Changes in Microbial Functional Diversity and Activity in Paddy Soils Irrigated with Industrial Wastewaters in Bandung, West Java Province, Indonesia

Characteristics, such as microbial biomass, basal respiration, and functional diversity of the microbial communities, were investigated in paddy soils located in Bandung, West Java Province, Indonesia, that have been heavily polluted by industrial effluents for 31 years. Paddy soil samples (10?C20 cm) were taken from two sites: polluted soils and unpolluted soils (as control sites). The polluted soils contained higher salinity, higher sodicity, higher nutrient contents, and elevated levels of heavy metals (Cr, Mn, Ni, Cu, and Zn) than unpolluted soils. Soil physicochemical properties, such as maximum water holding capacity, exchangeable sodium percentage, sodium adsorption ratio, and swelling factor, in polluted soils were much greater than those in unpolluted soils (P?<?0.05). Changes in the physical and chemical soil properties were reflected by changes in the microbial communities and their activities. BIOLOG analysis indicated that the functional diversity of the microbial community of polluted soils increased and differed from that of unpolluted soils. Likewise, the average rate of color development (average well color development), microbial biomass (measured as DNA concentration), and the soil CO₂ respiration were higher in polluted soils. These results indicate that major changes in the chemical and physical properties of paddy soils following the application of industrial wastewater effluents have had lasting impacts on the microbial communities of these soils. Thus, the increased activity, biomass, and functional diversity of the microbial communities in polluted soils with elevated salinity, sodicity, and heavy metal contents may be a key factor in enhancing the bioremediation process of these heavily polluted paddy soils.     

Spatial variability of soil solution chemistry under Hinoki cypress (Chamaecyparis obtusa) in Tama Hills

A monitoring study on precipitation and soil solution was conducted to analyze soil acidification processes at the Rolling Land Laboratory (RLL), Hachioji, Tokyo based on the spatial variability of the soil solution chemistry around the Hinoki cypress (Chamaecyparis obtusa) trunk. Soil solution samples were taken at various distances from the tree trunks and at various depths. Soil solution pH at the depth of 10 cm decreased to 4.1–4.2 on the downslope side of large tree trunks, presumably due to the heterogeneity of throughfall input and extensive infiltration of acidic stemflow. Ammonium ions brought by throughfall and stemflow were nitrified and provided large amounts of H⁺. Protons were replaced with exchangeable cations. When base cations were depleted, aluminum ion became the dominant cation species. On the average, Ca²⁺ concentration in the soil solutions at the depth of 10 cm decreased from 0.28 mmol_c L^-1 at the reference site to 0.18 mmol_c L^-1 on the downslope side and Mg²⁺ concentration decreased from 0.30 mmol_c L^-1 to 0.15 mmol_c L^-1. Arithmetic mean aluminum concentration at the depth of 10 cm on the downslope side was 0.35 mmol_c L^-1. Here aluminum dissolution was the main acid sink. Based on the spatial variability of the soil solution chemistry, soil solution acidification processes were divided into four stages.     

Butyltin and phenyltin compounds in river i bay sediments of Tokyo

The occurrence and current status of butyltin and phenyltin compounds were investigated in sediments collected from the Arakawa and Sumida Rivers and Tokyo Bay in 2000. A series of butyltin and phenyltin compounds, including monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPT), diphenyltin (DPT), and triphenyltin (TPT) was detected by gas chromatography-mass spectrometry (GC-MS). The total concentrations of the butyltin (MBT + DBT + TBT) and phenyltin (MPT + DPT + TPT) compounds ranged from 25.7 to 116 and from non-detectable levels to 22.4 ng g' (as Sn), respectively. The concentrations of the organotin (OT) compounds in sediments were relatively lower than those of the samples collected in 1984. OT compounds accounted for 124% (as Sn) of total Sn in the sediments. Among the OT compounds investigated, MBT was the most prevalent in the sediments.     

Abstracts of Nippon Dojohiryogaku Zasshi

Abstract

The humus composition was analyzed and the humic acid characterized by UV and visible absorption spectroscopy in order to investigate the rotting and maturing process of city refuse compost according to the method of Kumada et al. During the composting process, the following findings were obtained: (1) the HT value was almost constant, but the HE/HT ratio varied somewhat, (2) HA increased with decrease in FA, and the PQ value so increased clearly, (3) the shoulder-like absorption at a wavelength near 270 nm weakened, and (4) the RF value of humic acid increased, whereas the Δ log K value seldom varied.

