Soils Nutrient Management Lesson

Nitrogen is a component of which essential plant compounds?

• proteins

• chlorophyll

• enzymes

• DNA

• All Above

A deficiency of N typically ________ the maturity of annual plants.

• speeds up

• delays

• does not affect

Applied to agricultural crops, the term lodging refers to:

• pre-mature fruit drop as a result of N deficiency.

• infestation with a high number of insect larvae lodged in the fruits or seeds.

• short, stubby plants starving for N or S.

• plants falling over, often as a result of too much N.

• plants losing their leaves because of a N imbalance.

Grass clippings from a healthy lawn can be expected to contain approximately ________% N (on a dry weight basis).

• .01

• .2

• .5

• 3.0

In the early stages of plant nitrogen deficiency, the most obvious symptoms are:

• yellowing of the youngest leaves

• brown spots and tiny holes on the underside of most leaves

• purple of the youngest leaves

• yellowish colors in the oldest leaves

• brown edges on leaves

Plants obtain nitrogen from the soil by taking up ________.

• soluble anions

• soluble cations

• soluble organic compoundss

• all above

The great majority of nitrogen (95 to 98%) in soils can be found in the form of ________.

• primary minerals

• secondary minerals

• dissolved anions

• organic compounds

The process of ________ releases soluble nitrogen as the result of the breakdown of nitrogen-rich organic compounds.

• nitrification

• denitrification

• mineralization

• volatilization

The opposite process from mineralization is ________.

• immobilization

• nitrification

• ammonifcation

• none

Ammonium fixation would be expected to be greatest in soils containing a lot of ________.

• rhizobium bacteria

• vermicultie

• iron oxides

• both vermiculite and iron oxides