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| 1 acre=______hectares (ha) |
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| 1 hectare (ha) = ______ m2 |
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| 1 hectare (ha)=______acres |
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EC = electrical conductivity (mmhos/cm)
(measures salt content in saturated extract) |
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| ESP = exchangeable Sodium Percentage |
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F = -De A dC/dx
F=flow
A=area of diffusion
C=c'tration
x=distance |
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| Freundlich equation for measuring P adsorption |
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q = acb
where...
q = mmol P/kg soil
c = mmol P/L solution
What's a? What's b? |
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| If pH = 5, [H+] = ______moles/L (M) |
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| If pH = 7, [H+] = ______moles/L (M) |
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| Langmuir equation for measuring P adsorption |
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q = (abc)/(1 + ac)
where...
q = mmol P/kg soil
c = mmol P/L solution
What's a? What's b? |
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| normalized difference vegetative index |
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| Q10 of S mineralization/immobilization |
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| another way to express meq/100g |
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cmol(+)/kg
more accepted nowadays |
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| how %ECCE factors into decisions |
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| Select material with least cost per unit of % ECCE |
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| how fertilizer ratio is determined |
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| (fertilizer grade) / (lowest grade (LG)) |
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| how to Estimate Nutrient Movement by Mass Flow |
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| (Concentration of nutrients in soil solution) X (Volume of water transpired by the plant) |
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| how to calculate % Effective Calcium Carbonate (%ECC) |
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| % ECCE = [% CCE x % Fineness Factor]/100 |
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| how to calculate % saturation of a particular ion in CEC |
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| (meq of that ion/100g)/(total CEC)=% saturation for that element |
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| how to calculate CEC based on the concentration of NH4+ in the extracted solution |
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| (mg NH4+/L) x (L of solution) x (meq/mg NH4+) x (1/g soil analyzed) x (100 g soil/100 g soil) = meq/100 g |
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| how to calculate CEC of specific ion based on concentration in solution |
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| mg/L x ((L solution/g soil)/(mg/meq)) x (100/100) |
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| how to calculate Calcium Carbonate Equivalent (CCE) |
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| CCE = (Eq. Wt. CaCO3)/(Eq. Wt. Material) x 100 |
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| ESP = (Na+ in CEC/Total CEC) x 100 |
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| how to calculate LBC30 in meq/kg soil/pH unit |
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| (mL of solution added) x (N of solution added, expressed in meq/mL) x (1/kg soil) x (1/(change in pH)) = meq/kg soil/pH unit |
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| how to calculate LBC30 in mg/kg soil/pH unit |
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| LBC30 = (N, expressed in meq/kg) x (mg/meq) = mg/kg soil/pH unit |
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| how to calculate N recommendation using the yield goal approach |
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| N fert = N uptake + N losses - N soil - N min from OM - N min from residues - N from manures |
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| how to calculate N uptake |
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| N uptake = yield goal x N/Unit Yield |
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| NDVI = (% near infrared - % visible)/(% near infrared + % visible) |
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| how to calculate P and K recommendation using the fertilize the soil approach when it's below optimum |
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| total recommendation = crop removal + buildup |
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| Q10=(rate of rxn at temp T)/(rate of same rxn at (T-10°C)) |
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| -log[H+]=log(1/[H+])
that is, the one on the left is the negative log and the one on the right is the antilog |
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| how to calculate available P |
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| Available P = Water-soluble + Citrate-soluble |
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| how to calculate buffering capacity (BC) |
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Definition
BC=ΔQ/ΔI
Q=adsorbed (quantity)
I=solution (intensity) |
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| how to calculate diffusion coefficient (De) |
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Definition
De = (Dw) x (Θ) x (1/T) x (1/BC)
where
Dw = Diff. Coeff in water
Θ = vol. water content
T = tortuosity factor
BC = buffering capacity |
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| how to calculate equivalent water pH |
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| Equivalent water pH = pH in 0.01 M CaCl2 + 0.6 |
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| how to calculate equivalent weight |
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| Equivalent weight = ((weight of one mole)/valence) |
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| how to calculate how many moles of N are mineralized per ha |
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| (73.4 kg N/ha) x (1000 g N/kg N) x (1 mol N/14 g) = (5243 mol N/ha) |
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| how to calculate how much the pH would increase due to N mineralization |
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| ((meq/kg soil) x (kg soil))/(meq buffering capacity) = pH units of increase |
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| how to calculate lb C/A assimilated |
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| (lb C/A in residue) x (%efficiency of bacteria) = lb C/A |
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| how to calculate lb C/A in the residue |
