The dependencies of the planting date on rainfall and soil moisture in paddy fields in Cambodia were analyzed to quantify farmers’ empirical knowledge regarding their decision of the planting date. Remote sensing data from multiple satellites covering the 2003–2019 period were analyzed. The planting dates in rain-fed paddies ranged from April to August, with large spatial variations and year-to-year fluctuations. In years when planting was suppressed in April and May, planting was extensively enhanced in June and August compared to normal years, and vice versa. Over the northeastern side of Tonle Sap Lake and south of Phnom Penh city, the areas planted in April and May were found to have positive correlations with rainfall and soil moisture, suggesting that wetter-than-average conditions encouraged farmers to plant earlier in the season. In contrast, this relationship was unclear on the western side of Tonle Sap Lake, where the rainfall amounts were larger throughout the year than in other areas in Cambodia. In this region, the relationship between the planting area and soil water availability was either unclear or was even slightly negative from June to August. Since more frequent dry spells have been detected after the onset of the rainy season in recent years, further studies and disseminations of potential changes in dry spells are important for the agronomic adaptation of planting dates under climate change.

分析了柬埔寨稻田中种植日期对降雨量和土壤水分的依赖性，以量化农民关于他们决定种植日期的经验知识。分析了 2003-2019 年期间多颗卫星的遥感数据。雨养稻田的播种期为4-8月，空间变异较大，年际波动较大。在4月和5月抑制种植的年份，与正常年份相比，6月和8月的种植量大大增加，反之亦然。在洞里萨湖东北侧和金边市南部，发现 4 月和 5 月的播种面积与降雨量和土壤水分呈正相关，表明高于平均水平的湿润条件鼓励农民提早播种. 相比之下，洞里萨湖西侧的这种关系并不明确，那里全年的降雨量比柬埔寨其他地区大。在该地区，种植面积与土壤水分有效性之间的关系在 6-8 月之间要么不明确，要么略呈负向。由于近年来在雨季开始后发现更频繁的旱期，进一步研究和传播旱期潜在变化对于气候变化下种植日期的农艺适应性具有重要意义。种植面积与土壤水分有效性之间的关系在 6 月至 8 月之间要么不明确，要么甚至略呈负向。由于近年来在雨季开始后发现更频繁的旱期，进一步研究和传播旱期潜在变化对于气候变化下种植日期的农艺适应性具有重要意义。种植面积与土壤水分有效性之间的关系在 6 月至 8 月之间要么不明确，要么甚至略呈负向。由于近年来在雨季开始后发现更频繁的旱期，进一步研究和传播旱期潜在变化对于气候变化下种植日期的农艺适应性具有重要意义。