Nutrient Sources and Management Flashcards

Denitrification in waterlogged soils converts nitrate primarily into:

Answer: Nitrogen gases (N₂ and N₂O)

Under anaerobic conditions, bacteria convert nitrate through denitrification to nitrogen gases (N₂ and N₂O) that escape into the atmosphere.

Which micronutrient is most commonly deficient in high-pH, calcareous soils because it precipitates as insoluble compounds?

Answer: Iron

Iron availability drops sharply in high-pH soils because iron forms insoluble hydroxide and carbonate compounds, causing iron chlorosis.

The nutrient management concept of the '4Rs' refers to right:

Answer: Source, Rate, Time, Place

The 4R Nutrient Stewardship framework stands for the right Source, right Rate, right Time, and right Place of fertilizer application.

Which nitrogen source has the highest potential for ammonia volatilization when surface-applied to high-pH soils without incorporation?

Answer: Urea

Urea hydrolyzes rapidly to ammonium carbonate, which readily releases ammonia gas—especially problematic on high-pH soils.

Luxury consumption of potassium occurs when:

Answer: Plants absorb K beyond their growth needs when soil K is high

Luxury consumption means plants absorb more potassium than required for maximum yield when soil potassium levels are high.

Foliar fertilizer applications are most beneficial for correcting:

Answer: Acute micronutrient deficiencies detected mid-season

Foliar applications are best suited for correcting mid-season micronutrient deficiencies quickly because nutrients are absorbed directly through leaf tissue.

Which soil property most strongly governs cation exchange capacity (CEC) and thus the ability to hold calcium, magnesium, and potassium?

Answer: Soil texture and organic matter content

CEC is primarily determined by clay content (texture) and organic matter, both of which carry negative charges that retain cations.