Building Variable Productivity Ratios for Improving Large Scale Spatially Explicit Pruning Biomass Assessments

Daniel García-Galindo,Fernando Cay Villa-Ceballos,Arkadiusz Dyjakon

doi:10.3390/en12050957

Abstract

Biomass assessments of agro–residues performed at large geographical scales generally base calculations on single constant pruning productivity ratios (RSRs). Reliability of biomass assessments shall be improved if RSRs respond to prevailing regional crop growing conditions. The present paper describes the methodology applied to create geographically varying pruning RSR ratios–tons of dry matter per hectare—for five crop groups: vineyard, olive, fruit species, citrus and dry fruits. A newly created database containing 230 records–from seven EU28 countries—is submitted to statistical analysis. Results reveal that agro-climatic conditions are able to explain a not negligible share of the pruning productivity as dependent variable. Subsequent regression analysis provides two equations—for vineyard and citrus—achieving a reasonable good fitting (R2 0.18 and 0.42 respectively) between RSR and the agroclimatic variables. Analysis of olive, fruit species and dry fruits scatter and whisker plots were useful for zoning and inducing ramp functions. A Geographical Information System (GIS) was utilised to apply the functions to the agroclimatic raster coverages in order to obtain RSR raster grids. Zonal statistic procedures applied by European regional units (NUTs0, NUTs2, NUTs3) provide a specific crop RSR ratio per administrative unit as a principal output of the present work.

Highlights

Biomass assessments in large scales have been object of multiple research efforts for providing estimations and scenarios of biomass availability
The present paper describes transparently a new methodology scoped to obtain pruning biomass productivity ratios—either Residue to Surface Ratio (RSR) or Residue to Product Ratio (RPR)—tailored to local regional prevailing crop growing conditions
The present work is inspired by the method applied by Scarlat and co-workers [9,12] to obtain a set of adjusted curves correlating the productivity of agricultural herbaceous residues (RPR expressed as kg of residue per kg of grain) with the crop yields

Summary

Introduction

Biomass assessments in large (global, regional or national) scales have been object of multiple research efforts for providing estimations and scenarios of biomass availability. The objective of large-scale biomass estimations is usually to provide an overview of biomass availability as first step for preparing biomass action plans, or regional strategies for promoting new biomass supplies. In such large scale works, agricultural residues assessments have usually started from agricultural statistics and yearbooks (global, regional, national and subnational data). Among the variety of figures presented in agricultural databases and yearbooks, the assessment of agricultural residues have usually based on two records: either (a) the cropped area and, or (b) the crop production Starting from these two variables, the methods applied usually calculate the biomass

Methods

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Discussion

Conclusion