[目的]比较长期不同施肥措施对两种典型土壤(黑土和棕壤)团聚体分布和稳定性的影响，探究影响团聚体稳定性的关键因素，为缓解土壤结构退化提供理论支撑。[方法]依托34年黑土和45年棕壤长期定位试验，选取两定位点共有的不施肥(CK)、化肥(NPK)、化肥配施有机肥(NPKM)处理，以及黑土特有的化肥配施秸秆(NPKS)处理、棕壤特有的有机肥——猪厩肥(M)处理，采集0-20 cm 土层土壤样品，测定土壤化学性质，采用湿筛法对土壤团聚体进行筛分。[结果]相比于CK，NPK处理下黑土和棕壤大团聚体(＞0。25 mm)比例显著降低8。6％和11。3％，团聚体平均重量直径(MWD)分别显著减少18。6％和10。7％，说明单施化肥导致黑土和棕壤团聚体稳定性显著降低;NPKM和M处理下棕壤的MWD分别显著增加44。2％和17。9％，而NPKM处理下黑土 MWD未发生显著变化，但NPKS处理下黑土 MWD显著提高11。8％，说明在棕壤中施用猪厩肥，黑土中秸秆还田是提高团聚体稳定性的重要措施。土壤团聚体的稳定性主要受土壤化学性质的影响。长期施用化肥(NPK)导致黑土和棕壤的pH和交换性钙、镁离子(Ca2+、Mg2+)降低，阻碍了大团聚体的形成和稳定。施用有机物料(M、NPKM、NPKS)抑制了土壤pH的降低，提高土壤颗粒态有机碳(POC)和矿物结合态有机碳(MAOC)的含量，促进有机碳与铁铝氧化物、钙镁离子的结合，推动了黑土和棕壤颗粒的团聚过程，进而维持和提高了团聚体的稳定性。综合分析表明，影响黑土团聚体稳定的因素从大到小依次为络合态氧化铝(A1p)、Ca2+、POC、pH、MAOC，其中黑土团聚体稳定性与A1p显著负相关，与其余因素显著正相关。影响棕壤团聚体稳定性的关键因素从大到小依次为POC、络合态氧化铁(Fep)、pH、Mg2+、Ca2+、无定形态氧化铝(A1o)、A1p、无定形态氧化铁(Feo)，其中棕壤团聚体稳定性与A1。和Fe。显著负相关，与其他因素显著正相关。[结论]化肥配施有机物料(猪厩肥、秸秆)可以抑制土壤酸化，通过增加土壤POC和Ca2+含量，提高黑土和棕壤团聚体的稳定性，是延缓土壤结构退化的重要施肥措施。
Effects of Long-Term Fertilization on Soil Aggregate Stability and Its Driving Factors in Black Soil and Brown Soil
[Objective]The effects of long-term different fertilization practices on aggregate distribution and stability of two typical soils(black soil and brown soil)in the black soil area were compared,and the key factors affecting aggregate stability were explored to provide the theoretical support for alleviating soil structural degradation.[Method]Based on a 34-year long-term positioning experiment in black soil and a 45-year long-term positioning experiment in brown soil,soil samples of 0-20 cm were collected by selecting the common fertilization treatments:no fertilization(CK),chemical fertilizer(NPK),and chemical fertilizer combined with organic fertilizer(NPKM),as well as the special treatments of chemical fertilizer plus straw(NPKS)in black soil and manure(M)in brown soil.Soil chemical properties were determined and soil aggregates were sieved by wet-sieving procedure.[Result]Compared with CK,the proportion of microaggregates(＞0.25 mm)under the NPK treatment in black soil and brown soil was significantly reduced by 8.6％and 11.3％,respectively,and the mean weight diameter(MWD)of aggregates was significantly reduced by 18.6％and 10.7％,respectively,indicating that the stability of aggregates in black soil and brown soil was significantly reduced by chemical fertilizer alone.The MWD under the NPKM and M treatments in brown soil increased significantly by 44.2％and 17.9％,respectively,whereas that had not noticeably changed under the NPKM treatment and significantly increased by 11.8％under the NPKS treatment in black soil,indicating that the application of pig manure in brown soil and straw return in black soil were important measures to improve aggregate stability.The stability of soil aggregates was mainly affected by soil chemical properties.NPK resulted in the decrease of pH and exchangeable Ca and Mg ions in black soil and brown soil,which hindered the formation and stability of microaggregates.The application of organic fertilizers(M,NPKM,NPKS)inhibited the decrease of soil pH,increased the content of particulate organic carbon(POC)and mineral-associated organic carbon(MAOC),and promoted the association of organic carbon with Fe/Al oxides and Ca/Mg ions,which accelerated the aggregation process of soil particles,maintaining and improving the stability of aggregates.The comprehensive analysis showed that the factors affecting the stability of black soil aggregates were chelated Al(Alp),Ca2+,POC,pH and MAOC in order from the largest to the smallest,among which the stability of black soil aggregates was significantly negatively correlated with Alpand positively correlated with other factors.The key factors affecting the stability of brown soil aggregates were POC,chelated Fe(Fep),pH,Mg2+,Ca2+,amorphous Al(Alo),Alp and amorphous Fe(Feo)in order from the largest to the smallest,among which the stability of brown soil aggregates was significantly negatively correlated with Alo and Feo and positively correlated with other factors.[Conclusion]The application of organic fertilizers(pig manure,straw return)could mainly increase the contents of soil POC and Ca2+,inhibit soil acidification,and improve the stability of aggregates in black soil and brown soil,which were important fertilization practices to delay the degradation of soil structure in black soil areas.
万方数据
维普
