Agn 115 Final

Pathogens and a failure to separate industrial waste (e.g. heavy metals) from human waste can complicate the use of sewage in agriculture.

Southern corn leaf blight (1970-71) ____.

Among common domesticated livestock, manure from ____ contains the lowest level of water, which makes it more affordable to transport for use as a fertilizer

Plants that use the C3 photosynthetic pathway do well under relatively hot/dry conditions compared to plants using the C4 pathway

After land is put into cultivation (i.e. tilled) loss of soil organic matter happens ____.

Phosphorus is an important component of many structures in plant and animal cells, including membranes, nucleic acids, ATP, amino acids, and chlorophyll

In a mass-selected plant variety, overall genetic diversity within the variety is greater than that of any individual seed in the variety.

While the crop production industry has narrowed its genetic basis over time, the livestock industry, which relies more on cross-breeding, has maintained a high level of diversity.

Of the major grains we rely upon in the USA, corn and soybean are native species, which is part of why they are commonly planted as a rotation in the USA.

Polyploid plants often produce larger seeds and fruits than their normal diploid ancestors because of inbreeding depression

_______ clay minerals have more surface area for the exchange of nutrient ions when hydrated.

In the USA, water erosion is typically a bigger problem in eastern states.

Windbreaks (a.k.a shelterbelts or hedgerows) are not meant to stop the wind, but rather to change its course and rate of flow.

___ is regarded as the “Father of soil conservation” in the USA.

Stiff-stemmed grasses could be used to prevent "sandblasting" injury to sensitive crops if the grasses are planted perpendicular to the prevailing direction of erosive winds.

Soil organic matter could be called the "signature or evidence of past plant and biological activity

Few plants, especially agricultural crops, grow well outside of the pH range of 5 to 8.

The least obvious form of soil erosion is called sheet erosion. It can be a severe problem but can escape notice since thin layers of soil are lost over time.

Raindrop impact on tiny soil particles was equated to a bomb blast during lecture because of the power of raindrops to disperse soil particles from unprotected soil.

Lawn clippings and soil from edging become sources of organic contaminants and nutrients in untreated storm runoff. They should be

Soil Structures can be promoted by

Some methods of reducing soil erosion include:

In Teaming with Microbes the authors say that pesticides, salts from fertilizers, and ____ can kill or injure portions of the soil food web.

As the name implies, "no-till" agricultural equipment cause zero disturbance of the soil during planting operations.

Excess water in the soil can lead to high levels of oxygen in the soil as a result of root respiration.

The shrink-swell capacity of a soil is an important consideration for an engineer when constructing a building, road, or bridge.

Where a healthy dynamic soil community (e.g. bacteria, nematodes, etc.) is present, nutrient availability to plants can be maintained even when crop residues of higher C:N are present.

The USDA map used in lecture identified areas subject to wind erosion as the states of the Great Plains and coastal areas in eastern and southern states. Only the southeastern "bootheel" region of Missouri is identified as being at risk of wind erosion.

During lecture we examined a photograph of cotton roots growing within the soil profile. In the photograph, many roots grew where ____.

The ___ soil horizon normally has the lowest bulk density in undisturbed soil.

Types of tillage that result in more disturbance (e.g. moldboard plowing vs. chisel plowing) result in greater losses of soil carbon into the atmosphere.

“High-traffic” areas around campsites (e.g. around fire pit or tent) become compacted and can have runoff levels ____ than uncompacted areas; erosion and plant moisture stress can result from compaction. Therefore, camping in designated areas is recommended.

Mycorrhizal fungi infect the roots of most crop plants in a beneficial (symbiotic) relationship. The mycorrhizae gain carbohydrate from the plant, while the plant gains ____.

In the assigned reading (Liming Missouri Soils, G9102), the authors indicated that soybean yields might be reduced 18% when soil pH decreases to about 5

In the assigned MU extension guide G9107, we learned that the material most commonly used to adjust soil pH to a higher level is ___.

In addition to the millions of tons of topsoil in “dust bowl’ storms, thousands of people suffered (and many died) from mysterious illnesses resulting from dust inhalation.

In Teaming with Microbes, the authors say that ___ are in control of the soil food web because of what they release into the soil.

The tendency of a soil or clay mineral to increase or decrease in volume when they are hydrated is called its "shrink-swell capacity".

An ideal soil will have 50% of its volume as pore spaces, which could be occupied by air and water

Windbreaks (trees planted in a line perpendicular to the prevailing wind direction) can modify windspeed to reduce soil erosion for a distance of 10X the tree height (or more).

___ is often used as an alternative to planting permanent windbreaks of trees or shrubs.

A strip-tillage system results in ___.

Soils differ in the amount of water they hold at ____ , which is the moisture left in the soil after the downward pull of water has pulled away gravitational water.

The ability of soil to hold and buffer nutrient ions (i.e. a measure of soil fertility) is measured by ___.

____ results in lower runoff and erosion.

Unfortunately, no genetic varieties (within a crop species) have been identified that are more resistant to wind and lodging

Most crops will generally perform well in a loamy soil, however, paddy rice requires a clayey soil.

Human-accelerated erosion is typically many times worse -- perhaps 10 or 1000X worse -- than geological erosion.

In the soil biota videos assigned during lecture, Terry Tollefson said that soil scientists had estimated that there might be as many as ____ different species in a gram of soil.