Carbon and nitrogen stocks and their mineralization potentials are higher under organic than conventional farming practices in Japanese Andosols

ABSTRACT

This study aimed at understanding whether and how long-term organic rice farming affects soil carbon (C) and nitrogen (N) stocks and their mineralization potentials in submerged rice paddies in Tochigi, Japan. An incubation experiment was carried out to assess the impacts of internal nutrient cycling after organic farming (OF) for 4–5 years (4OF), 8–9 years (8OF), and 12 years (12OF), compared with a conventional rice field (CF). Soil samples were collected at 0–15 cm and 15–20 cm in flooded rice fields after harvest in October 2013. pH and bulk density at 0–15 cm were significantly lower in 12OF fields than in CF fields (by 0.22 unit pH and 17.5%, respectively). Compared with CF, 12OF fields showed significant differences in soil organic carbon (SOC) and total nitrogen (TN), but 4OF and 8OF fields did not. In 8OF fields, the C decomposition (Co) and N mineralization (No) potentials were significantly higher (by 34.0% and 35.6%, respectively, at 0–15 cm, and by 67.1% and 24.5% at 15–20 cm) than in CF fields. Similarly, in 8OF fields at 0–15 cm, the Co:SOC and No:TN ratios were 19.8% and 23.2% higher, respectively, than in CF fields. Co, No, Co:SOC, and No:TN in 12OF fields were higher than those in CF fields, demonstrating the effects of prolonged organic rice farming. Additionally, in 12OF fields, C and N stocks were significantly higher (by 15.5% and 17.2%, respectively, at 0–15 cm, and by 4.8% and 12.1% at 15–20 cm) than in CF fields. Our findings suggest that long-term organic rice farming increases soil C and N stocks as well as C and N mineralization in Japanese Andosols.     

Behavioural analysis of a nonionic detergent in the kraft pulp washing process using cryo-time-of-flight secondary ion mass spectrometry and cryo-scanning electron microscopy

In order to understand the kraft pulp decolouring mechanism on using a nonionic detergent, the pulp washing process and the resulting pulp handsheets were investigated by examining the brightness, kappa number, thioacidolysis product yield, and dewatering efficiency in the pressing sheet making process. The pulp decolouring could be attributed to a decrease in the lignin content and an improvement in the dewatering efficiency. Furthermore, the detergent distribution in the aqueous pulp suspension obtained during the pulp washing process was visualised using cryo-time-of-flight secondary ion mass spectrometry/scanning electron microscopy (cryo-TOF-SIMS/SEM). The detergent was clearly observed at the transverse surface of the pulp fibre cell wall and was also detected in the lumen of the fibres, suggesting the permeation of the detergent into the pulp fibre cell wall. Based on these results, the pulp decolouring mechanism can be proposed as follows: the detergent permeates into the pulp fibre cell wall and promotes the solution-exchange between the inside and the outside parts of the fibre cell wall, finally washing away the chromophoric substances such as lignin and its degradation products owing to the enhanced dewatering efficiency.     

Biological dinitrogen fixation and soil microbial biomass carbon as influenced by free-air carbon dioxide enrichment (FACE) at three levels of nitrogen fertilization in a paddy field

