Lecture 18 &19- Plant Nutrition 1 and 2 (1).pptx

Plant Nutrition 1 Soils and Plants Concepts 37.1-37.3 Campbell. Biology. 3rd ed Outline • 1. Formation, Structure and Function of Soils • 2. Mineral Nutrition • 3. Soil Conservation and Sustainable Agriculture • 1. Formation, Structure and Function of Soils • Soil = Outer, weathered layer of ea...

Plant Nutrition 1 Soils and Plants Concepts 37.1-37.3 Campbell. Biology. 3rd ed Outline • 1. Formation, Structure and Function of Soils • 2. Mineral Nutrition • 3. Soil Conservation and Sustainable Agriculture • 1. Formation, Structure and Function of Soils • Soil = Outer, weathered layer of earth's crust which has the potential to support plant life • Soil is formed through the interaction of climate, parent material, topography, vegetation, living organisms and time. • Solid portion of soil consists of minerals and organic matter. • Pore spaces between solid particles filled with air or water. • 50% solid : 50% pore space SOIL COMPONENTS The fifth component: Soil Profile • The layers from the soil surface to the bedrock are called horizons, and the whole transect is called profile. • The surface layer, or the A horizon, varies in depth& contains most of the roots. • O horizon is the part of the A horizon that is most rich in organic matter • The B horizon is the zone of accumulation. • The C horizon is unweathered to http://en.wikipedia.org/wiki/Soil_horizon 5 SOIL FORMATION Soil = f(Cl, O, R, P, T) Factors: • Cl= climate (precipitation and temperature) • O = organisms (plants and animals) • R = relief (topography, drainage) • P = parent material (rocks) • T = time Climate • Climate varies throughout the globe, as does its role in weathering of rocks • Deserts - Little weathering by rain, and soils poorly developed • In areas of moderate rainfall - Well-developed soils • Areas of high rainfall - Excessive water flow through soil leaches out important minerals. Living Organisms and Organic Composition • In soil there are many kinds of organisms, roots and other plant parts. • Bacteria and fungi decompose organic material from dead leaves, plants and animals. • Roots and other living organisms increase the rate at which minerals dissolve. • Small animals alter soil by their activities and by their wastes. • Organic matter - Partially decomposed plant and animal material, and often gives soil a dark color Relief (Topography) https://pertgroup3.blogspot.com/2016/04/soil- • Topography - Surface features • Steep areas: • Soil may erode via wind, water or ice. • Flat, poorly drained areas: • Pools and ponds may appear. • Development of arrested soils • Ideal topography permits drainage PARENT MATERIAL • Parent rocks contain the nutrients that will be found in parent material, and later in the soil. • Parent rocks from which soil can be formed: • (A) igneous. • (B) sedimentary. • (C) metamorphic. KINDS OF ROCKS • Igneous rocks(i.e., lava, magma) are formed from the hardening of various kinds of molten rock material and are composed of minerals such as quartz and feldspar. • Sedimentary rocks are generally unconsolidated and composed of rock fragments that have been transported and deposited by wind, water, or glaciers. Limestone, sandstone & shale. • Metamorphic rocks form from igneous or sedimentary rocks that have been subjected to sufficiently high pressures and temperatures to change their structure and composition. Slate, gneiss, schist & marble are metamorphic rocks. SOIL PARTICLE SIZE 12 http://www.ctahr.hawaii.edu/mauisoil/a_comp01.aspx http://water.me.vccs.edu/concepts/velocitysusp.htm SOIL TEXTURE • Soil texture refers to the relative proportions of sand, silt and clay in a soil sample. Finer textured soils tend to have greater ability to store soil nutrients. Loam is the ideal soil texture for growing plants http://ecorestoration.montana.edu/mineland/guide/analytical/physical/soil.htm SOIL STRUCTURE (aggregation of individual particles into groups) Platy Angular Prismatic Sub-angular GRANULAR is the Columnar preferred soil structure for growing plants Granular PORE SPACE IN SOILS • Coarse soils have larger individual pores, but less total pore space • Fine soils have smaller pores, but greater total pore space • Greater water holding capacity • Porosity of surface soil decreases as particle size increases. • Wide pore spacing