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 rhizosphere 0.3 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 about 0.5 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， R2>0.87) . 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 .

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甘肃省科技支撑项目“黄土丘陵沟壑区(庄浪)梯田沙覆盖节水高效种植技术研究与示范”(1304ZKCA151)、兰州市科技局项目“兰州砂田退化和衰老机理与恢复改良对策研究”(2011-1-151)部分内容