• Authors:
    • Yashima, M.
    • Zsuposne Olah, A.
    • Vago, I.
    • Katai, J.
    • Nagano, H.
    • Kong, Y.
    • Inubushi, K.
  • Source: Soil Science and Plant Nutrition
  • Volume: 59
  • Issue: 3
  • Year: 2013
  • Summary: The production/consumption of greenhouse gases (GHG) in soils are of great importance in global warming, but the involved soil physico-chemical and biological characteristics affecting GHG production and consumption potentials are poorly understood in different land-use types. Carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) production/consumption potentials from four land-use types and 10 soil types in central Japan and eastern Hungary, and their relationships with soil characteristics, were investigated. The average of CO2 production in Japanese soils was significantly higher than that of Hungarian soils due to the relatively higher microbial biomass carbon (MBC) content. N2O production from both countries' soils did not exhibit a significant difference. Most soils except Japanese paddy and soybean soils showed the potentials for CH4 consumption. Forest and grassland soils had relatively higher CO2 and N2O production than orchard and cropland soils for both countries. From regression analyses, it could be concluded that soil total nitrogen (TN) and ammonium-nitrogen (NH4 (+)-N) account for 40.8% and 25.5% variations of the soils' CO2 and N2O productions, respectively. The CH4 consumption was positively correlated with soil carbon/nitrogen (C/N) ratio, while soil MBC availability could account for 15% variation of CH4 consumption under aerobic conditions.
  • Authors:
    • Oikawa,S.
    • Okada,M.
    • Hikosaka,K.
  • Source: Plant and Soil
  • Volume: 373
  • Issue: 1-2
  • Year: 2013
  • Summary: The effects of elevated CO2 on leaf area index (LAI) vary among studies. We hypothesized that the interactive effects of CO2 and nitrogen on leaf area loss have important roles in LAI regulation. We studied the leaf area production and loss using nodulating soybean and its non-nodulating isogenic line in CO2-controlled greenhouse systems. Leaf area production increased with elevated CO2 levels in the nodulating soybean stand and to a lesser extent in the non-nodulating line. Elevated CO2 levels accelerated leaf area loss only in nodulating plants. Consequently, both plants exhibited a similar stimulation of peak LAI with CO2 elevation. The accelerated leaf loss in nodulating plants may have been caused by newly produced leaves shading the lower leaves. The nodulating plants acquired N throughout the growth phase, whereas non-nodulating plants did not acquire N after flowering due to the depletion of soil N. N retranslocation to new organs and subsequent leaf loss were faster in non-nodulating plants compared with nodulating plants, irrespective of the CO2 levels. LAI regulation in soybean involved various factors, such as light availability within the canopy, N acquisition and N demands in new organs. These effects varied among the growth stages and CO2 levels.
  • Authors:
    • Inubushi, K.
    • Iwasa, H.
    • Dubey, S.
    • Singla, A.
  • Source: Biology and Fertility of Soils
  • Volume: 49
  • Issue: 7
  • Year: 2013
  • Summary: Biogas production generates digested slurry as a by-product. It can be used as fertilizer especially after its conversion into digested liquid. A microcosm-based study was conducted in order to compare the effects of single application of digested liquid or chemical fertilizer on N2O flux and crop yield of komatsuna vegetable. Analysis revealed that digested liquid-treated soils released almost equal cumulative N2O (0.43 g N m(-2)) compared to chemical fertilizer (0.39 g N m(-2)). The uncropped soils treated with the digested liquid and chemical fertilizer released more N2O compared to corresponding cropped soils. The N2O emission factor and soil mineral N contents were similar for the digested liquid and chemical fertilizer-treated soils. Plant biomass in the first crop after digested liquid application was significantly higher (5.59 g plant(-1)) than that after applied chemical fertilizer (4.78 g plant(-1)); but there was no significant difference for the second crop. Nitrogen agronomic efficiency was improved by the digested liquid compared to chemical fertilizer. This study indicates that cumulative N2O flux was similar after application of the digested liquid and chemical fertilizer, while the overall yield from both croppings was increased in the digested liquid-treated soil compared to chemical fertilizer-treated soil.
