Plant Nutrition pt 2 Flashcards
plants absorb nearly all their water and minerals from what layer of soil
the top layers, contain a bunch of microorganisms that can associate with plants.
soil composition forms layers called
horizons
which horizon are topsoils? what does this consist of?
- horizon A
- consists of inorganic compounds: soil particles (-) bind with positive cations
- organic compounds: humus (organic matter)
plants get their nutrients from between the soil particles, which soil is best for nutrients?
loams are the most fertile topsoil, consisting of pores of 50% water, 50% air
(loams are horizon A)
what positive cations do soil particles bind with
K+, Mg2+, Ca2+ (salts)
how are nutrients dissolved in the soil so plants can obtain them?
Cation exchange.
* cations are displaced from soil particles by other cations (H+)
* More clay and organic material in the soil, more cation exchange
how does fertilization help overcome decreased plant yields
by providing N, P, K
what’s the downside of fertilizing soils
- soil mismanagement and nutrient overloading of ecosystems
-removing native plant species with deep roots can erode the topsoil, leaving poor nutrient quality behind
-ex: lake winnipeg nutrient enrichment leads to massive algal blooms and toxic aquatic conditions
Water can be very limiting in arid regions or areas
with longer days (equatorial)
how does Irrigation help? what happens when there’s too much irrigation?
Irrigation allows for water to be diverted to the soils. Since water has lots of dissolved nutrients, it can increase soil nutrient levels.
too much irrigation can leave behind salts due to evaporation, which can decrease the plants ability to absorb water (more salt in soil, water will go out of plant, plant wilts).
since we are constantly planting and not giving enough time for soil to get back nutrients we must
fertilize the soil
fertilizers often have
N, P, K.
Soil pH can affect the plant’s ability for cation exchange, most plants prefer what acidity?
slightly acidic soil (need H+ for cation exchange). pH 8 too much calcium not iron. pH 5 or lower toxic mineral like aluminum become more soluble.
water and wind erosion can remove layers of topsoil. what can be done to counteract this?
- Wind breaks
- hillside crops
- contour patterns of crop cultivation
- no-till agriculture (minimally disturbs soil, reduces erosion)
phytoremediation
non destructive biotechnology that uses the special ability of some plant species to remove contaminants/pollution from soil
what are essential elements
elements needed to complete a plant’s life cycle and reproduce.
what are the macronutrients? 9 essential elements needed in larger amounts.
MgSOCKCaNPH
(my good socks cannot posses holes)
what are the micronutrients? 8 essential (sometimes 9) elements needed in small amounts
- Cl, Fe, B, Mn, Zn, Cu, Ni, Mb
- sometimes Na for C4 and CAM plants
Cl-FeyB. Mun, Zun, CooNiMb. (sometimes NAh im special I’m a C4 or a CAM)
what’s chlorosis? what’s it caused by?
Mg deficiency, causes chlorophyll to break down and turn leaves yellow (though it could also be caused by iron or nitrogen deficiency since these are used as a cofactors in chlorophyll synthesis)
if nutrients move freely does symptoms of nutrient deficiency appear in the older or younger tissues/organs first
- symptoms will appear in older tissues bc younger tissues get priortiy.
if nutrients are immobile do symptoms of deficiency appear in young or old tissues
young tissues (can’t move from old to new growing tissues). Like sulphur deficiency, chlorosis is in young leaves.
which macronutrients are a major component of plant’s organic compounds, what are the visual signs when they’re deficient?
Carbon, Oxygen, and hydrogen. When deficient there is poor growth
what’s rhizobacteria
live associated with plant roots or in soil surrounding plant roots (rhizosphere). they depend on the nutrients secreted from plant roots.
what benefits do rhizobacteria provide
- antibiotics to prevent root disease
- absorb toxic materials so plants do not
absorb them - Nitrogen fixation -> converting atmosphere
N2 gas to ammonium/nitrate
what does nitrogen fixation do, what organisms do it and what environment is needed
converts nitrogen gas to NH3, bacteria do it, need anearobic environment.
