This study investigated the behavior and meat productivity of Satsuma Black Aigamo ducks (SBA ducks) raised through free ranging in a paddy field. The control (free-ranging SBA ducks in a 0.2 a fallow field) and experimental groups (free-ranging SBA ducks in a 4 a paddy field) comprised 10 (♂5: ♀5) and 8 (♂4: ♀4) birds, respectively, and were fed a commercial diet (crude protein 15%, metabolizable energy 2,800kcal/kg) ad libitum from 1 to 9 weeks of age. After free ranging, both groups were fattened from 9 to 15 weeks of age in a duck shed through ad libitum feeding of the commercial diet, following which all birds were slaughtered. The eating and moving behaviors of the ducks in the experimental group were more intense than those in the control group at 2 and 4 weeks of age (P<0.05). As a result, the free-ranging ducks in the paddy field were more effective in pest and weed control than those in the fallow field. A significant difference was found in the body weight at 9 weeks of age between the treatments (2,513g for control group and 2,855g for experimental group; P<0.05). The feed conversion ratios for the control and experimental groups during the experimental period were 6.8 and 7.2, respectively. The fat color b* score of breast meat was significantly lower in the experimental group (P<0.05). However, the body weight and carcass characteristics at 15 weeks of age were not different between the groups. These findings indicated that SBA ducks had high weed control, pest control, and meat production potential in integrated rice and duck farming.

Raising rice seedlings in Japan typically starts early in the spring when ambient temperatures are low. To promote growth, temperature and insolation conditions around the seedlings are usually optimized by using greenhouses and/or by covering the seedlings with sheetings. However, on hot days with fine weather, using greenhouses and sheetings increases the risk of high-temperature damage to rice seedlings. In particular, organically grown seedlings are at higher risk because organic farming does not use agrochemicals to supplement growth. In this study, a new sheeting for covering growing seedlings was developed. The sheeting has a high-thermal-insulation capacity which prevents the damage. An optimal method for raising seedlings using the sheeting was also examined.

Air and bed-soil temperature under the new sheeting (Tokan-Honami/Tokankosan Co., Ltd. Japan) was 5°C cooler than when conventional sheeting was used (Silver-Love #80/Tokankosan Co., Ltd.) on hot days with fine weather. The new sheeting prevented damage to rice seedlings. Conversely, the growth of rice seedlings under the new sheeting was delayed at low air temperatures associated with cloudy and rainy weather. This delay in growth could be overcome by overlaying the new sheeting with the conventional sheeting (Silver-Polyto #80/Tokankosan Co., Ltd.) at only the chilly days.

Compared to conventional methods, the new sheeting provided a more secure environment for raising seedlings. Moreover, the new sheeting was particularly well suited to raising seedlings for organic farming in shallow outdoor plastic pools.

Tentative reference values for soil diagnostics were calculated from the quantitative relationship between yield levels and soil chemical characteristics in 70 upland fields used for organic farming in Hokkaido. Relative yields in each field were estimated through comparison with that in the nearby conventional field for reference. There were 32, 36, and 2 fields at the lower, comparable, upper levels of elevation, respectively. These fields were separated into the lower level group (LLG; n＝32) and the comparable+upper level group (CULG; n＝38) for a comparative analysis of soil chemical characteristics, since the number of upper level fields was small. The parameters considered for quantifying soil chemical characteristics (after harvesting) were pH (H₂O), electrical conductivity (EC), total carbon (T-C), total nitrogen (T-N), T-C/T-N, exchangeable CaO (Ex-CaO), exchangeable MgO (Ex-MgO), exchangeable K₂O (Ex-K₂O), Ex-CaO/Ex-MgO, Ex-MgO/Ex-K₂O, cation exchange capacity (CEC), base saturation percentage (BSP), nitrogen present as NH₄⁺ (NH₄-N), nitrogen present as NO₃^－ (NO₃-N), free inorganic nitrogen with incubation (30°C, 4 weeks), autoclave extractable nitrogen (AEN, 105°C, 1 hr), available phosphorus (Truog method), phosphate absorption coefficient, Cl^－, and sulfur present as SO₄^2－ (SO₄-S).

Statistically, CULG had higher NO₃-N (P＝0.006), SO₄-S (P＝0.038), AEN (P＝0.074), and T-C/T-N (P＝0.082); and lower BSP (P＝0.013), pH (H₂O) (P＝0.016), and Ex-MgO/Ex-K₂O (P＝0.082) values than LLG. Out of the 7 parameters described above, 5 showed a dependence on the applied fertilizer type, but the relationship between application of specific fertilizers and yield levels remained unclear.

Tentative reference values for soil diagnostics were proposed by using the 25 and 75 percentile groups for each parameter measured in CULG fields for defining the lower and upper limits, respectively. Although a detailed comparison of soil properties between the two groups would require all 7 parameters discussed above, only NO₃-N and pH (H₂O) values are enough for yearly diagnostic checks.