冲积性水稻土锰素特征与小麦缺锰的土壤条件

FEATURES OF MANGANESE ON PADDY SOIL CONDITIONS OF MANGANESE DEFICIENCY ON WHEAT

本文研究了冲积性水稻土的锰素特征与小麦缺锰的土壤条件。结果表明:冲积性水稻土因受种稻影响,与冲积土比,全锰和有效锰特别是活性锰明显降低,而代换锰在活性锰中有较大比率;土壤剖面内全锰和活性锰随深度的增加而增加;水旱轮作造成耕层土壤锰的淋失是本区小麦缺锰的主要原因。但对于pH较低的土壤,活性锰即使低于15ppm,小麦也不会缺锰;石灰性、轻质和水旱轮作是小麦缺锰的主要土壤条件。对于冲积性水稻土,若没有使pH升高的因素出现,小麦大面积发生缺锰症的可能性不大。此外,还发现国内常用的有效锰临界指标在本区土壤上偏高。

A experiment on the developed tendency of manganese deficiency for wheat on alluvial Paddy solis along river in Sichuan was conducted in 1987-1988 by analyzation of the Mn content of top-soil and abservation of the soil profile. The results showed that the content of total Ma and available Mn (especially active Mn) in the alluvial paddy soil were lower than its original soil (alluvial soil) but exchangeable Mn/active Mn were bigger, the content of total Mn and active Mn in soil profile of the alluvial Paddy soil were increased approximately with the increasing of soil layer in depth due to the Mn leachinged during planting rice. The Mn leaching loss form toP-soil was a important reason of Mn deficiency on wheat in this area,but wheat diden't aPPear Mn deficiency in low pH soil where the active Mn level was lower than 15pppm. There were three main conditions of Mn deficiency on wheat,they were the calcarears, the coaree texture and the rotation between dry-land crop and paddy rice system. If there was no other factors which make the value of soil pH rise on the alluvial paddy soil, the sympton of Mn deficiency on wheat alluvial will not be appeared.In addition, the results showed that the critical level of available Mn on the paddy soil in this study was lower than that many reports in China.