at the soil surface increases the rate of water infiltration. CATION EXCHANGE • Soils ability to hold and release minerals/nutrients • Plant roots are able to extract and absorb nutrient cations (+ ions) from the clay surface. This is known as cation exchange. • CEC affected by type of clay, amount of clay, amount of organic matter • Cation exchange capacity (CEC) of soil is important for maintaining adequate quantities of plant Exchange of cations between a root and soil colloids. available calcium (Ca2+), magnesium (Mg2+) and potassium (K+) in soils. https://lsuagcenter.com/profiles/aiverson/articles/page1563205546102 WATER HOLDING CAPACITY of SOILS • Moisture holding capacity of soil increases as the • level of organic matter (OM) rises • Size of mineral particle decreases • What is organic matter? • Which mineral particle size is the smallest? 17 SOIL MOISTURE • Combined water: component of soil particle, and unavailable to plants • Hygroscopic water: very thin layer around soil particles, and unavailable to plants • Capillary water: exist in films around and between soil particles, available to plants • Gravitational water: Moves downward, normally lost from root zone after 1-3 days of irrigation/rain. https://www.topcropmanager.com/wet-dry-soil-problems/ SOIL ACIDITY & ALKALINITY • Most plants do not grow well in highly acid or highly alkaline soils. • Most plants will grow range of pH 5 to 7, but specific plants have a narrower range of optimum pH. https://www.pda.org.uk/pda_leaflets/24-soil-analysis-key-to-nutrient-management-planning/influence-of-soil-ph-on-plant-nutrient-availability/ SOIL PH • Affects nutrient availability • Alkalinity causes some minerals, such as copper, iron and manganese to become less available. • Counteract by adding sulfur, which is converted to sulfuric acid by bacteria, or by adding nitrogenous fertilizers • Acidity inhibits growth of nitrogen-fixing bacteria. • Counteract by adding calcium or magnesium compounds = liming EFFECTS OF LIME APPLICATION on Acidic Soils • CaCO3 + H2O ↔ Ca2+ + HCO3 + OH • Direct effect: • A reduction in concentration of H+ • An increase in concentration of OH• Greater availability of Ca++ and Mg++ • Indirect effect: • Decrease in solubility of aluminum, iron and LOWERING THE SOIL pH • Use sulfur, iron sulfate, ammonium sulfate, or zinc sulfate (fertilizers) • The availability plant nutrients including iron, zinc, copper, and manganese is increased • Example: • zinc sulfate (ZnSO4) • Produces H2SO4 (sulfuric acid) ZnSO 4+ ZnO + which acidifies the soil H 2O Water H2SO4Sulfuric Zinc Zinc sulfate oxide acid 26 SALINIZATI ONWHAT IT LOOKS LIKE • 2. Mineral Nutrition CHO – required in large amounts; Carbontaken up through pores in leaf (stoma) as carbon dioxide and used in photosynthesis to make carbohydrates. Oxygen – uptake with C in carbon dioxide, also taken up as water via roots. Hydrogen – primary uptake via roots. Mineral nutrition •Macronutrients: N, P, K, Ca, Mg, S •Micronutrients – Fe, Cl, Zn, Mo, B, Cu, Mn •--------------------------------------------------------------------•Mobile nutrients: N, P, K, Cl, Mg, Mo. Visual deficiencies will first occur in the older or lower leaves. •Immobile nutrients: B, Ca Cu, Fe, Mn, Ni, S, and Zn are not translocated from one plant part to another and deficiency symptoms will initially occur in the younger or upper leaves and be localized. Nitrogen • General yellowing of older leaves (bottom of plant). • The rest of the plant is often light green. Sulfur • Younger leaves turn yellow first, sometimes followed by older leaves. Potassium (K) • Older leaves may wilt, look scorched • Interveinal chlorosis begins at the base • scorching inward from leaf margins. Calcium New leaves (top of plant) are distorted or irregularly shaped. Causes blossom-end rot Boron •Cauliflower • Brown patches in the head • Hollowing of the head • Bad smell • Secondary attack by pathogens Phosphorus (P) Purpling of the older leaves, particularly the leaf veins http://aggie-horticulture.tamu.edu/publications/tomatoproblemsolver/leaf/phos.html • 3. Soil Conservation and Sustainable Agriculture TILLAGE • Tillage is defined as mechanical manipulation of soil to provide a favorable environment for crop growth. • Ideally, soils should hold enough water to maintain the plant for several days between