茶园土壤镁供应状况及镁肥施用效果研究

Status of Mg Availability and the Effects of Mg Application in Tea Fields of Red Soil Area in China

对取自我国茶叶主产区浙江等 7省共 2 87个土壤样品交换性镁含量的分析表明 ,0～ 2 0cm和 2 0～ 4 0cm土层含量低于 4 0 μg/g的比例分别为 5 7.9%和 6 4 .0 % ,并表现自北向南逐渐降低的特征。不同茶园土壤非交换性镁的释放强度 (5次 1mol/L中性NH4OAC连续提取量 )与其总量 (1mol/LHNO3 煮沸提取 )呈显著正相关 (r =0 .6 78 ,n =17)。在浙江等地进行的田间试验 (土壤交换镁含量 2 0～ 6 9μg/g)表明 ,施镁平均增产茶叶 5 .7%。施镁增加茶叶游离氨基酸含量 ,增加范围 1.2 %～ 16 .8% ,平均 7.0 % ,这可能与施镁显著增强硝酸还原酶活性 。

A total number of 287 soil samples were collected from 7 major tea producing provinces of red soil area in China and the exchangeable Mg content was analyzed. The soils with exchangeable Mg below 40 μg/g accounted for 57.9% and 64.0% of the total samples in the surface soil (0-20 cm) and subsoil (20-40 cm), respectively, exhibiting a zonal distribution with their values declining gradually from the northern to the southern tea growing provinces. The release magnitudes of non exchangeable Mg by serial extraction of NH 4OAC after removal of exchangeable form correlated positively (r=0.678 ** , n=17) with their total contents extracted by boiling 1 mol/L HNO 3 for 10 min. In 5 field experiments (exchangeable Mg 20-69 μg/g), the results showed that Mg application either as Kieserite (MgSO 4·H 2O) or Sul Po Mag (containing 22% K 2O, 11% MgO and 22% S) increased tea yield by a mean of 5.7%. The concentration of free amino acids was increased averagely by 7.0% through Mg application, which in a pot experiment was showed to be associated with enhanced nitrate reductase activity in tea plant with sufficient Mg supply.