Boost Your Bulbs Quiz Quiz

Assess your understanding of proper onion fertilization practices in horticulture, including nutrient needs and timing. Discover key principles that help grow healthy onion crops.

1. Essential Nutrient Identification

   Which nutrient is most crucial for encouraging strong bulb development in onions during the growing season?

   1. Calcium
   2. Nitrogen
   3. Potassium
   4. Phosphorus

   Explanation: Potassium plays a major role in bulb formation and overall onion development. Nitrogen supports leaf growth but excessive use can delay bulbing. Phosphorus is important for root establishment but less critical for bulb growth. Calcium helps with cell wall strength but does not directly influence bulb size.

2. Fertilizer Application Timing

   At what onion growth stage should the majority of nitrogen fertilizer be applied for best results?

   1. Early vegetative stage
   2. Bulbing stage
   3. Seed dormancy
   4. After harvest

   Explanation: Applying most nitrogen during the early vegetative stage ensures strong leaf growth, which drives the energy that forms bulbs later. Applying during bulbing can cause excessive leaf growth at the expense of bulbs. Applying after harvest or during seed dormancy has no benefit for current crop production.

3. Recognizing Fertilizer Deficiency

   If an onion crop shows yellowing of older leaves and reduced growth, which nutrient is most likely deficient?

   1. Nitrogen
   2. Magnesium
   3. Sulfur
   4. Iron

   Explanation: Nitrogen deficiency typically causes yellowing of older leaves and stunted growth in onions. Magnesium deficiency often presents as interveinal chlorosis. Iron deficiency usually affects new leaves first. Sulfur deficiency may cause pale leaves but is less common in onions.

4. Optimal Soil Condition

   What is the optimal soil pH range for maximum onion nutrient uptake?

   1. 6.0–7.0
   2. 4.5–5.0
   3. 5.0–5.5
   4. 7.5–8.0

   Explanation: Onions perform best in soils with a pH between 6.0 and 7.0, where most nutrients are available for uptake. Lower pH values (5.0–5.5 or 4.5–5.0) can cause nutrient deficiencies. Higher pH (7.5–8.0) may also limit nutrient availability and hinder growth.

5. Fertilizer Placement Practice

   Which fertilizer placement method minimizes risk of burning young onion roots while ensuring nutrients are accessible?

   1. Side-dressing fertilizer in shallow bands
   2. Broadcasting fertilizer without incorporation
   3. Mixing fertilizer deep beneath bulbs
   4. Applying all fertilizer directly on top of seedlings

   Explanation: Side-dressing places fertilizer in shallow bands beside the rows, reducing root burn risk while making nutrients accessible. Applying directly on seedlings can cause injury. Deep placement can put nutrients out of reach. Broadcasting without incorporation can lead to nutrient losses and uneven uptake.