Lab 4 Soil pH: Acidity and Liming
Why is it important to maintain relatively neutral soil pH?
What are some of the natural sources of soil acidity? 3. How do nitrogen fertilizers produce soil acidity?
Farmer Brown’s CEC for his West Tennessee silty loam soil was 12 cmolc/kg soil. The acid saturation percentage (aluminum and hydrogen) was 30% of the total CEC. As a soil professional why might that value concern you? What issues might arise due to this high acid saturation percentage?
Explain how CEC and soil texture in general effects the buffering capacity in soils. For instance, Farmer John’s silty clay has a CEC of 25 cmolc/kg with soil water pH of 6.5 and Adams-Evans Buffer value of 7.0 while his loamy sand has a CEC of 8 cmolc/kg with soil water pH of 5.5 and Adams-Evans buffer value of 7.9. Explain how their difference in texture, clay percentage and thus CEC help shape those values. What effects might this also have on the amount of lime that will be required to alter the pH of each of those soils?
Soil Acidity and Liming: Basic Information for Farmers and Gardeners
Why is it important to test both soil water pH as well as soil buffer pH? What pools of acidity do each of those test, which one is most easily counteracted, and which one is the most important long term in maintaining neutral soil pH?
Farmer Jim is liming his row crop acreage and ended up with some extra lime and would like to potentially use it on his alfalfa field, but does not have time to send it off for official analysis; Jim’s daughter is close and happens works in a soils lab on campus and reports back that his soil water pH is 5.8 and his Adams-Evans buffer pH is 7.4. Based on UT recommendations, approximately how much lime did his daughter recommend he add to his pasture?
Describe two additional lime quality metrics besides just the amount of product required utilized to ultimately determine how much of a liming product will be needed to counteract soil acidity.
What are some defining characteristics of saline soils? (Hint: moisture, pH, nutrient deficiencies,
CEC, clays, etc.)
Why does irrigation in arid regions contribute to salinity issues?
What is dispersion? What role does the ion on the exchange site (i.e. sodium vs
calcium/magnesium) play in the tendency to disperse?
Describe the three major components of soil organic matter.
The nutritional requirement for the microbial community is important in the degradation
process. Explain the concept of a carbon to nitrogen ratio (C:N). Why is it important? What C:N ratios might enhance degradation and what rations might slow degradation?
Describe some agronomic management tools to help build soil organic matter.
Lab 6 Soil Nitrogen – Use of Colorimetric Assays
Intro Soils – Lab 4 Soil pH: Acidity and Liming