2. -Anchors plant -Basic physical properties of soils and
-Fertilizer the factors that govern soil qualities.
-Helps retain water -Why certain inorganic nutrients are
-Holds nutrition for plants essential for plant function.
-Nutritional adaptations that have
evolved in plants, often in
relationships with other organisms.
3. 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.
4. Inorganic Components
Cations adhere to
negatively charged
soil particles.
During cation
exchange, cations
are displaced from
soil particles by
other cations.
5. Organic 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.
6. The goal of sustainable agriculture is to use faming methods that are
conservation-minded, environmentally safe, and profitable.
Irrigation
Fertilization
Adjusting Soil pH
Controlling Erosion
Preventing Soil Compaction
Phytoremediation
15. -Plants & soil have two-way relationship
Many 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
16. -Nitrogen Cycle-describes transformations of
nitrogen & nitrogenous compounds in nature
-Nitrogen-fixing bacteria converts atmospheric N2
to nitrogenous minerals that plants
17. •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–
18. 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.
19. -Nitrogen fixation: conversion of nitrogen
from N2to NH3
-The agricultural perks of mutualistic
nitrogen fixation underlies most types of
crop rotation
20. -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.
21. Epiphytes
Absorb water & minerals from rain, mostly through leaves
not roots. Ex: staghorn fern
Parasitic Plants
Absorb sugars & minerals from living hosts, although some
species are photosynthetic. Ex: mistletoe
Carniverous Plants
Photosynthetic, but they obtain some of the minerals by
killing & digesting insects & other small animals. Ex: venus fly
trap