不同利用年限蔬菜温室土壤性质垂直变化研究

为了进一步摸清温室土壤性质的垂直变化与蔬菜作物生长的关系,采取野外调查、实验室分析等方法.对不同利用年限温室土壤的主要肥力指标进行综合研究,结果显示蔬菜温室土壤次生盐渍化、酸化、硝酸盐含量与利用年限呈正相关.温室土壤全盐含量自上而下呈现出高-次高-低-中的变化规律,盐分主要集中在根系密集的0-40cm土层;耕层土壤全盐量变幅在1.3~5.7g/kg之间,平均为3.2g/kg,属重度盐害.中度盐害程度以上(总盐>2.0g/kg)的占调查对象的75%,全剖面中,随着土层的下移,盐害程度逐渐降低.耕层pH均值7.96,与对照相比,下降0.61个单位.60-80cm的土层pH均值8.3,呈碱性,与对照相比,平均下降0.27个单位,温室土壤0-80cm内pH值呈不同程度的下降,有一定的“弱酸化”现象.耕层土壤硝酸盐平均高达63.3mg/kg,是对照的5.5倍,60-80cm土层硝酸盐则是对照的6.8倍.全土壤剖面硝酸盐淋洗现象明显.除特殊的温室环境影响外,主要归因于有机肥用量少,过量或偏施化肥,常年连作,不合理灌排等.

A Study on the Vertical Change of Greenhouse Soil Quality for Vegetables in Different Duration

Field research and lab analysis are used to clarify the relation between the vertical change of greenhouse soil quality and the growth of vegetables.In vegetable greenhouse,a vertical change of the soil quality shows the salt accumulation and acidulation are increasing with cultivation years.The salt accumulation appears to be regularly changed arranging from high,less,low to medium,which is mainly in root-densed soil level,0-40 cm.The salt accumulation in cultivate soil level range from 1.3 g/kg to 5.7 g/kg,which is heavy salt harm.Medium salt harm and above(total salt>2.0 g/kg) takes 75% of the survey.On the section,with the soil lower,the degree of salt harm reduces successively.pH is averagely 7.96 in cultivated level,which reduce 0.61 in comparison.pH in soil level 60-80 cm is average 8.3 and appears to be alkaline,which reduces 0.27 in comparison.pH in soil level 0-80 cm reduces to different extent and appears to be weak acid.NO₃^--N in cultivated soil level reaches 63.3 mg/kg,5.5 times of the control,and 6.8 times in 60-80 cm,which proves to be NO₃^--N leaching loss.The reason is owning to over fertilizer,poor organic manure,continuous cropping,illogical irrigation,etc.