Long-Term Field Experiment for Monitoring Soil Carbon Content in Japanese Grasslands: Initial Data from 2010 to 2012

A long-term field experiment for monitoring soil carbon content in Japanese grasslands started in 2010 to investigate the changes in soil carbon content and the effect of composted livestock manure application. We established grassland plots with 3 levels of manure application treatment at 10 sites. Bulk density values in many sites had wide inter-replicate and inter-annual variability. It is reasonable to suppose that the variability in the bulk density reflect spatial variability of physical properties within the grasslands because the annual trends of the bulk density values were not consistent. Organic carbon concentration tended to increase yearly in the surface layer (0–5 cm), whereas those for the subsoil layer (5–30 cm) stayed relatively constant. The organic carbon concentration in the surface layer tended to increase with increasing latitude and the amount of manure applied. When data from all the sites were taken into account, carbon content also tended to increase over time following grassland renovation. These results indicate that Japanese grasslands have the potential to sequester organic carbon. The monitoring has just begun, and it is important to continue the effort to achieve the goals of this study

N2O and CH4 Emissions from Andosols in an Intensive Dairy Farming Region, Japan

Symposium Pape

Modelling N2O emissions from Andosols in an intensive dairy farming region, Japan

Session 2: Nitrogen, Green House Gasses and Agricultur

Integrated Evaluation of Soil Carbon Budget by Manure Application on Forage Production

Grasslands and forage crop fields produce forages and also have many services and functions such as repositories of biodiversity, climate regulation and soil conservation (Sala and Paruelo, 1997). Carbon budget is one of these important ecosystem services by high levels of carbon sequestration below ground (Hungate et al., 1997). Manure application increases carbon budget and also affects forage production, NO3- leaching to underground water and N2O emission to atmosphere. Integrated evaluation of these various environmental impacts is important to find optimum condition for forage production and environmental impacts. LIME2 (Life-cycle Impact assessment Method based on Endpoint modeling 2, Itsubo and Inaba, 2010) is one of the methods to evaluate environmental impacts and to integrate them into a single index of environmental damages with the unit of Japanese yen. By comparing this index to economic benefit of forage production, integrated evaluation of environmental damages and profit of farmers is achieved. In this study, the effects of manure application to forage production, carbon budget, NO3- leaching and N2O emission were evaluated and optimum level of manure application level was estimated with LIME2 integration factors

Grazing Affects Exosomal Circulating MicroRNAs in Cattle

<div><p>Circulating microRNAs (c-miRNAs) are associated with physiological adaptation to acute and chronic aerobic exercise in humans. To investigate the potential effect of grazing movement on miRNA circulation in cattle, here we profiled miRNA expression in centrifugally prepared exosomes from the plasma of both grazing and housed Japanese Shorthorn cattle. Microarray analysis of the c-miRNAs resulted in detection of a total of 231 bovine exosomal miRNAs in the plasma, with a constant expression level of let-7g across the duration and cattle groups. Expression of muscle-specific miRNAs such as miR-1, miR-133a, miR-206, miR-208a/b, and miR-499 were undetectable, suggesting the mildness of grazing movement as exercise. According to validation by quantitative RT-PCR, the circulating miR-150 level in the grazing cattle normalized by the endogenous let-7g level was down-regulated after 2 and 4 months of grazing (<i>P</i> < 0.05), and then its levels in housed and grazing cattle equalized when the grazing cattle were returned to a housed situation. Likewise, the levels of miR-19b, miR-148a, miR-221, miR-223, miR-320a, miR-361, and miR-486 were temporarily lowered in the cattle at 1 and/or 2 month of grazing compared to those of the housed cattle (<i>P</i> < 0.05). In contrast, the miR-451 level was up-regulated in the grazing cattle at 2 months of grazing (<i>P</i> = 0.044). The elevation of miR-451 level in the plasma was coincident with that in the <i>biceps femoris</i> muscle of the grazing cattle (<i>P</i> = 0.008), which suggests the secretion or intake of miR-451 between skeletal muscle cells and circulation during grazing. These results revealed that exosomal c-miRNAs in cattle were affected by grazing, suggesting their usefulness as molecular grazing markers and functions in physiological adaptation of grazing cattle associated with endocytosis, focal adhesion, axon guidance, and a variety of intracellular signaling, as predicted by bioinformatic analysis.</p></div