Chapter 37: Plant nutrition

**Humus**

Remains of dead organisms and other organic material

**Topsoil**

Mixture of derived materials from humus and inorganic materials

**Soil horizons**

Soil layers with characteristics that differ from those above it

**Soil horizons A**

Topsoil

**Soil horizons B**

Less organic material

**Soil horizons C**

Broken down rock

**Organic chemicals**

Chemical compounds containing carbon

**Inorganic chemicals**

Chemical compounds that don’t contain carbon

**Leaching**

Slow movement of water through pores in the soil or permeable rock

**Anion**

Negatively charged atom

**Cation**

Positively charged atom

***Streptomyces***

Found in soil, used to develop antibiotics; gram positive

**Fertilization**

Addition of minerals and nutrients in the soil, allows for soil renewal

**Crop rotation**

Growing an array of crops in the same area across different seasons in order to prevent soil destruction

**Sustainable agriculture**

Long-term farming practices that are environmentally friendly

**Nitrifying bacteria**

Bacteria that oxidize ammonium to nitrite and then nitrite to nitrate which is absorbed by plants

**Denitrifying bacteria**

**Bacteria that reduce nitrate to nitrite**

**Inorganic fertilizers**

Contain the direct minerals needed

**N-P-K ratio**

the ratio of nitrogen, phosphorous, and potassium in fertilizers, written on bag

**Organic fertilizers**

Contain biological waste or products that contain the minerals needed, must be broken down first

**pH**

The concentration of protons in a solution

**Citrate synthase**

An enzyme that synthesizes citric acid which increases aluminum resistance

**Phytoremediation**

A type of bioremediation that relies on the ability of select plants to remove pollutant from the soil

**Bioremediation**

introduction of microorganisms or other organisms to break down pollutants in soil

***Thlaspi caeruescens***

**Plant that can accumulate zinc 300x higher than most plants can tolerate**

**Essential elements**

CHNOPS

**Hydroponic cultures**

Plants grown in water infused with vital minerals and nutrients instead of soil, can be used to test which nutrients are essential

**Macronutrients**

Nutrients that are required in large amounts

**Micronutrients**

Nutrients that are required in small amounts

**Enzyme cofactors**

A substance that helps enzymes in their functions

**Mutualism**

relationship in which both parties benefit

**Rhizobacteria**

Bacteria that live in or near plant roots

**Rhizosphere**

Area close to plant roots where bacteria live

**Mycorrhizae**

Symbiotic relationship of a fungus and plant roots; different kinds

**Nitrogen cycling**

Series of steps where nitrogen containing compounds are cycled through the soil, organisms, and the air

**Ammonia**

NH3

**Ammonium**

NH4+

**Nitrate**

NO3

**Nitrite**

NO2

**Nitrogen gas**

N2

**Nitrogen fixing-bacteria**

Bacteria that capture Nitrogen from the air and reduce it to ammonia

**Nitrogen fixation**

The conversion of atmospheric nitrogen to a form of nitrogen usable by plants

**Nitrogenase**

Enzyme responsible for nitrogen fixation

**Ammonifying bacteria**

Bacteria that convert amino acids in the soil into ammonium

***Rhizobium***

*Root living bacteria found in legumes*

**Nodules**

Swellings in the roots of legumes where rhizobium live

**Epiphytes**

Plants that grow on other plants, do not tap into vascular system, produces own nutrients

**Parasitic plants**

Plants that absorb nutrients from other plants

**Carnivorous plants**

Plants that a photosynthetic and supplement their diet with insects and other small organisms

How does the nitrogen cycle work

Nitrogen (N2) is oxidized to NH3 by nitrogen fixing bacteria. NH3 is then taken up by nitrifying bacteria to produce NO3 which is absorbed by plants. NO3 is then taken up by denitrifying bacteria that release it back into the air as N2