琯溪蜜柚镁素养分状况及其影响因素分析

Analysis of magnesium nutrient status and its influencing factors in Guanxi pomelo

【目的】研究琯溪蜜柚镁素营养状况及其影响因素,为蜜柚合理施用镁肥提供参考依据。【方法】在福建省平和县采集312个蜜柚园的土壤、叶片样品及29个蜜柚园的土壤剖面0~20、20~40和40~60 cm土层的土壤样品,测定土壤和叶片中的镁含量,分析影响土壤交换性镁含量的因素及土壤与叶片镁含量的关系。【结果】312个蜜柚园的土壤交换性镁含量为3.23~272.25 mg·kg^(-1),其平均值为56.59 mg·kg^(-1),蜜柚园土壤交换性镁含量属于低量(<80 mg·kg^(-1))、适量(80~125 mg·kg^(-1))、高量(>125 mg·kg^(-1))的样品数占312个蜜柚园的比例分别为77.25%、14.42%、8.33%。随着剖面土层深度的增加,土壤交换性镁含量降低,而其含量属于低量(<80 mg·kg^(-1))的样品比例却提高了。相关性分析结果表明,土壤交换性镁含量与土壤pH值、土壤阳离子交换量(CEC)、土壤碱解氮、速效钾、交换性钙的含量间均呈极显著正相关;土壤交换性镁与有效磷含量间的关系因有效磷含量的不同而异,当土壤有效磷含量<350 mg·kg^(-1)时,土壤交换性镁含量随着有效磷含量的提高而增加,而当有效磷含量>350 mg·kg^(-1)时,土壤交换性镁含量随着有效磷含量的提高而下降。有机质可增加土壤交换性镁的含量,施用生物有机肥、有机肥、有机无机复混肥均可以补充土壤镁素。312个蜜柚园的蜜柚树体叶片中的镁含量为0.17%~0.72%,其平均值为0.35%,叶片镁含量属于低量(<0.32%)的样品比例为35.90%,叶片镁含量与土壤交换性镁含量间存在极显著正相关。【结论】琯溪蜜柚的镁素营养普遍缺乏,土壤酸化、有机质含量不高、土壤保肥能力低、养分不平衡是造成土壤镁素缺乏的主要原因,生产上应施用氧化镁、白云石、钙镁磷肥等含镁肥料,重视平衡施肥和增施有机肥。

【Objective】In order to provide some references for the rational application of magnesium fertilizer in Guanxi pomelo orchards,the nutritional status of magnesium and influencing factors of pomelo were studied.【Method】Soil and leaf samples in 312 pomelo orchards and soil samples from three soil layers(0-20,20-40,and 40-60 cm)of 29 soil profiles were collected from Pinghe county,Fujian province,the magnesium content of soil and leaves was determined,the factors affecting soil exchangeable magnesium content and the relationship between soil and leaf magnesium content were analyzed.【Result】The content of soil exchangeable magnesium in 312 pomelo orchards ranges from 3.23 to 272.25 mg·kg^(-1),with an average value of 56.59 mg·kg^(-1).The proportion of soil exchangeable magnesium content belong to low(<80 mg·kg^(-1)),adequate(80-125 mg·kg^(-1))and high(>125 mg·kg^(-1))were 77.25%,14.42%and 8.33%,respectively.The results of correlation analyses showed that soil exchangeable magnesium content was significantly positively correlated with soil pH,CEC,alkali-hydrolyzable nitrogen,available potassium and exchangeable calcium contents.The relationship between the contents of soil exchangeable magnesium and available phosphorus varies with the change of available phosphorus.When the soil available phosphorus content was less than 350 mg·kg^(-1),soil exchangeable magnesium content were increased with the increase of available phosphorus.When the soil available phosphorus content was higher than 350 mg·kg^(-1),the exchangeable magnesium content decreased with the increase of available phosphorus.Soil organic matter increased the content of exchangeable magnesium because organic fertilizer,microbial organic fertilizer,organic-inorganic compound fertilizer could supply soil magnesium nutrition.The range and the average content of magnesium in leaves were 0.17%-0.72%and 0.35%,respectively.The proportion of samples with low magnesium content(<0.32%)was 35.90%.There was a very significantly positive correlation between leaf magnesium and soil exchangeable magnesium.【Conclusion】Magnesium nutrition of pomelo in Pinghe county is generally deficient.Soil acidification,low organic matter content,low soil fertility retention capacity,and unbalanced nutrient application are the causes of soil magnesium deficiency.Magnesium-containing fertilizers such as magnesium oxide,magnesium hydroxide,dolomite,calcium magnesium phosphate fertilizer should be applied in pomelo production,and attention should be paid to balanced fertilization and increased application of organic fertilizer.