HORT 102 Week 8 Notes
HORT 102 Week 8 Notes 4616 - HORT 102
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This 5 page Class Notes was uploaded by Irene A. on Monday March 2, 2015. The Class Notes belongs to 4616 - HORT 102 at Washington State University taught by Michael Pumphrey in Winter2015. Since its upload, it has received 40 views. For similar materials see Intro to Cultivated Plants in Agricultural & Resource Econ at Washington State University.
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Date Created: 03/02/15
HORT 102 WEEK 8 NOTES LESSON 9 Lecture 15 Soil Properties 0 Soil 0 weathered rock amp organic matter 0 medium to support plant growth I provides nutrients water oxygen amp physical support 5 SoilForming Factors mineral matter lying underneath upper soil layers Material from which the soil above is formed composed of rocks weathered by physical amp chemical processes O O O O I Carbonation reaction between carbon dioxide amp water to form carbonic acid I Hydration addition of water to materials I Hydrolysis Reaction between parent material amp water I Oxidationreduction reaction of parent material with oxygen 0 I Temperature Changes causes expansion amp contraction in material I Glacial Till rocks embedded in glaciers scrape over material as glacier moves I Moving Water carries rocks which collide and break up O affects rates of formation amp types of soil formed 0 rate affected by moisture humidity frost head wind erosion amp sunlight 0 soil type in uenced by types of vegetation in soil surrounding organisms O microorganisms amp earthworms break down organic matter 0 slope characteristics 0 determines erosion rate amp depth of soil 0 modifies climate determines patterns amp drainage rates O 0 soil formation is slow but continuous rate affected by composition of parent material amp intensity of weathering I vertical cross section showing soil horizons soil profile characteristics 0 0 older soils have more defined profileshorizons zone of leaching upper layers are quotwashedquot as water moves through higher organic matter levels darker in color zone of accumulation subsoil layers accumulate materials transported from upper layers I parent material is found below subsoil soil profiles give a historical record of past climate used to classify soils amp determine uses amp management OOOOO mineral matter 40 organic matter 10 air 25 water 25 air volume water volume pore space percentage of sand silt amp clay particles 0 smallest to largest clay silt sand Loam mixture of all 3 particle sizes 0 O O O 40 sand 40 silt 20 clay Coarse soil main component sand Medium soil main component silt fine soil main component clay Importance of Particle Size 0 impacts water amp air ow I sand large pore spaces I clay small pores I silt intermediate Soil Texture In uences OOOOOO Water intake infiltration rates Water storage Drainage Ease of tillage Aeration gas exchange Nutrient retention and soil fertility Soil Structure 0 combination of sand silt amp clay w organic matter into particles called 0 results from climate weathering and plants organic matter 0 structural aggregates affect I pore size I waterholding capacity I water infiltration rate I soil permeability I soil compaction 0 Soil structure can be manipulated through I amendments materials incorporated into the soil grass clippings manure I disruption plowing compaction tillage Lecture 16 Soil Water and Nutrients Soil texture amp soil permeability effects 0 size of soil pores 0 surface area surface forces that account for water retention 0 attraction of water molecules to soil particles 0 attraction of water molecules to one another size of particles texture determines amount of water soil holds 0 small particles hold water more tightly due to smaller pore size amp greater surface area 0 water bonds stronger to clay than to sand 0 water leaches farther in I Sandy loams gt loams gt clay loams Forms of soil water 0 free water lingers in soil shortly and is pulled down by gravity 0 capillary water held in pores amp present as layers around soil particles 0 bound unavailable water tightly held by soil particles can39t be extracted by plant roots Adhesion strength Water is held more tightly to clay than sand so less water runs through a clay type soil than a sandy soil Water Availability to Plants 0 Field Capacity pore space is filled only with water the soil can hold against gravity 0 Permanent Wilting Point plant can no longer extract water from soil I clay has higher PWP holds water more tightly amp makes it difficult for plants to extract 0 Available Water Field Capacity Permanent Wilting Point Saturation capacity all pores filled with water 0 sand SC lt clay SC 0 high water level in clay decreases amount of available oxygen roots need oxygen to grow Salinity 0 measure of soluble inorganic elements sodium calcium magnesium chloride sulfate bicarbonate O salty soils problematic in arid regions or poor drainage areas 0 salts cause quotchemical droughtquot 0 problems can be solved by I using salt tolerant plants I leaching salts from soil w clean water Salts originate from O mineral weathering 0 inorganic fertilizers amp manures O irrigation waters 0 other sources Soil Fertility 0 plants obtain nutrients from decomposed organic matter 0 decaying OM supports bacteria amp fungi which bring insoluble soil minerals in amp improve soil condition Mineral Nutrition 0 O O needed for plant development required in large quantities I primary nitrogen phosphorus amp potassium I secondary calcium magnesium sulfur required in small quantities I molybdenum boron copper iron manganese zinc chlorine 0 Sources I inorganic fertilizers manures composts green manures 0 Types of Fertilizers 0 chemical fertilizers 0 organic fertilizers 0 green manures
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