水肥状况对土壤剖面中锰的移动和水稻吸锰的影响

EFFECT OF WATER AND FERTILIZATION ON MOVEMENT OF MANGANESE IN SOILS AND ON ITS UPTAKE BY RICE

水旱轮作条件下小麦缺锰是四川冲积性水稻土上主要的养分胁迫问题。为了深入探讨这一问题，作者利用模拟土柱试验研究了不同水肥状况对四川两种典型冲积土中锰的迁移、转化及其对水稻吸锰的影响。结果表明，淹水种稻后土壤活性锰减少，DTPA态锰和交换态锰等可溶性锰的含量增加，引起锰随渗漏液向剖面下部淋溶、淀积和水稻对锰的奢侈吸收，造成土壤总有效锰库减少。湿润处理比相应淹水处理显著地减缓土壤中锰的这种转化，并大大降低水稻对锰的吸收；而施肥（有机肥和化肥）的效应远不如水分状况明显。目前尚未表现缺钙的灰棕潮土，在淹水种稻过程中锰的活化淋溶规律与水旱轮作后缺锰的灰潮土相似，说明灰棕潮土水旱轮作条件下也有潜在缺锰的可能。

Mn deficiency of wheat is a main problem of plant nutrition in Sichuan Province, which was considered to be relation closely with paddy-upland rotation. An experiment with model soil--column was conducted to study the characterishcs of Mn movement and its uptake by rice (Oryza sativa L.) in two alluvial soils under different water and fertilization status. It was found that soil active Mn (easily reducible Mn) decreased while DTPA-Mn and exchangeable Mn increased as soil was waterlogged, which caused the Mn leashing through 1 meter soil column and its excessive uptake by rice plant. The total storage of available Mn thus decreased. The effect of water and fertilization on Mn followed the following sequence: CK > NPK and NPKM (the above beatmentS were waterlogged) >> Wetting with NPK fertilizer (NPKM/Wet). The sequence of DTPA--Mn and exchangeable Mn in soil layers (especially 0--20cm) was CK and NPK > NPKM >> NPKM/Wet > the original upland soil, but active Mn in soil was reverse. This phenomenon was more obvious in gray alluvial soil than in gray--brown alluvial soil. It showed that Mn is an active element which is easily affected by water and fertilization status, and wetting treatment can slow down the Mn transformation in soil and decrease the uptake of Mn by rice plant greatly. Therefore, to adjust the transformation of Mn in soil and its availability to plant through the management of water status woutd be practicable.