福建省主要土壤类型的镁素含量

通过测定9种土壤类型g4个土样,研究福建省主要土壤类型全镁和交换性镁(包括水溶性镁)的含量及其影响因素。结果表明我省土壤镁素含量较低。除盐土外,土壤全镁含量平均为0.33％,交换性镁含量0.82毫克当量/100克土。不同土壤类型全镁量高低顺序为:盐土>紫色土>水稻土>黄红壤、红壤>山地黄壤、赤红壤>山地草甸土>风沙土。交换性镁高低顺序为:盐土>水稻土>风沙土>紫色土>山地黄壤>黄红壤>赤红壤、红壤>山地草甸土。成土母质对土壤全镁和交换性镁含量有一定影响。土壤交换性镁与全镁含量呈极显著正相关,与土壤有机质含量呈极显著负相关,与土壤pH值呈显著正相关,与土壤粘粒(<0.001毫米)含量和阳离子交换量(CEC)呈正相关,但不显著。以土壤交换性镁饱和度10％作为足量指标进行划分:盐土和风沙土镁素充足,水稻土有75％样点土壤不缺镁,紫色土有50％样点土壤供镁充足,而红壤性土壤有80～90％样点土壤缺镁,山地草甸土镁素都是不足的。

THE STATUS OF MAGNESIUM IN THE MAIN FUJIAN SOILS

An investigation was made in evaluating the total and exchangeable Mg as well as the factors affecting the exchangeable. Mg status through determining 94 soil samples including 9 main soil types in Fujian Province. Results show that total Mg status in Fujian soils is relatively low. With the exception of saline soil, the total Mg content is only in an average of 0.33% with exchangeable Mg 0.82meq/100g. The total Mg content may be arranged in decreasing sequence as follows: (1)saline soil, (2)purple soil, (3)paddy soil, (4)yellow-red soil, red soil, (5)mountain yellow soil, lateritic soil, (6)mountain meadow soil, and (7) wind erosion sandy soil; while in the exchangeable Mg are: (1) saline soil, (2) paddy soil, (3) wind erosion sandy soil, (4) purple soil, (5) mountain yellow soil, (6)yellow-red soil, (7)lateritic soil, red soil, and (8)mountain meadow soil. If taking 10% Mg of CEC as the criteria of available Mg, then saline soil and wind erosion sandy soil are considered as rich in Mg; 75% paddy soil, and 50% purple soil are considered sufficient; while 80-90% red soil and all mountain meadow soil are considered as deficient. Calculations of correlation indicate that the exchangable Mg shows positive correlation singnificantly with total Mg and pH, but not in significant with clay content (<0.001 mm)and CEC, while a negative correlation very significantly existed with organic matter content.