Whether or not urban expansion will have a significant effect on global crop production in the future is a controversial issue. In the present study, urban areas in 185 countries from 2000 to 2100 are projected based on the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) using geographical data from previous studies of global urban areas. Losses to existing cropland due to urban expansion are then predicted, after which reductions in potential crop production are calculated. The following results emerge from these analyses. (1) The total global urban area in 2000 was estimated to be 1.12 million km² after adjusting the urban area in MOD12 (or MODIS global land cover product). (2) The global urban area in 2050 will be 3.12 million km² in the A2r scenario, 2.99 million km² in the B1 scenario, and 3.09 million km² in the B2 scenario. (3) Losses to global cropland in 2050 will be 1.01 million km² in the A2r scenario, 0.89 million km² in the B1 scenario, and 0.98 million km² in the B2 scenario. (4) Consequently, potential crop production in 2050 will decrease by 8.5 percent in the A2r scenario, 7.4 percent in the B1 scenario, and 8.3 percent in the B2 scenario compared to figures from 2000. Reduction rates will be remarkably higher in Asian developing countries than in the rest of the world.

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To evaluate the suppressive effect of five additives on cadmium (Cd) uptake by komatsuna (Brassica rapa var. perviridis cv. Early komatsuna), a pot experiment with Cd-contaminated acidic soil was conducted in a greenhouse. Autoclaved lightweight aerated concrete (ALC), lherzolite (Lherzo), gypsum made from waste plasterboard (Gyp-w), magnesia cement (Magwhite) and calcium carbonate containing less than 10 % pure gypsum (Cacar-G) were added to the soil (1 %, w / v). The shoot Cd concentration of the plants was considerably suppressed by the application of Cacar-G and Magwhite, following by ALC moderately, Lherzo and Gyp-w slightly. The order was similar to that of the additives which increased the soil pH. In addition, the order except Gyp-w was in agreement with that of the additives which decreased the exchangeable Cd concentration in the soil. Gyp-w increased the water-soluble Cd concentration in the soil. We presumed that the Cd uptake of the plants might be controlled by the soil pH and the level of water-soluble and exchangeable Cd. It is concluded that Cacar-G and Magwhite are considerably effective soil amendments in the suppression of the Cd uptake by the plants; ALC is moderately effective, whereas Lherzo and Gyp-w are scarcely effective when they are added at 1 % concentration to the soil.

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Reduction of the environmental impact of the chemicals used in industrial activity has become important, and as an example of that, environmentally friendly agriculture is being promoted as a part of agricultural environmental policy. The active ingredient application frequency is used as an indicator of the reduced environmental influence of agricultural chemicals, but it is not clear whether there has been an actual reduction in environmental impact. The purpose of this study was to examine which indicator is preferable for the environmental management of farms. We analyzed six kinds of environmental indicators and found that the correlation between the risk score of agricultural technology for pesticide use (RST) and other indicators is small. The use of a simpler indicator showed that environmental impact was not necessarily reduced. When we analyzed the potential influence on the environment according to the agricultural chemicals usage, we found it necessary to change the means of each kind of vegetable to determine the agricultural chemicals environmental impact reduction. The advantages of the use of RST instead of the chemicals application frequency are as follows: (1) it is possible to evaluate the environmental performance of the entire management by examining two or more sections and to compare the environmental performance with past management, (2) it is effective for the development of agrotechnology, (3) the planning process for agricultural chemicals application can be introduced into the control points, and the RST indicator can be used as the environmental management indicator of good agricultural practice (GAP), (4) environmental information can be presented on the commodity label for the agricultural producer.

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