摘要
肥际是肥料与土壤接触后肥料养分浓度很高、肥料与土壤组分相互作用强烈的区域。P肥肥际反应尤为强烈，其过程对肥料P在土壤中迁移及生物有效性可能起着至关重要的作用。本文以肥际为切入点，通过土柱培养试验，研究了磷酸二氢钙（MCP）在石灰性潮土肥际的形态转化及肥料P的迁移。结果表明，MCP施肥31天后，肥料P的迁移距离达45mm。MCP异成分溶解导致约30％的肥料P残留在原施肥点；另有约70％进入土壤。无机P形态分级结果显示，进入土壤的肥料P仍保持较高的有效性，且主要以磷酸钙盐存在。其中，近10％仍以水溶态（WE-P）存在，近35％转化为Ca2-P，近35％转化为Ca8-P，近15％转化为AI-P，约5％转化为Fe-P，仅不足1％转化成O-P，而Ca10-P没有明显变化。肥际（0～2mm）新增各形态含P矿物中，Cas-P所占比例显著增加，O-P的比例略有增加，其他形态P的比例相应减少。MCP施肥后土壤WE-P和Ca2-P的分布呈明显的分段特征，即由自施肥点开始的快速线性下降阶段和随后的缓慢线性下降阶段构成，其他形态的P的分布也有肥际集中分布特性，使得进入土壤的肥料P90％左右集中在不足一半的扩散距离内。MCP施肥引起肥际土壤pH显著下降，对肥际碳酸盐及铁、铝矿物溶解破坏作用极为显著，特别是2mm内碳酸盐被完全分解。土壤CaCO3溶解释放的Ca2＋是进入土壤的肥料P转化固定的主要因素，其次是施肥伴随的Ca2＋，肥际铁、铝矿物溶解释放出的Fe3＋、Al3＋对P的固定也有重要贡献。MCP对土壤矿物的溶解破坏及其异成分溶解作用是石灰性土壤中该肥料有效性的主要限制因素。
In order to investigate the importance of reaction in fertisphere （the soil zone immediately surrounds fertilizer and characterized with intense reactions） on phytoavailability of phosphorus （P） fertilizer, the transformation and the distribution of fertitizer-P with monoealeium phosphate monohydrate （MCP） application in a calcareous fluvo-aquic soil, which obtained from Henan China, were studied using slice sectioning by 31-day incubation with soil columns. There was about 30% of fertilizer-P remained as residue due to amphoteric hydrolyzation of MCP; otherwise, about 70% fertilizer-P was moving into soil columns. Fractionation studies showed that fertilizer-P moved into the soil columns major presented as Ca2-P and CaB-P, then Al-P, water-extracted P （WE-P）, and Fe-P, there was only slight increment of O-P, whereas, there was no significant change of Ca10-P. The proportions of new-increased P form were 9.6%, 35.8%, 34.9%, 13.8%, 5.4% and 0.5% for water-extracted P （WE-P）, Ca2-P, CaB-P, Al-P, Fe-P and O-P, respectively. However, in the fertisphere （0-2 mm）, the proportion of new-formed Ca4-P significantly increased to 53.1%, and O-P also slightly increased to 0.6%, with the deceasing of other P forms, they were 25.0%, 11.4% and 4.4%, for Ca2-P, AI-P and Fe-P, respectively. Furthermore, the distributions of WE-P and Ca2-P showed two different stages： first they linearly declined down sharply, and then slowly they linearly reduced down to original levels of bulk soil; and the distribution of other P forms also characterized with two stages, which caught about 90% of fertilizer-P only moved to the halves of which it could be reached. WE-P and Ca2-P significantly increased in 45 mm, but major presented in 20 ram. Ca4-P, Al-P and Fe-P significantly increased in 30 mm, but major existed in 20 mm. however, O-P only formed and major presented in 10 mm. Whereas, the peaks of the distribution of all P forms were presented in 0-2 mmo MCP significantly reduced the soil pH, and drastically destroyed soil CaCO3 in fertisphere. The Ca2＋ released by CaCO3 dissolution could fix half of fertilizer-P that moved into soil, furthermore, the Fe3＋ and Al3＋ released form the decomposition of soil compounds also play an important role in P fixation. The results clearly demonstrated the amphoteric hydrolyzation and the dissolution of CaCO3 played a pivotal role in inhibiting the mobility, but enhancing the fixation of fertilizer-P with MCP application in calcareous soil.
出处
《土壤》
CAS
CSCD
北大核心
2009年第1期72-78,共7页
Soils
基金
国家“973”项目(2007CB109301)
国家自然科学基金项目(30671202)资助。
关键词
潮土
磷酸二氢钙
肥际
磷
迁移
转化
有效性
Fluvo-aquic soil, MCP, Fertisphere, P, Translocation, Transformation, Availability fractionation, P mobility
