Post-fire recovery of soil organic carbon, soil total nitrogen, soil nutrients, and soil erodibility in rotational shifting cultivation in Northern Thailand

The hill tribes in Thailand traditionally depend on rotational shifting cultivation (RSC). However, insufficient understanding remains on post-fire soil properties and soil erodibility (k-values) with fallow years. To address this gap, the levels of soil organic carbon (SOC), soil total nitrogen (STN), soil nutrients, and soil erodibility after fire in RSC were investigated. Topsoil (0–10 cm) samples from sites with 4 (RSC-4Y), 5 (RSC-5Y), and 7 (RSC-7Y) fallow years in Chiang Mai Province, northern Thailand, were taken at four time points: before burning, 5 min after burning, 9 months after burning, and 2 years after burning. Soil pH, electrical conductivity, and soil nutrient (available P, K, and Ca) levels were increased after burning and remained higher than the pre-burning levels for at least 2 years. The SOC stock decreased after burning in all fallow fields. At 2 years after burning, the SOC stock in RSC-4Y was higher than before burning, whereas in RSC-5Y and RSC-7Y, the levels had not reached the pre-fire levels. The STN stocks of all studied fields significantly decreased after burning and had not reached the pre-burning levels after 2 years. After burning, the topsoil of RSC-4Y was most susceptible to erosion. However, only in RSC-4Y, the k-value was unchanged at 2 years after burning. Three different approaches are recommended for post-fire land management: 1) farmers should not cut and remove the weeds and grasses at the soil surface, 2) burning should be performed around late winter or early summer (November–February) to inhibit complete combustion, and 3) contour-felled log erosion barriers should be made by using the trunks remaining after the fire to trap the sediment and slow down surface runoff

Rice Straw Vermicompost Enriched With Cellulolytic Microbes Ameliorate the Negative Effect of Drought in Wheat Through Modulating the Morpho-Physiological Attributes

Wheat growth and productivity are unfavorably pretentious by a lack of sufficient water (drought or water deficit) worldwide. Drought stress significantly affects all the morpho-physiological and biochemical characteristics and the agronomical yield of wheat. Different management approaches have been adopted to cope with the negative effects of water deficit. Soil-applied vermicompost is helpful in improving the growth and developmental processes of wheat under water deficit conditions. Therefore, a trial was carried out to optimize the best amount of vermicompost and to assess its role in ameliorating the negative effects of drought for sustainable crop production. The treatments consisted of 1) two contrasting wheat cultivars Faisalabad-08 (drought-tolerant) and Galaxy-13 (drought-sensitive), 2) drought with three levels [D0 = 70% of field capacity (no drought), D1 = 45% of field capacity (mild drought), and D2 = 30% of field capacity (severe drought)] and 3) cellulolytic microbe-enriched vermicompost prepared from rice straw with four levels (VT0 = Control, VT1 = 4 t ha−1, VT2 = 6 t ha−1 , and VT3 = 8 t ha−1). Data on various morphological, physiological, and biochemical parameters were recorded from sowing to crop harvesting. In this study, it was demonstrated that all these parameters were negatively affected by moisture deficit conditions. The application of vermi-fertilizer significantly increased (p < 0.05) the aforementioned parameters of wheat in both the absence and presence of drought. Under severe drought, VT2 treatment increased the seedling length by 14.02–26.14%, fresh weight by 15.16–22.91%, and dry weight by 0.37–28.20% in both cultivars compared with control. In addition, VT2 treatment reduced the leaf water potential by 6.36 and 3.36%, leaf osmotic potential by 1.74 and 1.68%, and increased the turgor potential by 4.83 and 3.36%, and photosynthetic rate by 18.59 and 26.42% in Faislabad-08 and Galaxy-13, respectively, over control. We concluded that the application of vermicompost is a valuable approach to alleviate the adverse impacts of water stress on wheat

Toward Sustainable Environmental Quality : Priority Research Questions for Asia

Environmental and human health challenges are pronounced in Asia, an exceptionally diverse and complex region where influences of global megatrends are extensive and numerous stresses to environmental quality exist. Identifying priorities necessary to engage grand challenges can be facilitated through horizon scanning exercises, and to this end we identified and examined 23 priority research questions needed to advance toward more sustainable environmental quality in Asia, as part of the Global Horizon Scanning Project. Advances in environmental toxicology, environmental chemistry, biological monitoring, and risk-assessment methodologies are necessary to address the adverse impacts of environmental stressors on ecosystem services and biodiversity, with Asia being home to numerous biodiversity hotspots. Intersections of the food–energy–water nexus are profound in Asia; innovative and aggressive technologies are necessary to provide clean water, ensure food safety, and stimulate energy efficiency, while improving ecological integrity and addressing legacy and emerging threats to public health and the environment, particularly with increased aquaculture production. Asia is the largest chemical-producing continent globally. Accordingly, sustainable and green chemistry and engineering present decided opportunities to stimulate innovation and realize a number of the United Nations Sustainable Development Goals. Engaging the priority research questions identified herein will require transdisciplinary coordination through existing and nontraditional partnerships within and among countries and sectors. Answering these questions will not be easy but is necessary to achieve more sustainable environmental quality in Asia. Environ Toxicol Chem 2020;39:1485–1505

