砂砾粒径对砂田西瓜根际温度的效应

Temperature Effects of Rhizosphere in the Gravel-sand Mulching Soil with Different Grain Size on Watermelon Field

以不覆砂露地（CK）为对照,通过铺设砂石粒径为1~3 mm的毛砂、10~20 mm豆砂、80~120 mm扁平椭圆卵石和1~100 mm当地砂田普通混砂,研究不同粒径砂砾覆盖对砂田西瓜根际温度的效应,监测砂田0~25 cm不同深度土壤温度变化。结果表明,砂田早春0~25 cm土壤日均温度比对照高0.3~3.0℃,日最高温度随土层深度的增加而逐渐降低,各层土壤最高温度出现时间比对照滞后0.5~2.5 h。毛砂、豆砂、卵石和混砂覆盖下砂层5 cm处根际平均温度分别比对照增加了20.03%、20.66%、0.47%、8.48%,除卵石外,早春其余粒径砂砾覆盖的砂田砂下5 cm处根际温度显著高于对照;砂层下5 cm处土壤温度受外界环境的影响最大,其变化规律可用一元三次函数y=ax3＋bx2＋cx＋d拟合,各处理拟合相关性系数均在0.87以上,其它土层曲线变化规律不明显。不同粒径的砂砾覆盖0~25 cm土壤温度增加效应从高到低顺序为豆砂、毛砂、混砂、卵石,其增加幅度随土壤深度的增加而减缓,豆砂和毛砂增温较慢,但增加幅度较大,卵石增温散温都快但增加量小。覆砂后0~25 cm根际最高温度毛砂、豆砂、卵石和混砂分别比对照增加了2.52、2.00、0.64、1.04℃,但不同深度土壤温度变化规律无明显差异。

We conducted trial to study the temperature effects of rhizosphere in the gravel-sand mulching soil with different grain size on watermelon field. The trial involved four levels of gravel and sand diameter：1~3 mm（A）,10~20 mm（B）,80~120 mm（C）,1~100 mm（D）and no gravel and sand mulching（CK）. All of treatments were randomized with three replications. The results shows that there was a change of reduce firstly then increase and reduce lastly in the temperature effects of rhizosphere in the gravel-sand mulching soil with different grain size on watermelon field. All the treatments increased the temperature of rhizosphere0.3 to 3 ℃ compered with no gravel and sand mulching（CK）. The maximal temperatue of rhizosphere was higher 20.03%、20.66%、0.47%and 8.48% than control,and it reduced with increase of soil deepth,what is more,the time of occurrenc of it was late about0.5 to 2.5 hours. The trents of temperature development of surface layer under 5 cm was same to the atmosphere,and developed regularity with three function（y =ax3 ＋ bx2＋cx ＋d,R20.87）. The average temperature of suface layer 5 cm of the treatment A,B,C,D was 15.90、15.99、13.31 and 14.37 ℃. The order of increased temperature in the gravel-sand mulching soil with different grain size on watermelon field was：B A D C. The rate of increase to temperature become slowly with the deepth of soil.Temperature of treatment A and B increased slowly but greadly,treatment C was quickly and less. There were no dfifference in dfifferent deepth of soil.