A new cultivation method, based on a concept of hydroponics, for vegetable crop production under wet lowland field conditions in Southeast Asia

在低洼地区，甘薯块根和胡萝卜贮藏根的生长发育普遍受到涝渍或土壤含水量过高的影响。本研究表明，在潮湿的低地条件下，甘薯块根和胡萝卜贮藏根的生长发育受到土壤通气性的显著影响。本研究旨在开发改善根际土壤通气性的新技术，以提高热带和亚热带潮湿低地地区甘薯和胡萝卜的产量。本研究结果表明：(1)在土脊内添加稻秆、稻壳和稻壳炭等本地植物材料，改善了土壤空气成分。（ii）土壤中二氧化碳浓度较低，土壤垄沟含水量较低，促进了甘薯和胡萝卜的光合作用和生长。研究表明，如果在土壤脊内提供足够的空气空间，使用适当体积的适当材料，例如宽度为150毫米，厚度为120毫米的稻壳木炭以未混合的块状形式施用，那么在潮湿的低地条件下生产甘薯和胡萝卜是可能的。本研究开发的栽培方法可应用于其他蔬菜作物以及甘薯和胡萝卜等在潮湿低地条件下生长不良的作物，甚至在已被遗弃为荒地的潮湿低地也可以利用。本研究中用于改善土壤通气性的本土植物残渣在热带和亚热带国家容易获得，成本低，并且易于降解。因此，这种种植方式有助于建立良好的农业生态系统，实现可持续农业。

The tuberous roots of sweetpotato and storage roots of carrot have generally showed poor growth and development in low-lying areas due to water logging or excess moisture content of the soil In the present study, the growth and development of the tuberous roots of sweetpotato and storage roots of carrot were significantly influenced by the soil aeration nuder wet lowland conditions. The present study was then, conducted to develop new techniques to improve the rhizosphere soil aeration for increasing sweetpotato and carrot production under wet lowland areas in tropical and subtropical countries.In the result of the present study, (i) soil air composition wasimproved with providing the indigenous plant materials like rice straw, rice husk and rice husk charcoal inside the soil ridges. (ii) photosynthesis arid thus growth of sweetpotato and carrot was promoted due to lower carbon dioxide concentration in the soil and lower soil water content of the soil ridges.It is revealed that sweetpotato and carrot production under wet lowland conditions is possible if sufficient air spaces are provided inside the soil ridges using an appropriate volume of appropriate materials, e.g. a width of 150 mm and thickness of 120 mm of rice husk charcoal applied in the unmixed mass form.The cultivation method developed in the present study can be applied to other vegetable crops as well as sweetpotato and carrot which show poor growth under wet lowland conditions and can be utilized even in wet lowlands that have been left as wasteland.The indigenous plant residues used in this study to improve soil aeration are easily available with low cost in tropical and subtropical countries and easily degradable materials. Therefore, this cultivation method would contribute to establish the better agro- ecosystem for sustainable agriculture.