不同土壤水分条件下拖拉机行走对四川丘陵旱地土壤特性及小麦生长的影响

Effects of Tractor Traffic on Soil Properties and Wheat Growth in Sichuan Hilly Areas Under Different Soil Moisture Content

以四川丘陵地区广泛使用的小四轮拖拉机为对象,研究其在不同土壤水分(16.5%,20.0%和22.5%)条件下行走对土壤特性及小麦生长的影响。结果表明:机械压实造成土壤容重、毛细孔度、硬度显著增加,总孔隙度显著降低,不同土壤水分处理间差异显著。土壤水分16.5%条件下,拖拉机行走显著影响0-10cm土层土壤特性;土壤水分20.0%和22.5%条件下,则显著影响0-20cm土层土壤特性,但以22.5%水分条件下0-20cm土层各土壤特性参数变化值最大。同时,土壤含水量越高,土壤压实后地表径流出现时间越早,土壤含水率16.5%,20.0%及22.5%处理0-30cm土层的含水量分别降低0.3,1.1,1.8个百分点。另外,土壤水分16.5%条件下,机械压实对小麦群体生长及产量的影响较小;但土壤水分上升至20.0%或22.5%后,压实处理的小麦单株干物质积累速率、单株及群体干物质积累量显著降低,群体有效茎蘖数、千粒重显著减少,最终分别显著减产8.7%和11.8%。综合来看,四川丘陵旱地小四轮作业时土壤含水率不宜超过20.0%。

Based on the small wheeled tractor widely used in Sichuan hilly areas, the effects of small wheeled tractor traffic on soil properties and wheat growth under 16.5G, 20.0% and 22.5G soil moisture content conditions were investigated. The results showed that mechanical compaction resulted in the significant in- crease of soil bulk density, capillary porosity and hardness, and the significant decrease of total porosity, what＇s more, the difference among soil moisture content treatments reached at the 5 % significant level. Un- der 16.5G soil moisture content condition, tractor traffic mainly impacted the soil properties in 0--10 cm depth. Under 22. 0% and 22. 5% soil moisture content condition, tractor traffic mainly impacted the soil properties in 0--20 cm depth, but under 22.5% soil moisture content condition, the change values of soil properties parameters in 0--20 cm depth was maximum. Meanwhile, the higher soil moisture content, the earlier surface runoff of compacted soil appeared, and soil moisture content in 0--30 cm depth of 16.5%, 20.0% and 22.5% soil moisture content treatments decreased significantly by 0.3, 1.1, and 1.8 percent, re- spectively. In addition, mechanical compaction had little influence on wheat growth and yield under 16.5% soil moisture content condition. However, after soil moisture content rose to 20.0% or 22.5%, mechanical compaction caused the significant decrease of dry matter accumulation rate per plant and dry matter accumu- lation of individual and population, as well as the significant reduction of effective spike number, 1 000 grains weight. Finally, grain yields of 20.0% and 22.5G soil moisture content treatments decreased by 8.7% and11.8%, respectively. In conclusion, the soil moisture content should not exceed 20. 0% when the small wheeled tractor worked in Sichuan hilly areas.