| 摘要: |
| 【目的】筛选核桃林下适宜的复合种植模式,并分析其对培肥土壤和提高林地经济效益的影响。【方法】在四川省雅安市大渡河干热河谷区，于核桃林下设置了4种种植模式，即核桃+甘蓝+甘蓝(HGG)、核桃+甘蓝+马铃薯(HGM)、核桃+白菜+大豆(HBD)、核桃纯林(HCK)，并以农地(玉米+马铃薯，NCK)为对照，测定不同种植模式林下土壤的微团聚体组成和分形维数（D）、物理性质、养分含量和微生物数量，并探讨D和特征微团聚体组成比例（PCM）、微团聚体各粒级含量及土壤理化性质、微生物数量的关系。【结果】与NCK相比，4种复合种植模式林下土壤中的粒径＞0.25 mm土壤微团聚体含量均显著增加，粒径＜0.02 mm土壤微团聚体含量显著降低；不同种植模式林下土壤的D和PCM值由大到小依次表现为NCK＞HCK＞HBD＞HGM＞HGG。与NCK相比，HGG、HGM、HBD、HCK种植模式的土壤自然含水量及非毛管孔隙度、毛管孔隙度和总孔隙度分别增加12.2%~50.4%，2.4%~14.8%，2.8%~29.1%和2.6%~23.1%，体积质量降低4.6%~17.6%；有机质、全氮和碱解氮含量分别增加5.1%~14.9%，3.9%~12.5%和25.1%~112.5%；细菌、放线菌、真菌和总微生物数量分别增加21.4%~54.3%，19.2%~58.1%，17.8%~58.4%和21.2%~54.6%。相关分析表明，D和PCM值与土壤自然含水量、孔隙度、养分含量和微生物数量均呈极显著负相关，与体积质量呈极显著正相关。【结论】大渡河干热河谷区采用“核桃+甘蓝+甘蓝”种植模式，能有效改善核桃幼林林下土壤微团聚体组成，降低土壤D和PCM，提高土壤养分含量和微生物数量，是该地区最佳的核桃林下复合种植模式。 |
| 关键词: 核桃幼林 种植模式 林地效益 土壤微团聚体 土壤分形维数 |
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| 基金项目:四川农业大学新农村发展研究院雅安服务总站科技计划项目(2017-05)；四川省科技厅项目(2016NYZ0035,2017-NFP0051,2017NFP0126) |
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| Effects of different planting patterns on composition and fractal dimension of soil micro-aggregates in young walnut forest |
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WU Jiahui,LUO Yongfei,GONG Wei,et al
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| Abstract: |
| 【Objective】Suitable planting patterns under walnut forests were selected to fertilize soil and improve the economic benefits of forest land.【Method】Under different compound planting patterns including walnut+cabbage+cabbage (HGG),walnut+cabbage+potato (HGM),walnut+Chinese cabbage+soybean (HBD),walnut forest (HCK) and farmland control (corn+cabbage,NCK),soil microaggregates composition,fractal dimension (D),physical properties,nutrient contents and microbial number were determined in dry hot valley of Dadu River in Ya’an,Sichuan.The relationships between fractal dimension (D) with composition of characteristic soil microaggregates (PCM),particle contents of microaggregates,physicochemical properties and microbial number were explored.【Result】Compared with NCK,the contents of soil microaggregates with size of >0.25 mm in the four planting patterns increased and the contents of soil microaggregates with size of <0.02 mm decreased.D and PCM values were in the order of NCK>HCK > HBD>HGM>HGG.Compared with NCK,natural water content,noncapillary porosity,capillary porosity,and total porosity of soil in four planting patterns were increased by 12.2%-50.4%,2.4%-14.8%,2.8%-29.1% and 2.6%-23.1%,respectively.The bulk density was decreased by 4.6%-17.6%,while organic matter,total nitrogen and alkali-hydrolyzable nitrogen contents were increased by 5.1%-14.9%,3.9%-12.5% and 25.1%-112.5%,respectively.Bacteria,actinomycetes,fungus and total microorganism counts were increased by 21.4%-54.3%,19.2%-58.1%,17.8%-58.4% and 21.2%-54.6%,respectively.D and PCM values had significantly negative correlation with natural water content,porosity,nutrient content and microbial number,while they had significantly positive correlation with soil bulk density.【Conclusion】The development of walnut+cabbage+cabbage planting in the dry-hot valley of Dadu River can effectively improve soil microaggregate composition,reduce D and PCM values,and increase contents of soil nutrients and microorganisms.It is the best compound planting pattern under walnut forest in dry hot valley of Dadu river. |
| Key words: young walnut forest planting pattern economic benefits of forest land soil microaggregates soil fractal dimension |