Ecotoxicological assessment of diffuse pollution using biomonitoring tool for sustainable land use in Thailand

As a developing country, Thailand has a significant issue with diffuse pollution of the soil ecosystem due to an indiscriminate use of agrichemicals and poorly regulated disposal of a wide variety of hazardous wastes. Practical risk assessment tools based on locally-occurring species are needed to assess the effects of diffuse pollutants on the soil ecosystem in Thailand because reliance on soil criteria developed for overseas conditions may provide inadequate protection. Native soil organisms in Thailand may be more or less sensitive to contaminants compared to overseas test species. This article described a biological indicator approach for ecological risk assessment of diffuse pollution in the soil ecosystem of Thailand from pesticide application with the aim of developing standardized protocols using native species and locally generated data to better evaluate the ecological risks of non-point source soil pollution. It was found that ecotoxicological assessment provided a better understanding of the ecological impacts that diffuse pollution induced on Thai environmental conditions. Thai soil biota species were more sensitive to soil contaminants than similar species overseas. Soil series also had an influence on the ecotoxicology of contaminants to soil biota. Collembolan, Cyphoderus sp., was demonstrated as a useful alternative test species to Folsomia candida (international test species) for terrestrial ecotoxicological testing of Thai soils. In addition, the soil biota activities such as soil respiration and earthworm avoidance including soil biodiversity and the litter bag decomposition technique are also good tools to assess the effects of diffuse pollution by pesticides on the soil ecosystem of Thailand

Assessment of pesticide contaminated sediment using biological response of tropical chironomid, Chironomus javanus Kiffer as biomarker

Objective To investigate the use of a biomarker for assessment of the effects on the tropical chironomid, Chironomus javanus (C. javanus), Kiffer of sediment contaminated with an insecticide (chlorpyrifos). Methods A wide range of biological responses to the tropical chironomid exposed were measured, including survival, growth rate and Acetylcholinesterase (AChE) activity. Results The measured median lethal concentration (96 h LC) of chlorpyrifos to C. javanus was 0.056 (95% CI 0.024–0.124) μg/kg. For sub-chronic levels of chlorpyrifos between 0.001 and 0.25 μg/kg administered for 10 days, the effects on the growth of C. javanus were reduced (larva size, head structure width and dry weight) at the significance level (P < 0.01) and the effects were concentration dependent. Following exposure to chlorpyrifos at the level of 0.001 μg/kg for 48 and 96 h, the AChE activity in C. javanus was inhibited compared with control samples (P < 0.05). Conclusions This study demonstrated that C. javanus was sensitive when exposed to chlorpyrifos. This species could serve as a potential biomarker for assessing pesticide contamination at low environmental persistence and provides limited effects data on the sensitivity of tropical biota to contaminants for ecological risk assessment of organophosphate pesticides in the tropical aquatic ecosystem

Earthworm: potential bioindicator for monitoring diffuse pollution by agrochemical residues in Thailand,”

Abstract The use of pesticides has long been a feature of conventional agricultural practice and their use has made it possible to increase crop yields and food production. However, the impact of many of these chemicals on ecosystem and human health has been of concern due to widespread impacts beyond crop protection. Economical monitoring procedure for assessing agrochemical non-point source pollution is needed. Earthworms are important components in agro-ecosystem. They play a significant role in soil functioning and soil fertility. The purpose of this investigation was to assess the potential of earthworm as bioindicator of agrochemical residues in soil. The survey of earthworm population was conducted in the different land used management in Khon Kaen Province, Thailand during year 2006-2007. The physical soil properties (bulk density, moisture and porosity) and the chemical soil properties (pH, EC, organic matter, CEC, Total nitrogen, available phosphorus, Exchangeable K, Na, Mg and Ca) and pesticide residues were analyzed to correlate the results with the biological parameters. Ecotoxicological study of pesticide to earthworm has confirmed the results in the field. The results showed that the earthworm cast of Pheretima sp. per square meter in different land uses was significantly different (p&lt;0.05) from each site and the earthworm casts in land used without using pesticide were higher than land use with using pesticide. The earthworm population was positively correlated with habitat suitability but negatively correlated with the degree of agrochemical residues in soil