Biochars can be used as soil amendments for improving soil properties and crop yield. The objective of this research was to study the plant growth, yield, yield components, and seed quality, including nutrients and heavy metals (Pb, Cd, and Hg), in the soybean plant (Glycine max [L.] Merr.) and soil. The experiment was conducted from September 2010 to January 2011 in a greenhouse located in the Dan Khun Thot District, Nakhon Ratchasima Province, Thailand. The research comprised six treatments with four replicates in a completely randomized design. Quail litter biochar (QLB) at rates of 0, 24.6, 49.2, 73.8, 98.4 and 123 g per pot mixture were provided to soybean cv. Chiang Mai 60. The results showed that QLB could be used as a soil fertility improvement and amendment for soybean production with an optimum rate of 98.4 g per pot mixture, which gave the best performance in terms of the number of nodes, height, DM accumulation, total yield, and seed quality. After the experiment, the nutrient contents in the soil increased as the QLB content increased, but the heavy metal residues in the leaves and seeds did not change. However, QLB at levels higher than 98.4 g per pot mixture is not advisable because QLB is alkaline in nature, which may affect soil pH.

Biochar can improve soil structure and water retention, enhance nutrient availability and retention, ameliorate acidity, and reduce heavy metal toxicity to plant roots. In this study, a basin experiment was conducted to investigate the effects of quail litter biochar (QLB) on the availability of Cd to physic nut (Jatropha curcas L.) plants. QLB was applied to the soil in which four new physic nut varieties (Takfa, Doi Saket, Lao, and Rayong) in factorial combinations at four levels (0, 5, 10, and 15 g kg -1 soil) to soil that contained 60.8 mg Cd kg -1. After transplanting plant height and canopy radius were measured every 2-mo and the number of leaves and branches at 6-mo, while yield components and Cd residues were measured at 8-mo intervals. The contaminated soil was analyzed for chemical characteristics, nutrients, and Cd residue after the plant harvest. The addition of QLB to soil caused a significant increase in the soil's growth potential and physic nut yield components (P < 0.05), a significant decrease in the Cd residue in the plant (P < 0.05), and a significant increase in the chemical characteristics, nutrients, and Cd residue in soil (P < 0.05). In conclusion, QLB application can significantly decrease the bioavailability of Cd to physic nut plants, increase plant growth potential and yield, and has potential to remediate Cdcontaminated soil. However, QLB levels higher than 15 g kg -1 soil mixture were not advisable because QLB is alkaline in nature, and this can affect soil pH.

Agriculture, forestry, and other land use approximately contribute to 24 percent of 2010 global greenhouse gas (GHGs) emissions. This study, therefore, focuses on assessing the environmental impacts of jasmine rice production. The life cycle assessment method is used to find the hotspots that are of high environmental impacts. Face-to-face interviewing was conducted with 49 rice producers engaged in chemical, organic, and good agricultural practices in farming activities. The results show that most of the emissions were caused during the post-harvest management stage. Following eco-efficiency, organic jasmine rice production offers a reduction in the consumption of resources, reduced impact on the environment, and increased product value. Furthermore, our study shows that crop residue is a key to increase rice yields and decrease GHGs emissions. Our findings thus add to the limited literature on organic jasmine rice production and propose a recommendation for policymakers to promote sustainable agricultural practices to reduce the environmental impact. Graphic abstract

Suppadit, T., Jaturasitha, S. and Pripwai, N. 2006

Watermeal (Wollfia arrhiza) is a small aquatic plant which we have used to treat water from black tiger shrimp ponds. The relationship between watermeal biomass and treatment length, the changes in water quality parameters, and N-balance were evaluated for the treatment of black tiger shrimp farm effluent in low-salinity areas. A biomass of 12 g of watermeal per litre of shrimp farm effluent and a treatment period of 30 days were found to provide the best conditions for the growth of watermeal, and the quality of the treated effluent in terms of biological oxygen demands, suspended solids, total phosphorus, nitrate, total ammonia nitrogen, and total Kjeldahl nitrogen. The pH and salinity were similar for each level of biomass. The watermeal biomasses of 4-12 g per litre of effluent were suitable for watermeal survival over time. Since watermeal can fix nitrogen from the atmosphere, it can grow very well in effluent containing a low level of nitrogen, maintaining the N-balance.