Masakazu Komatsuzaki

Physical properties, structure, and shape of radioactive Cs from the Fukushima Daiichi Nuclear Power Plant accident derived from soil, bamboo and shiitake mushroom measurements.

We conducted an elution experiment with contaminated soils using various aqueous reagent solutions and autoradiography measurements of contaminated bamboo shoots and shiitake mushrooms to determine the physical and chemical characteristics of radioactive Cs from the Fukushima Daiichi Nuclear Power Plant accident. Based on our study results and data in the literature, we conclude that the active Cs emitted by the accident fell to the ground as granular non-ionic materials. Therefore, they were not adsorbed or trapped by minerals in the soil, but instead physically adhere to the rough surfaces of the soil mineral particles. Granular Cs* can be transferred among media, such as soils and plants. The physical properties and dynamic behavior of the granular Cs* is expected to be helpful in considering methods for decontamination of soil, litter, and other media.

Isolation and Molecular Characterization of a Multicellular Cyanobacterium, Limnothrix/Pseudanabaena sp. Strain ABRG5-3

A cyanobacterium, semi-filamentous multicellular strain ABRG5-3, was isolated and its unique nature was characterized. This axenic strain formed colonies and was motile on an agarose plate. The 16S rRNA gene of ABRG5-3 exhibited similarities to those of the Limnothrix and Pseudanabaena strains, which are known as filamentous and nonheterocystous cyanobacteria. Peaks in absorbance for the accumulation of chlorophyll a, phycocyanin, and phycoerythrin were observed in the cell extract. Natural separation of the pigments occurred in the supernatant of the autolysed cells. The cell lysis was promoted by osmotic shocks and lysozyme treatments. Chlorophyll a and total DNA were abundantly recovered from the cells. Analysis of the restriction-modification system for genomic DNA revealed novel diversity. Moreover, we made a successful attempt to create antibiotic-resistant strains by conjugation with a foreign plasmid, which indicates that strain ABRG5-3 is transformable.

The effect of minimum tillage with weed cover mulching on organic daikon (Raphanus sativus var. longipinnatus cv. Taibyousoufutori) yield and quality and on soil carbon and nitrogen dynamics

Minimum tillage with weed cover mulching (MT) could be one alternative practice for root vegetable production because of soil erosion control and energy savings. This study compared the effects of MT and conventional tillage with weed removal (CT) on daikon yield and quality, soil carbon and nitrogen dynamics, and physical properties under organic farming practices. Root yields of daikon were 77% higher on average in MT than in CT although weed biomass was higher in MT than in CT in both years. Organic fertilizer application also significantly increased daikon yield. Nitrate-N content in daikon root was lower in MT than in CT. Soil total C and N at 0–2.5 cm soil depth were significantly higher in MT than in CT in both years but organic fertilizer application did not increase soil total C and N. Soil bulk density at 0–7.5 cm soil depth was significantly lower in MT than in CT. Penetration resistance between daikon rows was also significantly lower in MT than in CT at 0–4 cm soil depth, although this relationship was reversed in between 11 and 17 cm soil depth. These results suggest that MT is a beneficial approach for root vegetable production, given that it produces excellent crop yields and increased soil total C and N with minimum disturbance to agro-ecosystems.

Effects of tillage and winter cover cropping on microbial substrate-induced respiration and soil aggregation in two Japanese fields

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.

Cover Crop Nutrient and Biomass Assessment System Using Portable Hyperspectral Camera and Laser Distance Sensor

This study evaluated the potential of portable spectral camera techniques for measuring cover crop chemical composition in different growth stages. A height measurement system was also developed using a laser distance sensor to predict cover crop biomass. PLS (Partial Least Squares) regression was used to evaluate the relationship between cover crop nutrient content and spectral data. The study revealed that a partial cross-sectional area of canopy had a slightly higher correlation with the cover crop biomass than that of the canopy height. High correlations were observed between the predicted and observed accumulation of N (R2 = 0.8698), Ca (R2 = 0.8512), Mg (R2 = 0.8415) and K (R2 = 0.9451). This method can be used to obtain information on cover crop nutrient accumulation without disturbing cover crop growth.

