Skip to contents

Calculate Crop Yield from NPP

Source: R/analysis_indicators.R
wapor_calc_yield_npp.Rd

Implementation of the FAO WaPOR yield estimation formula based on Net Primary Production (NPP): $$AGBM = \left(AOT \times f_c \times \frac{NPP \times 22.222}{1 - MC}\right) / 1000$$ $$CropYield = HI \times AGBM$$

Usage

wapor_calc_yield_npp(npp_gc_m2, mc, fc, aot, hi)

Arguments

npp_gc_m2

Numeric or SpatRaster. Seasonal sum of NPP in gC/m2.

mc

Numeric. Moisture content (0-1).

fc

Numeric. Light use efficiency correction factor.

aot

Numeric. Above ground over total biomass production ratio.

hi

Numeric. Harvest index.

Value

Numeric or SpatRaster. Crop yield in t/ha.

Details

where:

  • NPP * 22.222 converts gC/m2 to dry matter production (kgDM/ha).

  • 1 / (1 - MC) adjusts dry matter to fresh storage moisture content.

  • AOT is the above-ground over total biomass ratio (e.g. 0.8).

  • fc is the light use efficiency / crop-specific correction factor (typically 1.0).

  • 1000 converts kg/ha to t/ha.

  • HI is the Harvest Index (ratio of economic yield to above-ground biomass).

References

Steduto, P., Hsiao, T. C., Fereres, E., & Raes, D. (2012). Crop yield response to water. FAO Irrigation and Drainage Paper 66. Food and Agriculture Organization of the United Nations, Rome.

Bastiaanssen, W. G. M., & Steduto, P. (2012). The water productivity score (WPS) for irrigated crops: Concept and application. Agricultural Water Management, 108, 119-132.