东北雨养区草甸土玉米田氮素淋溶累积特征

Characteristics of Nitrogen Leaching in the Maize Farmland of Meadow Soil in Rain-fed Area of Northeastern China

为明确东北雨养区草甸土玉米田氮素淋溶特征,该文采用田间小区试验,原位监测不同氮肥施用水平下0~100 cm剖面土壤淋溶液氮素浓度及氮素累积情况。结果表明:监测期氮素淋溶均由暴雨等级的强降雨所引起,且以硝态氮为主。第一次淋溶时期,未施肥处理(T1)土壤淋溶液NO_(3)^(-)-N由表层向下逐渐减少,而施肥处理(T2、T3、T4)在60 cm土层处出现峰值;第二次淋溶时期,中高施肥处理(T3和T4)土壤淋溶液NO_(3)^(-)-N在40~60 cm土层处降至最低,而后向下逐渐增加。玉米收获后,低施肥处理(T2)土壤NO_(3)^(-)-N累积峰出现在40 cm土层处,而中高施肥处理(T3和T4)则出现在80 cm土层处,且在100 cm土层处T4处理土壤NO_(3)^(-)-N累积量比T2、T3处理高出65.6%和16.2%。此外,春播前土壤淋溶液NO_(3)^(-)-N浓度高于8月份降雨淋溶期。

To determine the characteristics of N leaching loss in the maize farmland of meadow soil in rain-fed area of Northeastern China,the field experiment was conducted to in-situ monitor N concentration of leaching water in the 0~100 cm soil profile and soil N accumulation under the different N treatments.The results showed that the N leaching events were caused by the heavy rain of rainstorm level and the nitrate-N(NO_(3)^(-)-N)was the main form of the leached N.During the first leaching events,NO_(3)^(-)-N concentrations of the leaching water gradually decreased from the topsoil to subsoil in the unfertilized treatment(T1),whereas NO_(3)^(-)-N concentrations in the fertilization treatment(T2,T3,T4)peaked at the soil layer of 60 cm.During the second leaching events,under the moderate and high level of fertilizer application(T3 and T4),NO_(3)^(-)-N concentrations of the leaching water had a decrease trend and bottomed at the soil layer of 40~60 cm,followed by a gradual increase.After corn harvest,soil NO_(3)^(-)-N in the low fertilizer application(T2)had a cumulative peak at the soil layer of 40 cm,while the cumulative peak in T3 and T4 occurred at the soil layer of 80 cm.Furthermore,soil NO_(3)^(-)-N accumulation at the soil layer of 100 cm was 65.6%and 16.2%greater in T4 treatment than those in T2 and T3.In addition,NO_(3)^(-)-N concentrations of the leaching water were larger before maize sowing than that in August(rainfall-leaching).