缓控释肥深施对黏性土壤麦田氮素去向的影响

黏性土壤严重影响土壤水肥运移.采取适宜的农艺措施优化土壤无机氮分布，减少该类型土壤的氮素损失是农业绿色可持续发展的关键.为明确缓控释肥种肥深施对黏性土壤麦田氮素损失的影响，选择常规化肥(CN)和缓控释肥(RCU)这2种类型肥料，采用撒播撒施(B)和机械化条播深施(D),研究了缓控释肥种肥深施对黏性土壤小麦产量、季节麦田氮素径流流失、氨挥发和N₂O排放的影响；并分析了其耕层土壤的无机氮时空分布特征.结果表明，相同肥料类型下，D处理的小麦产量显著高于B处理；而相同施肥方式下，RCU处理的产量显著高于CN处理.D-RCU处理的小麦产量最高，达6.97 t·hm^-2.季节径流和氨挥发氮损失量高于N₂O形态的氮损失，且不同损失途径对肥料类型和施肥方式的响应不同.肥料类型和径流发生时间是麦田径流氮素流失的主要影响因素.受监测年份降雨年型分配影响，RCU处理的季节径流氮素流失量(20.35 kg·hm^-2)较CN处理(10.49 kg·hm^-2)显著增加.生育后期是麦田氨挥发损失的主要时期，...

Effect of Deep Fertilization with Slow/Controlled Release Fertilizer on N Fate in Clayey Soil Wheat Field

Clayey soil seriously affects water-holding capacity and nutrient movement. Adopting appropriate agronomic measures to optimize the distribution of soil inorganic nitrogen (SIN) and reduce the nitrogen (N) loss in this soil is the key to agricultural sustainable development. To clarify the effect of deep fertilization of slow/controlled release fertilizer with sowing on N loss in a clayey soil wheat field, two types of fertilizers, conventional fertilizer (CN) and slow/controlled release fertilizer (RCU), were selected in this study. Here, we evaluated the effects of these two fertilizer types on wheat yield, seasonal N runoff loss, ammonia volatilization, and N₂O emissions in wheat fields in two typical fertilization modes (manual surface sowing and spreading (B) and belowground fertilization of slow/controlled release urea with mechanized strip sowing (D)). The temporal and spatial distribution characteristics of SIN in topsoil were also analyzed. The results showed that under the same fertilizer type, the wheat yield of D treatment was significantly higher than that of B treatment, whereas the yield of RCU was notably higher than that of CN under the same fertilization mode. D-RCU achieved the highest yield of 6.97 t·hm^-2. The seasonal N losses from runoff and ammonia volatilization were higher than that from N₂O emissions, and the responses of different N loss pathways to fertilizer types and fertilization methods were diverse. Fertilizer type and runoff occurrence time were the main influencing factors of N runoff loss, and N runoff loss of the RCU treatment was higher in the non-fertilization period. Unfortunately, affected by annual rainfall pattern, the seasonal N runoff loss of the RCU treatment (20.35 kg·hm^-2) was significantly higher than that of the CN treatment (10.49 kg·hm^-2). The late growth period was the main phase of ammonia volatilization, and the later period was jointly affected by fertilization modes and fertilizer types. The B-CN treatment induced the highest seasonal ammonia volatilization (18.15 kg·hm^-2), which was significantly higher than that of the other treatments (7.31-8.38 kg·hm^-2). Additionally, the D-RCU treatment (2.41 kg·hm^-2) tended to reduce the N₂O emissions in comparison to that in the B-CN treatment (4.02 kg·hm^-2). The results also indicated that the horizontal movement of SIN was higher than the vertical movement. Deep fertilization of RCU was conducive to optimizing the spatial and temporal distribution of SIN, which was the main reason for the increase in wheat yield and the control of N loss from wheat fields. These results suggest that RCU is a suitable alternative fertilizer for increasing yield and reducing N loss in clayey soil wheat fields; D-RCU can increase the wheat yield and reduce ammonia volatilization and N₂O emissions in wheat fields by optimizing the spatial and temporal distribution of SIN, and its increasing effect on N runoff loss in the non-fertilization period deserves attention.