秸秆炭覆盖垄沟集雨种植对土壤结构和紫花苜蓿产量的影响

Effects of ridge-furrow rainwater harvesting withmaize straw biochar application on soil structureand alfalfa fodder yield in semi-arid regions of China

摘要:

【目的】 探寻我国半干旱黄土高原区紫花苜蓿可持续生产的适宜有机覆盖垄沟集雨种植模式。【方法】 采用随机区组设计布置大田试验，以平作（FP）为对照，研究秸秆炭覆盖垄沟集雨连续种植第5 年不同秸秆炭覆盖量（0、30 和60 t/hm²） 和不同垄沟比（垄宽∶沟宽分别为30∶60、45∶60 和60∶60（cm∶cm））对种植沟和集雨垄表层土壤结构和紫花苜蓿产量的影响。【结果】 秸秆炭覆盖垄沟集雨种植显著降低沟和垄中表层土壤容重，显著提高同土层土壤孔隙度和改善土壤团聚体稳定性。随垄沟比增加，秸秆炭覆盖垄沟集雨种植对土壤结构影响不显著；随秸秆炭覆盖量增加，土壤容重和广义土壤结构系数（ TSPI）呈减小趋势，土壤孔隙度呈增加趋势，＞0. 25 mm水稳性团聚体含量（WR0. 25）和紫花苜蓿产量呈先增加后降低趋势。与FP 相比，秸秆炭覆盖垄沟集雨种植紫花苜蓿全生育期实际干草产量提高3. 6%~24. 0%。与0 和60 t/hm² 秸秆炭覆盖量相比，30 t/hm² 秸秆炭覆盖垄沟集雨种植具有较低土壤容重、较高土壤孔隙度和较好土壤团聚体稳定性，其土壤三相结构分布接近理想状态，促使紫花苜蓿产量提升。【结论】 当秸秆炭覆盖量为30 t/hm² 和垄沟比为30∶60 时，秸秆炭覆盖垄沟集雨种植紫花苜蓿产量提升效果最佳。未来生物炭应用长期时间尺度内土壤结构变化规律与紫花苜蓿根系构型间关系需进一步研究。

Abstract:

【Objective】 To ensure the stability and sustainability of alfalfa productivity in the semi‐arid Loess Plateauof China.【Method】 A field experiment was conducted in randomized complete block design to determine the effectsof different maize straw biochar application rates （0，30，and 60 t/hm²） and ridge to furrow ratios（ 30∶60，45∶60and 60∶60（ cm∶cm）） on soil structure and alfalfa forage yield during the fifth year of continuous planting of alfalfa，usingflat planting （FP） as a control.【Result】 RFRH with maize straw biochar application significantly reduced soilbulk density，increased total porosity，and improved the soil aggregate water stability. As maize straw biochar applicationrates increased，soil bulk densityand three soil phase index（TSPI） decreased；total porosity increased；andWR0. 25and alfalfa forage yield first increased and then decreased. Compared to FP，annual forage yields increased by3. 6%~24. 0%inridge‐furrowrainwaterharvesting with maize straw biochar application. Ridges compacted with maizestraw biochar at an applicationrate of 30 t/hm² had lower soil bulk density，higher total porosity，and improved soil waterstability of aggregates. The soil three‐phase distribution was closed to ideal state，which resulted in higher alfalfaforage yield compared with ridges compacted with maize straw biochar at an application rate of 0，and 60 t/hm².【Conclusion】 Maize straw biochar at an application rate of 30 t/hm² and a30∶60 （cm∶cm） ridge to furrow ratiowaswasfound be suitable for increase fodder yield in semi‐arid regions of China. Future researchshould be conducted inthe form of long‐term field study to determine relationship between biochar‐inducing soil structure variety and root architectureof alfalfa.