Toposequential Variation in Soil Fertility and Rice Productivity of Rainfed Lowland Paddy Fields in Mini-Watershed (Nong)in Northeast Thailand
Toposequential Variation in Soil Fertility and Rice Productivity of Rainfed Lowland Paddy Fields in Mini-Watershed (Nong)in Northeast Thailand
复制标题
泰国东北部小流域（Nong）雨养低地稻田土壤肥力和水稻生产力的时序变化
DOI：
10.1626/pps.6.147
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发表时间：
2003
影响因子：
2.5
通讯作者：
N. Kabaki
中科院分区：
文献类型：
--
作者：
K. Homma;T. Horie;T. Shiraiwa;N. Supapoj;N. Matsumoto;N. Kabaki
摘要 被称为 Nongin Thai 的小流域是泰国东北部雨养低地水稻文化的地理组成部分，在了解该地区雨养水稻产量低且不稳定的环境限制方面构成了独特的单位。通过土壤采样的植物测定和水稻生长和产量的田间测量，研究了小流域内土壤肥力的时序变化及其与水稻生产力的关系。使用从每个小流域内的不同稻田中取样的土壤进行灌溉盆栽稻的植物测定实验表明，通过水稻干物质生产评估的土壤肥力在田间最多存在 5 倍的差异。土壤肥力的差异主要归因于氮（N）供应能力的差异，而氮（N）供应能力本身与土壤有机碳（SOC）含量有很强的相关性。因此，盆栽水稻的生物量产量与SOC成正比。表明 SOC 作为土壤肥力评价指标的有用性。粘土对土壤肥力的影响远小于SOC。各田地的实际水稻产量也表现出相当大的田间差异，其中大部分是由 SOC 含量、水稻生长持续时间和施肥量来解释的，尽管水分利用率也会影响产量。产量与生长持续时间呈正相关，因此与早期移植呈正相关。随着小流域内田地海拔的升高，田地的 SOC 和粘土含量均呈现出陡峭的梯度，导致水稻产量呈现明显的顺序分布。土壤有机碳和粘土含量的时序分布表明，森林砍伐后的水稻种植加速了土壤侵蚀，从上到下。土壤肥力的大序列梯度需要针对每个序列位置进行不同的资源和作物管理，以提高整个小流域的水稻生产力。
Abstract Mini-watersheds called Nongin Thai are geographical components of rainfed lowland rice culture in Northeast Thailand, and constitute distinct units in understanding environmental constraints for low and unstable rainfed rice production there. The toposequential variation of soil fertility and its relation to rice productivity within mini-watersheds, was examined by phytometry of sampled soils and field measurements of rice growth and yield. The phytometry experiment with irrigated potted rice using soils sampled from various rice fields within each mini-watershed, revealed that soil fertility as evaluated by rice dry matter production showed a 5 times difference among the fields at most. The difference in the soil fertility was ascribed primarily to that in nitrogen (N) supply capacity, which itself had a strong correlation with soil organic carbon (SOC) content. Accordingly, the biomass production of pot-grown rice was proportional to SOC. content, which suggested the usefulness of SOC as an index for soil fertility evaluation. The effect of clay on the soil fertility was much less than that of SOC. The actual rice yield in each field also showed quite large field-to-field variation, most of which was explained by the SOC content, rice growth duration and fertilizer application rate even though water availability also affected the yield. The yield positively correlated with growth duration and hence with earlier transplanting. Both SOC and clay contents of fields showed steep gradients with ascending field elevation within mini-watersheds, resulting in a marked toposequential distribution of rice yield. The toposequential distributions of SOC and clay contents imply that rice culture after deforestation accelerated soil erosion from upper to lower fields. The large toposequential gradient in soil fertility requires different resource and crop management for each toposequential position, in order to improve rice productivity of the mini-watershed as a whole.