What does it do?
This model generates graphic outputs illustrating the interaction of E (edaphic) nutrient (soil), (T) temperature and (W) water balance on biomass production in a natural ecosystem. The first graph shows the general relationship of diminishing marginal returns to an increasing single input as other inputs remain fixed. In the other four examples the range of T and W is 1 to 10 with E having the values: 1,5,10 and 20 respectively. In the last case T & W are limiting. |
Information used
Input data are the edaphic (E), temperature (T) and water (W) axes in a particular location. Measured in terms of available nutrients (fertility), temperature in oC and water availability (measured in terms of water deficit).
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Formulae
General form of the EWT Complex relationship to biomass
B = (E*W*T)/(E*W + E*T + W*T)
Where:
B is biomass output; E is the Edaphic axis2 (mainly nutrients); W is the Water axis and, T is the Temperature axis.
More elaborate crop specific relationships require coefficients which relate the phenotypic biomass response of the genotype of the plant concerned to the relevant input factors. The Edaphic axis contribution to the relationship varies according to soil particulate make-up and structure as well as other factors.
2 axis: this term is applied because each EWT component is not simply a single uni-morphic variable but is a result of other interactions. For example water can take the form of liquid as well as gaseous and humidity fractions and temperature varies according to location such as soil, ambient and as a result of microclimatic factors such as shading effects of other plants, slope and relative location.
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Scripts & code details
The distinction in this mdel is the use of the DScript graphic capabilities.
| Credits
Design: SEEL (2007) used in modified forms to establish ecosystem stability measures as well as to generate farm profitability maps for ISEE 2007-2008 Seminar "Fundamental relationships in the feedstocks, fibres & food domain"
References: "A three-dimensional production function", McNeill H.W., Food Research Institute, TP in Trade & Development, Stanford, 1968 and "Computer-based simulation of 3DPF", McNeill H.W. & Jino M., CNAE, National Research Council, Brazil, 1969.
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