Preface to the special issue on biohydrology dedicated to the memory of Dr. Louis W. Dekker

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Contribution of systems thinking and complex adaptive system attributes to sustainable food production: Example from a climate-smart village

Climate-smart agriculture (CSA) conceptually has the potential to contribute to the sustainable development goals of achieving zero hunger, reducing land degradation, eliminating poverty, tackling climate change, and promoting gender equality. The scaling-up needed to achieve goals of CSA represents a challenge, as it entails understanding synergies between often opposing socioeconomic and environmental priorities and trade-offs over temporal and spatial scales. In this paper, we tested new approaches to support scaling-up of sustainable food production through investigating the contribution of systems thinking as a conceptual approach and complex adaptive system (CAS) attributes as a framework for analysis of CSA. This was done through examining (i) to what extent CSA represents a CAS and (ii) what contribution systems thinking and CAS attributes can make to understanding and scaling-up sustainable food production systems through CSA. The CSA situation was conceptualized through systems thinking sessions with women farmers in the climate-smart village (CSV) of Doggoh-Jirapa, northern Ghana, and was guided by the Distinctions, Systems, Relationships and Perspectives (DSRP) framework. Systems thinking, and CAS attributes provide system-wide understanding of elements, dynamics and trade-offs over temporal and spatial scale in selected agri-food systems. As such it could aid horizontal and vertical scaling-up by informing policy developoment and selection of a context-specific portfolio of technologies and practices at landscape and farm levels to achieve synergies between goals. In this study, systems thinking enabled women farmers in the CSV to identify income-generating and tree planting activities, with desirable simultaneous system-wide impact. The paper calls for further testing of tools, approaches, and methods that enable dynamic systems thinking to inform scaling-up efforts, while embracing the transdisciplinary nature and complexity of CSA as a constituent of the food production system

Wind erosion processes and related glyphosate transport in the loess pampean region of Córdoba province, Argentina

The results of this experiment will provide: Insight on glyphosate and AMPA concentrations in wind-eroded sediment; Valuable information on the losses of glyphosate and AMPA to off-site environments due to wind erosion; A strong contribution to the Argentinean decision makers, stakeholders and the international community in the knowledge of glyphosate/AMPA transport by wind erosion, and its potential impact to the environment and human health.Fil: Bento, Célia P. M. Wageningen University. Soil Physics and Land Management; Países Bajos.Fil: Geissen, Violette. Wageningen University. Soil Physics and Land Management; Países Bajos.Fil: Riksen, Michel. Wageningen University. Soil Physics and Land Management; Países Bajos.Fil: Mol, Hans. Wageningen University. Research Centre. RIKILT Institute of Food Safety; Países Bajos.Fil: Murialdo, Raquel. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales; Argentina.Fil: Ritsema, Coen. Wageningen University. Soil Physics and Land Management; Países Bajos.Fil: Reyna, Santiago. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales; Argentina.Otras Ingeniería del Medio Ambient

MEASURING PRECIPITATION, INFILTRATION AND WATER DISCHARGE ON A CATCHMENT SCALE FOR SOIL EROSION MODELING IN THE SOUTH PACIFIC REGION

Abstract The work presented here was done in the framework of the CROPPRO project. CROPPRO aims to provide assistance to Pacific Island countries with the development of integrated farming approaches for sustainable crop production in environmentally constrained systems. The project focuses on the development of tailor-made farming approaches for major crop-soil units aiming at maximizing agricultural production and minimizing environmental deterioration. Special attention is paid to knowledge transfer and participatory, culture-sensitive training for stakeholders and end-users. One aspect of the work within the framework of CROPPRO projects is the continuous measurement of the dynamic features of the catchment hydrology. These data are needed to calibrate the LISEM model that is used to evaluate different land use scenarios. The work presented in this paper focuses on methods used and results obtained using various measuring methods and equipment, with respect to precipitation, slope hydrology, and catchment discharge. Two catchments on Fiji and Samoa were instrumented with automatic rain gauges to measure precipitation and precipitation intensity spatially, with data loggers equipped with Frequency Domain Reflectometry (FDR) sensors installed on a slope to measure the water content profile and sub-surface flow. At the outlet of the catchments a flume was constructed to measure outflow using ultrasonic water level sensors, and sediment content using automatic samplers. A sample of data collected using these systems is presented

