Chp 37- Soil & Plant Nutrition

soil horizon

stratified layers of soil

topsoil

consists of mineral particles, living organisms, and hums

humus

decaying organic matter

anions

negatively charges ions (ex: nitrate, phosphate, & sulfate)

cations

positively charged ions (ex: potassium, calcium, & magnesium)

cation exchange

cations are displaced from soil particles by other cations

fertilization

the addition of mineral nutrients to the soil

sustainable agriculture

farming methods that are conservation-minded, environmentally safe, and profitable

irrigation

a huge drain on water resources when used for farming in arid regions

aquifers

underground water reserves

salinization

the concentration of salts in soil as water evaporates

drip irrigation

slowly releases water directly at the root zone

main nutrients of fertilizer

nitrogen, phosphorus, and potassium

importance of soil ph

soil pH affects mineral availability through cation exchange and the chemical form of minerals

no-till agriculture

reduces erosion by creating furrows for seeds and fertilizer with minimal soil disturbance

phytoremediation

involves the uptake and concentration of soil pollutants in plant tissues that are then removed for safe disposal

essential elements

chemical elements required for a plant to complete its life cycle and reproduce

9 macronutrients required for plants

carbon, oxygen, hydrogen, nitrogen, phosphorus, sulfur, potassium, calcium, and magnesium

hydroponic culture

used to determine which chemical elements are essential

symbiosis

a close, long-term interaction between two different species

mutualism

both species benefit from the interaction

parasitism

the symbiont benefits and the host is harmed

lichen

a mutualistic association between a fungus and a photosynthetic partner

rhizosphere

the layer of soil closely surrounding the plant’s roots

rhizobacteria

bacteria that live in close association with plant roots or in the rhizosphere

endophytes

nonpathogenic bacteria that live inside the plant

nitrogen fixation

the conversion of nitrogen to ammonia

nodules

swellings composed of plants cells “infected” by Rhizobium bacteria

legumes

beans

bacteroids

form nodules, contained within vesicles formed by the root cell

crop rotation

pioneered by George Washington Carver, used to restore the concentration of fixed nitrogen in the soil

ectomycorrhizae

the mycelium of the fungus forms a dense sheath, or mantle, over the surface of the root

arbuscular mycorrhizae

microscopic fungal hyphae extend into the root cortex, penetrate the cell wall but not the plasma membrane

epiphyte

grows on another plant and obtains water and minerals from rain

parasitic plants

absorb water, minerals, and sugars from their living host plant

carnivorous plants

obtain nitrogen by killing and digesting mostly insects, have adaptations for trapping insects and other small animasl