Chapter 4 HW

Which of these ions is most likely to be leached from the soil?

chlorine ions

Under which conditions are the processes of weathering, leaching, and input of organic material from plants into soil maximized?

warm temperatures and abundant water

The mechanical destruction and/or chemical modification of rock into smaller particles is called

weathering

What name is given to the process seen in this animation?

cation exchange

Three types of chemical weathering processes are particularly important for transforming minerals within rocks into weathered products. These are hydrolysis, oxidation, and dissolution. Through hydrolysis reactions, minerals are weathered in the presence of water, often rainwater. Through oxidation reactions, iron-rich materials transform in the presence of oxygen in air. And through dissolution, minerals dissolve in water, making their chemical products ions within water. You will sort each example into its category of chemical weathering process.

Hydrolysis: granite to clay Oxidation: red color of rocks in national park yellow stained rocks Dissolution caves formed in limestone salty taste of ocean

In temperate regions dominated by deciduous forests, seasonal changes result in __________.

a larger leaf area index during summer months

How do cations enter root hairs?

diffusion

Rank the rocks in order of the rate of chemical weathering they would experience, assuming they are all located in the same warm, wet climate. Rank from slowest to fastest.

granite granite with cracks basalt basalt with cracks

In comparing the removal of cadmium with the removal of zinc, the alpine penny-cress removed a _____ % and a ____ mass of cadmium than of zinc.

higher, lower

If the area contaminated with heavy metals contained 10,000 kg of soil, after 5 years of phytoremediation one would expect alpine penny-cress to have removed:

10 kg zinc

If plants continue to remove zinc at the rate shown, it would take _____ years to remove all the zinc.

15 years

Prior to phytoremediation the concentration of Cd in the soil was:

19 mg/kg soil.

After 1 year of phytoremediation, alpine penny-cress removed ____ mg/kg soil of zinc.

200

What percentage more nitrogen would be saved annually by using reduced tillage rather than conventional tillage?

37%

Given that annual crop yields in each of the study plots were approximately 4 metric tons/ha, what is the ratio of soil lost to crop yield under conventional tillage?

4,000 kg soil/1 ton

Which of the following statements is FALSE?

Plants remove water from the soil, influencing soil formation.

What is salt weathering?

the formation of minerals in rock cracks during the evaporation of salty water, forcing rock apart

You are designing an experiment to test methods to prevent soil erosion in agricultural production. Which of the following are NOT good experiment ideas?

Compare tillage of a wheat field with tillage of a corn field.

You want to investigate the difference in available water capacity of local farms. Which of the following would be an appropriate hypothesis?

Farms with intermediate particle size will have the highest available water capacity.

With the addition of water, the minerals in granite rocks chemically weather into other minerals, known as products. Test your knowledge of the by-product of each mineral as a result of chemical weathering by labeling the minerals below with their respective products.

Feldspar - Clay Quartz - No chem change Olivine - Limonite

Approximately how much more soil was lost using conventional tillage rather than reduced tillage?

5,000 kg/ha

How much more organic carbon would be saved annually by using reduced tillage?

70 kg/ha

Why does water frozen in the cracks of a rock help to break down the rock?

Water expands when frozen and physically forces the rock apart.

Based on the information given, sort each environment into the correct bin for an environment that would experience predominantly mechanical weathering or predominantly chemical weathering.

cold climate = mechanical weathering hot/warm = chemical weathering

Acid precipitation _____.

decreases soil fertility

The amount of light at any depth in a forest canopy is affected by the leaves above. The best way to measure the impact of those leaves on light availability is to __________.

determine their total area

The binding of H+ ions to soil particles _____.

displaces mineral cations

The release of CO2 into the soil results in the formation of _____.

hydrogen ions and carbonate ions

Look at the descriptions below of scenarios and determine whether the scenario inhibits weathering or enhances weathering.

inhibits weathering: bare field, now planted with trees and shrubs. rows of trees planted to deflect wind. enhances weathering: forest fire destroys with no regrowth. constant grazing. animals burrowing. tree roots breaking up rock on rocky hill. human removes vegetation to plant other things. lichens secreting acid on rock.

Terrestrial organisms typically __________.

must cope with a much wider range of temperatures than that found in aquatic systems

What process is the source of the CO2 that root hairs release into the soil?

respiration

Sort the statements by the type of agriculture that each best describes.

traditional agriculture: relies on human and animal power. controlls pests with natural ways. many crops planted together on a small plot. industrial agriculture: synthetic pesticide pest control. synthetic fertilizer. single crops, large plot. fossil fuel powered machinery.

The processes of chemical weathering results in the decomposition of minerals within rocks over time. Fill in the sentences below to explore the different chemical weathering processes. Match each key term to the appropriate sentence. Be sure to complete each sentence before submitting your answer. You don't need to use all words.

1. Chemical weathering alters the internal structure of rock materials. 2. Potassium feldspar weathers in the presence of water containing carbonic acid. 3. Iron weathers through the process of oxidation. 4. A greenhouse gas called carbon dioxide influences the rate of chemical weathering.

What do freeze-thaw and salt weathering have in common?

Both freeze-thaw and salt weathering require rain and force rocks apart physically.

Predict how the results of this experiment might vary if repeated in a less mountainous region with lower annual rainfall.

Lower soil loss for both conventional and reduced tillage treatments

The surface layer of soils is referred to as the

O horizon.