Use of Clay Dispersed in Water for Decreasing Soil Water Repellency

In this study, we examined the efficiency of a kaolinite clayey soil to mitigate water repellency of a sandy soil with olive trees. The treatment was applied to the soil zone below the tree canopy, which displayed the highest degree of water repellency [average water drop penetration time (WDPT) value = 820 s]. Both dry (incorporated onto the top soil) and wet clay applications (after dispersion in irrigation water) were examined in a replicated experiment, with control trees being used for comparison. The application rate of the clayey soil was maintained in both cases (wet and dry mode) equal to 1 kg m−2, while the effect of subsequent wetting and drying cycles on the treatment performance was evaluated. The results of the study verify that clay application was effective to mitigate soil water repellency. Dry supplementation displayed low efficiency (26% reduction of the air-dry WDPT compared with the control soil) within the first week of application. The efficiency of the dry-clay treatment increased to 76% after applying three subsequent wetting and drying cycles. In comparison with the dry mode, the wet clay was efficient immediately after application (74% reduction of the WDPT), indicating that the limiting step in the overall process was clay dispersion. Based on the findings of this study, it was proposed that wet clay application is of interest for controlling soil water repellency in agricultural land

The effects of wildfire frequency on post-fire soil surface water dynamics

Increasing wildfire frequency in the Mediterranean Basin could affect future plant-soil–water-dynamics. The capacity of soils to retain water is a key parameter affecting plant post-fire regeneration. Yet, few research has looked at how different soil properties related to water retention is affected by increasing wildfire frequency. This study aimed at understanding the relationship between wildfire frequency, soil–water-related properties and the dynamics of surface water in soils. To this, after a 2012-summer wildfire in Portugal, three sets of three replicate maritime pine stands with contrasted wildfire frequency were selected (0 vs. 1 vs. 4 fires since 1975). At each of the nine study sites, three re-sprouter shrubs and neighbouring bare soil were chosen (54 microsites). There, soil cover, soil–water retention curves and surface (0–5 cm) soil–water-related properties (texture, bulk density, organic matter content, soil moisture, soil surface water repellency) were monitored for one year. Furthermore, records of post-fire soil moisture dynamics were analysed continuously using 72 probes installed at 2.5 and 7.5 cm depth. The hillslopes affected by 1 fire showed higher plant recovery than the 4 fires hillslopes. During the dry season, the threshold for water stress was reached 17 days sooner in the 4 fires hillslopes, and also 10 days sooner on bare microsites. Periods of plant water stress were longer and bare soil patches size bigger. The increase in wildfire frequency promoted high soil organic matter contents but less available water content, stressing the importance of soil organic matter quality characterization in water-related properties.Open access funding provided by FCT|FCCN (b-on). This work was funded and performed within the scope of the CASCADE-PROJECT (Catastrophic shifts in drylands: how can we prevent ecosystem degradation? Grant agreement: 28306), funded by the European Commission (FP7-ENV.2011.2.1.4-2-Behaviour o ecosystems, thresholds and tipping points). We acknowledge financial support to CESAM by FCT/MCTES thought national funds (UIDP/50017/2020+UIDB/50017/2020+LA/P/0094/2020). We also acknowledge financial support the University of Aveiro through the assistant research contract of Oscar González-Pelayo (CDL-CTTRI-97-ARH/2018 (REF. 190-97-ARH/2018), and to the MED & CHANGE-University of Évora through the auxiliary research contract (Ref. UIDB/05183/2020). Thanks are also due to FCT for the research contract of Sérgio Prats (CDL-CTTRI-88-ARH/2018 REF.-138-88-ARH/2018) and auxiliary research contract (CEECIND/01473/2020), and Maruxa Malvar (SFRH/BPD/97977/2013), and the IF research grant of Jacob Keizer (IF/01465/2015) funded by national funds (OE), through the Portuguese Foundation for Science and Technology (FCT/MCTES)