  • Authors:
    • Kitano, M.
    • Yasunaga, E.
    • Setoyama, S.
    • Araki, T.
    • Tamanoi, A.
    • Matsubara, K.
    • Ohara, M.
    • Yano, T.
  • Source: Environmental Control in Biology
  • Volume: 51
  • Issue: 1
  • Year: 2013
  • Summary: Light condition is a fundamental environmental factor for high-quality plant production. In this paper, we discuss how light condition affects fruit development in the long and short term, and attempt to clarify management methods for active fruit development under conditions of low solar radiation, by using quantitative research on fruit water and carbon balance during greenhouse cultivation of Satsuma mandarin (Citrus unshiu Marc.). A significant decrease in yield due to shading was not detected, but we confirmed that shading treatment affected the dry weights of source-sink units, fruit volume, increase in volume of the fruits, and fruit quality parameters, such as sugar accumulation, acid content, and rind color. Qualitatively, the carbon balance of Satsuma mandarin fruit is comparable to that of tomato fruit or rice panicle, but quantitatively, the carbon balance of Satsuma mandarin fruit may differ, as shown by low sink relative growth rate. In addition, fruit growth parameters such as translocation rate for a fruit and fruit relative growth rate showed significant positive correlations with dark respiration, despite the shading treatment. The fruit carbon demand may be simply described by fruit dark respiration as the sum of new photosynthetic carbon and stored carbon translocation for a fruit.
  • Authors:
    • Ohta, H.
    • Sumi, H.
    • Inafuku-Teramoto, S.
    • Taira, I.
    • Asikin, Y.
    • Takara, K.
    • Wada, K.
  • Source: Journal of Agricultural & Food Chemistry
  • Volume: 60
  • Issue: 32
  • Year: 2012
  • Summary: Citrus peels are important sources of various pleasant aroma compounds and valuable bioactive substances. To investigate differences in the composition and content of Shiikuwasha ( Citrus depressa Hayata) peels from different cultivation lines, the composition of volatile aroma components, flavanones, and polymethoxylated flavones (PMFs) in four Shiikuwasha cultivation lines was examined. The composition of volatile aroma components in cold-pressed extracts of Shiikuwasha peels was analyzed using gas chromatography-flame ionization detection and gas chromatography-mass spectrophotometry. The extracts contained mainly monoterpene hydrocarbons (93.40-97.25%), including limonene (46.52-68.26%) and gamma-terpinene (21.48-30.52%). Differences in the composition of volatile aroma compounds in the Shiikuwasha cultivation lines were revealed using principal component analysis. Additionally, the composition of flavanones and PMFs was determined using high-performance liquid chromatography methods. Neohesperidin (96.58%) was the predominant flavanone in 'Izumi kugani' peel, while the other peels had high hesperidin contents (89.26-98.66%). Moreover, the PMFs of Shiikuwasha peels were composed of nobiletin (56.74-64.77%) and tangeretin (23.17-34.70%).
  • Authors:
    • Hoshino, Y.
    • Hirata, T.
    • Sarwar, A.
    • Araki, H.