An experiment was conducted in an Andosol paddy field in Shizukuishi (Iwate Prefecture, Japan) to determine the effects of free-air CO₂ enrichment (FACE) on biological N₂-fixation activity and soil microbial biomass C at three levels of N application. Rice (Oryza sativa L. cv. Akitakomachi) plants were grown under ambient CO₂ or FACE (ambient +200 µmol mol^-1 CO₂) conditions throughout the growing season with each treatment having four replicated plots. Three levels of N fertilizer (high, standard and low; 15, 9 and 4 g N m^-2, respectively) were applied to examine the effect of different N availability under both CO₂ conditions. Soil samples were collected at four different times from upper and lower soil layers (0-1-cm and 1-10-cm soil depths, respectively) and analysed for biological N₂-fixation (BNF) activity and microbial biomass C (MBC) by the acetylene reduction and chloroform fumigation-extraction methods, respectively. The amounts of chlorophyll-type compounds (Chls), an index of algal growth, and soil available C were also determined. Compared to the ambient CO₂ treatment, the FACE treatment had significantly higher BNF activity in both the upper and lower soil layers at ripening only in low-N soil and at harvest at all three levels of N fertilization rates. MBC was significantly increased by FACE in both the upper and lower soil layers from the middle to later period of the growing season compared to the ambient CO₂ treatment. The FACE treatment increased the Chls in the upper soil layers at ripening only in low-N soil and at harvest at all three levels of N fertilization rates. The amount of soil available C was not significantly different between FACE and ambient CO₂ treatments in both the upper and lower soil layers throughout the cropping season. From these results it can be concluded that the FACE treatment had a significantly positive influence on BNF activity, MBC and Chls at different levels of N fertilization rates in paddy field during the cropping season.     

Post-exposure treatment of cats with mouse-cat chimeric antibodies against feline herpesvirus type 1 and feline calicivirus

In order to confirm the in vivo effectiveness of anti- feline herpesvirus type 1 (FHV-1) mouse-cat chimeric antibody (FJH2), and anti-feline calicivirus (FCV) mouse-cat chimeric antibody (F1D7), cats that had been experimentally infected with FHV-1 or FCV were administered intravenously with the chimeric antibodies, and observed for clinical manifestations. The symptoms due to FHV-1 or FCV infection in the cats administered FJH2 or F1D7 were obviously decreased when compared with those of the non-administered control cats. From these results, it was confirmed that both FJH2 and F1D7 were effective at reducing the appearance of symptoms due to FHV-1 and FCV infection, respectively.     

Cryptic occurrence of <Emphasis Type="Italic">Chattonella marina</Emphasis> var. <Emphasis Type="Italic">marina</Emphasis> in mangrove sediments in Probolinggo,East Java Province,Indonesia

Mangrove forests and adjacent creeks are known to be highly productive estuaries, which are partly supported by benthic microalgae that grow on the sediments. During surveys investigating the microalgal floras of mangrove swamps in the eastern part of Java Island, a mud sample unexpectedly included large numbers of a notorious fish killer, Chattonella-like motile cells, and its resting cysts. These motile cells were established as clonal cultures for further identification and physiological tests. The cysts were examined through palynological and molecular biological means. Identification based on light microscopy and ribosomal RNA gene sequences confirmed that these cells and cysts were Chattonella marina var. marina. While the strains were genetically identical to the temperate strains isolated from Japan and China, temperature experiments showed that the Indonesian strains possessed a high maximum quantum yield of photosystem II even after exposure to 34 °C, a temperature at which the Japanese strain could not survive. Salinity experiments showed adaptation of the strains to a salinity of 15. These findings, together with the discovery of populations of cysts in the mangrove sediment, highlight the tough and unique nature of the Indonesian strains, which are likely adapted to wide fluctuations of temperature and salinity in mangrove swamps, and pose a potential risk to fisheries in Indonesia.     

Axle-less F1-ATPase rotates in the correct direction

F1-adenosine triphosphatase (ATPase) is an ATP-driven rotary molecular motor in which the central gamma subunit rotates inside a cylinder made of three alpha and three beta subunits alternately arranged. The rotor shaft, an antiparallel alpha-helical coiled coil of the amino and carboxyl termini of the gamma subunit, deeply penetrates the central cavity of the stator cylinder. We truncated the shaft step by step until the remaining rotor head would be outside the cavity and simply sat on the concave entrance of the stator orifice. All truncation mutants rotated in the correct direction, implying torque generation, although the average rotary speeds were low and short mutants exhibited moments of irregular motion. Neither a fixed pivot nor a rigid axle was needed for rotation of F1-ATPase.     

