Abstract: To investigate the effects of nitrogen reduction combined with mushroom substrates application on the growth characteristics，fruit quality，nutrient absorption，and soil microbial environment of sweet melon under different soil humidities，the thin‑skinned sweet melon Super Sweet White Phoenix was selected as the test object.Four nitrogen reduction+mushroom substrates treatment levels were set at two soil humidities（60%，90% soil moisture content），including conventional nitrogen application of 210 kg/ha（N₁₀₀），nitrogen reduction of 50%（N₅₀），nitrogen reduction of 50%+500 kg/ha mushroom substrates（N₅₀+SMS₁），and nitrogen reduction of 50%+1 000 kg/ha mushroom substrates（N₅₀+SMS₂），for a total of eight treatments. The results showed that with the increase of soil moisture content，the growth characteristics and fruit quality of melon showed an overall increasing trend. Under the same soil moisture conditions，compared with N100，sweet melons treated with N₅₀+SMS₂ had the highest plant height，stem thickness，and leaf area during the flowering and fruit setting stage and fruit enlargement stage. The soluble total sugar，vitamin C，soluble protein，and soluble solids content in sweet melon fruits increased by 29.6%—36.2%，9.3%—10.8%，11.3%—12.4%，and 13.7%—14.3%，respectively.The nitrogen，phosphorus，and potassium content in sweet melon stems and leaves also significantly increased，and the yield of sweet melons treated with N50+SMS2 under 90% soil moisture content was as high as 15.46 t/ha. In addition，the activities of sucrase，urease，and polyphenol oxidase in different soil layers of sweet melon soil showed a trend of 20—40 cm>0—20 cm. Nitrogen reduction combined with mushroom substrates could increase the activities of sucrase，urease，polyphenol oxidase，and catalase to varying degrees at different soil depths. Compared with N₁₀₀，the microbial biomass carbon（MBC）and microbial biomass nitrogen（MBN）in various soil layers treated with N50+SMS2 increased by 38.6%—79.2% and 56.5%—76.9%，respectively，while MBC/MBN showed no significant change. Soil soluble carbon（DOC） and soluble nitrogen（DON） increased by 52.8%—57.7% and 43.0%—81.5%，respectively，while DOC/DON also showed no significant change.The conclusion is that N₅₀+SMS₂ treatment under different soil moisture can effectively improve the soil environment，enhance the absorption of nitrogen，phosphorus，and potassium by melons，and is an effective way to reduce nitrogen fertilizer application，improve quality，and increase yield.

Key words: Melon, Soil moisture, Nitrogen reduction, Mushroom substrates, Soil enzymes, Nutrition, Microorganisms

摘要： 为研究不同土壤湿度下减氮配施菌渣对甜瓜生长特性、果实品质、营养元素吸收以及土壤环境的影响，以薄皮甜瓜超甜白凤为供试对象，设置2个土壤湿度（60%土壤持水量、90%土壤持水量）下4个减氮+菌渣处理水平［常规施尿素210 kg/hm²（N₁₀₀）、减氮50%（N₅₀）、减氮50%+500 kg/hm²菌渣（N₅₀+SMS₁）和减氮50%+1 000 kg/hm²（N₅₀+SMS₂）］，共8个处理。结果表明，随土壤持水量的增加，甜瓜生长特性、果实品质总体呈增加的趋势。同一土壤湿度条件下，与N100相比，N₅₀+SMS₂处理下的甜瓜在开花坐果期和果实膨大期株高、茎粗以及叶面积最大，甜瓜果实中可溶性总糖、维生素C、可溶性蛋白、可溶性固形物含量分别提高29.6%~36.2%、9.3%~10.8%、11.3%~12.4%、13.7%~14.3%，甜瓜茎、叶中氮、磷、钾含量也显著增加，且90%土壤持水量下N₅₀+SMS₂处理的甜瓜产量最高，达15.46 t/hm²。此外，甜瓜土壤各土层深度内蔗糖酶、脲酶、多酚氧化酶活性表现为20~40 cm>0~20 cm，减氮配施菌渣能不同程度地提高不同土层深度下蔗糖酶、脲酶、多酚氧化酶、过氧化氢酶活性；与N₁₀₀相比，N₅₀+SMS₂处理的各土层深度内微生物量碳（MBC）、微生物量氮（MBN）分别提高38.6%~79.2%和56.5%~76.9%，MBC/MBN无显著变化，土壤可溶性碳（DOC）、可溶性氮（DON）分别提高52.8%~57.7% 和43.0%~81.5%，DOC/DON 也无显著变化。综上，不同土壤湿度下N₅₀+SMS₂处理能有效改善土壤环境，增强甜瓜对氮、磷、钾的吸收量，是减少氮肥施用、改善品质、增加产量的有效方式。

关键词: 甜瓜, 土壤湿度, 减氮, 菌渣, 土壤酶, 营养, 微生物