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Flashcards in Crop Management Deck (76)
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What are the advantages/limitations of crop rotations as compared to monoculture crop?

Risk spread across more than one commodity

Pest life cycle can be interrupted improving pest control

Yield of one or more of the rotational crops can increase compared to a single crop system

Erosion may be less due to soil coverage

Soil physical properties (infiltration, tilth) may improve

Requires a higher level of management, more planning

May require more or different equipment

Yield of one or more of the rotational crops may decrease compared to a monoculture

Time management (seeding, fertilization, pest control) may be difficult

May be more soil compaction from implements


What is the role of a fallow in a cropping system?

Used to store soil water, control weeds, and increase nutrient availability


What role do green manure crops and cover crops play in a cropping system?

They are grown to retain nitrogen in the root zone for the subsequent crop, to protect the soil surface from erosion, to increase the soil organic matter, to increase infiltration and decrease runoff and may be used for grazing.


What role do companion crops play in a cropping system?

They are grown within a major crop to more completely cover the soil surface with harvestable crop. Some erosion control is possible but main role is to be a second harvestable crop on the same acreage.


What is herbicide carryover?

When pesticide used on a crop damages the succeeding crop


Define allelopathy

When one plant impairs the growth of another by release of a chemical toxin


Define a cultivar/variety

Plants that are clearly different from others and whose offspring retain distinguishing characteristics of the parents


Define a hybrid

The offspring of two plants that differ genetically; used to create offspring that are superior, but different characteristics from their parents.


What is the difference between a hybrid and open-pollinated varieties?

In a hybrid, pollination is controlled, while in an open-pollinated variety pollination is natural.


What is plant maturity and how does it influence hybrid or variety selection?

Maturity: the point in time when harvest can begin

Can be used to avoid environmental stresses (temp, drought), decrease harvest loss (shattering, wet/dry cycles), use harvesting equipment effectively, allowing double cropping, etc


What is yield potential and how does it influence hybrid or variety selection?

Yield potential: refers to the yield that can be achieved in the absence of stress for a given geographical area.

If the yield potential is high and stress can be controlled, the variety is desirable.


Define a transgenic crop

Genes in that species have been altered directly or through insertion of foreign genetic material.


Why are randomization and replication important in field trial?

Randomization is used to place experimental treatments in locations within a field trial so that differences among treatments can be determined as real (significant) or arbitrary (not significant).

Replications are used to estimate the variability within a treatment across the field trial.


What is required in order for a seed variety to be protected?

Must be shown to be new (never sold)

Distinct (unique characteristics)

Uniform (same characteristics within seedlots)

Stable (can reproduce with same characteristics)


What characteristics does a high quality seed have?

High percentage of pure seed

Low percentage of other varieties, other crops, noxious weeds, objectionable weeds, total weed seed, hard seed, and inert matter

High germination percentage

High tolerance of environmental stresses

High resistance to disease


What conditions reduce seed quality?

Early freezes or excessively high temps

Excessive moisture and disease

Alternate wetting/frying cycles

Improper combine settings

Improper storage causing heating and diseases

Improper use of grain handling equipment


What is the standard germination test?

Seeds not in dormancy are germinated under controlled temp, moisture, and light.

Seed germination percentage is the percentage of viable seedlings of the total seedlings tested

If seed is not stored properly, germination can decline


How is pure live seed calculated?

PLS= fractional pure seed content * germination fraction time* 100


How is amount of seed calculated?

Amount of seed needed = seed rate/ %PLS as a decimal fraction.

Seeding rate can be adjusted for large/small seed sizes and for an insurance factor


What is a seedlot?

A quantity of seed that has the same characteristics within approved limits or tolerances.

Characteristics can include amounts of pure seed, other crop seed, seed seed, and inert matter; germination percentage; and dormant seed


What conditions alter recommended planting depth?

Excessive moisture at normal seeding depth

Lack of moisture at normal seeding depth

Low/high temps


What factors influence planting date?

Soil temp optimum for germination

Soil moisture between field capacity and permanent wilting point

Soil aeration to provide sufficient oxygen

Soil problems absent (salinity, extremes in pH)

Availability of labor and equipment

Anticipated weather patterns

Adaptation of crop to soil and climatic conditions


What are the consequences of seeding earlier or later than optimum?

Delayed germination

Stand losses


Yield loss


How do planting practices affect seeding rate?

If plants/ac are to remain constant, seed planted per row foot will decrease as rows become more narrow

If plants/ac are to increase, seed planted per row foot will also increase as rows become more narrow


How does soil tilth affect seeding rate?

Poor soil tilth causes less germination and emergence, necessitating higher seeding rates


How does soil salinity affect seeding rate?

Soil salinity can reduce stands and cause seedling death. Removing salts by soil amendments and leaching is preferable to increasing seeding rate


How do environmental conditions affect seeding rate?

Adverse climatic conditions lead to less germination and emergence necessitating higher seeding rates


How does crop residue affect seeding rates?

Crop residue can reduce germination and emergence necessitating higher seeding rates


How does seed size affect seeding rates?

As seed size increases, the seed per bushel decreases, and higher seeding rates are recommended


How does seed quality affect seeding rates?

As the percentage of pure seed and germination rate decrease, higher seeding rate is recommended