Water extract of compost (WEC) can be used to develop eco-friendly fertilizers and presents plant biostimulant effects. The aim of this study was to evaluate WEC bioactivity effects on maize growth and root organic acid exudation. Maize plants were cultivated 24 days in nutrient solution with WEC addition at the concentrations of 0, 2, 5, 15, 40, and 75 mg L⁻¹ of C. The SPAD index, shoot dry matter (SDM), root dry matter (RDM), and nutrient accumulation in maize shoot were measured, and organic acid root exudate was determined. WEC application increased maize growth in 30%, compared to control plants. Furthermore, SPAD index, N, K, S, and Mn shoot accumulation; K and Mn uptake efficiency; and S, Fe, and Mn translocation efficiency increased over WEC concentrations. Root organic acid exudation of isocitric, oxalic, and tartaric increase about 100%, citric and malic about 200%, and succinic was more than four times higher, in relation to maize plants not treated with WEC. WEC augmented maize growth and stimulated root organic acid exudation. The optimum WEC concentration was about 40 mg L⁻¹ of C in nutrient solution.

堆肥水提取物（WEC）可用于开发环保肥料并具有植物生物刺激作用。本研究的目的是评估 WEC 生物活性对玉米生长和根部有机酸渗出的影响。玉米植株在添加了 0、2、5、15、40 和 75 mg L ^{-1 的}WEC 的营养液中培养 24 天C.测定了玉米地上部SPAD指数、地上部干物质(SDM)、根干物质(RDM)、养分积累，测定有机酸根系分泌物。与对照植物相比，WEC 应用使玉米生长增加了 30%。此外，SPAD 指数、N、K、S 和 Mn 枝条积累；K和Mn吸收效率；S、Fe 和 Mn 易位效率随着 WEC 浓度的增加而增加。与未用 WEC 处理的玉米植物相比，异柠檬酸、草酸和酒石酸的根部有机酸渗出量增加约 100%，柠檬酸和苹果酸增加约 200%，琥珀酸增加四倍以上。WEC 促进玉米生长并刺激根部有机酸渗出。最佳 WEC 浓度是营养液中约 40 mg L ^-1的 C。