抄録
For establishment of cropping technique of eggplant (Solanum melongena L.) in non-flooded clayey paddy without underdrainage, soil moisture, oxidation in subsoil and yields of eggplants (cv. Niigata Kuro Juzen and cv. Senryo Nigo) grown in first- and fourth-year non-flooded clayey paddies were investigated, comparing with those of an upland field (sandy loam). Taro (Colocasia esculenta), soybean (Glycine max) and tomato (Licopersicon esculentum) were produced in each previous year in fourth-year non-flooded clayey paddy. Soil moistures (pF) in the 3 tested fields were similar until the middle of July. The pF in upland field maintained near 2.5 value after late of July. The pF of the first- year drained continued to exhibit a low value (1.5-2.0), whereas, that of the fourth-year drained paddy showed higher value, varying 1.9-2.6, in August. Soil oxidation was occasionally observed in the reduced layer of the fourth-year non-flooded paddy. The frequencies of soil clods less than 20mm after rotary tillage were 75-76% in the first- and fourth-year drained paddies, which were lower than that observed in the upland field. Though the growth of eggplant in the first-year non-flooded paddy was reduced, growth reduction was not recognized in the fourth-year non-flooded paddy, compared with that in the upland field. The yield of eggplant in the fourth-year non-flooded paddy increased in August, while it was small in the first- year non-flooded paddy. The total yield of eggplant grown in the fourth-year non-flooded paddy was significantly larger than those in the first-year non-flooded paddy and the upland field. From these results, it was recognized that soil properties in 4th-year non-flooded clayey paddy approached that of upland soil and it contributed the yield increase of eggplant.
