• Authors:
    • Shindo, J.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 94
  • Issue: 1
  • Year: 2012
  • Summary: Gross and per unit agricultural land area nitrogen balance (NB (G) and NB (A), respectively) in agricultural areas were estimated with a nitrogen-flow model for 13 Asian countries, for regions within a country, and for individual grid cells, from 1970 to 2005. Country- and regional-level estimates showed that NB (A) is higher in Japan and South Korea than in other Asian countries, but has recently been stable or decreasing. The contribution of inorganic fertilizer to the nitrogen input is decreasing, whereas that of livestock manure is increasing in these countries. In many other countries, the primary nitrogen source is inorganic fertilizer and its input rate and NB (A) have increased sharply since the 1980s. NB (A) of some Chinese provinces and Indian states were as high as those of Japan and South Korea. The results suggest that regional-scale estimation is necessary because of the large spatial variability in nitrogen flows within a country. Based on the NB (G) estimated for each 0.5A degrees A xA 0.5A degrees grid cell, nitrogen outflow from agriculture into major river basins was evaluated. About 20 % of the nitrogen balance flowed into China's Changjiang River basin, versus 10 % into the Ganges River basin. Uncertainties in the basic data and estimation results, and the use of an alternative measure of a country's environmental performance were discussed.
  • Authors:
    • Akiyama, H.
    • Nishimura, S.
    • Uchida, Y.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 156
  • Year: 2012
  • Summary: Factors controlling soil respiration ( RS) are of great interest because RS plays a critical role in determining global atmospheric carbon dioxide (CO 2) concentrations. Substrate availability is one of the most important factors controlling RS. Soil microorganisms consume various substrates ranging from simple sugars supplied by aboveground photosynthesis to complex humic acids in soil organic matter; however, substrate decomposition rates depend on substrate availability. Thus, RS is partly determined by the amount and quality of available substrate. However, accurate quantification of the amount of available substrate is difficult because soil microorganisms utilize carbon (C) substrates of varying quality for RS. Water-soluble C (WSC), hot-water-soluble C (HWSC), and microbial biomass C are known as indicators of the amount of available soil C substrate. We continuously measured RS in two contrasting soils, Andosol and Fluvisol, during the cultivation of soybean and brassica crops with a 6-month fallow period between them. The total annual RS in Andosol and Fluvisol were 37623 and 40849 g CO 2-C m -2, respectively, with no significant difference between them. WSC and HWSC were measured every month during RS measurement. During the soybean growth period, RS and WSC were correlated, and soil type did not affect RS. During the fallow period, RS, HWSC and microbial biomass C in Fluvisol were higher than those in Andosol, despite the total soil C in Andosol being higher than that in Fluvisol. RS during brassica crop growth was not correlated with any of the measured substrate indicators. We therefore concluded that the relationships among the measures of available substrates and RS at the field level could provide vital information on seasonal changes in the interaction between the effects of soil type and plants on RS, thereby leading to a better understanding of belowground C dynamics.
  • Authors:
    • Zahoor, A.
    • Fujimaki, H.
    • Andry, H.
    • Inoue, M.
    • Uzoma, K. C.
    • Nishihara, E.
  • Source: Soil Use and Management
  • Volume: 27
  • Issue: 2
  • Year: 2011
  • Summary: In this study, we performed a greenhouse experiment to investigate the effect of cow manure biochar on maize yield, nutrient uptake and physico-chemical properties of a dryland sandy soil. Biochar was derived from dry cow manure pyrolysed at 500 degrees C. Cow manure biochar was mixed with a sandy soil at the rate equivalent to 0, 10, 15 and 20 t biochar per hectare. Maize was used as a test crop. Results of the study indicated that cow manure biochar contains some important plant nutrients which significantly affected the maize crop growth. Maize yield and nutrient uptake were significantly improved with increasing the biochar mixing rate. Application of biochar at 15 and 20 t/ha mixing rates significantly increased maize grain yield by 150 and 98% as compared with the control, respectively. Maize net water use efficiency (WUE) increased by 6, 139 and 91% as compared with the control, with the 10, 15 and 20 t/ha mixing rate, respectively. Nutrient uptake by maize grain was significantly increased with higher biochar applications. Application of cow manure biochar improved the field-saturated hydraulic conductivity of the sandy soil, as a result net WUE also increased. Results of the soil analysis after the harvesting indicated significant increase in the pH, total C, total N, Oslen-P, exchangeable cations and cation exchange capacity. The results of this study indicated that application of cow manure biochar to sandy soil is not only beneficial for crop growth but it also significantly improved the physico-chemical properties of the coarse soil.
