Agricultural practices-induced pollution runoff has been widely acknowledged to be a significant source of nutrients fueling cyanobacterial bloom. The impact of topdressing activities on cyanobacterial bloom phenology (key parameters for depicting bloom process), however, has not been verified. Taking Lake Erhai, a typical eutrophic plateau lake, as an example, this study explored the spatio-temporal characteristics of phenological metrics and coverage extent for surface cyanobacterial bloom, based on phycocyanin pigment series retrieved from satellite and investigated the bloom responses to environmental forces. The results showed that higher intensity and earlier onset bloom with a larger coverage extent mainly occurred in the northern region. We identified three distinct cyanobacterial bloom growth patterns with large inter-annual variability in their bloom initiation timing (BIT). The earlier BIT is highly linked to elevated total nitrogen level and decreased wind speed. The bloom amplitude is mainly related to summer TN in 2003–2011, while associated with winter TN/TP ratio (TN, total nitrogen; TP, total phosphorus) during 2016–2019. Additionally, we found direct evidence linking agricultural topdressing and the BIT of a typical autumn bloom. After one week for the topdressing practice, the BITs lagged by approximately average 23 days, coinciding with high rainfall intensity. Our research demonstrates the topdressing activity should be reduced through agricultural planting adjustments. High TN and TP loss crops should be prohibited; planting adjustments should decrease high TP loss crop plantings in response to regional environmental forces.

由农业实践引起的污染径流已被广泛认为是促进蓝藻繁殖的重要养分来源。追肥活动对蓝藻花期物候（描述花期过程的关键参数）的影响尚未得到证实。以典型的富营养化高原湖泊Er海为例，本研究基于卫星提取的藻蓝蛋白色素系列，探索了表层蓝藻水华的物候指标时空特征和覆盖范围，并研究了水华对环境力的响应。结果表明，强度较高，花期较早，覆盖程度较大的地区主要在北部地区。我们确定了三种不同的蓝藻花开生长模式，它们的花开起始时间（BIT）具有较大的年际变化。早期的BIT与升高的总氮水平和降低的风速高度相关。盛花幅度主要与2003-2011年夏季的TN有关，而与2016-2019年冬季的TN / TP比（TN，总氮，TP，总磷）有关。此外，我们发现了直接的证据，将农业施肥与典型的秋季开花的BIT联系起来。经过一周的追肥实践，双边投资协定平均滞后了约23天，这与高降雨强度相吻合。我们的研究表明，应通过调整农业种植来减少追肥活动。应禁止高TN和TP损失作物；