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| (lb residue/A) x (%C as decimal) = lb C/A |
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| how to calculate lb N/A assimilated |
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| lb C/A x (1/(C:N ratio of bacteria)) = 101 lb N/A assimilated |
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| how to calculate lb N/A in the residue |
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(lb C/A in residue) x (1/(C:N ratio of residue)) = lb N/A in residue
if the C:N ratio is 58:1, (1/(C:N ratio))=1/58 |
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| how to calculate lb N/A that needs to be immobilized |
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| (lb N/A assimilated) - (39.8 lb N/A in residue) = lb N/A needs to be immobilized from soil |
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| how to calculate lime requirement (LR) for 15cm (6in) depth, lb/A |
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| LR = LBCEq x (Target pH - Initial pH) x 2 |
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| how to calculate lime requirement (LR) for 15cm (8in) depth, lb/A |
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| LR = LBCEq x (Target pH - Initial pH) x 8/6 |
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| how to calculate mass soil per ha to a specific depth |
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| (m3/ha) x (kg/m3) = (kg/ha) |
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| how to calculate meq of H+ produced per kg of soil. |
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(mol N/ha) x (1000 mmol N/mol N) x (2 mmol H+/mmol N) = meq H+
then
(meq H+/ha) x (1 ha/kg soil) = (meq H+/kg soil) |
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| how to calculate molarity (M) |
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| molarity=(moles of solute)/(liter of solution) |
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| how to calculate moles of N as NH4+ initially present in the litter. |
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| kg litter/ha x (g N/kg litter) x (1 kg/1000 g) x (1 mol/14 g N) = moles N |
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| how to calculate moles of N nitrified per ha. |
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| Total moles nitrified = Initial + mineralized N = moles of N nitrified per ha |
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| how to calculate normality (N) |
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normality=(equivalents of solute)/(liter of solution)
or
normality=Molarity*Valence |
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| pH = -log10([H+ concentration]) |
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| how to calculate pH decrease |
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| (meq H+/kg soil)/(buffer capacity in meq/kg/ph unit) = pH units |
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| how to calculate pH of a mixture of 2 solutions |
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| (([H+] solution 1)/(L solution 1))+(([H+] solution 2)/(L solution 2))=(([H+])/(L mixture))
then -log([H+])=pH |
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| how to calculate pH of a mixture of solutions w/ different pH |
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| recall that pH=-log10([H+ c'tration])
then find ((V1*[H+1])+(V2*[H+2]))/(V1+V2)
the pH of the mixture is the -log of the answer |
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| how to calculate relative yield |
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| relative yield = Ck yield + yield with fertilizer |
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| how to calculate salt index of N fertilizer |
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| (increase in osmotic potential of fertilizer X)/(increase in osmotic potential of NaNO3) |
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| how to calculate temperature factor (Ft) |
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| how to calculate the # of meq of H+ consumed per kg of soil |
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| (mmol N/ha) x (mmol H+/mmol N) = (mmol H+/ha)
(mmol H+/ha) = (meq H+/ha)
(meq H+/ha) x (1 ha/kg soil) = (meq H+/kg soil) |
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| how to calculate the amount of N in broiler litter that gets mineralized |
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| Nm = (Nf in g N/kg litter)(1-e-k x Ft x Fw x t) + (Ns in g N/kg litter)(1-e-h x Ft x Fw x t) = g N/kg litter
where...
Nm = N mineralized (g N kg-1 broiler litter)
k = rate of mineralization of fast pool,
h = rate of mineralization of slow pool
t = time in days |
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| how to calculate the amount of N that needs to be immobilized from soil |
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| N required – N in residue = N immobilized |
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| how to calculate the amount of a particular compound needed for the desired increase in soil pH, assuming fineness factor is 100% |
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Definition
| first, make sure LBCeq is expressed in meq/kg soil/pH unit
then: (meq/kg soil/pH unit) x (mg/meq) = (mg/kg soil/pH unit)
then: (mg/kg soil/pH unit) x (change in pH) = (mg needed/kg soil)
then convert to lb/A and/or kg/ha |
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| how to calculate the amount of a particular compound needed to decrease the exchangeable sodium percentage (ESP) to the desired ESP |
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Definition
((current meq Na/100g soil) - (current meq Na/100g soil)) x (mg of that particular compound/meq) = (mg of that particular compound/kg soil)
then convert to mg/kg, then to lb/A and/or kg/ha |
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| how to calculate the amount of inorganic N content in the soil (lb N/A) after the bacteria immobilize N from the soil |
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| (initial inorganic N content in lb N/A) – (N immobilized from soil in lb N/A) = 18.8 lb N/A remaining in soil |
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| how to calculate the change in pH due to mineralization of N in broiler litter |
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| 1: calculate the mass of the soil to the specified depth
2: calculate moles of N mineralized
3: calculate how many meq of H+ per kg of soil
4: calculate how much the pH increases |
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| how to calculate the final pH of the soil after all the NH4+ initially present in the litter plus the NH4+ released thru mineralization gets nitrified |
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Definition
| 1: Calculate moles of N as NH4+ initially present in the litter.
2: Calculate moles of N nitrified per ha.
3: Calculate meq of H+ produced per kg of soil.
