Crop Management Systems Flashcards

Under which condition would a farmer MOST likely choose a reduced tillage system over no-till?

Answer: Heavy clay soils with severe compaction and drainage problems that no-till alone cannot correct

Severely compacted or waterlogged clay soils may need at least one deep tillage pass to re-establish macroporosity before transitioning to no-till.

Biological nitrogen fixation in legume crops is carried out by:

Answer: Rhizobium bacteria living symbiotically in root nodules

Rhizobium and related genera form root nodules in legumes and convert atmospheric N2 to ammonia using the enzyme nitrogenase in a symbiotic exchange.

A crop consultant recommends intercropping corn and squash using the Three Sisters system. The primary agronomic advantage of this system is:

Answer: Diverse species use space, light, and nutrients complementarily, reducing weed pressure and improving system productivity

The Three Sisters system uses complementary niches — corn for vertical structure, beans for nitrogen fixation, and squash for ground cover — to maximize overall system productivity.

Which metric is MOST useful for evaluating the productivity efficiency of an intercropping system?

Answer: Land Equivalent Ratio (LER)

Land Equivalent Ratio (LER) compares the land area needed in monoculture to produce the same total yield as the intercrop, with LER > 1.0 indicating an efficiency advantage.

Which scenario BEST describes a situation where drip irrigation would be preferred over overhead center pivot irrigation in a crop management system?

Answer: High-value vegetable or fruit crops on irregular terrain where foliar disease management is critical

Drip irrigation delivers water directly to the root zone without wetting foliage, reducing disease pressure and making it economically justified for high-value crops on varied terrain.

In a crop management decision regarding planting date, which factor has the GREATEST influence on optimal timing for corn in the U.S. Corn Belt?

Answer: Soil temperature at 2-inch depth reaching and holding 50°F

Corn seed germination is minimal below 50°F soil temperature, and cold, wet soils increase seedling disease risk, making soil temperature the primary planting trigger.

Which management approach BEST represents the concept of 'ecological intensification' in modern crop systems?

Answer: Enhancing ecosystem services such as nutrient cycling and pest suppression to reduce external input dependency

Ecological intensification leverages biological processes — soil health, biodiversity, natural pest control — to sustain productivity with fewer synthetic inputs.