氮磷添加对青稞人工草地生产生态功能的影响分析

Analysis of the influence of nitrogen and phosphorus addition on the ecological function of barley artificial grassland production

青稞长期适应寒冷干旱的高原气候,在西藏牧业生产区域作为补饲草料进行了广泛种植,受当地各级政府和广大牧民群众的欢迎。现代农业力求低碳高产,然而,多年来因为管理方法和施肥技术不统一,种植效果达不到理想的要求。文章为了确定低碳高产的青稞人工草地施肥管理方式,设置了N0(不施氮)、N1(16 g/m^2)和N2(32 g/m^2)三个氮水平和P0(不施磷)、P1(7 g/m2)和P2(14 g/m2)三个磷水平的青稞人工草地随机交互处理实验。测定地上生物量、地下生物量、8-9月份净生态系统碳交换(NEE)和生态系统碳排放。结果显示,氮磷添加均提高青稞人工草地的地上生物量,其中N1P1,N1P2,N2P1,和N2P2处理分别提高青稞地上生物量的195%、202%、216%和241%,但对地下生物量没有显著影响。单独的氮添加促进8—9月青稞人工地的碳排放,而单独磷添加对青稞人工草地碳排放没有显著影响。这一结果导致氮添加降低人工草地的碳汇功能而磷添加显著提高青稞人工草地碳汇功能。因此,该研究结论为单独的磷添加从生产-生态功能考虑是比较理想的青稞人工草地施肥管理方式。

Barley originated from the Qinghai-Tibet plateau and has been adapted to the cold and arid plateau climate. Barley as a feeding forage has been widely cultivated in the Tibetan animal husbandry production area and has been welcome by the local government at all levels and the vast number of herdsmen. Modern agriculture has strived for low carbon and high yield, however, over the past decades due to inconsistency between the management method and fertilization technology, the efficiency of cultivation does not meet the requirements. In this paper, in order to study the management mode of barley artificial grassland fertilization with low carbon and high yield, random mutual combination experiments were set up with three different nitrogen levels added, i.e.with non-nitrogen(N0), 16 g/m^2 nitrogen(N1) and 32 g/m^2 nitrogen(N2), and three different phosphorus levels added, i.e. with non-phosphorus(P0), 7 g/m^2 phosphorus(P1) and 14 g/m^2 phosphorus(P2). Above-ground biomass, underground biomass, net ecosystem carbon exchange(NEE), and ecosystem carbon emissions were measured for those established experiments. Our results showed that the addition of nitrogen and phosphorus can increase the above-ground biomass of the barley artificial grassland, and the increasing rate are 195%, 202%,216% and 241% for the combination of N1 P1, N1 P2, N2 P1, and N2 P2 treatment, respectively. However, these treatments had no significant effect on the underground biomass. It is also found that only nitrogen addition can promotes carbon emissions of the study site, while only phosphorus addition has no significant effect on carbon emissions. This result indicated that nitrogen addition can lead to reduce the carbon sink function of artificial grassland, while phosphorus addition can significantly improves the carbon sink function. Therefore, the conclusion of this study is that the only phosphorus addition is a relatively ideal management method of barley artificial grassland fertilization from the consideration of production-ecological function.