Jesús D. Fernández-Bayo

Evaluation of the sorption process for imidacloprid and diuron in eight agricultural soils from southern Europe using various kinetic models.

Kinetic studies are of great concern for understanding the processes and parameters involved in the sorption of pollutants by soils. Sorption kinetics of imidacloprid and diuron in eight soils of different characteristics, with very low organic carbon content were investigated. Pseudosecond-order kinetic reactions closely correlate with the experimental kinetic (R(2) > 0.98) in all soils. The sorbed amount of diuron was higher than that for imidacloprid. The low OC content of these soils correlated neither with the sorbed amount nor with the kinetic parameters for both pesticides. Imidacloprid sorption was correlated with silt and sand content and cation exchange capacity (CEC); meanwhile for diuron, no correlation was found. Thus, sorption kinetics take place throughout different mechanisms related mainly to the chemical character of the pesticides. Sorption kinetic parameters determined using three of the four models selected (pseudosecond-order kinetic reactions, Elovich equation, and Weber-Morris models) have been shown to be worthy to distinguish the process controlling the sorption kinetic of both pesticides.

Effect of Vermicomposts from Wastes of the Wine and Alcohol Industries in the Persistence and Distribution of Imidacloprid and Diuron on Agricultural Soils

The persistence and distribution of diuron (D) and imidacloprid (I) in soils amended or not with winery vermicomposts were recorded for several months. Sandy loam (S1) and silty clay loam (S2) soils with organic carbon contents of <1% were selected. After incubation, around 78% of I remained in the soil and no metabolites were found. Diuron was dissipated more rapidly except in the unamended soil S1 with DT(50) values of 259 days. The addition of vermicomposts to S1 soil decreased the persistence of D, and high amounts of DPMU (40%) and DPU (20%) metabolites were found. In unamended and amended S2 soils, the persistence of D was lower than in S1 (DT(50) < 42 days) but only DPMU was determined (up to 5%). Different simulation models from FOCUS guidelines were applied to the experimental data. No relationship between pesticide degradation and soil enzyme activities was found.

Weed seed inactivation in soil mesocosms via biosolarization with mature compost and tomato processing waste amendments.

BACKGROUND Biosolarization is a fumigation alternative that combines passive solar heating with amendment-driven soil microbial activity to temporarily create antagonistic soil conditions, such as elevated temperature and acidity, that can inactivate weed seeds and other pest propagules. The aim of this study was to use a mesocosm-based field trial to assess soil heating, pH, volatile fatty acid accumulation and weed seed inactivation during biosolarization. RESULTS Biosolarization for 8 days using 2% mature green waste compost and 2 or 5% tomato processing residues in the soil resulted in accumulation of volatile fatty acids in the soil, particularly acetic acid, and >95% inactivation of Brassica nigra and Solanum nigrum seeds. Inactivation kinetics data showed that near complete weed seed inactivation in soil was achieved within the first 5 days of biosolarization. This was significantly greater than the inactivation achieved in control soils that were solar heated without amendment or were amended but not solar heated. CONCLUSION The composition and concentration of organic matter amendments in soil significantly affected volatile fatty acid accumulation at various soil depths during biosolarization. Combining solar heating with organic matter amendment resulted in accelerated weed seed inactivation compared with either approach alone.

Assessment of Two Solid Anaerobic Digestate Soil Amendments for Effects on Soil Quality and Biosolarization Efficacy

Anaerobic digestion is an organic waste bioconversion process that produces biofuel and digestates. Digestates have potential to be applied as soil amendment to improve properties for crop production including phytonutrient content and pest load. Our objective was to assess the impact of solid anaerobic digestates on weed seed inactivation and soil quality upon soil biosolarization (a pest control technique that combines solar heating and amendment-induced microbial activity). Two solid digestates from thermophilic (TD) and mesophilic (MD) digesters were tested. The solarized TD-amended samples presented significantly higher mortality of Brassica nigra (71%, P = 0.032) than its equivalent incubated at room temperature. However, biosolarization with digestate amendment led to decreased weed seed mortality in certain treatments. The plant-available water, total C, and extractable P and K were significantly increased (P < 0.05) in the incubated amended soils. The results confirm the potential of digestates as beneficial soil amendments. Further studies are needed to elucidate the impacts of digestate stability on biosolarization efficacy and soil properties.

Comparison of thermophilic anaerobic and aerobic treatment processes for stabilization of green and food wastes and production of soil amendments

The management of organic wastes is an environmental and social priority. Aerobic digestion (AED) or composting and anaerobic digestion (AD) are two organic waste management practices that produce a value-added final product. Few side-by-side comparisons of both technologies and their digestate products have been performed. The objective of this study was to compare the impact of initial feedstock properties (moisture content and/or C/N ratio) on stabilization rate by AED and AD and soil amendment characteristics of the final products. Green and food wastes were considered as they are two of the main contributors to municipal organic waste. Stabilization rate was assessed by measurement of CH4 and CO2 evolution for AD and AED, respectively. For AD, CH4 yield showed a second-order relationship with the C/N content (P < 0.05); the optimal C/N ratio indicated by the relationship was 25.5. For AED, cumulative CO2 evolution values were significantly affected by the C/N ratio and moisture content of the initial feedstock (P < 0.05). A response surface model showed optimal AED stabilization for a C/N of 25.6 and moisture of 64.9% (wet basis). AD final products presented lower soluble chemical oxygen demand (COD) but lower humification degree and aromaticity than the products from AED. This lower stability may lead to further degradation when amended to soil. The results suggest that composting feedstocks with higher C/N produces an end-product with higher suitability for soil amendment. The instability of end products from AD could be leveraged in pest control techniques that rely on organic matter degradation to produce compounds with pesticidal properties.

