施氮对陇中黄土高原旱作农田土壤颗粒态有机碳的影响

Effects of Different Nitrogen Addition Levels on Soil Particulate Organic Carbon in Dry Farmland of Central Gansu Province on the Loess Plateau

为探明不同施氮水平对陇中黄土高原旱作农田土壤有机碳的影响,以布设于2013年的施氮定位试验为研究对象,利用碘化钠重液分组法,探究了N0,N52.5,N105,N157.54种施氮水平对陇中黄土高原旱作农田土壤总有机碳(STOC)、游离态颗粒有机碳(FPOC)、闭蓄态颗粒有机碳(OPOC)、矿质结合态有机碳(MOC)的影响。结果表明:在0—20 cm土层,不同处理下STOC,FPOC,OPOC,MOC含量及FPOC/STOC,OPOC/STOC均随土层加深而降低,MOC/STOC随土层加深而增大。较N0处理,N52.5,N105,N157.5处理均可提升STOC,FPOC,OPOC含量以及FPOC/STOC,OPOC/STOC,且N105处理下提升效应最优;N105和N157.5处理可显著提升0—20 cm各土层MOC含量,且N105处理下提升效应最优。综上所述,N105处理可有效促进土壤固碳能力、节约投入成本,可筛选为该区春小麦栽培的合理施氮量。

In order to explore the effects of different nitrogen addition levels on soil organic carbon in dry farmland in central Gansu Province on the Loess Plateau,based on the nitrogen addition location experiment conducted at the Rainfed Agricultural Experimental Station of Gansu Agricultural University,Dingxi City,Gansu Province,in 2013,the density fractionation method[NaI:(1.70±0.02)g/cm3]was used to explore the effects of four nitrogen addition levels(N0,N52.5,N105,N157.5)on soil total organic carbon(STOC),free particulate organic carbon(FPOC),occluded particulate organic carbon(OPOC),mineral-associated organic carbon(MOC).The results showed that the contents of STOC,FPOC,OPOC,MOC,and FPOC/STOC,OPOC/STOC decreased with the increase of depth of soil layer under different treatments in the 0—20 cm soil layers,and MOC/STOC increased with the increase of depth of the soil layer;compared with the N0 treatment,N52.5,N105 and N157.5 treatments could increase the FPOC/STOC,OPOC/STOC and the contents of STOC,FPOC,OPOC,and N105 treatment had the best effect on these ratios;N105 and N157.5 treatments significantly increased the MOC content in 0—20 cm layer,and N105 treatment had the best effect on the increase of MOC content.In conclusion,N105 treatment can effectively promote soil carbon sequestration capacity,reduce input costs,and can be selected as the reasonable application amount of nitrogen fertilizer for spring wheat cultivation in this area.