Open Access
Tillage effects on soil quality after three years of irrigation in Northern Spain
(MDPI, 2017) Apesteguía Barberena, Marcos; Virto Quecedo, Íñigo; Orcaray Echeverría, Luis; Bescansa Miquel, Paloma; Enrique Martín, Alberto; Imaz Gurruchaga, María José; Karlen, Douglas; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Irrigation is being initiated on large areas of traditionally rainfed land to meet increasing global demand for food, feed, fiber and fuel. However, the consequences of this transition on soil quality (SQ) have scarcely been studied. Therefore, after previously identifying the most tillage-sensitive SQ indicators under long-term rainfed conditions, conversion of a research site on a Haplic Calcisol in Navarre, in northeast Spain provided an ideal location to reevaluate those SQ indicators after three years of irrigated management. The Soil Management Assessment Framework (SMAF) was used to test our hypothesis that adopting irrigation could change the sensitivity and importance of non-irrigated SQ indicators. Several soil physical, chemical, and biological indicators along with crop yields were used to evaluate SQ three years after initiating irrigation on a long-term conventional tillage (CT), minimum tillage (MT) and no-tillage (NT) study where either barley (Hordeum vulgare L.) or wheat (Triticum aestivum L.) was being grown. The results confirmed our hypothesis that irrigation would change the relative importance of various SQ indicators and suggested that some SMAF algorithms, such as those used to assess bulk density, needed to be recalibrated for these Mediterranean soils.
Open Access
Under-vine cover crops: Impact on physical and biological soil proprieties in an irrigated Mediterranean vineyard
(Elsevier, 2023) Abad Zamora, Francisco Javier; Marín Ederra, Diana; Imbert Rodríguez, Bosco; Virto Quecedo, Íñigo; Garbisu Crespo, Carlos; Santesteban García, Gonzaga; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura; Ciencias; Zientziak; Gobierno de Navarra / Nafarroako Gobernua, 0011-1383-2022-000000
We present a novel approach to harmonic disturbance removal in single-channel wind turbine acceleration data by means of time-variant signal modeling. Harmonics are conceived as a set of quasi-stationary sinusoids whose instantaneous amplitude and phase vary slowly and continuously in a short-time analysis frame. These non-stationarities in the harmonics are modeled by low-degree time polynomials whose coefficients capture the instantaneous dynamics of the corresponding waveforms. The model is linear-in-parameters and is straightforwardly estimated by the linear least-squares algorithm. Estimates from contiguous analysis frames are further combined in the overlap-add fashion in order to yield overall harmonic disturbance waveform and its removal from the data. The algorithm performance analysis, in terms of input parameter sensitivity and comparison against three state-of-the-art methods, has been carried out with synthetic signals. Further model validation has been accomplished through real-world signals and stabilization diagrams, which are a standard tool for determining modal parameters in many timedomain modal identification algorithms. The results show that the proposed method exhibits a robust performance particularly when only the average rotational speed is known, as is often the case for stand-alone sensors which typically carry out data pre-processing for structural health monitoring. Moreover, for real-world analysis scenarios, we show that the proposed method delivers consistent vibration mode parameter estimates, which can straightforwardly be used for structural health monitoring.
Open Access
Additional carbon inputs to reach a 4 per 1000 objective in Europe: feasibility and projected impacts of climate change based on century simulations of long-term arable experiments
(Copernicus, 2021) Bruni, Elisa; Guenet, Bertrand; Huang, Yuanyuan; Clivot, Hugues; Virto Quecedo, Íñigo; Farina, Roberta; Kätterer, Thomas; Ciais, Philippe; Martin, Manuel; Chenu, Claire; Ciencias; Zientziak
The 4 per 1000 initiative aims to maintain and increase soil organic carbon (SOC) stocks for soil fertility, food security, and climate change adaptation and mitigation. One way to enhance SOC stocks is to increase carbon (C) inputs to the soil. In this study, we assessed the amount of organic C inputs that are necessary to reach a target of SOC stocks increase by 4‰yr-1 on average, for 30 years, at 14 long-term agricultural sites in Europe. We used the Century model to simulate SOC stocks and assessed the required level of additional C inputs to reach the 4 per 1000 target at these sites. Then, we analyzed how this would change under future scenarios of temperature increase. Initial stocks were simulated assuming steady state. We compared modeled C inputs to different treatments of additional C used on the experimental sites (exogenous organic matter addition and one treatment with different crop rotations). The model was calibrated to fit the control plots, i.e. conventional management without additional C inputs from exogenous organic matter or changes in crop rotations, and was able to reproduce the SOC stock dynamics. We found that, on average among the selected experimental sites, annual C inputs will have to increase by 43.15±5.05%, which is 0.66±0.23MgCha-1yr-1 (mean±standard error), with respect to the initial C inputs in the control treatment. The simulated amount of C input required to reach the 4‰ SOC increase was lower than or similar to the amount of C input actually used in the majority of the additional C input treatments of the long-term experiments. However, Century might be overestimating the effect of additional C inputs on SOC stocks. At the experimental sites, we found that treatments with additional C inputs were increasing by 0.25% on average. This means that the C inputs required to reach the 4 per 1000 target might actually be much higher. Furthermore, we estimated that annual C inputs will have to increase even more due to climate warming, that is 54% more and 120% more for a 1 and 5C warming, respectively. We showed that modeled C inputs required to reach the target depended linearly on the initial SOC stocks, raising concern on the feasibility of the 4 per 1000 objective in soils with a higher potential contribution to C sequestration, that is soils with high SOC stocks. Our work highlights the challenge of increasing SOC stocks at a large scale and in a future with a warmer climate.

Virto Quecedo, Íñigo

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