  • Source: Acta Horticulturae
  • Issue: 950
  • Year: 2012
  • Summary: As asparagus plants are grown for a long period after transplanting, it is not possible to plow the field for soil improvement. Recently, because of global warming, establishment of new cropping system with carbon sequestration in soil has been expected. Cover crops provide a large amount of organic matter into the soil in many cropping. The effects of living mulch of cover crops on weed control and carbon storage were evaluated in the asparagus field planted for more than 16 years at the Experimental Farm of Hokkaido University, Sapporo, Japan. Wheat 'Hokushin' and 'Mulchi-mugi', barley 'Temairazu' and rye 'Kita-midori' were used as living mulch and were sown from early April to middle in May. Cropping with living mulch was repeated from 2006 to 2008. Wheat and barley continued vegetative growth because of no meeting of low temperature when they were sown in late April and May. However they were planted in early April, heading was observed in some plants. Weeds in interrow space were controlled by the emerged leaves of living mulch. Weed control ability of barley was high because of broad leaves emerged. Weed dry weight in summer reduced to 5% in barley living mulch compared with bare field when barley was planted at seeding density of 10 kg/10 a, in 2008. It reduced to 25% in wheat 'Mulch-mugi' which has tolerance to hot temperature. Heading was observed in rye even if rye was sown in May. Carbon content in the top soil with barley and rye increased 0.26-0.28% in average compared with bare field (no living mulch), however, there was no significant difference in soil carbon content among observed fields with or without cover crops. Spear yield was measured in 'Gijnlim' field, 8 years old, treated with living mulch in 2008 and significant difference was not recognized between rows with and without wheat living mulch in spring 2009.
  • Authors:
    • Hirata, T.
    • Komatsuzaki, M.
    • Nakamoto, T.
    • Araki, H.
  • Source: Soil Science and Plant Nutrition
  • Volume: 58
  • Issue: 1
  • Year: 2012
  • Summary: We hypothesized that cover cropping could increase soil microbial activities under various tillage systems and that increased microbial activities would improve soil properties. Soil sampling was conducted at two fields in Japan in 2009. At the Ibaraki field (Andosol, clay loam), three tillage practices (no-tillage, plowing to 30 cm, and rotary tillage to 15 cm) and three types of winter cover cropping [bare fallow as control, hairy vetch ( Vicia villosa Roth), and rye ( Secale cereale L.)] were conducted from 2003 to 2009. At the Hokkaido field (Fluvisol, light clay), two tillage practices (autumn tillage and rotary tillage with a rotary tiller to a depth of 15 cm once in autumn and twice in a year, respectively), and four types of winter cover cropping (bare fallow, hairy vetch, bristle oat ( Avena strigosa L.), and a mixture of hairy vetch and bristle oat) were conducted from 2006 to 2009. Soil microbial activities and the fungal-to-bacterial activity ratio (F/B ratio) were estimated by the substrate-induced respiration (SIR) method with the use of selective antibiotics. At the Ibaraki field, rye cover cropping showed higher microbial SIR than bare fallow at depths of 0-30 cm and rotary tillage maintained higher microbial SIR than no-tillage or plowing at depths of 7.5-15 cm. There was no meaningful interaction effect between cover cropping and tillage on microbial SIR. At the Hokkaido field, cover cropping and tillage had only limited effects on microbial SIR. High F/B ratios (indicating fungal dominance) were recorded with the use of cover crops in both fields. Fungal SIR, estimated from the microbial SIR and F/B ratio, was closely related to the content of total soil organic carbon (SOC) and the mean weight diameter (MWD) of water-stable aggregates. Based on SOC, fungal SIR was significantly higher under rye cover cropping. The relationship between fungal SIR and MWD was affected by tillage. We conclude that rye cover cropping and rotary tillage were very effective in increasing fungal SIR, SOC, and MWD in the Ibaraki soil. Field practices that enhance fungal activities might be effective in improving certain types of arable soil.
  • Authors:
    • Kometani, T.
    • Hosoda, A.
    • Hashimoto, H.
    • Taniguchi, H.
    • Tsuno, T.
    • Adachi, S.
  • Source: Nippon Shokuhin Kagaku Kogaku Kaishi = Journal of the Japanese Society for Food Science and Technology
  • Volume: 59
  • Issue: 7
  • Year: 2012
  • Summary: Consuming rice as the staple, 0.95 million tons of rice bran is produced annually in Japan as a by-product from the rice milling process. Bran is used in several applications such as animal feed and fertilizer for mushroom cultivation, but most of it has been discarded as an agricultural waste although it contains various functional substances, such as gamma-oryzanol, ferulic acid, sterol, wax, ceramide, phytin, inositol and protein. It could be considered a scarcely used but promising resource. As such, continuous efforts have been dedicated to exploring its effective utilization. In this context, functionalities of the substances contained in the bran are summarized, and our attempts for improving functionality, improving ease of use, and exploring new applications are presented.
