氮磷添加下施用保水剂对油茶林土壤氧化亚氮排放的影响

  目的  化肥施用导致土壤氧化亚氮(N₂O)排放增加，加剧了全球气候变化。在干旱和降水分配不均地区，土壤含水量是影响土壤N₂O排放的关键因子，施用保水剂(如聚丙烯酰胺)可能影响土壤N₂O排放。本研究目的是探究氮(N)与磷(P)肥添加下施用聚丙烯酰胺对土壤N₂O排放的影响。  方法  以油茶Camellia oleifera林土壤为研究对象，设置不同处理，包括不同肥料添加N、P、N+P、不施肥(ck)]，不同聚丙烯酰胺用量(C₀:0 g·kg?1，C₁:1.0 g·kg?1，C₂:2.0 g·kg?1)以及两者交互处理，利用静态箱-气相色谱法测定油茶苗生长期内土壤N₂O排放。  结果  ①施用聚丙烯酰胺显著提高了油茶林土壤含水量(P＜0.05)，且土壤含水量随保水剂施用量的增加而增加。与C₀相比，C₁和C₂土壤的含水量分别增加47.1%和57.4%，但施用聚丙烯酰胺不会促进土壤N₂O排放(F=2.75，P＞0.05)。②施磷肥显著提高土壤N₂O累积排放量(P＜0.05)，相较于ck增加13.3%。③与只添加聚丙烯酰胺的土壤相比，1.0 g·kg?1聚丙烯酰胺分别与N、P、N+P肥混施处理的土壤N₂O排放通量分别显著增加56.0%、61.7%、40.7% (P＜0.05)；2.0 g·kg?1聚丙烯酰胺与P、N+P肥混施处理的土壤N₂O排放通量分别显著增加38.7%、58.1% (P＜0.05)。  结论  施用聚丙烯酰胺不仅能有效提高油茶土壤保水能力，而且还不会促进油茶土壤N₂O排放，有利于发展高效节水林业和缓解全球气候变化。图5表1参35

Effects of water-retaining agent on soil nitrous oxide emission in Camellia oleifera forest under nitrogen and phosphorus addition

  Objective  The application of chemical fertilizer accelerates soil nitrous oxide (N₂O) emission and intensifies global climate change. Soil moisture content is a key factor affecting soil N₂O emission in arid and uneven rainfall distribution areas, so the application of water retaining agent (such as polyacrylamide) affects soil N₂O emission. The purpose of this study is to explore the effect of polyacrylamid on soil N₂O emission under the application of N and P fertilizer.  Method  Taking Camellia oleifera forest soil as the research object, different treatments were set, including different fertilizer additions (N, P, N+P, ck), different polyacrylamide dosage (C₀: 0 g·kg?1, C₁: 1.0 g·kg?1, C₂: 2.0 g·kg?1) and their interaction. The soil N₂O emission during the growth of C. oleifera seedlings was determined by static chamber gas chromatography.  Result  (1) The application of polyacrylamide significantly increased the soil moisture content of C. oleifera (P＜0.05), which increased with the increase of the application amount. Compared with C₀, the soil moisture content of C₁ and C₂ increased by 47.1% and 57.4% respectively, but the application of polyacrylamide did not promote soil N₂O emission (F=2.75, P＞0.05). (2) The application of P fertilizer significantly increased the cumulative soil N₂O emission (P＜0.05), which increased by 13.3% compared with ck. (3) Compared with the soil supplemented only with polyacrylamide, the N₂O emission fluxes of soil treated with 1.0 g·kg?1 polyacrylamide and N, P, N+P fertilizer increased significantly by 56.0%, 61.7%, and 40.7%, respectively (P＜0.05). The N₂O emission fluxes of soil treated with 2.0 g·kg?1 polyacrylamide and P, N+P fertilizer increased significantly by 38.7% and 58.1%, respectively.  Conclusion  The application of polyacrylamide in C.oleifera soil can effectively improve soil water holding capacity, but will not promote soil N₂O emission, which is conducive to the development of efficient water-saving forestry and the mitigation of global climate change. Ch, 5 fig. 1 tab. 35 ref.]