Sulfur for Stronger Crops Quiz Quiz

Explore the importance of sulfur fertilization in agriculture, including nutrient roles, deficiency symptoms, and best management practices. Enhance your understanding of how proper sulfur use can impact crop growth and yield.

1. Sulfur's Plant Role

   Which essential function does sulfur serve in crop plants?

   1. It acts as a main source of phosphorus.
   2. It is a vital component of certain amino acids and proteins.
   3. It regulates the opening and closing of stomata.
   4. It directly provides energy for photosynthesis.

   Explanation: Sulfur is essential for synthesizing some amino acids and proteins in plants, which are key for growth and enzyme activities. Regulating stomata is mainly a potassium function. Energy for photosynthesis is directly provided by sunlight, not sulfur. Sulfur does not serve as a phosphorus source.

2. Sulfur Deficiency Symptoms

   What is a common visible symptom of sulfur deficiency in crops such as canola or corn?

   1. Wilting and leaf rolling at midday
   2. Purple discoloration of stems
   3. Leaf edge browning on oldest leaves first
   4. Uniform yellowing of younger leaves

   Explanation: Sulfur deficiency typically shows up as yellowing (chlorosis) on young leaves because sulfur is not easily mobile in plants. Purple stems are more characteristic of phosphorus deficiency. Browning edges on older leaves are symptoms of potassium deficiency. Wilting and rolling are often related to water stress.

3. Sulfur Loss from Soils

   Which process most commonly causes the natural loss of sulfur from agricultural soils?

   1. Fixation by clay particles
   2. Conversion to phosphorus compounds
   3. Leaching below the root zone by rainfall
   4. Volatilization during cold conditions

   Explanation: Sulfur is frequently lost from soils when sulfate forms are washed below the effective root zone by rainfall or irrigation. Clay particles do not fix sulfur like certain other nutrients. Volatilization of sulfur mainly occurs at high temperatures. Sulfur does not convert to phosphorus compounds.

4. Sources of Sulfur Fertilizer

   Which fertilizer would provide the fastest sulfur availability to plants?

   1. Elemental sulfur powder
   2. Gypsum rock
   3. Ammonium sulfate
   4. Organic compost only

   Explanation: Ammonium sulfate contains sulfate-sulfur, which is immediately available to plants after application. Elemental sulfur requires microbial conversion before plants can use it. Gypsum supplies calcium and sulfur, but in less soluble form than ammonium sulfate. Organic compost releases sulfur slowly over time.

5. Sulfur Management Practice

   Why is it important to monitor sulfur levels even if nitrogen fertilization is adequate in cereal crops?

   1. Sulfur is only needed in organic crop systems.
   2. Plants can substitute potassium for sulfur in all reactions.
   3. Sulfur is needed for efficient nitrogen use and protein formation.
   4. Nitrogen always increases available sulfur naturally.

   Explanation: Sulfur supports nitrogen metabolism and protein synthesis—without enough sulfur, crops may not effectively use applied nitrogen. Nitrogen does not naturally increase sulfur in soils. Potassium and sulfur have distinct functions and cannot substitute for each other. Sulfur is needed in both conventional and organic systems.