irrigations. • The “ideal” soil is often considered to consist of 50% solid and 50% open or pore space. CONVENTIONAL TILLAGE • Practiced until the last decade or so • The standard tillage practice for many crops was use of the moldboard (MB) plow for primary tillage followed by several secondary tillages and mechanical cultivation after the crop was up. • Now about two-thirds of row crops are planted without use of the MB plow (Allmaras et al., 1997), and mechanical cultivation is often limited to one, or no operations. https://aitc-canada.ca/en-ca/learn-about-agriculture/conservation-tillage REDUCED TILLAGE • Reduced tillage is usually done with a chisel plow and leaves 15% to 30% residue coverage on the soil. https://aitc-canada.ca/en-ca/learn-about-agriculture/conservation-tillage http://passel.unl.edu/pages/informationmodule.php ?idinformationmodule=1088801071&topicorder=10 &maxto=16 Primary vs reduced tillage https://www.tradefarmmachinery.com.au/features/1410/field-cultivator-buying-guide-part-1 CONSERVATION TILLAGE • Conservation tillage leaves at least 30% residue coverage on the soil. • Conservation tillage methods include: • no-till, where no tillage is done at all and seeds are placed directly into the previous season's crop residue; • strip-till, in which only the narrow strip of land needed for the crop row is tilled; • ridge till; and • mulch till (till and mulch) https://www.growing produce.com/vegeta bles/considering-cov er-crops-find-out-whi ch-method-works-be st/ LAND DEGRADATION • Excessive tillage is a contributing factor • Accelerated runoff and erosion • Reduced water infiltration and storage • Waterlogging / reduced aeration • Soil compaction • Accumulation of chemicals • (salinity, sodicity, metals) • Nutrient and Organic matter depletion • Desertification Areas subject to soil degradation Types of Soil Erosion Water Erosion - Splash - Sheet - Rill - Gully Wind SOIL AND WATER CONSERVATION STRATEGIES Riparian Buffer Strips Shelterbelts CONTOUR FARMING An easy cropping practice that reduces topsoil losses is to till the land on the contour (level elevation) instead of up and down the hill. Contour farming allows for runoff to be directed by row direction SEDIMENT BASINS •Sediment Basins are •ponds or basins •that holds and slows runoff until the sediment has settled. CRITICAL AREA PLANTINGS •Areas that would be otherwise eroding should covered in vegetation. WINDBREAKS •Windbreaks provide multiple benefits •crop protection •water conservation •wildlife habitat CROP RESIDUE MANAGEME NT Corn in crop residue Soybeans in corn residue Soybean in cotton residue Grain No till LOW & NOTILL FARMING • Instead of plowing, disking & otherwise cultivating to remove old vegetation, crop are planted directly into standing stubble • In some cases herbicides are used to kill the vegetation which is left in place. SOIL AND PLANT TESTING Nutrient Management Plan COVER CROPS AND GREEN MANURES ● Protect the soil with a vegetative cover ● Add organic matter and nitrogen ● Reduce weed populations ● Can provide habitat for beneficial insects ● Provide a break between pest cycles Buckwhe at The End • Thank you • Question? • Have a glorious day! Review – Plant Nutrition 1 – Soils and Plants Question1 • Name three soil forming factors • Answer = climate, organisms, relief (topography), parent material, time Question2 • Soils formed in very wet climates tend to be the most developed due to extensive weathering by precipitation • True/False • Answer = False Question3 • Which of the following types of soil water is available for plant uptake • A) capillary • B) hygroscopic • C) combined • D) gravitational • Answer = A Question5 • Secondary tillage involves the use of moldboard plow to fully invert the soil • True/False • Answer = False Question6 • A No till system leaves between 15%-30% of residues on the soil surface • True/False • Answer = False Question7 • List two benefits of cover crops • Answer = reduced evaporation from the soil surface; weed control; add organic matter and nitrogen; habitat for wildlife; break up disease cycles Question8 • The topsoil is part of which layer in the soil horizon • A) A horizon • B) B horizon • C) C horizon • Answer = A Question9 • Clay soils have smaller pores but greater pore space and therefore greater water holding capacity compared to sandy soils • True/False • Answer = True Plant Nutrition 2 Water and Plants Concepts 36.1-36.5 Campbell. Biology. 