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Ndecide: exponential reponse curve for predicting response of crop yield and (optionally) net return to nitrogen application rate, parameterised by:
- yield potential
- starting nitrogen in soil
- efficiency coefficient for soil nitrogen
- efficiency coefficient for applied nitrogen
- (optional) crop price
- (optional) nitrogen cost
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Pdecide: exponential reponse curve for predicting response of crop yield and (optionally) net return to phosphorus application rate, parameterised by:
- yield potential
- starting phosphorus in soil
- efficiency coefficient for soil phosphorus
- efficiency coefficient for applied phosphorus
- (optional) crop price
- (optional) phosphorus cost
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NPdecide: combined Ndecide and Pdecide models, assuming no NP interaction. The NPdecide model is described in detail in Robertson, M. J., Lyle, G and Bowden J. W. (2008), ' Within-field variability of wheat yield and economic implications for spatially variable nutrient management', Field Crops Research, Vol 105(3), pp 211-220.
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Select Your Nitrogen (SYN): a weekly time-step simulation model for predicting response of crop yield and net return to nitrogen applications, taking into account:
- paddock history and estimated residual organic nitrogen in the soil
- timing and type of up to three nitrogen fertiliser applications
- leaching of nitrogen due to rainfall and the movement of due to downward movement of the wetting front
- soil type
- amount of organic carbon in the soil
- crop type, crop price and yield potential
Documentation for the original NPdecide too is provided as part of this package: https://github.com/fionahevans/Ragronomy/blob/master/inst/doc/NPDECIDE%20-%20Users%20Manual.pdf.
This package uses a Javascript version of Select Your Nitrogen (SYN) that is linked to R using the V8 package, see: https://cran.r-project.org/web/packages/V8/vignettes/v8_intro.html. The Javascript code was created using the original spreadsheet version of the model, available from the Western Australian Department of Primary Industries and Regional Development, https://www.agric.wa.gov.au/soils/soils-decision-support-tools. The only documentation for the model and spreadsheet tool is in the form of the Users Manual, provided as part of this package: https://github.com/fionahevans/Ragronomy/blob/master/inst/doc/Select%20Your%20Nitrogen%20Users%20Manual.pdf.