Pesticide residues in European agricultural soils – A hidden reality unfolded

Pesticide use is a major foundation of the agricultural intensification observed over the last few decades. As a result, soil contamination by pesticide residues has become an issue of increasing concern due to some pesticides' high soil persistence and toxicity to non-target species. In this study, the distribution of 76 pesticide residues was evaluated in 317 agricultural topsoil samples from across the European Union. The soils were collected in 2015 and originated from 11 EU Member States and 6 main cropping systems. Over 80% of the tested soils contained pesticide residues (25% of samples had 1 residue, 58% of samples had mixtures of two or more residues), in a total of 166 different pesticide combinations. Glyphosate and its metabolite AMPA, DDTs (DDT and its metabolites) and the broad-spectrum fungicides boscalid, epoxiconazole and tebuconazole were the compounds most frequently found in soil samples and the compounds found at the highest concentrations. These compounds occasionally exceeded their predicted environmental concentrations in soil but were below the respective toxic endpoints for standard in-soil organisms. Maximum individual pesticide content assessed in a soil sample was 2.05 mg kg−1 while maximum total pesticide content was 2.87 mg kg−1. This study reveals that the presence of mixtures of pesticide residues in soils are the rule rather than the exception, indicating that environmental risk assessment procedures should be adapted accordingly to minimize related risks to soil life and beyond. This information can be used to implement monitoring programs for pesticide residues in soil and to trigger toxicity assessments of mixtures of pesticide residues on a wider range of soil species in order to perform more comprehensive and accurate risk assessments.</p

Microplastic appraisal of soil, water, ditch sediment and airborne dust: the case of agricultural systems

Although microplastic pollution jeopardizes both terrestrial and aquatic ecosystems, the movement of plastic particles through terrestrial environments is still poorly understood. Agricultural soils exposed to different managements are important sites of storage and dispersal of microplastics. This study aimed to identify the abundance, distribution, and type of microplastics present in agricultural soils, water, airborne dust, and ditch sediments. Soil health was also assessed using soil macroinvertebrate abundance and diversity. Sixteen fields were evaluated, 6 of which had been exposed to more than 5 years of compost application, 5 were exposed to at least 5 years of plastic mulch use, and 5 were not exposed to any specific management (controls) within the last 5 years. We also evaluated the spread of microplastics from the farms into nearby water bodies and airborne dust. We found 11 types of microplastics in soil, among which Light Density Polyethylene (LDPE) and Light Density Polyethylene covered with pro-oxidant additives (PAC) were the most abundant. The highest concentrations of plastics were found in soils exposed to plastic mulch management (128.7 ± 320 MPs.g-1 soil and 224.84 ± 488 MPs.g-1 soil, respectively) and the particles measured from 50 to 150 μm. Nine types of microplastics were found in water, with the highest concentrations observed in systems exposed to compost. Farms applying compost had higher LDPE and PAC concentrations in ditch sediments as compared to control and mulch systems; a significant correlation between soil polypropylene (PP) microplastics with ditch sediment microplastics (r2 0.7 p < 0.05) was found. LDPE, PAC, PE (Polyethylene), and PP were the most abundant microplastics in airborne dust. Soil invertebrates were scarce in the systems using plastic mulch. A cocktail of microplastics was found in all assessed matrices

Leaching of microplastics by preferential flow in earthworm (Lumbricus terrestris) burrows

In the current study, we examine how the activities of earthworms (Lumbricus terrestris) affect microplastic (MP) distribution and concentration in soil, with a focus on low density polyethylene (LDPE). We also want to determine if MPs can be flushed out with water. We used a laboratory sandy soil column (polyvinyl chloride tube) experimental set-up and tested five different treatments: (1) treatment with just soil (control) to check if the saturated conductivity (Ksat) could be impacted by MP, (2) treatment with MP, (3) treatment with MP and litter, (4) treatment with earthworms and litter as a second control for treatment 5 and (5) treatment with MPs, earthworms and litter. Each treatment consisted of eight replicates. For the treatments with MP, the concentration of MP added at the start of the experiment was 7 % by weight (3.97 g, polyethylene, 50 % 1 mm-250 μm, 30 % 250 μm-150 μm and 20 % <150 μm) based on 52.78 g of dry litter from Populus nigra. In the treatments using earthworms, two adult earthworms, with an initial average weight of (7.14 ± 0.26) g, were placed in each column. Results showed that LDPE particles could be introduced into the soil by the earthworms. MP particles were detected in each soil sample and within different soil layers for the earthworm treatments. Earthworms showed a tendency to transport the smaller MP particles and that the amount of MPs in size class <250 μm increased in soil samples with increasing soil depth in comparison to the other size classes. After leaching, MPs were only detected in the leachate from the treatments with the earthworms, and the MP had similar size distributions as the soil samples in the 40-50 cm layer of the treatment with MP, earthworms and litter. The results of this study clearly show that biogenic activities can mobilise MP transport from the surface into the soil and even be leached into drainage. It is highly likely that biogenic activities constitute a potential pathway for MPs to be transported into soil and groundwater.</p