1. Discussion – Using your own figures, answer the questions below. Responses sh
ID: 105338 • Letter: 1
Question
1. Discussion – Using your own figures, answer the questions below. Responses should double spaced and well organized with a neat, professional appearance. Grammar and spelling MUST BE correct:
a. In one or two paragraphs, explain how lime effectiveness is influenced by lime chemistry (think about the chemical formula) (10 pts)
b. In one or two paragraphs, explain how lime effectiveness is influenced by lime particle size (10 pts)
c. In one or two paragraphs, explain how lime rate is influenced by soil texture (10 pts)
Explanation / Answer
1 a. Influence of lime chemistry in the Effectiveness of lime
The effectiveness of a liming material is dependent upon its neutralising value, the fineness of grinding, reactivity and the relative hardness of the parent rock.Limes vary in their ability to reduce acidity. Effective Neutralising value (ENV) is a measure of the effectiveness of the neutralising substances. So, the higher the ENV, the more effective the lime will be at increasing pH.
Liming materials and its Effectiveness
1. Agricultural lime or calcium carbonate
Agricultural limestines found in the limestone rock deposits with calcium carbonate (CaCO3) contents ranging from 48% to 97%.The calcium content will be 30 to 40%. This is the most commonly used liming material in the agricultural lands. It consists of limestone crushed to a fine powder and is usually the cheapest material for correcting soil acidity.
2. Burnt lime or calcium oxide
This is also known as quicklime. The Burnt lime is extracted by heating limestone to drive off carbon dioxide. It is more concentrated and caustic than agricultural lime and unpleasant to handle, so is rarely used in agriculture.It is a faster-acting lime and hence used only in for horticulture.
3. Hydrated lime or calcium hydroxide
This is made by treating burnt lime with water, and is used mainly in mortar and concrete. It is more expensive than agricultural lime. This has a higher neutralising value than agricultural lime and hence not used in agricultural lands.
4. Dolomite
Dolomite is a mixture of calcium carbonate and magnesium carbonate.Good quality dolomite has a neutralising value of 95–98, and contains 22% calcium and 12% magnesium.Dolomite is frequently used in horticulture as a source of magnesium and very rarely in pastures.
5. Lime and cement kiln dusts
Lime kiln dust is the very fine dust produced by kilns used to burn lime. It contains both limestone and burnt lime. Cement kiln dust has similar properties, plus it can contain significant amounts of potassium (commonly 3% to 5%).
1 B. Influence of llime particle in the Effectiveness of lime
The particle size of the lime has an influence on the effectiveness of the lime. Decreasing the lime particle sizes will increase lime efficiency. When the average particle size of a given weight of lime is decreased to a finer size, it actually increasesthe total surface area and therefore increases therate at which lime will dissolve. To obtain a realistic comparison of the effectiveness of different sized lime particles, limestone will crushed to meet the specification of different sieve sizes.
From various research works, it is found that the finer lime have very high pH value and the coarse lime are ineffective when compared to the fine lime. Soft lime with very less particle size are likely to dissolve more quicker, while the larger lime particles impart a longer benefit because they dissolve more slowly. Where the soil acidity is usually very low, smaller lime particles will be more effective on the soils.
1 C Soil texture and lime rate
Soil acidity can reduce crop production by directly affecting roots and changing the availability of essential nutrients. Adding lime can alter the soli acidity and can raise soil pH to the ideal range for crop production, and increase the levels of calcium or magnesium ions.
Soil texture is an important soil characteristic that drives crop production and field management. The textural class of a soil is determined by the percentage of sand, silt, and clay. The amount of lime needed to increase soil pH varies with cation exchange capacity (CEC), which is a measure of cations attracted to soil particles. Soil CEC is related to a combination of factors, including soil texture, type of clay present, and soil organic matter content. As clay and organic matter content increase, CEC increases. In turn, the amount of hydrogen ions (H) that need to be neutralized by lime also increases. When soils in the same field differ greatly in texture , they will have different liming requirements.
University of Nebraska lime recommends lime rate based on raising soil pH to 6.5. The below table gives the CEC value and pH value of various soil textures determined in the research.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.