广东木薯园土壤肥力调查及评价

Investigation and evaluation on soil fertility of cassava plantations in Guangdong

分别选择国家木薯产业技术体系广州综合试验站位于广东兴宁、翁源、遂溪、开平、云安5个示范县的木薯园作为代表点,采集木薯根际表层土壤(0～20cm),测定土壤pH值、有机质含量等12个指标,分析广东木薯园的土壤肥力。结果显示,调查木薯园pH值值普遍较低(4.5～6.0),土壤酸性较强;云安和翁源土壤有机质含量处于中等水平(25.28g/kg和22.37g/kg),而兴宁、遂溪和开平较低,各样点有机质平均含量为16g/kg;整体供氮水平较低、平均含量75.95mg/kg,有效磷含量相对较高(> 20mg/kg),有效钾含量分布不均匀,最低为兴宁(85.61mg/kg)、最高为翁源(252.66mg/kg);土壤交换性钙含量普遍处于中等水平(平均409.41mg/kg),交换性镁含量较低(平均39.50mg/kg);铜、铁两种微量元素并不缺乏(平均含量分别为0.66、122.86mg/kg);有效锌含量分布不均匀,表现为云安>开平>兴宁>遂溪>翁源;有效锰含量除兴宁(62.29mg/kg)外,其他4个木薯园均较低;5个木薯园均存在缺硼现象(平均含量0.13mg/kg)。因此应该合理施肥,提高广东木薯种植地土壤有机质含量水平,重视镁肥和硼肥施用,以改善镁硼缺乏现象。

Samples of the top soil(0 to 20 cm beneath the ground)from cassava plantations in five demonstration counties(Xingning,Wengyuan,Suixi,Kaiping,and Yunan)of CARS-12 Guangzhou Comprehensive Test Stationb,were selected to detect twelve indexes including pH value and organic content etc,to investigate the soil fertility of cassava plantations in Guangdong.Results showed that pH value of the soil ranged from 4.5 to 6.0,showing strong acidity.Organic matter content in Yunan and Wengyuan was at the average level(25.28 g/kg and 22.37 g/kg),while that in Xingning,Suixi and Kaiping was relatively low(16 g/kg on average).With the average 75.95 mg/kg,the nitrogen content in the cassava plantations investigated was low,while the available phosphorus content was relatively high(>20 mg/kg).The available potassium content was not uniform,with the minimal of 85.61 mg/kg in Xingning and the maximal of 252.66 mg/kg in Wengyuan.The exchangeable calcium content in soil was generally at the medium level with an average of 409.41 mg/kg,while the content of exchangeable magnesium was low with an average of 39.50 mg/kg.There was no Cu and Fe deficiency in the cassava plantations investigated with an average of 0.66 mg/kg and 122.86 mg/kg,respectively.The distribution of available Zn was not uniform,ranking as follows:Yunan>Kaiping>Xingning>Suixi>Wengyuan.Except Xingning(62.29 mg/kg),the content of available Mn in other four cassava plantations was at a low level.With an average content of 0.13 mg/kg,boron deficiency existed in all those five cassava plantations.Accordingly,reasonable fertilization by increasing the content of soil organic matter and paying more attention to the applying of magnesium and boron fertilizer was suggested to improve the magnesium and boron deficiency of cassava plantations in Guangdong.