Understanding Agricultural Chemistry and Soil Fertility
Posted on May 12, 2024 in Chemistry
Chemical, Biological, and Soil Fertility
Agricultural Chemistry Fundamentals
- Studying agricultural chemistry involves:
a) the formation, properties, and transformation of matter
b) the art of cultivating the land
c) the constitution, properties, and processing of materials related to the generation and modification of agricultural products
d) the entire universe. - ________________ considers water as the main food for plants, initiated studies of the plant-soil relationship, and invented the word “Gas”.
a) Von Liebig (1803-1873)
b) H Davy (1813)
c) Boussingalt (1802-1887)
d) Van Helmont (1577-1644). - ____________________ are essential elements for plants.
a) Ti, V, Si, Al
b) N, O, C, S
c) Hg, Pb, Cr, As
d) Re, W, Po, Ba - The future prospects of agricultural chemicals are: _____________________.
a) Soils and their role in water chemistry
b) Minimizing excessive fertilization to transform agriculture
c) Combating soil degradation
d) Phytoremediation of soils
Macronutrients and Micronutrients
- Macronutrients are:
a) Fe, Mn, Cu, Zn, B, Cl, Mo, Ni
b) K, Ca, Mg, Fe, Mn, As
c) C, H, O, N, P, S, K, Ca, Mg
d) C, H, Cu, Zn, Hg, Pb - The negative absorption sites for cation exchange capacity are in:
a) sand, silt, and clay
b) clays and organic matter
c) soil solution
d) sand and humus - The negative charge on organic matter is dependent on the ____________ as this increases, there is greater cation exchange capacity.
a) humus
b) negative charges
c) pH
d) CIC - The basic structures of clays are: ___________.
a) sand
b) kaolinite and illite
c) tetrahedra and octahedra of Si and Mg
d) none of the above - Montmorillonite clay has a(n) ____________ structure with ____________ CIC.
a) 1:1 … … … … … … … 3-15meq/100g
b) 3:1 … … … … … … .. 500 to 750meq/100g
c) 2:1 …………………….. less than 30 meq/100 g
d) 2:1 … … … 80 A150 meq/100g
Soil Chemistry and pH
- The state reached by a reacting mixture, where the speeds towards one direction and the other are equal is:
a) Cap. Intercable. Cat (ICC)
b) Field Capacity
c) chemical equilibrium
d) ionization constant - An acid is:
a) A solution that has an excess of H+.
b) is made up mainly of water.
c) has a very high pH. - A base is:
a) A solution with a pH of 7 or more.
b) A solution that has an excess of OH- ions.
c) A solution with a pH of 7. - Acidic and basic cations are ___________________ _______________________.
a) Ca, Mg, K, Na … … H, Al
b) Fe, Zn, Mn, Si … … H, Al
c) H, Al … …. Fe, Zn, Mn, Si
d) H, Al … … … Ca, Mg, K, Na - If you have a high cation exchange capacity, the buffer capacity to prevent soil acidification is ___________.
a) Low
b) High
c) Average
d) does not affect the acidification - What is the textural class of a soil with 25% clay, 25% silt, and 50% sand?
a) free
b) sandy clay loam
c) sandy frank
d) clay loam - Of the soil characteristics that affect CIC, which of them could move more easily?
a) Bulk density
b) clay
c) Organic matter
d) pH - Most soil cations are at 99% _________________.
a) clays and organic matter
b) soil solution
c) organic matter
d) clay - From the ___________________, we determine whether a plant can develop and what nutrients are most limiting for the development of crops.
a) CIC
b) Texture
c) pH
d) soil organisms - “Life is a constant struggle, not against sin, not against the power of money, not against malicious animal magnetism in humans, but against hydrogen ions.”
a) I disagree
b) might
c) no
d) I agree - Strong acids are _________________________ while weak acids are ___________________.
a) HCl, HClO4, HNO3, H2SO4 readily yields a proton … …. H3COOH, H2CO3, HCN, HF difficulty cede with a proton
b) NaOH, KOH, Ba(OH)2, Ca(OH)2 readily accepts a proton … … NH3 readily yields a proton, C6H5NH2, CH3NH3Cl - Reserve acidity is in _______ while active acidity is in _________.
a) CIC …. Soil solution
b) soil solution … … CIC
c) both
d) None - For questions 21 and 22, see graph:
The nutrients that are more available in acidic pH are:
a) S, K, Mo, P
b) Fe, Zn, Mn, Al
c) B, N, Fe, S
d) Cu, B, S, Mo - The most abundant nutrients in alkaline pH are:
a) Fe, Zn, Mn, Al
b) Cu, B, S, Mo
c) Mo, K, P, Ca, Mg
d) S, K, Mo, P
Soil Organisms and Nutrient Cycling
| Nutrient Cycling | Structure |
|---|
| Microflora (bacteria) | A | b |
| Microfauna | c | d |
| Mesofauna | D | C |
| Macrofauna | B | |
- a) They break down organic matter, mineralize and immobilize nutrients
- b) fragmenting plant tissues
- c) Provide for fungal and bacterial populations
- d) Provide for smaller populations, fragmented plant tissues
| Structure |
|---|
| a | Mix mineral soil with organic matter and create pores, addition of organic matter (excreta) |
| b | Cohesion aggregate, hyphae of the fungus |
| c | Add organic matter (excreta), create pores |
| d | Indirectly affect structure |
- A low carbon nitrogen (C/N) ratio means:
a) Microbes require less external N to decompose waste.
b) Microbes need more external N to decompose waste.
c) External microbes need nitrogen to decompose waste.
d) None of the above. - Which of the following has the highest C/N ratio?
a) Alfalfa
b) Wheat straw
c) manure
d) sawdust - The law that states that crop yield depends on the most limiting factor is the law of:
a) maximum
b) minimum
c) decreasing returns
d) income superfluous - This law operates when there are limiting factors. The fewer the limiting factors, the greater the crop yields.
a) maximum
b) minimum
c) decreasing returns
d) income superfluous
