This study compared a work system consisting of deep plowing （plowing depth: 20 cm） with a chisel plow （deep plowing→wheat→shallow tillage→soybean→shallow tillage→rice: chisel deep plowing system） with a conventional system consisting of shallow tillage （depth of tillage: 10 cm） with a rotary tiller （shallow tillage→wheat→shallow tillage→soybean→shallow tillage→rice） to investigate the effects of pre-crop soil chemical property, soil hardness at rice transplantation, work speed and accuracy for rice transplantation, water requirement in depth during rice cultivation, yield, and grain quality, in a paddy upland rotation field with three-crop rotation of rice, wheat, and soybean in two years. The chisel deep plowing system resulted in lower soil hardness （11–20 cm below the surface） at rice transplantation, and the rice transplanter sank deeper, increasing the slip rate, resulting in slower work speed compared to the conventional system. In the same system, the unevenness of the plow sole slightly reduced the driving of the rice transplanter, but this was within the range that could be handled by steering wheel controls by the operator, and planting accuracy was equivalent. The water requirement in depth during rice cultivation was the same as for the conventional system, because the lower layer of subsoil became the layer limiting permeability. In the chisel deep plowing system, deep plowing before wheat cropping caused the subsoil with low T-C, T-N, and available N to mix into the plow layer, resulting in a reduction of straw weight in some areas, but there was no effect on yield or grain quality. The results suggested that deep plowing before wheat cropping with a chisel plow had little practical effect on rice transplantation and no effect on planting accuracy, water requirement in depth, yield, or grain quality, and can be managed in the same way as conventional cultivation.

This study compared a work system consisting of deep plowing with a chisel plow (deep plowing→soil pulverization→wheat seeding→shallow tillage→soybean seeding, hereinafter referred to as “chisel deep plowing system”) with a conventional seeding system consisting of shallow tillage with a rotary tiller (shallow tillage→wheat seeding→shallow tillage→soybean seeding) to investigate the effects of soil moisture and rate of soil pulverization during seeding-related operations, soil physical properties, drainage, growth and yield during soybean cultivation, in an upland field converted from paddy field with three-crop rotation of rice, wheat, and soybean in two years without underdrain construction. The results showed that the chisel deep plowing system reduced soil moisture during shallow tillage before soybean seeding, and increased the work speed and rate of soil pulverization, and slightly improved the soil pulverization rate during seeding. In addition, the porosity, gas phase ratio, available water, and saturated hydraulic conductivity were increased in the subsoil, and these effects were maintained until soybean harvest. Furthermore, drainage of the plow layer during soybean growth was improved by the improvement of physical properties in the subsoil. The results showed that soybean yield was increased by 11-13％ with increases in number of branches, total number of pods, and number of ripening pods under the chisel deep plowing system. However, without underdrain construction and with poor water permeability of the subsoil, and with intermittent heavy rainfall before soybean seeding, seeding may be delayed and soybean yield may be decreased, even with the chisel deep plowing system. Therefore, the chisel deep plowing system should be combined with drainage technology in the subsoil, if necessary for stable introduction of the system to a production site.

NDVI（Normalized difference vegetation index）measurements have become easier to recent years. This study compares handheld NDVI sensor values with light sources（H-NDVI）and NDVI calculated from images taken by drones equipped with multispectral cameras and spectral sunlight sensors（D-NDVI）. Root mean square error（RMSE）of the H-NDVI estimated from the D-NDVI, the assumed error and the range of NDVI used for growth diagnosis revealed the need for conversion between H-NDVI and D-NDVI. The effect of differences in sunlight conditions on D-NDVI measurements was also investigated. D-NDVI and H-NDVI were measured in the field plots of potato（Solanum tuberosum L.）varieties, 'Konahime' and 'Toya'. The regression equations were obtained with coefficients of determinations greater than 0.98, slopes ranging from 0.976 to 0.994, and intercepts from 0.005 to 0.017. The two regression equations were statistically combinable and the RMSE was small enough at 0.036, which were sufficiently small. The combined regression equation was used to convert D-NDVI to H-NDVI （estimated H-NDVI）, and no significant difference was found between the differences in D-NDVI and estimated H-NDVI respectively and H-NDVI．D-NDVI did not need to be converted to H-NDVI by the regression equation. The effect of direct sunlight on the D-NDVI measurements was compared among the different conditions of hourly sunshine hours and solar radiation. The results showed that the measured values were stable regardless of these conditions.

Nematode-suppressive tropical forage palisade grass （Urochloa brizantha） was introduced into the upland field crop rotation system, which was conducted in two fields in the southern Kyushu region. The crop rotation system was palisade grass–spinach–sweet potato–cabbage, hence this was a trial of arable and livestock corporation in the region. During the field crop rotation system experiments, conditions of fertilization and inter-row spacing, methods of seeding and inter-row management, and cultivation duration for palisade grass were modified. By these modifications, the forage nitrate content was improved, and the suitable cultivation system was clarified. After the cultivations of nematode-susceptible sweet potato cultivar “Koganesengan”, the root-knot nematode densities were increased. However, after every palisade grass cultivations, the nematode densities were suppressed to suitably low densities. The control manure of plant-parasitic nematode density by the introduction of forage crop palisade grass to the crop rotation system was demonstrated and confirmed.