3rd ed Outline • 1. Transport of Water and Minerals via Xylem • 2. Movement of Sugars via Phloem • Osmosis is primary way water enters plants from environment. • Pathway of water through plant: – Enters from soil into cell walls and intercellular spaces of root hairs and roots – Crosses differentially permeable membrane and cytoplasm of endodermis, then into xylem – Flows through xylem to leaves and diffuses out through stomata ROOTS = -0.6 MPa Water potential of pure water = 0 4. Transport of Water and Minerals via Xylem • Transpiration - Water vapor loss from internal leaf atmosphere • More than 90% of the water entering a plant is transpired. ❖Water needed for: • Cell activities • Cell turgor • Evaporation for cooling – If more water is lost then taken in, stomata close. Regulation of Transpiration • Stomatal apparatus regulates transpiration and gas exchange. • Stomatal apparatus = 2 guard cells + stoma (opening). • Transpiration rates influenced by humidity, light, temperature, and carbon dioxide concentration. Regulation of Transpiration • When photosynthesis occurs, stomata open. • Guard cells expend (use) energy to acquire potassium ions from adjacent epidermal cells. • Causes lower water potential in guard cells • Water enters guard cells via osmosis. • Guard cells become turgid and stomata opens. Regulation of Transpiration • When photosynthesis does not occur, stomata close. • Potassium ions leave guard cells. • Thus, water leaves. • Guard cells become less turgid and stomata close. Regulation of Transpiration • Stomata of most plants are open during day and closed at night. • Water conservation in some plants: • Stomata open only at night - Desert plants • Conserves water, but makes carbon dioxide inaccessible during day. • Thus, undergo CAM photosynthesis • Carbon dioxide converted to organic acids and stored in vacuoles at night. • Organic acids converted to carbon dioxide during day. • Stomata recessed (attached) below surface of leaf or in chambers. • Desert plants, pines ❖The Cohesion-Tension Theory Transpiration generates tension to pull water columns through plants from roots to leaves. • Water columns created when water molecules adhere to tracheids and vessels of xylem and cohere (united) to each other. ❖The Cohesion-Tension Theory • When water evaporates from mesophyll cells, they develop a lower water potential than adjacent cells. • Water moves into mesophyll cells from adjacent cells with higher water potential. • Process is continued until veins are reached. • Creates tension on water columns, drawing water all the way through entire span of xylem cells • Water continues to enter root by osmosis. ROOTS = -0.6 MPa Water potential of pure water = 0 5. Movement of Sugars via Phloem • Mass-flow hypotheses • Included in the pressure-flow hypothesis • flow into sieve tubes at source regions (leaves) raises the osmotic pressure (increased solute concentration ie sugars) in the sieve tube • removal of sugars from sieve tubes in sink regions—i.e., those in which sugars are removed or imported for growth and storage—lowers it. • pressure gradient from the area of photosynthesis (source) to the region of growth or storage (sink) is established in sieve tubes that would allow solution flow. Pressure FLow Hypothesis • Important function of water is translocation of food substances in solution by phloem. • Pressure-Flow Hypothesis (widely accepted theory)Organic solutes (sugars) flow from source, where water enters by osmosis, to sinks, where food is utilized, and water exits. • Organic solutes move along concentration gradients between sources and sinks. • Specifics of Pressure-Flow Hypothesis: • Phloem loading - Sugar enters by active transport into sieve tubes. • Water potential of sieve tubes decreases, and water enters by osmosis. • Turgor pressure develops and drives fluid through sieve tubes toward sinks. • Food substances actively removed at sink and water exits sieve tubes, lowering pressure in sieve tubes. • Mass flow occurs from higher pressure at source to lower pressure at sink. • Water diffuses back into xylem. https://www.plantscience4u.com/2020/06/phloem-translocation-and-mass-flow-hypothesis-simple- The End THANK YOU QUESTIONS HAVE A GREAT DAY!