Homework for PSS 264

Please provide concise but complete answers, using your knowledge of soil and water chemistry. Pay attention to the points given to each question when dividing your effort. Use any source but work individually. Cite any important source you used if it was not the text or the lecture notes.

1. Briefly describe the structural differences between hematite and goethite. Why does climate affect the relative amounts of these two minerals in soils? (5 pts)

Hematite can be described as a type of mineral iron (III) oxide (Fe2O3) it is classified as one of iron oxide. It is one of the oldest minerals to be ever found on earth, and it has spread in stones and soil (Ahmed et al., 2018). It crystallizes in the lattice system, and its structure can be compared with corundum and ilmenite. It forms a very strong solid at a room temperature of around 950 °C (1,740 °F). On the other hand, goethite is referred to as the iron hydroxide mineral. It mostly found soil and another area with low temperature. Based on these mineral structures, Hematite is black, red or grey. Whereas goethite is color is yellowish or brown (Frierdich et al., 2019). These minerals are profoundly affected by temperature because of their oxidation rate.

2. Describe how the surface charge characteristics of hydrous oxides and 2:1 layered phyllosilicates differ. (5 pts)

The surface charge characteristics of hydrous oxides and 2:1 layered phyllosilicate can be evaluated using Sodium iron and chloride iron as the main counter irons from Sodium chloride solution. In such an experiment the negative charge is observed in hydrous oxides, this charges can only be determined using hydrous alumina on the other hand 2:1 layered phyllosilicate shows both negative and positive charges. In both cases, the charges are based on the PH and series of negative charge that decreases as opposed to an increase in positive charge.

3. Exactly why would kaolinite make a better sorbent for nonpolar organic molecules than smectite or vermiculite? (5 pts)

Kaolinite is one of the most common ions used as sorbate; this is attributed by its benefit as well as having less impact on the environment of organic matter. The inorganic cations have an impact on kaolinite. Another reason for the adoption of Kaolite is based on its absorption rate; this is not the case with smectite or vermiculite which take much time to absorb the required mineral. It can be noted that the structured sorbate is mostly recollected by kaolinite, which is also contained with hydrogen bonding. It is not easy to assess to determine the rate of weathering in soil because the carbon in soil absorbs HOCs, which interns affect the soil structure.

4. Why is it difficult to accurately determine weathering rates in soils? (5 pts)

5. Describe the general weathering scheme of muscovite to dioctahedral vermiculite. (5 pts)

The dioctahedral vermiculite is derived or transformed from muscovite by exposing it to molten LiNO3 and then subjecting to heat and AlCl3 solution for at most five days. The extracted vermiculite is examined using the X-ray diffraction technique, discrepancy warm air analysis, absorption of electron micrography and spectroscopy. The vermiculite had to be decreased to about 10.7 A when subjected to heating in N KOH-N KCl. This is converted to glycerol sorption when the heat in the presence of NH4NO3. The differential warm air is prepared to the vermiculite that indicates the endothermic high of close to 5000C and exothermic of about 9000 C.

6. Calculate the activities coefficients for Al3+ and K+ in a soil solution in which they are each 1 mmolar (10-3 molar) and the balancing anion is SO4-2. Show your work. Why are they so different? (5 pts)

7. Phosphorus is not a macronutrient and there should be plenty of total P in most soils. Why is often necessary to add more P to obtain optimum plant growth? (5 pts)

Phosphorus is one of the essential macro elements that plants need. It plays an imperative role in plant metabolism process such as respiration, photosynthesis and breaking down of carbohydrates. This mineral is found in soil, other minerals and various types of organic compound. Nonetheless, the amount is available in the soil is very low; hence there is a need to add more in the soil. Adding more phosphorus in the soil helps in meeting the crop requirements. The mineral dissolves in the soil; hence plants can easily access and benefit from it. There is a balance between phosphorus in the soil and one in the solution. Plants have the ability to dissolve phosphorus in solution form; this is attributed by the fact that phosphorus is found in stable condition. There is less amount of phosphorus in at the given time in the soil. Plants need phosphorus to aid in their growth and development since there is less P in the soil; it is necessary to add more to the soil. The amount of P in the soil is determined by the soil PH and other types of minerals in the soil. A compound in the soil mostly contains aluminum, calcium, and manganese.