  • Authors:
    • Inubushi, K.
    • Ohkubo, S.
    • Kato, S.
    • Nagano, H.
  • Source: Soil Science & Plant Nutrition
  • Volume: 58
  • Issue: 6
  • Year: 2012
  • Summary: Here we have investigated the emission of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from long- and short-term organic farming Andosols in Matsumoto city of Nagano, in central Japan. We focus on three upland plots in Matsumoto, distinguished by how long they had each experienced continuous organic farming (OF)in these three cases, since 1971, 2009, and 2010 (plots hereafter termed M39-OF, M1-OF, and M1F-OF, respectively). Since 2001, in M39-OF, mainly rye (Secale cereale L., as green manure) and soybeans [Glycine max (L.) Merril, as crop] were cultivated, in winter and summer respectively, without tillage, other fertilizers and agro-chemicals. In contrast, from 2001 to 2008 in M1-OF, and from 2001 to 2009 in M1F-OF, these plots underwent conventional farming of some vegetables with tillage, fertilizer and agro-chemicals. Soils sampled from M39-OF and M1-OF in August 2009 were incubated for 4 weeks in darkness at 25 degrees C. During these 4 weeks, M39-OF emitted 8.0 times more CO2 and 274 times more N2O than M1-OF. Less than 2?mu g carbon (C) kg1?dry soil of CH4 was emitted from both soils. From February 2010 until January 2011, CO2, CH4, and N2O emission rates of M39-OF and M1F-OF were measured almost monthly, using a closed-chamber method. Annual CO2, CH4, and N2O emissions were 317, 1.7, and 27?g CO2-C equivalent m2 in M39-OF, and 138, 0.2, and 21?g CO2-C equivalent m2 in M1F-OF, respectively. The rye yield in M39-OF was 334?g?C?m2. Soybeans in M39-OF and M1F-OF yielded 290 and 286?g?C?m2, and withdrew 230 and 224?g?C?m2, respectively. Greenhouse gas (GHG) balance was calculated at 52 and 97?g CO2-C equivalent m2 in M39-OF and M1F-OF, respectively. Negative GHG balance indicated that M39-OF was acting as a GHG sink, with higher CH4 absorption than M1F-OF. Further, this beneficial function for global warming was thought to be based on its cultivation system, which had included green manure application since 2001. The difference in gas exchange between incubation and field experiments was considered a reason for the difference in N2O emission between incubation and field experiments.
  • Authors:
    • Takebe, M.
    • Karasawa, T.
  • Source: Plant and Soil
  • Volume: 353
  • Issue: 1-2
  • Year: 2012
  • Summary: Aims A field experiment was conducted where maintenance of indigenous arbuscular mycorrhizal (AM) fungal populations was attempted using AM host cover crops arranged temporally or spatially during growth of nonmycorrhizal crops. Methods To arrange AM hosts temporally, sunflower or oat was grown as a cover crop after non-host cropping (cabbage) or fallowing. In order to arrange AM hosts spatially, red clover, white clover or vetch was intercropped during growth of non-host cabbage. Results The AM colonization and growth of maize with previously introduced sunflower or oat were much greater than those without introduction of cover crops or those with introduction of non-host cover crops. The AM colonization and yield of winter wheat grown after cabbage with AM host intercropping were greater than those after cabbage only cropping, suggesting that arrangement of AM hosts between cabbage rows is effective for maintaining the AM fungal population in soil during non-host cropping. Conclusions Mycorrhizal hosts cropped after or during non-host cropping is an effective means to increase indigenous AM fungal populations. The results show that AM colonization, P uptake and productivity of crops after cultivation of nonmycorrhizal crops can be improved by arranging AM hosts temporally or spatially as cover crops.