  • Authors:
    • Ichiyama, K.
    • Jitsuyama, Y.
    • Iwama, K.
    • Uchino, H.
    • Sugiura, E.
    • Yudate, T.
  • Source: Plant Production Science
  • Volume: 14
  • Issue: 1
  • Year: 2011
  • Summary: The use of cover crops is an effective technique to control weeds, which are one of the most serious problems for crop production without using herbicides. This study investigated the characteristics of cover crops for weed suppression at an organic farming field in a snowy-cold region, Hokkaido. Nine, three and two species of cover crops comprising both Poaceae and Leguminosae were grown in 2003, 2004 and 2005, respectively, at different sowing densities from 50 to approximately 4000 seeds m -2. The relationships between weed dry matter production and characteristics of cover crops, such as plant height and coverage, were investigated at 4 and 10 weeks after cover crop sowing (WAS). Correlation analysis of the weed dry weight with characteristics of cover crops revealed that the cover crop coverage at 4 WAS had a strong and stable effect on weed suppression. The cover crop coverage at 4 WAS was affected primarily by their seed weight when cover crops with a large variation in seed weight were used, and by the sowing density when cover crops with a small variation in seed weight were used. These results suggest that to achieve high weed suppression it is important to obtain higher coverage at the early growth stage of the cover crops with a heavy seed weight and high sowing density.
  • Authors:
    • [Anonymous]
  • Source: Agricultural Information Research
  • Volume: 20
  • Issue: 3
  • Year: 2011
  • Summary: This special section contains four papers dealing with the establishment of the field server applications for high-quality mandarin orange production in Japan. It covers soil moisture measurement to support production of high-quality oranges for information and communication technology application, field datalogger system using mobile phones and a web-based interface, a new tool utilizing silicone rubber balls for fruit hardness determination, and agro-environmental monitoring using wireless sensor network.
  • Authors:
    • Nakamura, M.
    • Fujita, A.
    • Kameoka, T.
  • Source: Agricultural Information Research
  • Volume: 20
  • Issue: 3
  • Year: 2011
  • Summary: Satsuma mandarin cultivated in Nanki, Mie Prefecture, Japan, is a delicious and highly profitable crop. However, the lack of new agricultural workers makes it difficult to preserve specialized agricultural skills and transfer them to new generations of workers. To support farmers, we introduced a small, stationary agricultural robot, "Field Server", which measures environmental and growing conditions in real time in orchards that used a mulch and drip irrigation system able to produce high-quality fruit despite variable weather. We developed an important cultivation diagnosis tool to support farmers based on the hardness of fruit, and monitored soil and tree water stress by means of time-domain reflectometry, (TDR), evapotranspiration, and soil moisture stress, as well as meteorological conditions. Using these parameters, we developed a water stress index for satsuma mandarin. To provide practical diagnostic techniques to support orange cultivation based on the measured data, we developed a network of sensors for measuring soil moisture content and tree water stress. We also investigated the relationship between fruit quality and the soil and tree water status to test their effectiveness as a diagnostic index. We also compared a convenient soil moisture sensor (Watermark) based on TDR and showed farmers how to install the sensor in the orchards. It was possible to continuously measure the soil moisture content except where multiple water supplies complicated the measurement process. We also found that tree water stress could be accurately estimated using TDR to measure the soil and tree moisture contents.
  • Authors:
    • Shimazu, H.
