Use of earthworms (Eisenia fetida) to reduce phytotoxicity and promote humification of pre‐composted olive oil mill wastewater

BACKGROUND: Olive mill wastewaters (OMWW) contain a high recalcitrant organic load and an associated toxicity that make their treatment necessary before environmental application. The aim of this study was to evaluate the feasibility of promoting the valorization and reducing the phytotoxicity of OMWW through a pre‐composting process together with straw‐chip bulking materials followed by the application of earthworms (Eisenia fetida) in the presence of oat seedlings (Avena sativa L.) seedlings. RESULTS: After 3 months, the pre‐composted material showed properties similar to a partially digested compost with some significant amelioration of chemical–physical and biochemical properties. The application of earthworms permitted a significant decrease in chemical (total organic carbon, water‐extractable organic carbon, total nitrogen) and biological parameters (dehydrogenase enzyme activity), and an increase in humic substances and available nitrogen forms. In the presence of plants a higher C/N ratio and a lower content of nitrates were observed. In addition, the reduction in phenolic compounds observed in treatments with earthworms caused a decrease in phytotoxicity by about 50% with respect to the pre‐composted material, which results in an increase in germination index. CONCLUSION: The utilization of earthworms, in particular in the presence of plants, may be an ecologically sound and economically feasible technology to obtain a non‐toxic, high‐value product useful for agricultural purposes. Copyright © 2010 Society of Chemical Industry     

Vermicompost extracts influence growth,mineral nutrients,phytonutrients and antioxidant activity in pak choi (Brassica rapa cv. Bonsai,Chinensis group) grown under vermicompost and chemical fertiliser

BACKGROUND: Multiple studies have been reported on the effect of compost tea on suppression of certain plant diseases. However, relatively little work has been done to investigate the effect of vermicompost tea on yield and nutritional quality of vegetable crops. In this study, experiments were conducted to determine the effect of extraction method on vermicompost tea quality and subsequent effects on growth, mineral nutrients, phytonutrients and antioxidant activity of pak choi plants grown under organic (vermicompost) and synthetic (Osmocote) fertilisation. Three vermicompost teas obtained by different extraction methods, namely non‐aerated vermicompost tea (NCT), aerated vermicompost tea (ACT) and aerated vermicompost tea augmented with microbial enhancer (ACTME), were applied to the plants. Aerated water served as control. RESULTS: Mineral nutrients were significantly higher in ACTME compared with other teas, but total microbial population and activity did not differ with extraction method. All vermicompost teas similarly enhanced plant production, mineral nutrients and total carotenoids, and this effect was most prominent under organic fertilisation. Antioxidant activity and total phenolics were higher under organic compared with synthetic fertilisation. Vermicompost teas generally decreased phenolics under organic fertilisation and increased them under synthetic fertilisation compared with the control. CONCLUSION: The effect of vermicompost tea on crop growth is largely attributable to mineral nutrient, particularly N, uptake by plants. Non‐significant differences among extraction methods on plant response within fertiliser regimes suggest that aeration and additives are not necessary for growth promotion and nutrient quality under the conditions reported here. Copyright © 2009 Society of Chemical Industry     

蚯蚓粪基质对茄果类蔬菜穴盘苗耐热性的影响

为深入了解蚯蚓粪基质茄果类蔬菜穴盘苗的耐热性,以常规草炭系基质为对照,测定了番茄、茄子、辣椒穴盘苗叶片叶绿素含量、抗氧化酶(SOD、POD、CAT)活性、电解质渗出率和丙二醛(MDA)含量等指标。结果表明:高温胁迫下对照叶绿素总量降低幅度较大,比蚯蚓粪基质穴盘苗提高3.13%～246.02%;蚯蚓粪基质穴盘苗在高温胁迫下叶片抗氧化酶活性增强,对照抗氧化酶活性有所减弱;高温胁迫下对照穴盘苗叶片电解质渗出率和MDA含量增加幅度较大,分别比蚯蚓粪基质穴盘苗提高20.21%～122.53%和13.88%～58.14%,说明蚯蚓粪基质茄果类蔬菜穴盘苗具有较强的耐热性。     

Improved extraction of humic acids from vermicomposted organic waste by a column-based continuous elution method

A column-based continuous elution (CCE) method was developed for extracting humic acids (HA) from vermicomposted organic waste. Dissolution of HA by passing extractant (0.2 M NaOH) through vermicompost in a column followed by elution under gravity resulted in yields of 47.5% and 74.7% extractable HA in 24 h by International Humic Substance Society (IHSS) method and CCE method, respectively. These results were 63.3% and 97.9% in 48 h, respectively. The extracted HA showed similar FTIR absorption spectra and chemical compositions. Rate of oxidative degradation of HA during extraction by the CCE method was lower as compared with the IHSS method indicating improvement in extraction without altering the quality.     

Modelling of energy transformations in fertilized tropical fish ponds

The energy budget patterns of three tropical ecosystems in which the polyculture of fish was practised were studied. The rates of organic production of the three tropical ponds over two annual cycles were evaluated. Study of the utilization of energy in the three ponds, which were fertilized with vermicompost, cow dung and diammonium phosphate, revealed that herbivores were more efficient in utilizing energy than were autotrophs. The available energy in these systems was supplied by autochthonous sources. Silver carp was found to be the most efficient organism in converting energy in the grazer food chain in the ponds. The efficiency of the system in regard to fish production was 0.052, 0.049, and 0.051%, respectively, of the total available solar radiation. Organisms in various trophic levels were all characterized by energy changes in the studied ponds, forming the food webs contained in them.     

Yield and vitamin C content of tomatoes grown in vermicomposted wastes

Increasing quantities of earthworm digested materials (vermicompost) are being marketed as a peat‐free growth medium for amateur and professional food producers. Several studies indicate that growing tomatoes in peat mixed with low concentrations of vermicompost (10–20% by volume) produced by the earthworm Eisenea fetida increases yield of plants and marketability of fruits. Here we examined the effect of substituting commercial peat‐based compost with four different vermicomposts produced by the earthworm Dendrobaena veneta. Vermicompost was added to peat‐based compost at rates of 0%, 10%, 20%, 40% and 100% (v/v) and the following characteristics of tomato (Lycopersicon esculentum var. Money maker) assessed: germination, yield, marketability, fruit weight and ascorbic acid concentration. Vermicompost significantly increased germination rates (176%) and improved the marketability of fruits at 40% and 100% substitution rates due to the lower incidence of physiological disorders ('blossom end rot' and fruit cracking). Total fruit yield, marketable fruit yield, fruit number, individual fruit weight and vitamin C concentration were unaffected by the presence of vermicompost. Although vermicompost may provide a viable alternative to peat‐based growth media, overall, we found little added benefit from using vermicompost. We conclude that some of the previously reported benefits of vermicompost on horticultural production may be overstated and that marketing strategies should reflect this in order to preserve consumer confidence in vermicompost products. Copyright © 2007 Society of Chemical Industry     

以“蚯蚓粪-炭”为渗滤介质去除洗衣污水中的LAS的研究

洗衣污水是中国当前主要的生活污水之一。本研究试着将蚯蚓粪和炭按体积比混合组成渗滤介质,使洗衣污水从中渗透通过,对污水中的主要有害物质LAS（阴离子表面活性剂）进行吸附和降解。实验结果表明：洗衣污水经过这种混合介质（1︰1）的渗滤后,污水中的阴离子表面活性剂（LAS）的去除率达到96.78%,对洗衣污水起到明显的去污效果。