8. You’ve had a garden for a number of years and have added dairy manure compost to provide nitrogen. Now your soil test is ‘excessive’ in phosphorus. Is this a problem for your garden plants; for your local water body; for your self esteem? What should you do about it? What form of phosphorus is your soil test measuring? (10 pts)

The reason for excess phosphorus in the soil might be caused by the lack of mineral imbalance in the soil. The uptake of excess P from the soil interferes with uptake of other minerals such as iron, zinc, etc. The application of manure in the soil led to over fertilization hence unnecessary application of P. This usually happens with applying hydrogen to plants and carrying out irrigation using acidified water. Before taking any action, it is essential to carry out the phosphorus test to get the accurate measurement of soil and supply of P to the soil solution. After determining the P measure, it is essential to come up with an effective way of controlling its impact (Khan et al., 2018). I know it would be challenging to determine the amount of P in the soil, but I would adopt the most efficient testing method to forecast the fertilizer requirements in plants. There are different types of test to be used in this case, and each type is based on the type of soil and crops. I would use the P soil test to assess the soil capacity in supplying P in the soil solution. This test does not test or measure the amount of P supplied in the soil. This is because the amount of P in the soil is less than the total amount.

9. What is the basis for your group project, i.e. why is this research being done? How will your results be useful? (10 pts)

10. In your own words, explain the new ‘model’ for the molecular structure of soil organic matter (e.g. as detailed in Lehmann and Kleber, 2015—available on Blackboard under readings). What types of bonding keeps it together? Does this model make more sense than the older humic/fulvic acid model? Which model do you believe is correct and why? (15 pts)

According to Lehmann, soil aggregation plays an imperative role in the formation of soil organic carbon. This is important in the formation and development of soil structure; the soil aggregate gives the soil its physical protection for the organic matter as well as the formation of microhabitats and other microorganisms. Additionally, the colloid capacity to enhance transportation and control in addition to the retention of carbon. The mobilization of ecosystem changes depending on the environmental factors such as organic agitations, hydrological etc. Kleber also gave out organic information formation and its impact on the soil. One of an element that connects these two models is soil organism and factors affecting them.

11. As an expert, you have been asked to testify on the benefits of soil organic matter before a House subcommittee. Summarize the main points you would make and how you would support them with soil chemistry (i.e. what we’ve learned in this course). (15 pts)

The course was very informative. I have learned many things about organic matter and its significance to plants and soil. In noting that organic matter helps in increasing the biological action in the soil. For instance, hummus and clay particles help in ensuring that there is free circulation of air in the soil and minimizing the amount of nutrients leakage in the soil. I also noted that micro-organisms use the organic matter as food and breaking down of soil particles. This is one of the ways of enhancing soil structure, water retention, and water infiltration. The lesson also presented information about the reduction of soil erosion. Moreover, a high level of organic matter improves the soil temperature hence easy plant growth as well as moderating the soil PH.

12. As an expert, you have been asked to explain how soils can be used to sequester carbon and help ameliorate climate change. You audience is an intro soils course. Summarize your main points and discuss the different ways that carbon can be stabilized. Include a discussion of your views on soil organic matter recalcitrance. (15 pts)

As an expert in this field, I will have to explain the presence of carbon. It is found in all living organisms, and it is part of our life. Carbon can be found in most forms for instance in organic matter, biomass and carbon IV oxide in water or atmosphere. Carbon can be sequestered by process of photosynthesis; in this process plants take in some. Animals eat the rest of the carbon found in the plant tissue; this reduces the amount of carbon in soil.

13. Extra credit. You need to prepare a synthetic ‘acid rain’ solution that is equal molarity sulfate and nitrate. You have solutions of 1.00 molar HNO3 and 1.00 molar H2SO4. How many mLs of each would you dilute to 1 liter to create a pH 4.0 solution? Show your work. (5 pts)