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FAQ
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• Where can I find the meaning the exported variables? (JV)
A short explanation of the variables, including dimension, is displayed when scrolling through the list of "available fields" on the "Export Results" form of the Data Processing Module (DPM).
This list might not be complete in older versions (< v. 3.0) of the software.
- An updated list of variables can be found here
Note that this list does not contain the dimension of the variables as this depends on the "conversion settings" for a.o. weight and area in the DPM.
• Livestock model - Excretion model and conversion factors (JV)
The conversion fractions indicate the amounts of DM, N,P,K that are returned in excreted manure.
• ETQF - Flows from STOCK to HH (JV)
Flows from stock to household are often not monitored but can be entered using the DEM. The model does not simulate these flows.
• ETQF -How is irrigation dealt with? (JV)
There is no need to mark Irrigation water as a Special Flow. The product 'Irrigation water', as included in the OtherInputs table, is automatically classified as 'ptIrrigation' and then (optionally) used in the leaching calculations.
Note that Irrigation water has to be recorded in one of the units of measurement that can be converted to kg!. Units such as 'kg', 'l', 'm3', 'ton' are therefore allowed but 'hr', 'mm', 'times', 'acre' are not.
• ETQF - How are green manure and burning handled? (JV)
These flows are marked as 'SpecialFlow' in form 120 where they should be recorded as flows originating from a specific PPU. For each of these flows a 'return fraction' is applied per nutrient which are entered in table SpecialFlows of the BGDB. This return fraction indicates the nutrients that return to the PPU when applied. It is set to 1 for most flows except for Burning of N which is 0.2 (20%).
The destination of burning flows is made equal to the source automatically by the DPM. Losses to the environment are later calculated in OUT4-burning.
The quantity of material processed has to be estimated as accurately as possible for these flows.
• HTQF -Precipitation range for transfer functions (JV)
Range for leaching and gaseous losses formulas Smaling (OUT3 and OUT4) : 600-1500 mm.
• Livestock model - Determination of the 'grazed product' (JV)
Determination of grazed product at PPU level:
1 - if a unit is a PPU then all the crops on the PPU are scanned* for a material labeled 'CanBeGrazed'.
2 - if no CanBeGrazed material is found then the default product 'BROWSINGMATERIAL' from form 'Options' is used.
* Gets the first crop product that belongs to the Crop and that is marked 'CanBeGrazed'.
• Livestock model - N-content used for the determination of the 'desired' GrazingUptakePerUnit (JV)
The N-content used is that of the 'grazed product' that is determined for each PPU. The weighing factor based on N-content is NOT weighed!
• Livestock model -Use of Animal Type specific data at SPU level (JV)
FrUptakeDay/Night, FrExcretionDay/Night, frConversionBulk, frConversionNPK at Animal Type level are scaled up to SPU level by weighing them according the number of animals of each Animal Type group.
• BGDB - Milk; estimates for Dm, N, P and K (JV)
Older versions of the BGDB contain an error concerning the estimated dry matter and nutrient contents of milk. More realistic values, based on 1 kg of dry matter, are:
- DM : 0.013 (1.3%)
- N : 0.385 (38.5%)
- P : 0.069 (6.9%)
- K : 0.115 (11.5%)
- Energy required for production of 1 kg of milk (1.3% DM) is 3.2 MJ
This has been corrected in databases of version 1.1 and higher.
• Livestock model - Calculation of energy used for traction (JV)
For the calculation of the energy requirements for traction the traction should always be recorded in animal x hours in form 220. The energy for the traction product should be recorded in the BGDB in MJ/hr.
• Livestock model - Growth gains (JV)
Are expressed as GrowthNutr *NumAnimals * GrowthRate * DaysPerMonth. GrowthRate as kg fresh/day.
• Livestock model - Nutrient contents of body tissue (JV)
All nutrient contents that relate directly to animal body tissue are expressed in kg / kg fresh weight.
• Livestock model - Remaining grazing requirements after meeting constraints. (JV)
These are not resolved. This would suggest a accuracy that is more than realistic (HvK/JV).
• Financial - VALUE & CASH: Use of product prices (JV)
VALUE is the monetary value of a flow that is calculated with the average "price per kg" as stored in the BGDB (use BDM to manage these prices).
CASH is the monetary value of a flow calculated with the "price per measure" as actually monitored and registered in the DEM.
If no "price per measure"is entered the "average price per kg" from the BGDB will be used. Note that a "price per measure" of 0 (zero) is interpreted as 'for free' in the cash calculations.
• Financial - Earnings from land rented out (JV)
Earnings from land rented out are based on rent recorded in form 5 for land rented-out (no longer recorded in form 510!)
This value is used in NetFarmIncome, FarmNetCashFlow and HHNetCashFlow. Land rented-in is used in the same parameters but then as a negative term.
Land rented-out is not included in the calculation of TotalAreaFSU (as used for calculation of values at farm level). Land rented-in is added to the total area.
• Misc - Age of household members (JV)
The ages of household members (used for the calculation of the number of labour and consumer units) are calculated as the start year (i.e. the value entered as START_YEAR under model options) minus the Year Of Birth as entered in Form 2 of the inventory.
• Misc - When is a PPU supposed to be fallow? (JV)
A PPU is assumed to be fallow when the first crop is a crop that is supposed to be fallow. The remaining crops do not count for fallow at PPU level.
A crop is supposed to be fallow when its CropType is either "Natural pastures, ranges", "Trees and shrubs" or "Fallow" (CropTypeID s 67,68,69 which are hard coded).
• Financial - Direct Bonuses and Stock Bonus (JV)
The calculations of farm income are based on average prices (as in background db) as many products are often not sold but consumed by the household.
The bonuses represent income that the farmers earns from sales against prices that are better than the average prices or purchases against prices that are lower than the average prices.
calculation rules:
for each flow: Bonus = Cash - Value
EXT -> PPU/SPU/RU: Trade bonus = Trade bonus - Bonus
PPU/SPU/RU -> EXT: Trade bonus = Trade bonus + Bonus
EXT -> STOCK: Stock bonus = Stock bonus - Bonus
STOCK -> EXT: Stock bonus = Stock bonus + Bonus
Note that the bonuses can also be negative in case sales are made against prices lower than average or purchases are made against prces higher than average.
• Livestock model - Calculation of activity energy (JV)
Energy required for activity is assumed to be zero for on-farm units and is calculated only for time spent outside the farm (EXT).
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