Application of DNDC model to estimate N<Subscript>2</Subscript>O emissions from green tea fields in Japan

Heavy doses of N fertilizers are commonly applied to green tea fields in Japan, and cause large amount of nitrate leaching in ground water and emission of ammonia and nitrous oxide (N₂O) to the atmosphere. The Denitrification and Decomposition (DNDC) model was tested against experimental data on N₂O emissions from the tea field in Nishio, Aichi, Japan. There were reasonable agreements between the simulated and measured values of N₂O emissions for this site. The model was then applied for estimating the environmental impacts as affected by farm management practices, climate change, and soil properties. The model results were assessed with respect to major indicators of agro-ecosystems including crop yield, soil organic carbon sequestration, nitrate leaching loss, and N₂O emission. The results indicated that use of compost significantly reduced nitrate leaching and N₂O emissions in comparison with N fertilizer. When soil pH and texture shifted to non-acidic and coarser soil, N₂O emission increased; and a change in temperature and precipitation affected N₂O emission, nitrate leaching, and SOC sequestration. This study thus revealed the biogeochemistry model as a powerful tool in addressing the complex efficacy of the alternative farm management practices in tea fields across various climate and soil conditions.     

深色有隔内生真菌(DSE)引进菌株对铁皮石斛的接种效应

[目的]深色有隔内生真菌(DSE)是一类与植物共生的内生真菌,研究DSE对铁皮石斛苗生长的影响,可为铁皮石斛专用菌肥的开发利用提供理论依据.[方法]试验分为7个DSE菌株分别与铁皮石斛组培苗和盆栽苗共生培养两个阶段,按不同DSE菌株接种铁皮石斛组培苗设7个处理,另以不接种菌株为对照处理,测定不同处理下铁皮石斛组培苗生长指标;按不同DSE菌株制成的菌液浇灌盆栽苗设7个处理,以未浇菌液为对照处理,测定不同处理下铁皮石斛盆栽苗生长指标.[结果]供试菌株均能与铁皮石斛苗共生,其中菌株24L-4处理的促生作用较为突出;接种该菌株后,铁皮石斛组培苗的株高、叶宽、茎径和干重分别较对照处理显著增长33.3%、65.7%、27.3%和45.1%;铁皮石斛盆栽苗的茎径、鲜重和干重分别较对照显著增长104.0%、83.9%和114.7%;显微镜观察发现该菌株的深色有隔菌丝和类似微菌核的定殖结构分布于铁皮石斛根部皮层的细胞内.[结论]DSE真菌能明显提高铁皮石斛的生产能力,具有较好的开发利用潜力.     

Hydrogen peroxide produced by a low‐molecular‐weight compound in milk with high electrical conductivity in dairy cows

In dairy cows, hydrogen peroxide (H₂O₂) produced from a low‐molecular‐weight compound in milk from inflamed quarters was lower than that in milk from un‐inflamed quarters. In milk of delivery grade, characteristics of H₂O₂ production in milk with high electrical conductivity (EC) were examined in this study. Milk samples were collected from a total of 230 cows at 1‐month intervals, and the EC of skimmed milk was determined. Based on the highest and the lowest EC of a cow's quarter milk, the inter‐quarter difference of ≥0.6 mS/cm (mean + t_0.01 SE) was taken as a high EC. Milk with high EC was found in 52 quarters. In cows with milk of high EC, H₂O₂ production in milk with normal EC was higher than that in milk with high EC in the same animal but was lower than that in the control population. In milk with high EC, the decrease of H₂O₂ production correlated with the increase in EC. The production of H₂O₂ decreased in particular when the inter‐quarter difference exceeded 0.8 mS/cm. In milk collected from the same quarter 1 month before, EC changed from normal to high, and H₂O₂ production decreased. In milk from the other three quarters, EC remained normal and H₂O₂ production remained unchanged. We concluded that milk with high EC appeared in low H₂O₂‐producing cows. The results suggest that the degree of decrease in H₂O₂ production reflects the extent of quarter abnormality.