The IR spectrum of humic acid gradually changed as follows: (1) the absorption band in the 1700-1600 cm^-1 region and in the 1550-1500 cm^-1 region increased slightly, (2) the band in the 1100-1000 cm^-1 region decreased, and (3) the bands at 835 and 710 cm^-1 com pletely disappeared. On the whole, the shape of the IR spectrum of the city refuse compost became featureless. These changes were probably due to the oxidation which occurred in the composting process.     

Effect of two whole-crop rice (Oryza sativa L.) cultivars on methane emission and Cu and Zn uptake in a paddy field fertilized with biogas slurry

A field experiment was carried out to evaluate the effect of two whole-crop rice (Oryza sativa L.) cultivars, TULT and Takanari, on methane (CH₄) emission in a paddy field fertilized with biogas slurry (BS) at rates of 0 (NF), 100 (BS100) and 300 (BS300) kg nitrogen (N) ha^?1, in comparison with chemical fertilizer CF100 (100 kg N ha^?1). Takanari produced significantly higher biomass (P < 0.001) than TULT and showed significantly (P < 0.01) lower CH₄ emission than TULT. BS applications caused higher CH₄ emission (52 ± 27 and 80 ± 19 g m^?2 in BS100 and BS300, respectively) than did CF100 (42 ± 18 g m^?2) and NF (28 ± 10 g m^?2) in TULT. In contrast, there was no significant difference in CH₄ emission in Takanari among the treatments (26 ± 2, 26 ± 2, 32 ± 4, 29 ± 8 g m^?2 in NF, CF100, BS100 and BS300, respectively). Methane oxidizing bacteria (MOB) showed significantly (P < 0.05) higher populations in Takanari than in TULT at harvest, which might be due to the higher root biomass (10.3 ± 2.2 g hill^?1) in Takanari than in TULT (8.9 ± 1.8 g hill^?1). MOB was significantly correlated with tiller number (R² = 0.176*) and plant biomass (R² = 0.242*). BS application showed higher copper (Cu) uptake in Takanari while it was not high in TULT. In contrast, it showed no difference in zinc (Zn) uptake in both varieties. Uptake of Cu was not different between the two varieties, while uptake of Zn in the grain was higher in TULT than in Takanari. The present study suggests that CH₄ emission deriving from BS application in paddy field can be mitigated by selecting an appropriate cultivar, like Takanari. However, care should be taken for heavy metal uptake in selecting cultivars.     

Effect of cold-water irrigation on bacterial wilt pathogen of tomato

Bacterial wilt caused by Ralstonia solanacearum is one of the most devastating bacterial diseases of plants worldwide. Management of bacterial wilt in tomato and other crops has been difficult, and so novel but easily implemented control methods are being sought. To evaluate the effect of cold-water irrigation on bacterial wilt of tomato, four treatments were used in which CF (chemically fertilized) soil and CF + FYM (chemical fertilizer + farmyard manure [FYM]) soil were inoculated with a bacterial suspension (R. solanacearum strain YU1Rif43) at 10⁶ colony forming units (CFU) g^?1 soil. Tomato seedlings were grown in Agri-pots in a plant growth chamber. The soil was irrigated with water that was kept at the same temperature in each treatment: 4, 10, 20, or 30°C. Incidence and severity of wilt, counting of the colonies of the culturable population of pathogen, and dry-mass and height of the plants were examined. After 45 days and in both kinds of soil, most of the plants had wilted in soil irrigated at 30°C. Wilt incidence was substantially reduced when transplanted seedlings were irrigated at lower temperatures (4–20°C). Survival of R. solanacearum was also reduced after being irrigated with water at lower temperatures, indicating that the reduced incidence of wilt was linked to reduced survival of the pathogen. Dry-mass and plant height were slightly higher under control conditions than in soils irrigated at lower temperatures. This study suggests that cold-water irrigation could significantly reduce bacterial wilt of tomato and have an adverse effect on survival of the wilt pathogen.     