Structure and activity of thermophilic methanogenic microbial communities exposed to quaternary ammonium sanitizer

Food processing facilities often use antimicrobial quaternary ammonium compound (QAC) sanitizers to maintain cleanliness. These QACs can end up in wastewaters used as feedstock for anaerobic digestion. The aim of this study was to measure the effect of QAC contamination on biogas production and structure of microbial communities in thermophilic digester sludge. Methane production and biogas quality data were analyzed in batch anaerobic digesters containing QAC at 0, 15, 50, 100 and 150mg/L. Increasing sanitizer concentration in the bioreactors negatively impacted methane production rate and biogas quality. Microbial community composition data was obtained through 16S rRNA gene sequencing from the QAC-contaminated sludges. Sequencing data showed no significant restructuring of the bacterial communities. However, significant restructuring was observed within the archaeal communities as QAC concentration increased. Further studies to confirm these effects on a larger scale and with a longer retention time are necessary.

Effect of management of organic wastes on inactivation of Brassica nigra and Fusarium oxysporum f.sp. lactucae using soil biosolarization: Managing organic wastes to improve soil biosolarization to control pests

BACKGROUND Soil biosolarization is a promising alternative to conventional fumigation. Volatile fatty acids (VFAs) produced in the soil through fermentation of amended organic matter can affect pest inactivation during biosolarization. The objective was to determine how soil amended with organic wastes that were partially stabilized through either composting or anaerobic digestion affected the inactivation of Brassica nigra (BN; a weed) and Fusarium oxysporum f. sp. lactucae (FOL; a phytopathogenic fungus). RESULTS The mortality of BN seeds in the biosolarized soil was 12% higher than in the solarized soil, although this difference was not significant. However, a significant correlation between BN mortality and VFA accumulation was observed. The number of FOL colony-forming units (CFU) in solarized samples at 5 cm was 34 CFU g-1 of soil, whereas in the biosolarized samples levels were below the limit of quantification. At 15 cm, these levels were 100 CFU g-1 for solarized samples and < 50 CFU g-1 of soil for the biosolarized samples. Amendment addition positively affected the organic matter and potassium content after the solarization process. CONCLUSION The organic waste stabilization method can impact downstream biosolarization performance and final pest inactivation levels. This study suggests that organic waste management practices can be leveraged to improve pest control and soil quality.

Elucidating Local Food Production to Identify the Principles and Challenges of Sustainable Agriculture

Abstract Sustainable agriculture is the use of biological sources to produce food and fiber, among other products, while considering the environmental impacts. Herein, the use of local plants and animals is elucidated. This issue reflects many of the challenges and the potential of industrial and sustainable use of biologic resources. First, the definition of agriculture to include any foundational, initial steps of consumable goods (even when it does not implicitly involve cultivation of farms and land per se) is expected. Sustainable agriculture stands on four pillars: land management, resource management, human interface, and the ecosystem interface. The aim of this chapter is to explain the many ways in which local plants and animals are used. Domestication is one of the key advancements of humanity, which resulted in profound impacts on human diet, transport, social structure, economy, and more. These developments rooted in the cradle of domestication and agriculture resulted in a considerable change in plant and human dispersion, and today more food is consumed and exported long distances from its original homeland. To date, research and practical efforts are allocated to improve the use of existing crops rather than increasing the crop diversity by incorporating more species, some of which are already used locally. The commercial use of new crops has vast potential, but also many risks that we tackle in the next part of this chapter. The main advantages to explore local plants and animals and the challenges associated with their use are reviewed.

The effects of short-term biosolarization using mature compost and industrial tomato waste amendments on the generation and persistence of biocidal soil conditions and subsequent tomato growth

Conventional solarization and biosolarization with mature compost and tomato processing residue amendments were compared with respect to generation of pesticidal conditions and tomato ( Solanum lycopersicum L.) plant growth in treated soils. Soil oxygen depletion was examined as a response that has previously not been measured across multiple depths during biosolarization. For biosolarized soil, volatile fatty acids were found to accumulate concurrent with oxygen depletion, and the magnitude of these changes varied by soil depth. Two consecutive years of experimentation showed varying dissipation of volatile fatty acids from biosolarized soils post-treatment. When residual volatile fatty acids were detected in the biosolarized soil, fruit yield did not significantly differ from plants grown in solarized soil. However, when there was no residual volatile fatty acids in the soil at the time of planting, plants grown in biosolarized soil showed a significantly greater vegetation amount, fruit quantity, and fruit ripening than those of plants grown in solarized soil.