Low nitrogen availability and shallow plow layer decrease sugarcane (Saccharum officinarum L.) productivity in Kitadaito Island,Japan |
| |
Authors: | Koichi Yoshida Naoko Miyamaru Takeshi Kawanaka Yohey Hashimoto Koki Toyota |
| |
Institution: | 1. Department of Bio-Functions and Systems Science, Graduate School of Bio-Applications and System Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan;2. Okinawa Agricultural Technology &3. Development Co. Ltd, Itoman, Japan;4. Sugarcane and Ordinary Crops Section, Okinawa Prefectural Agricultural Research Center, Itoman, Japan;5. xEnvironmental Engineering Division, Okinawa Environmental Analysis Center Co. Ltd, Ginowan, Japan |
| |
Abstract: | Sugarcane is the main crop in Kitadaito Island, Okinawa, Japan. The average yield in Kitadaito Island for the past 30 years (1985–2015) was 44 Mg ha?1, 31% lower than that (64 Mg ha?1) in Okinawa Prefecture. Among the reasons for the low sugarcane productivity in Kitadaito Island, the effects of soil and cultivation factors have not been sufficiently studied. The objectives of this study were i) to evaluate the effects of soil physical and chemical properties and cultivation factors on sugarcane yield and sugar content in 50 fields of Kitadaito Island, and ii) to clarify factors affecting the sugarcane yield and sugar content. Statistical analysis of classification and regression trees (CART) showed that the sugarcane yield was low in fields with low available nitrogen (less than 16.5 mg kg?1) and with shallow plow layer depth (less than 29 cm). The soil available nitrogen had a significant positive correlation with soil humus (r = 0.39, P < 0.05). Two-times of subsoiling in the field before planting and during growing periods resulted in the significant increase of the depth of plow layer, compared to the fields with single and no subsoiling. A high sugar content was obtained in fields with exchangeable Mg more than 3.8 cmolc kg?1 and pH(H2O) less than 7.2. Our study therefore concluded that soil management practices for sugarcane production in Kitadaito Island should primarily be focused on available nitrogen, plow layer depth, and soil exchangeable Mg and pH. |
| |
Keywords: | available nitrogen kitadaito Island plow layer depth sugar content sugarcane yield |
|
|