Phosphorus flow analysis in maize cultivation: a case study in Thailand.

Phosphorus (P) is an essential element for plant cultivation, where the demand for agricultural products as food and feed are the main drivers of aggravated agricultural production systems. Maize is one of the main feedstocks for animal feed production in Thailand. Therefore, this study investigated P flows, using the conservation of mass-balanced concept to identify the major P flows in maize cultivation during rainy and dry seasons based on a survey of 131 plantation land plots. The result indicated that total amount of P input to maize fields during upland rainy and lowland dry season cultivation was determined as 27.76 and 34.96 kg P/ha, respectively, approximately 97% of which was in chemical fertilizers. P output in grain products accounted for 31.7 and 37.3% of the total P input or 32.9 and 38.0% of the applied fertilizer during maize cultivation in rainy and dry seasons, respectively. Agricultural soils were the main stock of P in maize cultivation systems. From the amount of applied P in rainy and dry seasons of maize cultivation, 43.9 and 41.3% remained in the soil, respectively, whereas 6.0 and 4.5% of those input during rainy and dry season were lost through runoff to the hydrosphere, respectively. This result indicated that seasonal and geographical factors may affect P flow pattern in maize cultivation. This revealed that P accumulation in soils and P loss occurring in rainy season were greater than those of dry season. Therefore, optimizing P flows through improved nutrient management should carefully consider helping reduce P loss during maize cultivation in Thailand.

Quality of life among Thai workers in textile dyeing factories.

The purpose of a cross-sectional study was to investigate factors influencing the quality of life among Thai workers in textile dyeing factories. Samples included 205 Thai workers from five textile dyeing factories located in the suburban area of Bangkok in Thailand. Data were collected with a self-administered questionnaire. Scales of the questionnaire had reliability coefficients ranging from 0.70-0.91. The results revealed that the overall quality of life among workers was most likely between good and moderate levels, and the percentage-mean score was 74.77. The seven factors associated with the overall quality of life were co-worker relationships, safety at work in the dimension of accident prevention, job characteristics, supervisory relationships, welfares, marital status, and physical environment. Furthermore, co-worker relationships, accident prevention, and marital status were three considerable predictors accounted for 23% of the variance in the overall quality of life among workers in textile dyeing factories.

Enhanced arsenic removals through plant interactions in subsurface-flow constructed wetlands.

Arsenic (As) removal in pilot-scale subsurface-flow constructed wetlands (CWs) was investigated by comparing between CW units with vetiver grasses (CWplanted) and CW units without vetiver grasses (CWunplanted) in order to determine the roles of vetiver grasses affecting As removal. Based on the data obtained from 147 days of experiment, it is apparent that CWplanted units could remove As significantly higher than those of CWunplanted units with approximately 7-14%. Although analysis of As mass balance in CW units revealed that only 0.5-1.0% of total As was found in vetiver grasses, the As retained within bed of the CWplanted units (23.6-29.7 g) was higher than those in the CWunplanted units (21.3-26.8 g) at the end of the experiment, illustrating the effect of vetiver grasses on As accumulation in the CW units. Determination of As in different fractions in the CW bed suggested that the main mechanism of As retention was due mainly to As entrapment into the porous of bed materials (50-57% of total fraction), this mechanism is likely not affected by the presence of vetiver grasses. However, fraction of As-bound in organic matters that could be released from plant roots decomposition indicated the increase adsorption capacity of CW bed. In addition, organic sulfides produced from their root decomposition could help remove As through the precipitation/co-precipitation process. Under reducing condition in those CWplanted units, As could be leached out in the form of iron and manganese-bound complexes.