Quiz 2 – Chemical Properties Review Questions Explain CEC Soils ability to exchange cations What 2 types of soil particles have high CEC? Clay and organic matter Define Base Saturation Percent of exchange sites occupied by base cations What 4 ions in prairie soils are classified as the base cations? Calcium, magnesium, potassium, sodium How much more acid is a pH of 5 than a pH of 8? 1000 x Which cation predominates at a pH of 8.5? sodium What cation can become so available that it is toxic in clay soils in very acid conditions? Aluminum In high rainfall areas is a soil more likely to be acid or alkaline? acid How does a soil become more acid? (generally) Addition of Hydrogen H+ ions What macronutrient becomes much less available at a pH of 7.5-8? phosphorous What is ideal pH for most micro-organism activity? 6-8 Define buffering capacity. Ability to resist a change in pH Which soil textural classification would have the highest buffering capacity? Clay Calcareous soils are high in……. Carbonates Check off which of the following will have an effect on pH Parent material - yes Vegetation - yes Precipitation - yes Irrigation water - yes Fertilizers - yes What causes iron deficiency and what does it look like? Ties up with alkaline cations – interveinal chlorosis What can you do to dissolve free lime in the soil? Add acid What is a salt Acid + base Which of the following is not a salt? Calcium chloride Sodium bicarbonate Potassium sulfate Ammonium nitrate Ammonium cation What does saline mean? High in soluble salts What does sodic mean? High in sodium What does EC test for? Soluble salts How do saline soils affect plants? Toxicity which shows up as burn or inability to absorb water which shows up as wilt What do sodic soils do to soil structure? deflocculate Which of the following can be a cause of high soluble salts? Check as many as pertain Low drainage - yes Parent material - yes Compost - yes Deicing sidewalks - yes Fertilizer overuse - yes High CEC - no The best way to treat soils higher in salts is….. Keep moist Add organic matter Incorporate gypsum (CaS04) (we didn’t mention this but it works) Leach