4: Calculate pH decrease. |
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| how to calculate the minimum average NO3-N concentration in the soil solution during the growing season based on the total uptake of NO3-N |
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Definition
| (kg N/ha) x (1 million mg N/kg N) x (1 ha/L transpired) = mg N/L |
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| how to calculate the number of equivalents applied per hectare |
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Definition
1: convert kg/ha to moles/ha
2: multiply by the valence |
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| how to calculate the number of gallons of N-P-K fertilizer needed per acre using the P value |
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Definition
| 1: (lb P/A) x (100 lb fert/lb P2O5) x 0.4366 = lb fert
2: (lb fert)/(lb/gal) = gal fert |
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| how to calculate the pH of the soil after hydrolysis of urea |
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Definition
1: (meq/kg soil) x (1 pH unit/(BC in meq/kg soil)) = change in pH
2: (initial pH) + (change in pH) = final pH |
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| how to calculate water content factor (Fw) |
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| Fw = ((g H2O)/g soil)/0.3 |
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| how to convert L water/ha to kg N/ha |
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Definition
| (L water/ha) x (mg N/L) x (1 kg N/1million mg N) = (kg N/ha) |
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| how to convert LBC30 into LBCEq when the LBC30 ≤ 250 |
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| LBCEq = (3.6709 x LBC30) - 188.25 |
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| how to convert LBC30 into LBCEq when the LBC30 ≥ 250 |
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| how to convert from % K to % K2O |
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Definition
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| how to convert from % K2O to % K |
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Definition
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| how to convert from P to P2O5 |
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Definition
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| how to convert from P2O5 to P |
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Definition
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| how to convert lbs/acre to kg/ha |
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Definition
| (lbs/acre) x (0.4536kg/lb) x (2.47 acres/ha) = kg/ha |
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| how to convert meq/100g to mg/kg |
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Definition
(meq/100g) x (mmol/meq) x (mg/mmol) = mg/g
then (mg/g) x (1000g/kg) = mg/kg |
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| how to convert pH to [H+] |
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Definition
| pH=X means [H+]=1x10-X mol/L |
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| how to convert ppm to lbs/acre |
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Definition
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| how to convert ppm to mass per unit of liquid volume |
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| how to determine the amount of CaCO3 needed to counteract the pH effect of N fertilizer over the span of a certain number of years |
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Definition
| 1: convert lbs N fertilizer/acre to ppm
2: multiply by the number of years
3: convert ppm N fertilizer to mmol/kg soil
4: multiply mmol N fertilizer by the number of moles of H+ ions generated per mole of N fertilizer to get the number of mmol of H+ ions/kg soil
5: divide the number of moles of H+ by 2 to get the number of mmol of CaCO3 needed per kg soil
6: convert mmol CaCO3/kg soil into mg CaCO3/kg soil, which is ppm CaCO3
7: convert ppm CaCO3 into lbs CaCO3/acre |
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| how to estimate how much inorganic N (lb N/A) would have to be immobilized from the soil by the bacteria in order to completely decompose the crop residue. |
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Definition
1: calculate lb C/A in the residue
2: calculate lb C/A assimilated
3: calculate lb N/A in the residue
4: calculate lb N/A assimilated
5: calculate lb N/A that needs to be immobilized |
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| how to estimate the drop in pH after nitrification of N fertilizer using the buffer capacity (ppm CaCO3/pH unit) |
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Definition
| 1: (ppm CaCO3/pH unit) = (mg CaCO3/kg soil/pH unit)
2: (mg CaCO3/kg soil/pH unit) x (1 meq/50 mg CaCO3) = (meq/kg soil/pH unit)
3: (mg N applied/kg soil) x (mmol/14 mg N) x (mmol H generated in rxn/mmol N) = (meq H/kg soil)
4: (meq H/kg soil) x ((kg soil x pH unit)/(meq CaCO3/kg soil)) = change in pH
5: 6-(change in pH) = final pH |
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| how to figure out how lb/A of a particular compound, such as K2SO4, to increase the saturation of a particular ion, such as K+ |
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Definition
(amount of meq/100g soil that needs to be added) x (mg of the compound/meq) = (mg that particular ion/100g soil)
convert to ppm
convert ppm to lb/A |
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| how to measure the effective CEC of a soil |
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Definition
| 1) saturating the soil with NH4Cl, which replaces all of the exchangeable cations with NH4+
2) removing the excess NH4+ by washing (or leaching the soil)
3) displacing the NH4+ in exchange sites by adding 1 M KCl
4) measuring the concentration of NH4+ in the KCl extract. |
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| how to measure total soluble cations in saline and sodic soils |
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Definition
| Total Soluble Cations (mg/L) = EC x 10 |
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| mmhos=millimhos; the mhos part is ohms spelled backwards, since this is backwards resistance |
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| multiplication factor for mega (M) |
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Definition
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| multiplication factor for micro (μ) |
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| pH at which H2PO4- < HPO42- |
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Definition
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| pH at which H2PO4- > HPO42- |
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Definition
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| pH at which H2PO4- ≈ HPO42- |
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| pH where ammonia volatilization is likely |
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| gravimetric water content, which is g water/g OD soil |
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| the Q10 for most biological rxns and physical rxns |
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Definition
| consistently around 2 for most biological rxns, but physical rxns tend to have higher number |
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| variables measured in saline and sodic soils |
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