CRSS 4590 Exam 1 Questions & Answers (GRADED A)

Potential acidity - ANSWER-The sum of exchangrable acidity and non-exchangreable acidity Active Acidity - ANSWER-Concentration of hydrogen ions in a soil solution, measureed by soil pH Exchangeable Acidity - ANSWER-Al3+ and H+ on exchange sites in soil Non-Exchangeable Acidity - ANSWER-Protons that can be released from surfaces as pH rises What are some of the affects of acidic soils on plant growth? - ANSWER-Stunted Plant Growth Reduced Lateral Root Growth Brownish Discoloration on roots Root Structure/Function Increases Root Permeability/Loss of Organic Substrates Reducing Nutrient Uptake How does the toxicity site on a root site effect the plant - ANSWER-Root cell division is inhibited/ceases, results in a reduction/cessation of tap and lateral root growth Magnesium is not readily available in low soil pHs. What can be done to increase Mg availaility? - ANSWER-Lime the soil with dolomitic lime How does liming increase pH and BS? - ANSWER-Liming removes H+ ions from the soil and will precipitate exchangeable Al3+ into Al(OH)3 Micronutrient Availability __________ with increasing pH - ANSWER-decreases Gypsum is not considered to be a liming material. Why? - ANSWER-Gypsum cannont neutralize H+ anions, but can increase Ca deficiencies when needed What is added to soils to make them more acidic? - ANSWER-Sulfur (Sulfuric Acid) Aluminum Sulfate Ammonium Polysulfide How is N2 converted to acailable N in plants? - ANSWER--Microoganisms that live symbiotially on legume roots -Free-living/nonsymbiotic soil microorganisms -Manufacture of synthetic N fertilizers In what forms fo plants absorb N? - ANSWER-Nitrate (NO3-) and Ammonium (NH4+ ) In warm environments, _____ is usually adsorbed better than ________ - ANSWER-Nitrate, Ammonium