Power Consumption of No-tillage Seeder under Different Cover Crop Species and Termination for Soybean Production

Abstract To achieve the maximum benefit of no-tillage with cover crop in the sustainable farming system, we conducted experiments on the performance and power consumption of a no-tillage seeder under different combinations of cover crop species, residue management and termination in soybean production. The results showed that the power consumption of the no-tillage seeder was higher with rye than hairy vetch and mixed-seeding, and increased with higher quantity of cover crop residue. The termination and management of cover crop significantly affected the cover crop biomass accumulation and power consumption of the no-tillage seeder. The results revealed that late cover crop termination increases the biomass while the performance of the no-tillage seeder declined. Therefore, flail mower cutting and mix seeding were appropriate for improving the no-tillage seeder in soybean production.

Fate of 15N-labeled Inorganic Fertilizer in an Upland Soil Applied with Sweet Sorghum Bagasse and N Uptake Efficiency by Komatsuna Plants

Abstract Sweet sorghum bagasse (SSB) is a soil amendment with potential for biofuel production. This study was conducted to determine the appropriate techniques for application of SSB and the effect of incorporation of inorganic fertilizer (IF) on the production of komatuna (Brassica rapa) plants. SSB was applied to the surface of the plant or incorporated into soil. The N fate of IF was evaluated by using 15N-labeled IF. The combination of surface application of SSB and incorporation of IF to soil decreased the N uptake by komatsuna plants but increased dry weight, whereas the incorporation of IF and SSB gave lower komatsuna dry weight than IF treatment alone. Moreover, the application of SSB tended to increase the N distribution from IF to komatsuna with decreased N loss from the plant-soil system. These results showed that surface application of SSB is effective for increasing crop production due to reduction of N loss and improved N use efficiency.

Application of portable hyper-spectral camera in andisols soil nitrogen assessment

Soil nitrogen content has very important influence on soil parameters and crop productions, so the soil nitrogen monitoring and management are urgently required to satisfy the demand for precision agriculture. This research is aimed to develop the simple and low cost monitoring methods to determine the soil nitrogen pools using hyper spectral camera in Andisols soil. Partial least square regression (PLSR) with cross-validation was used to calibrate the spectral data. The research estimated the potential of soil nitrogen qualitative analysis using visible (VIS) spectrographs, near infrared (NIR) spectrographs and combination of these two spectrographs. Results showed that model assessment accuracy by V10 (360nm-1010nm) spectrograph is higher than by N17E (900nm-1700nm) spectrograph. In addition, combining these two spectrographs increased the model prediction accuracy. Evaluation index (EI) test was employed in this research, and the results showed that prediction is acceptable to use of practical to predict soil nitrogen content.

Performance of a No-tillage Seeder with Different Cover Crop Species and Residue Management for Sweet Sorghum for Sustainable Biofuel Production

The strategy for sustainable biofuel production should be compatible with increasing SOM (soil organic matter) to improve soil quality for biomass productivity and reducing purchased inputs for production. Combining cover crops with no-tillage offers many benefits for improving soil quality, but requires a higher level of management to achieve maximum benefit. This study evaluated the performance of a no-tillage seeder for sweet sorghum production and identified appropriate ways of using the no-tillage seeder with various amounts of cover crop residue. Previous field research revealed that using a medium (360 rpm) PTO rotational speed and mixed-seeding of rye and hairy vetch with a no-tillage seeder is effective for increasing sweet sorghum germination under cover crop residue mulch.

Studies on the Relation between Persistence of Volunteer Cereals and Cropping System in Upland. VI Separating characteristics of rough rice separaters to contaminated barley by mixing of volunteer wheat grain.

We investigated the separating characteristics of rough rice separaters to contaminated barley grains by mixing of volunteer wheat grains.A principal factor in separation by rough rice separater was the difference ratio of grain length. So the difference ratio of grain length for barley and volunteer wheat grain were 1:0.78.The performance of a rough rice separater for removing volunteer wheat grain from barley grain was poor, when separating the rice from the chuff. When the pan oscilation was 160rpm and pan slope, 16°, the rough rice separater efficiently removed volunteer wheat grain. So barley grain had met the standerd requirements at inspecting.Then Newtons efficiency was 0.7. But thirty percent of the barley grain were discharged with wheat grain.This operation was an emergency measure of prevention against the contamination of barley grain by mixing of volunteer wheat grain. Because barley grain loss on separating by rough rice separater resulted from falling in shipment of barley.