Abstract: The utilization of cultured species diversity to promote the sustainable development of modern agriculture has been a concern worldwide. Integrated rice-fish farming is one of the patterns of cultured species diversity utilization. A critical question that needs to be addressed in the development of integrated rice-fish farming systems is how to rationally configure the proportions of rice and aquatic animals to achieve stable rice yields and obtain maximum aquaculture production, without causing negative impacts on the environment. In this study, we first compared the effects of different aquaculture densities on rice yield, and nitrogen (N) and phosphorus (P) characteristics in field water under integrated rice-fish (Cyprinus carpio qingtianensis) or rice-crayfish (Procambarus clarkii) system via field experiments. We then monitored the annual changes of N and P in the field water of the rice-crayfish system by a water quality on-line monitoring system. Field experiment results showed that in the rice-fish system, there were no significant differences in the rice yield, total nitrogen (TN), total phosphorus (TP) and ammonia nitrogen (NH4＋-N) contents at the low fish density (4.5×103 individuals/hm2 and 9.0×103 individuals/hm2, 14 g/individual) compared with the rice monoculture system. When the fish density reached 13.5×103 individuals/hm2 and 18.0×103 individuals/hm2 (14 g/individual), however, the TN, TP and NH4＋-N contents in the field water were significantly greater than those in the rice monoculture system. For the rice-crayfish system, the TN, TP and NH4＋-N contents in the field water significantly increased as the crayfish density increased. During the growing period, when the crayfish density reached 1.95×105 individuals/hm2 and 2.25×105 individuals/hm2 (3.5 g/individual), the TN, TP and NH4＋-N contents in the field water were close to or exceeded the limits set by Discharge Standard for Aquaculture Tailwater (DB 35/2160—2023). The four-year (2021—2024) monitoring data showed that the TN, TP and NH4＋-N contents in the discharged water from the paddy field did not exceed the limits set by Requirement for Water Discharge from Freshwater Aquaculture Pond (SC/T 9101—2007) during the rapid growth season of crayfish (middle February to late May), when the crayfish density was below 1.35×105 individuals/hm2 (3.5 g/individual). Our results suggest that there is an optimal range of aquaculture production for integrated rice-fish farming systems, within which the rice yield can be stable, and the risk of non-point pollution caused by N and P in the field water can be avoided.(利用农业物种多样性促进现代农业可持续发展一直受到全球关注。稻渔复合种养是农业物种多样性利用的典型模式。如何合理配置水稻和水产动物的比例，从而在稳定水稻产量和避免对环境产生负面影响的同时，最大化水产动物产量，是稻渔复合种养可持续发展亟须回答的问题。本文通过田间试验研究稻-鱼[青田田鱼（Cyprinus carpio qingtianensis），简称“田鱼”]和稻-虾[克氏原螯虾（Procambarus clarkii）]复合种养系统在不同养殖水平下对水稻产量、水产动物产量及水体氮磷特征的影响；并利用水质在线监测系统对稻-虾复合种养系统水体中氮磷的周年变化进行连续定位测定。田间试验结果表明：在稻-鱼系统中，当田鱼养殖密度较低（4.5×103尾/hm2和9.0×103尾/hm2，14 g/尾）时，水稻产量、稻田水体总氮（total nitrogen, TN）、总磷（total phosphorus, TP）及铵态氮（NH4＋-N）含量与水稻单作系统相比均没有显著差异；然而，当田鱼养殖密度提高至13.5×103尾/hm2和18.0×103尾/hm2（14 g/尾）时，水体中TN、TP及NH4＋-N含量均显著高于水稻单作系统。在稻-虾系统中，随着克氏原螯虾养殖密度的增加，水体中TN、TP及NH4＋-N含量均显著提高；在克氏原螯虾生长高峰期，高养殖密度（1.95×105尾/hm2和2.25×105尾/hm2，3.5 g/尾）处理的稻田水体中TN、TP及NH4＋-N含量接近或超过DB 35/2160—2023《水产养殖尾水排放标准》中的限值。2021—2024年的定位监测结果表明，当稻-虾系统中克氏原螯虾养殖密度降至1.35×105尾/hm2（3.5 g/尾）以下时，在克氏原螯虾快速生长季节（2月中旬至5月下旬），排出水体中的TN、TP及NH4＋-N含量均未超过SC/T 9101—2007《淡水池塘养殖水排放要求》中的限值。本研究明确了稻渔复合种养系统存在适宜的养殖产量范围，在该范围内可保障水稻产量稳定，并显著降低由稻田水体氮磷引起的面源污染风险。)
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