Management of Cephaleuros parasiticaus Karst (Trentepohliales: Trentepohliaceae), an algal pathogen of tea plant,Camellia sinsensis (L) (O. Kuntze)

The efficacy of certain biocontrol agents were evaluated against Cephaleuros parasiticus Karst, a causal organism of red rust disease in tea plants. Spraying of systemic fungicides was found to be superior to biocontrol agents followed by algicides in controlling the disease under field condition. Dipping of shears in the solutions of fungicide, detergent or biocontrol agents failed to protect the disease spread. The study on the impact of different harvesting practices on disease development showed the highest disease incidence in continuously shear harvested fields and least in hand plucked fields. There was a reduction in disease incidence in spraying of a solution containing urea and murate of potash mixture at 1% level. The maximum green leaf yield and productivity index were recorded in biocontrol agents treated plots. Among the various group of biocontrol agents evaluated, Streptomyces sannanensis and Streptomyces griseus belong to actinomycetes was better than bacterial and fungal antagonists in terms of disease protection and increase in yield potential. Similarly, tea bush canopy architecture, physiological and biochemical parameters were also increased in plants treated with biocontrol agents. In the case of untreated control plots, the disease incidence was increased from 36% to 44.5% and the plants were found unhealthy in terms of chlorosis, stunted growth and heavy flowering with banji buds. The shoots collected from treated and untreated control plots were subjected to manufacture CTC black tea which revealed almost all the tea quality parameters were significantly improved in the treated plot over the untreated plots.     

Contribution of dissolved organic nitrogen deposition to total dissolved nitrogen deposition under intensive agricultural activities

For elucidating the atmospheric deposition contribution of dissolved organic nitrogen (DON) to the total dissolved nitrogen (TDN) deposition rate, dissolved inorganic nitrogen (DIN: NH₄ ⁺ + NO₃ ^–) and DON deposition rates were annually and monthly estimated during 4 and half-yr monitoring period in an experimental multi-farm under intensive agricultural activities of N fertilizer use and animal husbandry in Central Japan. Annual NH₄ ⁺, DON and NO₃ ^– deposition rates in bulk and wet deposition data accounted for 48%, 32% and 20% of TDN deposition, respectively, which indicated that this area is strongly affected by the intensive agricultural activities. The DIN and DON deposition rates were respectively estimated at 21.6 and 10.1 kg N ha^?1 yr^?1, which ranked high in a worldwide regional data set. Consequently, this area has been exposed to a large amount of N deposition including DON with N fertilizer input. The difference between bulk and wet deposition rates (NH₄ ⁺ and DON) is one of important factors controlling the N deposition in this area. Monthly DON deposition showed positive correlations with DIN and NH₄ ⁺ deposition rates, respectively, with a significant linear regression curve. The linear regression curve of our monthly data (n = 127) indicates the same trend as the worldwide annual data set (n = 31).     

Field-specific variable rate fertilizer application based on rice growth diagnosis and soil testing for high quality rice production

This study was carried out to verify the applicability of variable rate fertilization (VRF) based on soil testing and diagnosis of rice plant growth for high quality rice production of var. Chucheongbyeo at the farm level. The field trials were conducted at Icheon in Gyeonggi province on a 10 ha farm consisting of 45 experimental fields. For comparative study, 15 field trials were carried out adopting fertilizer management (FPM) practices currently used by farmers. FPM fields were managed by each rice grower using current cultivation methods, but in each VRF field fertilizer application was prescribed using soil test results and the amount of N fertilizer for top-dressing at panicle initiation stage was calculated using rice growth value at that stage. In VRF fields, the total amount of N fertilizer application was less (72 kg ha⁻¹) than that in FPM fields (103 kg ha⁻¹). However, the amount of K₂O fertilizer application was more in VRF fields (60 kg ha⁻¹) than that in FPM fields (52 kg ha⁻¹). The amount of P₂O₅ fertilizer application was similar between the VRF and FPM fields. Plant height was significantly shorter and the number of tillers was significantly more at VRF fields than at the FPM fields. Coefficient of variation (CV) of each growth characteristic measured in VRF was lower than that of FPM fields at panicle initiation stage. There was no difference in culm and panicle length and panicle number between them at the grain filling stage, but CV of panicle numbers per m² decreased in VRF compared with that of the FPM fields. Rice yield was not different between VRF and FPM fields despite higher brown rice recovery and 1,000-grain weight in VRF fields. Under VRF management, head rice yield increased due to an increase in head rice ratio accompanied by a reduction in brown rice protein content and variation of quality characteristics. These results suggest that VRF application based on soil tests and measurement of rice growth value at panicle initiation stage has the potential for quality control and production of high quality rice through increasing uniformity of growth and reducing the variability in quality among individual fields.