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Soil & Plant Nutrition
Ally Bove, Laura Cox & Lindsey Richards
Chapter 37
What We Already Know
-Anchors plant-Fertilizer-Helps retain water-Holds nutrition for plants
What We Want to Learn
-Basic physical properties of soils and the factors that govern soil qualities. -Why certain inorganic nutrients are essential for plant function. -Nutritional adaptations that have evolved in plants, often in relationships with other organisms.
Soil Texture
Soil particles are classified by size from largest to smallest:-Sand -Silt-Clay
-Soil is stratified into layers called soil horizons. A type of topsoil called loam is the most fertile.
Topsoil Composition
Cations adhere to negatively charged soil particles.
During cation exchange, cations are displaced from soil particles by other cations.
Inorganic Components
Humus retains water and mineral nutrients. Also it increases the soils capacity to exchange cations.
Topsoil contains many organisms that help decompose organic material.
Organic Components
Soil Conservation & Sustainable Agriculture
The goal of sustainable agriculture is to use faming methods that are conservation-minded, environmentally safe, and profitable.
IrrigationFertilization
Adjusting Soil pHControlling Erosion
Preventing Soil CompactionPhytoremediation
Irrigation Fertilizer
Adjusting Soil pH Controlling Erosion
Preventing Soil Compaction Phytoremediation
Macronutrients and Micronutrients
Essential Elements In Plants (Macronutrients)
Essential Elements in Plants (Micronutrients)
Symptoms Of Mineral Deficiency
Smart Plants
Soil Bacteria & Plant Nutrition
-Plants & soil have two-way relationshipMany of the soil bacteria are called saprobes-lives on decaying organic material-Rhizobacteria-soil bacteria w/especially large population in rhizosphere (soil layer bound to plant roots)
Some are called plant-growth-promoting rhizobacteria then enhance plant growth by a variety of mechanisms
Bacteria in Nitrogen Cycle
-Nitrogen Cycle-describes transformations of nitrogen & nitrogenous compounds in nature
-Nitrogen-fixing bacteria converts atmospheric N2
to nitrogenous minerals that plants
•Plants absorb nitrogen as either NO3–or NH4+•Bacteria break down organic compounds or use N2to produce NH3, which is converted to NH4+•Nitrification is carried out by bacteria that convert NH3 into NO3–
Ecological Roles of Bacteria
Nitrifying bacteriaadds free nitrogen or nitrates to the soil by the process of nitrification.
Ammonifying bacteriaconverts ammonia into nitrates which is converted into free soil nitrogen by nitrifying bacteria.
Denitrifying bacteriareduces nitrates or nitrogen gas; most are found in soil
Nitrogen fixing bacteriahas an association with bacteria which infect their roots and in return for sugars from the plant, fix nitrogen which can be used by the plant for growth.
Nitrogen Fixation & Agriculture
-Nitrogen fixation: conversion of nitrogen from N2to NH3-The agricultural perks of mutualistic nitrogen fixation underlies most types of crop rotation
Fungi & Plant Nutrition
-Mycorrhizae: mutualistic associations of roots & fungi
-The fungal hyphae of both ectomycorrhizae and arbuscular mycorrhizae absorbs minerals and water to which they supply to their roots.
Epiphytes, Parasitic Plants, & Carniverous Plants
EpiphytesAbsorb water & minerals from rain, mostly through leaves not roots. Ex: staghorn fern
Parasitic PlantsAbsorb sugars & minerals from living hosts, although some species are photosynthetic. Ex: mistletoe
Carniverous PlantsPhotosynthetic, but they obtain some of the minerals by killing & digesting insects & other small animals. Ex: venus fly trap
Staghorn Fern Venus Fly Trap
Mistletoe