Download Components of Soil - Horticulture - Lecture Slides and more Slides Biology in PDF only on Docsity! Plant Environment: Soil • Soil – Components of soil • Weathered rocks (particles) • Decomposing organic matter • Living organisms (particularly bacteria, fungi, protists) • Spaces containing water an air – Functions for plants • Substance in which to anchor plants • Source of mineral elements (except C) • Source of water and oxygen Docsity.com Plant Environment: Soil • Mineral soil – Mineral soils = soils with less than 20% organic matter • Texture characteristics – Based on relative amounts of sand, silt and clay » Silt: medium mineral particles (medium grain) » Sand: large mineral particles (course grain) » Clay: small, flat mineral particles (fine grain) Docsity.com Plant Environment: Soil • Mineral soil – Texture types used for horticulture • Clay (> 50% clay, remainder sand and silt) – Poor drainage, poor aeration, easily compacted – Poor for horticultural production Docsity.com Plant Environment: Soil • Mineral soil – Texture and water movement • Water moves between soil particles down through soil – Abrupt changes in soil texture stop flow of water through soil – Water accumulates above change in texture (= perched water table) – Perched water table inhibits root growth (no oxygen) – Avoid perched water tables by mixing different soil textures (for potted plants, transplanting trees) Docsity.com Plant Environment: Soil • Organic soils – Soil with more than 20% organic matter • Muck soil (highly decomposed) • Peat (slightly decomposed) – Usually formed under long-term conditions of excess moisture – sphagnum peat main component of potting mixes – Greatly improved water holding of soil Docsity.com Plant Environment: Soil • Media used in containers – Most field soils not appropriate for containers • Not free of toxic substances and undesirable organisms • Become compacted with repeated waterings • Soilless potting mixes used in most greenhouses: – Sphagnum peat – Partly decomposed bark – Vermiculite – Perlite Docsity.com Plant Environment: Soil • Mulch – Advantages of using mulch • Water conservation (reduce evaporative water loss) • Weed control • Temperature modification (reduce temperature fluctuations) • Protect soil from erosion • Improve soil structure as mulch decays • Retain nutrients • Reduce some insect pests (aphids avoid white plastic mulch) • Hydroseeding of turf Docsity.com Plant Environment: Soil • Types of Mulch – Nonorganic • Plastic sheeting – Black used to prevent growth of weeds and heat soil – Used for high-value crops (e.g. strawberries, tomatoes) – Organic • Straw, wood chips, shredded bark, dry pine leaves – Provides organic matter as decomposes; aggregates soil particles and improves drainage and aeration (but must add N for microbes) – Blocks light and therefore controls weed growth – Reduces soil erosion and nutrient leaching – Reduces soil temperature Docsity.com
