Characterizing Livestock Production in Portuguese Sown Rainfed Grasslands: Applying the Inverse Approach to a Process-Based Model

Tiago Morais,Tiago Domingos,Ricardo Teixeira,Nuno Rodrigues

doi:10.3390/su10124437

Tiago Morais, Tiago Domingos + Show 2 more

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https://doi.org/10.3390/su10124437

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Abstract

Grasslands are a crucial resource that supports animal grazing and provides other ecosystem services. We estimated the main properties of Portuguese sown biodiverse permanent pastures rich in legumes (SBP) starting from measured data for soil organic carbon (SOC) and using the Rothamsted Carbon Model. Starting from a dataset of SOC, aboveground production (AGP) and stocking rates (SR) in SBP, we used an inverse approach to estimate root to shoot (RS) ratios, livestock dung (LD), livestock intake (LI) and the ratio between easily decomposable and resistant plant material. Results for the best fit show that AGP and belowground productivity is approximately the same (RS is equal to 0.96). Animals consume 61% of the AGP, which is within the acceptable range of protein and energy intake. Carbon inputs from dung are also within the range found in the literature (1.53 t C/livestock unit). Inputs from litter are equally distributed between decomposable and resistant material. We applied these parameters in RothC for a dataset from different sites that only comprises SOC to calculate AGP and SR. AGP and SR were consistently lower in this case, because these pastures did not receive adequate technical support. These results highlight the mechanisms for carbon sequestration in SBP.

Highlights

Livestock provide an important share of human nutrition, contributing to feeding the world population [1]
root to shoot (RS) ratio, livestock dung (LD), livestock intake (LI) and decomposable plant material (DPM)/resistant plant material (RPM) ratio, where each iteration corresponds to a different initial set of parameters given as input for the optimization process to run
When we used the optimum parameters to simulate soil organic carbon (SOC) dynamics in the original farms, we found that the model overestimates measured SOC by 1 ± 1.5 t C/ha

Summary

Introduction

Livestock provide an important share of human nutrition, contributing to feeding the world population [1]. Carbon sequestration provides climate regulation and mitigation services [5]. These are a relevant contribution for the sustainability of livestock production systems, where they are a countereffect to the large greenhouse gas emissions from enteric fermentation, manure management of production of feeds [6,7]. The pace and saturation of carbon storage in soils depends on the floristic composition and soil properties of grasslands, and their quality differs significantly considering grass and grazing management practices, climatic and site conditions, as well as presence or absence of tree cover [8,9]

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