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It has been demonstrated that inoculation of Welsh onions (Allium fistulosum) with arbuscular mycorrhizal (AM) fungi during the nursery period followed by transplantation was effective in improving growth and reducing phosphorus fertilizer application. However, what range of soil phosphorus fertility is suitable for AM fungal inoculation remains unclear. To elucidate the optimal level of soil phosphorus fertility in a non-allophanic Andosol, we conducted a series of Welsh onion inoculation experiments under field conditions. Experiments were conducted in 2009–2010 and 2015–2016 in experimental plots at Tohoku University, northern Japan. Soil phosphorus fertility levels varied as follows: very high, high, medium, and low at 750–1,000, 150–250, 70–150, and 30–70 mg P2O5 kg soil−1, respectively (Truog method). Welsh onions were inoculated with a commercial Rhizophagus sp. R10 inoculum and grown for 7–9 weeks in a greenhouse nursery bed. The seedlings were transplanted into plots under the application of one, two or three levels of phosphorus fertilization. In the medium and high plots, inoculation increased marketable yields of Welsh onions irrespective of phosphorus fertilization, while no effect was found in the very high plot. In the low plot, inoculation did not clearly improve the yield, which was low irrespective of the treatments. These results indicate that AM fungal inoculation of Welsh onions in this soil was effective when available phosphorus ranged from 70 to 200 mg P2O5 kg soil−1.

Winter flooding of paddy rice production is characterized by flooding of paddy fields during the winter fallow season. It has attracted attention in terms of its ecological function, supporting the biodiversity of paddy field ecosystems. Therefore, recent winter flooding in Japan has been conducted by organic farming. However, it is not well documented how organic farming with winter flooding affect the productivity of rice. We conducted field experiments to examine changes in rice yield in organic farming with winter flooding compared with those in conventional and organic farming over the period of 5 and 9 years. The yields in organic farming with winter flooding were lower than those in conventional farming but were almost the same as those in organic farming. We found a trend that shows the relative yield of organic farming with winter flooding compared to that of conventional farming increased during the first several years after the conversion from conventional farming to organic farming with winter flooding, but that it decreased after several years. This trend may be caused by the flourishing of weeds during continuous organic farming with winter flooding. Therefore, we tested four weed control methods: rice bran application, mechanical weeding, repeated puddling, and side-row fertilizer application. Although each method suppressed weeds to certain extents, some combinations of different weeding methods more effectively suppressed weed growth, thereby resulting in enhanced rice yields. We found a trend in rice yield and a possibility of combining several weed control methods in organic farming with winter flooding.

This paper discusses methods and numerical simulations of one-dimensional profiling of targets in the direction of electromagnetic wave incidence. Two types of target materials are considered: a perfectly conducting material and a lossy dielectric of which the dielectric constant is assumed known a priori. The inversions for profile reconstructions for perfectly conducting bodies are based upon the modified extended physical optics method (EPO) for a perfectly conducting target. The modified extended physical optics method assumes the modified physical optics current properly over the entire surface of conducting scatterers. For dielectric scatterers having a known dielectric constant, the Rayleigh method is used for the inversion. The inversion is carried out by performing iteratively or singly the Fourier transformation of the backscattered field in the frequency domain. Numerical simulation results of the target profiling are shown for axially symmetric bodies with nose-on backscattering.