deep rooting 62 General principles for watering •Don’t apply water at a greater rate than it can be infiltrated •Water cycling may be necessary to avoid run-off •Divide the total amount of water required per day into 2 - 4 cycles •Apply water as close to initial event as possible before soil dries out 16 2/26/2015 General principles for watering •Irrigate crop plants for optimum production •Irrigate landscape plants for good looks and maintenance That’s all folks !!! Any questions? 66 17