FANR 3060 1st Edition Lecture 14Outline of Last LectureI. SoilManagement (No-Till Agriculture)II. Soil Colloids – Permanent ChargeIII. Soil Colloids – Variable ChargeOutline of Current LectureI. Soil Colloids – Variable Charge (con’t)II. Ion ExchangeChapter 5I. SoilColloids – Variable Charge (con’t)a. The higher the pH, the more basic the solution, so the less amount of H+b. If pH = pK, the reaction will proceed exactly halfwayc. If pH>pK, the reaction goes to the right morei. Alkaline, few H+, gets less protonationd. If pH <pK, the reaction goes to the left morei. Acidic, lots of H+, more protonatione. Table 5.1i. Kaolinite 1. 70% of clay in the Piedmontii. Montmorillonite and vermiculite have lots of substitutionThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.f. Figure 5.4i. There’s an invisible film of water around the iron oxide moleculeii. How many H+’s go on and off this film and onto the surface of the Fe oxide depends on chargeg. Figure 5.5i. Humus is made of a bunch of functional groupsh. Major Functional Groupsi. Carboxyls1. Most important2. Lots of them, low pK, highly charged at soils pH 5-7ii. Figure 5.61. Want soil to be pH 5-7II. Ion Exchangea. Cationsi. Held onto negative sites on clay minerals and variable colloidsb. Anionsi. Held onto positive sites on variable colloidsc. CECi. Cation exchange capacity1. Big deal in plant growthd. AECi. Anion exchange
View Full Document
Unlocking...