    • Yagyu, H.
    • Numano, N.
    • Kamiya, T.
  • Source: Agricultural Information Research
  • Volume: 20
  • Issue: 3
  • Year: 2011
  • Summary: We developed a mobile phone-based field datalogger system for mandarin orange production. The system focuses on collecting data that can be used to determine the watering schedule for cultivation using multi combined with drip irrigation. In the study area at Kumano, in Japan's Mie Prefecture, automated field monitoring was performed using Field Server, a server computer installed in the field and a sensor network to collect weather information. However, indicators such as fruit size, fruit hardness, leaf roll, and soil or tree volumetric water content are still collected by visual inspection, creating a burden for the field workers. The system we developed lets them input measurements of these indicators directly in the field. The data is then stored by Field Server along with data from other users and environmental data measured by Field Server or Japan's AMeDAS system. The results can be visualized as a timeline using a Web-based system, and the users can compare their results with data from other users, and can then consult with experts in their area.
  • Authors:
    • Bhandary, N. P.
    • Koike, Y.
    • Nishimura, F.
    • Tsuno, H.
  • Source: Journal of Water and Environment Technology
  • Volume: 9
  • Issue: 2
  • Year: 2011
  • Summary: Matsuyama region, located in Shikoku Island, Japan faces the Seto Inland Sea on the west, where the annual rainfall is relatively less than in the other areas in Japan. In such favorable condition, the cultivation of citrus fruits is popular, and there are a large number of small reservoirs for irrigation purposes. The citrus groves are distributed in hilly areas surrounding the paddy fields and residential areas so there are higher chances for the nearby water environment to get affected by leachate from the groves. This paper investigates the water quality characteristics of the leachate from the groves, and studies the changes of the leachate quality near the collecting reservoirs. It was found that the grove soils are highly acidic and the leachate contains metals and nutrients in high concentration. On the other hand, the water quality of the leachate changed after it flowed into the reservoirs, and the concentrations became lower. It is understood that chemical and biological reactions help remove the contaminants in the reservoir, and from the standpoint of self-purification, reservoirs play an important role. This paper also discusses the kinetics of the self-purification and the quantitative estimation based on the experimental results.
  • Authors:
    • Honda, K.
    • Ohta, I.
  • Source: Annual Report of the Kansai Plant Protection Society
  • Issue: 53
  • Year: 2011
  • Summary: Sitobion akebiae is a promising alternative host aphid using a banker-plant system of Aphidius gifuensis. This study was conducted to evaluate the effect of host plant species and varieties on population growth of S. akebiae. Barley, wheat, oats and rye were tested in this study. The population increase of S. akebiae were lower on seedlings of the barley variety 'Shunrai' than other plants. But S. akebiae successfully increased on the matured plants with ears of 'Shunrai'. These results suggest that young seedlings of the barley 'Shunrai' should be useless for host plants of S. akebiae.
  • Authors:
    • Munkhtsetseg, E.
    • Kimura, R.
    • Şaylan, L.
    • Kamichika, M.
  • Source: Theoretical and Applied Climatology
  • Volume: 105
  • Issue: 1/2
  • Year: 2011
  • Summary: In this study, variations in carbon dioxide (CO 2) fluxes resulting from gross primary production (GPP), net ecosystem exchange (NEE), and respiration ( Re) of soybean ( Glycine max L.) were investigated by the Eddy Covariance method during the growing period from June to November 2005 on an irrigated sand field at the Arid Land Research Center, Tottori University in Tottori, Japan. Although climatic conditions were humid and temperate, the soybeans required frequent irrigation because of the low water holding capacity of the sandy soil at the field site. Finally, it has been found that the accumulated NEE, GPP, and Re fluxes of soybean over 126 days amount to -93, 319, and 226 gC m -2, respectively. Furthermore, the average ratio of GPP to Re was 1.4 and the average ratio of NEE to GPP was about -0.29 for the growth period of soybean. Daily maximum NEE of -3.8 gC m -2 occurred when LAI was 1.1.