Beneficis ambientals de l'ús de biocarbó com a esmena en cultiu de pinya de costa rica: efectes fisicoquímics i biològic en sòl i interacció amb agroquímics
- Autores: Juan Salvador Chin Pampillo
- Directores de la Tesis: Josep M. Alcañiz (dir. tes.), Xavier Domene Casadesús (codir. tes.), Cristina Chinchilla Soto (codir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2020
- Idioma: español
- ISBN: 9788449095191
- Tribunal Calificador de la Tesis: Gabriel Gascó Guerrero (presid.), Cristina Palet i Ballús (secret.), Robert Cruañas Terradas (voc.)
- Programa de doctorado: Programa de Doctorado en Ecología Terrestre por la Universidad Autónoma de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Pineapple production is an important economic activity in Costa Rica as shown by the increase in its cropped area in the last two decades. It involves a high generation of agro-wastes as well as an intensive application of pesticides, including the herbicides bromacil, and diuron. Their use is associated with problems of environmental, health and economic concern, because it has been detected in both surface water and groundwater. However, there is still scarce information about the environmental fate of these herbicides in tropical soils. The transformation of this agro-waste surplus by pyrolysis into biochar, a carbonaceous material, followed by its addition to soil as an amendment, has been suggested as a useful waste management practice. This is because it may improve the soil quality and carbon sequestration and potentially mitigate the mobility of pesticides. The aim of this thesis was to evaluate the benefits and unexpected effects of biochar addition to a Costa Rican agricultural soil cropped to pineapple, concurrently considering the effects on bromacil and diuron fate and efficiency as well as non-target soil ecotoxicological effects. For this purpose, pineapple stubble (PS), oil palm fiber (PF) and coffee hulls (CH) were pyrolyzed at 300 or 600 °C for one hour and then physically and chemically characterized. Mixtures of the charred materials (CM) with soil were prepared at application rates equivalent to 10 and 20 t ha-1. Sorption, degradation, and biodegradation of both pesticides were evaluated in the laboratory, and the results were used to predict their environmental risk with the Pesticide Impact Rating Index. In addition, lettuce emergence and growth (Lactuca sativa), invertebrates performance (collembolan Folsomia candida; enchytraeid Enchytraeus crypticus), and microorganism functional diversity (Microresp™) were used to test the effects of CM on the herbicides’ efficiency and on the non-target soil biological groups.
CM pyrolyzed at 300 °C were classified as torrefied materials (TM), while those pyrolized at 600 °C were classified as biochars (B). Biochars showed higher specific surface area, fixed carbon content and pH values than TM, while PS-B and PF-B presented a higher abundance of surface oxygenated chemical groups than CH-B and all the TM. A weak sorption of both herbicides to soil was observed suggesting a high mobility, while the degradation and biodegradation of bromacil was more limited compared to that of diuron. The addition of biochars increased the persistence of bromacil, while PS-TM and PF-TM increased the sorption of diuron. Despite that, the predicted mobility and aquatic toxicity of the herbicides were unaffected. The addition of CM did not reduce herbicide efficiency but increased seedling emergence without improving growth. The adding of herbicides had no toxic effects on collembolans and enchytraeids as it promoted their reproduction without affecting survival. A generalized avoidance of CM-mixtures by enchytraeids was observed as opposed to the general preference shown in collembolans, irrespective of the supplementation or not of herbicides. Finally, no changes in the microbial functional diversity by the sole addition of herbicides or CM were demonstrated, and a significant increase in the consumption rate of some substrates was observed only in some diuron-treated CM-mixtures.
In summary, the addition of CM did not change the efficiency of the herbicides nor their fate in a tropical clay Ultisol. Under pineapple cropping conditions of the northern region of Costa Rica, bromacil and diuron presented a high estimated environmental risk to surface water and groundwater, and the addition of CM did not change this risk. Simultaneously, no negative effects to the soil ecosystem were observed, but there was an improvement in soil as a habitat for some soil invertebrates.
