Chia-Hsing Lee

USING A SOIL QUALITY INDEX TO ASSESS THE EFFECTS OF APPLYING SWINE MANURE COMPOST ON SOIL QUALITY UNDER A CROP ROTATION SYSTEM IN TAIWAN

Soil quality indices (SQI) have been proposed in recent years as tools for assessing soil management practice effects on soil quality. In this paper, we report the result of our 4-year study on the use of a SQI to assess the effects of applying swine manure compost on soil quality. Cabbage (Brassica camperstris L.) and maize (Zea mays L.) were grown in rotation in plots applied with low, medium, and high rates of swine manure compost while the control received only chemical fertilizers. Selected soil physical, chemical, and biological properties (bulk density, aggregate stability, organic carbon content, soil pH, available N, P, and K, extractable Cu and Zn, and microbial biomass), all of which were identified as possible soil quality indicators, were monitored at regular intervals. Tissues of harvested crops were analyzed for Cu and Zn concentrations because they were anticipated to increase due to the high amounts of the metals in the manure compost. A SQI model was derived based on Mausbach and Seybolds research and on our soil database and research experience in Taiwan. Data from our manure application experiment were used to calculate the SQI values for the different treatments. Results revealed that application of swine manure compost improved the soil quality of surface soil as indicated by increased values of soil quality indicators, SQI, and yields of the crops. In addition, Cu and Zn levels in the soil and in the crop tissues did not increase to harmful levels. Thus, it seems that the SQI was an effective tool to assess the effects of swine manure compost application on soil quality. The soil indicators we found effective included the monitored properties except for bulk density. All of these soil properties were significantly increased by manure compost application. Long-term application of 40-60 tons ha−1 year−1 of manure compost may improve the soil quality and increase the yield of the crops without polluting the soil and crops with Cu and Zn.

Arsenic accumulation and speciation in rice grains influenced by arsenic phytotoxicity and rice genotypes grown in arsenic-elevated paddy soils

Rice consumption is a major route of As exposure to human for the population of worldwide. This study investigates the effect of phytotoxicity and rice genotypes on the content and speciation of As in rice grains grown in different levels of As-elevated paddy soils from Taiwan. Three levels of As-elevated soils and six rice genotypes commonly planted in Taiwan were used for this study. The results indicate that As contents in grains of rice is not proportional to soil As concentrations and they were equal or higher in indica genotypes than japonica genotypes used in this study. It was also found that the As phytotoxicity not only reducing the grain yields but also the As concentrations in grain of rice. The predominant As species found in rice grains were dimethylarsinic acid (DMA) and arsenite. The concentrations of DMA increased with total As concentrations, wherggeas the arsenite remained in a narrow range from 0.1 to 0.3 mg kg(-1). Because of the lower toxicity of DMA than inorganic As species, the health risks may not be increased through consumption of rice even when total As content in the grains is increased.

Increase of As release and phytotoxicity to rice seedlings in As-contaminated paddy soils by Si fertilizer application.

Silicon (Si) was shown to be able to reduce arsenic (As) uptake by rice in hydroponic culture or in low As soils using high Si application rates. However, the effect of Si application on As uptake of rice grown in As-contaminated soils using Si fertilizer recommendation rate has not been investigated. In this study, the effect of Si application using Si fertilizer recommendation rate on As release and phytotoxicity in soils with different properties and contents of As was examined. The results show that the concentrations of As in soil solutions increased after Si applications due to competitive adsorption between As and Si on soil solids and the Si concentrations in soil solutions were also elevated to beneficial levels for rice growth. The rice seedlings accumulated more As and its growth was inhibited by Si application in As contaminated/spiked soils. The results indicate that there is an initial aggravation in As toxicity before the beneficial effects of Si fertilizing to rice were revealed when Si application based on fertilizer recommendation rate to As-contaminated paddy soils. Therefore, for As-contaminated paddy soils with high levels of As, the application of Si fertilizer could result in increasing As phytotoxicity and uptake by rice.

The Effects of Compost-Derived Dissolved Organic Carbon on Cd, Zn, and Cu Release From Metal-Spiked Soils

Dissolved organic carbon (DOC) can affect the mobility or bioavailability of heavy metals in a soil system. We investigated the effects of two compost-derived DOC solutions on the release of Cd, Zn, and Cu from two metal-spiked agricultural soils via repeated extraction experiments under acidic conditions. The two soils used in this study were acidic (pH 5.1-5.7) and differed primarily in soil texture (Sankengtzu [Sk] sandy loam vs. Potu [Pu] silty clay loam). The soils were spiked with individual metals (Cd, Zn, or Cu) to levels close to the limits imposed by local regulations. The metal-spiked soils were treated with two acidified DOC solutions (10 mmol/L DOC; pH 3; Na+ exchanged), one derived from sewage sludge compost and the other from swine manure compost, followed by repeated extraction experiments. The results showed that the addition of DOC in the extraction solution can accelerate the acidification and the release of Cd, Zn, and Cu from the two soils. This effect was more obvious for the Sk sandy soil than for the Pu clay soil. The two DOC solutions, which were extracted from different sources, showed different behaviors of metal release. The differences might be related to the acid strength, metal-binding strength of acid sites, and the presence of other anions. The release of Cd from the soils was controlled mainly by the pH of the soil. Neither an inhibition effect of chloride ions nor an improvement effect of DOC on the Cd release was found. The release of Zn was slightly inhibited (∼10%) by the DOC solution extracted from the sewage sludge compost (or Neihu secondary sludge compost [NH2SC]-DOC), especially from the Sk sandy soil, which was assumed to be the result of the formation of sulfide. The use of DOC extracted from the swine manure compost (or SMC-DOC) can result in the release of more Cu (up to 35%-40%) from both soils. The DOC solutions can be used for enhancing the efficiency of acid-washing techniques used for metal-contaminated soil remediation (especially for Cu).

Video-assisted thoracoscopic surgery in continuous ambulatory peritoneal dialysis-related hydrothorax

A 50-year-old lady with end-stage renal disease developeddyspnea, nausea, and vomiting soon after commencingcontinuous ambulatory peritoneal dialysis (CAPD) for 1week. The chest X-ray showed massive right-sided pleuraleffusion (Figure 1a), which was transudative in characterwith high sugar levels. To establish the diagnosis ofCAPD-related hydrothorax, a peritoneal–pleural communi-cation was confirmed by Tc-99m peritoneal scintigraphy,where an uptake signal appeared in the right side of thoraxwithin 30min of tracer injection into the peritoneal cavity(Figure 1b). During the video-assisted thoracoscopic surgery,a defect about 0.3cm in diameter on the right diaphragm wasrepaired by direct suture with a mesh (Figure 2). Thepostoperative course was smooth and CAPD was resumed2 weeks later without event. The chest X-ray did not showany recurrence of the pleural effusion up to 5 months later.Both Tc-99m peritoneal scintigraphy and video-assistedthoracoscopic surgery with mesh repair provide a safe,simple, and quick way to diagnose and treat CAPD-relatedhydrothorax.