植物栽培体系消减华北潮褐土残留硝态氮的效果研究

Effects of Several Plant Cultivation System on Decreasing Residual Nitrate in Meadow Cinnamon Soil on North China Plain

【目的】探讨植物种类与种植制度消减土壤剖面累积硝态氮的效果。【方法】以华北平原潮褐土硝态氮高累积粮田为对象,设置作物、牧草、林木及休闲田间小区试验,采集测定土壤、植株及根系样品,分析几种植物栽培体系消减效果。【结果】(1)牧草单作或间作的地上生物量和吸氮量随种植年限增加明显递增,且种植2年后累积显著高于农作物轮作及生草休闲;杨树虽具有极大的生物量,但对氮素吸收在修复次年显著降低,明显低于牧草单作或间作,接近作物轮作和生草休闲。(2)0—200 cm土层硝态氮消减量呈现出杨树<生草休闲<苜蓿、苜蓿+无芒雀麦和作物轮作<苇状羊茅。(3)杨树根区及深层累积硝态氮具有强烈向下淋洗趋势,分别在80—100 cm和120—180 cm土层出现峰值,深层硝态氮较种植前向下淋移了60 cm;生草休闲累积硝态氮在剖面中发生一定程度的淋洗且至深层累积。(4)0—100 cm区域植物的根长密度与相应区域土壤硝态氮的消减量具有较好的正相关关系。【结论】在通体高量积累硝态氮的土壤上,可以通过牧草单作或间作实现土壤剖面硝态氮含量快速消减,而且苇状羊茅对深层累积硝态氮提取能力较强,苜蓿在相对长期的修复中具有优势。

【Objective】This study was to investigate the potential of decreasing plant for different plant species and cropping system to reduce nitrate accumulation in soil profile such as meadow cinnamon soil on North China plain.【Method】 Crop,forage,forest and catch crops were used as materials in a field experiment,the soil,plant and root samples were collected and measured,and the reduction effects of several plant cultivation systems were analyzed.【Result】 The results indicated that biomass and N uptake of grass monoculture or intercropping on the ground increased significantly with the cultivation period,and was significantly higher than crop rotation and catch crops after 2 years.Although poplar had the greatest biomass,N uptake was reduced significantly in the following year and less than grass monoculture or intercropping and close to crop rotation catch crops.Amount of nitrate reduction（0-200 cm） showed poplacatch cropsalfalfa and alfalfa＋bromus and crop rotationtall fescue.Root zone and the deep nitrate accumulation of poplar had a strong leaching downward trend.The peak appeared in the depth of 80-100 cm and 120-180 cm where it was leaching 60 cm below the labeled place.Under catch crops,leaching of nitrate occurred to some extent for deep accumulation in the profile.There was a significant positive correlation between plant root length density and soil nitrate decrease in 0-100 cm soil layer.【Conclusion】 In the high nitrate accumulation soil,grass monoculture or intercropping can reduce soil nitrate content rapidly.Nitrogen absorption in the topsoil of tall fescue was more than other plants.Alfalfa had a advantage in the relatively long term restoration.