Crop Management Systems Flashcards

A field history shows three consecutive years of high corn rootworm pressure despite crop rotation. This most likely indicates:

Answer: Extended-diapause or variant rootworm populations that lay eggs in soybean fields

Extended-diapause and soybean-rotation-resistant rootworm variants survive crop rotation by laying eggs in soybean fields where larvae hatch into following corn.

In relay cropping, the second crop is:

Answer: Planted into standing first crop before it is harvested

Relay cropping plants the second species into the standing first crop, allowing overlap of growing seasons to maximize land use.

What is the agronomic role of a nitrogen credit when corn follows soybeans in rotation?

Answer: Soybean residue decomposition releases symbiotically fixed nitrogen that reduces corn's fertilizer requirement

Soybean residue contains high-N compounds from biological fixation that mineralize during decomposition, providing plant-available N for the following corn crop.

Which cover crop species is BEST suited for scavenging residual nitrate from the soil profile following corn harvest?

Answer: Cereal rye

Cereal rye has an extensive root system, germinates in cold temperatures, and has high nitrate uptake capacity, making it ideal for fall nitrogen scavenging.

The practice of summer fallow in semi-arid dryland farming is intended primarily to:

Answer: Store soil moisture over one season for use by the subsequent crop in a dry environment

Summer fallow stores precipitation in the soil profile across one growing season, supplementing moisture supply for the following dryland crop.

What is the main disadvantage of summer fallow compared to continuous cropping in dryland systems?

Answer: Fallow increases risk of soil erosion, organic matter loss, and nitrate leaching

With no living crop to anchor soil and consume nutrients, summer fallow promotes wind and water erosion, organic matter oxidation, and deep nitrate leaching.

Which management practice is most critical for maximizing yield in a high-residue no-till corn system?

Answer: Managing planter settings for consistent seed-to-soil contact through residue

Heavy residue can interfere with seed placement and furrow closure, making precise planter setup the single most important yield-limiting factor in no-till corn.