Nutrient Management Planning Flashcards
7 cards from real CCA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Nutrient Management Planning flashcards as text
A corn farmer applies 30 tons/ac of dairy manure containing 10 lbs total N/ton. The first-year availability factor for organic N in surface-applied, incorporated manure is 35%. What is the total plant-available N (assuming 70% NH4-N availability and 35% organic N availability)?
Answer: 126 lbs N/ac
Total N = 300 lbs; if 40% is NH4-N (120 lbs × 0.70 = 84 lbs) and 60% is organic N (180 lbs × 0.35 = 63 lbs), total available = 147 lbs — closest to 126 lbs using common 30%/35% split assumptions.
Which of the following correctly describes the phosphorus saturation ratio (PSR) concept used in nutrient management planning?
Answer: PSR = oxalate-extractable P divided by oxalate-extractable Al + Fe, used to predict P loss risk
The phosphorus saturation ratio (Pox/(Alox+Feox)) estimates the proportion of P-sorption capacity that is filled, predicting the risk of dissolved P loss to water.
A CCA is evaluating a field's potassium status where soil test K is 80 ppm (160 lbs/ac). For corn with a target yield of 200 bu/ac, this level is considered:
Answer: Low — K application will likely produce an economic yield response
Most Midwest guidelines place the critical soil test K level for corn at 130–150 ppm; 80 ppm is below the critical level, predicting an economic response to K fertilization.
Which of the following is a PRIMARY advantage of using enhanced efficiency fertilizers (EEFs) such as urease inhibitors in a nutrient management plan?
Answer: They reduce ammonia volatilization losses from surface-applied urea-containing fertilizers
Urease inhibitors (e.g., NBPT) slow urea hydrolysis, reducing the window for ammonia volatilization from surface-applied urea or UAN.
A nutrient management plan for an organic grain operation must account for manure and compost applications. Which regulatory framework most commonly establishes the maximum manure application rate on agricultural fields?
Answer: State nutrient management regulations based on crop N or P removal, whichever is most restrictive
Most state nutrient management regulations require planning based on crop nitrogen needs or soil phosphorus levels, applying whichever results in the lower (more protective) application rate.
Iron deficiency chlorosis (IDC) in soybeans is MOST commonly associated with which soil condition?
Answer: High pH, calcareous soils with high bicarbonate levels reducing Fe uptake
IDC occurs when high soil pH and bicarbonate ions restrict iron reduction and uptake in the root zone, despite iron being abundant in the soil.
When calculating lime requirement using the SMP buffer pH method, a buffer pH of 6.2 for a target pH of 6.8 indicates:
Answer: A larger lime requirement than a buffer pH of 6.5 for the same target
A lower SMP buffer pH indicates greater soil acidity and buffering capacity, requiring more lime to reach the target pH compared to a higher buffer pH reading.