氮肥与有机肥配施对设施土壤净矿化氮动态变化的影响

研究设施栽培条件下氮肥与有机肥配施对土壤净矿化氮含量及其速率的动态变化的影响，以评估净矿化氮在设施土壤供氮能力方面的作用，为设施番茄生产的合理施肥提供重要的理论依据。以设施番茄栽培连续7年定位施肥田间试验为依托，选择不同施氮量（N0、N1、N2、N3）和不同氮量配施有机肥（MN0、MN1、MN2、MN3）8个处理土壤，采用室内连续好氧培养方法，研究了各施肥处理土壤净矿化氮含量及净氮矿化速率，分析了土壤净矿化氮含量与可溶性有机氮、微生物量氮含量之间的联系。研究结果表明:在0 ~ 20 cm土层，氮肥与有机肥配施处理土壤全氮和无机氮含量均显著高于单施氮肥处理（P < 0.05），施氮量对土壤全氮含量无显著影响，但对土壤无机氮含量则有显著影响，随施氮量的增加呈显著增加趋势。在培养过程中，各处理土壤净矿化氮含量随着培养时间延长呈先逐渐增加而后下降趋势，各处理土壤净氮矿化速率在培养7 d时最大，7 ~ 70 d期间快速下降，70 d后呈缓慢下降趋势，氮肥与有机肥配施处理土壤净矿化氮量和净氮矿化速率均显著高于单施氮肥处理（P < 0.05），氮肥与有机肥配施处理土壤净矿化氮含量和净氮矿化速率随施氮量增加呈下降趋势；与单施氮肥相比，氮肥与有机肥配施显著提高土壤可溶性有机氮与微生物量氮含量（P < 0.05），但受施氮量影响不显著；土壤净矿化氮含量与可溶性有机氮、微生物量氮之间有密切联系，但与可溶性有机氮之间的密切程度更大。综合来看，MN1、MN2处理可显著提高土壤供氮能力（无机氮 + 净矿化氮）。在设施番茄栽培条件下，连续7年氮肥与有机肥配施可显著提高设施土壤供氮能力，也可较好地协调设施土壤氮素供应与固持的关系。

Effects of Combined Application of Nitrogen Fertilizer and Manure on the Dynamics of Net Mineralized Nitrogen in Greenhouse Soil

To evaluate the role of net mineralized nitrogen (N) in the N supply capacity and provide theoretical basis for rational fertilization, the effect of combined application of N fertilizer and manure on the dynamic changes of net mineralized N content and net N mineralized rate were studied in greenhouse soil. A tomato field fertilization experiment with eight treatments of different N fertilizer (N0, N1, N2 and N3) combined with different manure (MN0, MN1, MN2 and MN3) was conducted for seven consecutive years in greenhouse. The net mineralized N and net N mineralization rate were measured under indoor aerobic cultivation method, followed by the analysis of the relationship between soil net mineralized N and soluble organic N (SON), microbial biomass N (MBN). The results showed that the contents of soil total N (TN) and inorganic N (N_in) with combined application of N fertilizer and manure were significantly higher than that with single application of N fertilizer (P < 0.05) in the 0-20 cm soil layer. The N application rate had no significant effect on TN, but it had significant effect on N_in, showing a significant increase trend with the increase of N application rate. The net mineralized N of each treatment increased gradually first and then decreased with the prolongation of incubation time. The soil net N mineralization rate of each treatment reached the maximum in the 7th day of incubation, and decreased rapidly during 7-70 days. After 70 days, it showed a slow decreasing trend. Soil net mineralized N and net N mineralization rate under the treatments of combined application of N fertilizer and manure were significantly higher than that of single application of N fertilizer (P < 0.05), indicating a downward trend with the increase of N application rate. The treatments of combined application of N fertilizer and manure significantly increased the contents of SON and MBN compared with single application of N fertilizer (P < 0.05), but there was no significant effect induced by N application. The net mineralized N was closely related to SON and MBN. In summary, the treatments of MN1 and MN2 could significantly increase soil N supply capacity (inorganic N + net mineralized N). Under the greenhouse conditions of tomato cultivation, the combined application N fertilizer and manure for seven consecutive years could significantly improve N supply capacity of greenhouse soil to better coordinate the soil N supply and immobilization.