【作者】 康欧；

【导师】 李廷轩； 周健民；

【作者基本信息】 四川农业大学 ， 植物营养学， 2010， 硕士

【摘要】 磷肥施入土壤后在肥料颗粒周围的肥际微域中会形成养分浓度梯度,肥料中的养分会随土壤溶液向土体迁移并发生转化。在肥际微域里高浓度的磷酸根离子对土壤矿物具有强烈的破坏作用,因此肥际反应可能对磷肥的有效性有着至关重要的作用。本文选择了几种不同的供肥模式,采用室内土培和土柱培养方式,研究了不同土壤、不同温度和淹水还原条件下,磷在土壤肥际微域中的迁移与转化特征。主要结果如下：磷肥施入土壤后在较短的培养周期内向O-P和Calo-P转化的量极少,大部分以W-P和Ca2-P形态存在,也有相当一部分向Ca8-P、Fe-P和A1-P等有效性相对较差的磷形态转化。在不同的土壤中磷的形态组成有所不同,水稻土中主要以Ca2-P和Ca8-P为主,Fe-P和A1-P含量所占比率也较大；在典型的钙质土壤中主要以Ca2-P和Ca8-P为主,其他形态的磷含量比较少。同种土壤不同温度条件下,土壤磷的形态组成亦不相同,5℃土壤W-P,Ca2-P含量较25℃多,Ca8-P、Fe-P和A1-P含量较25℃时少。在不同温度和土壤条件下,施入有机酸和牛粪均可增加土壤W-P、Ca2-P含量。有机酸和牛粪可不同程度的提高磷的有效性,这种能力大小依次为：牛粪>草酸>柠檬酸。磷在不同土壤中的迁移距离不同,在本实验条件下,施入的肥料磷在水稻土和潮土中的迁移距离分别为57.5mm和42.5mm,随着距施肥点距离的增加,土壤水溶性磷、有效磷和酸溶性磷含量迅速降低。磷在这两种土壤中迅速被固定,潮土比水稻土更容易固定磷,生物有效性更低。配施草酸处理减少了土壤对磷的固定增加磷肥的迁移量,提高了磷在土壤中的生物有效性,且在典型石灰性土壤中的效果更好。但是配施草酸并不能明显的增加磷在土壤中的迁移距离。包膜MAP在土壤中的释放速率远远低于水溶液,培养120d后也仅有20%左右的肥料被释放,包膜MAP处理P在土壤中的迁移距离很短,并且包膜MAP缓慢释放磷肥可能会增强土壤对磷的固定作用。磷在土壤中迁移与转化均受温度的影响,在实验条件下,当培养温度为5℃、20℃和35℃时,施入的肥料磷在土壤中的迁移距离分别为57.5mm、57.5mm和42.5mm,在35℃条件下磷在土壤中的迁移距离明显变短,磷的生物有效性低。配施草酸处理在个温度条件下并不能明显的增加磷在土壤中的迁移距离。土壤水溶性磷和有效磷在土壤中的含量随着温度的升高而降低。在各温度条件下配施草酸处理在可减少土壤对磷的固定增加磷肥的迁移量,在低温条件下作用更为明显。包膜MAP处理由于其释放量少迁移距离很短。包膜MAP在土壤中的释放速量随着温度的升高逐渐增加,但其释放量很低在培养120d后也仅有较少的肥料被释放。在35℃培养条件下,施用包膜MAP可增加土壤水溶性磷和有效磷所占比率,减少土壤对磷的固定。土壤淹水还原会明显影响磷在土壤中的迁移与转化。实验条件下,施入的肥料磷在未淹水条件和淹水还原条件下磷的迁移距离分别为57.5mm和65mm,在淹水还原条件下磷的迁移距离大于未淹水条件,淹水可增加磷的迁移距离。在淹水还原条件下土壤有效磷和水溶性磷含量低于未淹水条件下,淹水还原会降低磷的生物有效性。配施草酸处理在两种培养条件下均不能明显的增加磷在土壤中的迁移距离。未淹水条件相爱,配施草酸可提高磷的活性,而在淹水还原条件下反而使磷的有效性降低。在两种培养条件下包膜MAP在培养120d后仅有20%左右的肥料被释放,在两种培养条件下来磷在土壤中的迁移距离差异不大。更多还原

【Abstract】 A nutrient concentration gradient was formed in fertilizer microsites around fertilizer particles by adding phosphorus into soil. The fertilizer nutrient moved into soil in the effect of soil solution and transformed to different formations. High concentration of phosphate in fertilizer microsites strongly destroyed the soil minerals which played a main role in phosphorus availablility. In this thesis, effects of four fertilization on phosphorus transformation and movement in fertilizer microsites in soils under three temperatures were studied by an incubation experiment using soil column. The main conclusions were as follows.In a short period after adding phosphorus into soil, phosphorus mainly existed as W-P and Ca2-P while some of the others transformed into Ca8-P, Fe-P an Al-P. Less of them transformed into O-P and Ca10-P. However, the percentage of transformation differed in soils. In paddy soil, phosphorus mainly existed as Ca2-P and Cag-P while Fe-P and Al-P made secondary contribution. In calcareous soil, Ca2-P and Ca8-P were the main formations. Temperature also effected the transformation even in one soil. By increasing the soil temperature from 5 degree centigrade to 20 degree centigrade, percentages of W-P and Ca2-P decreased while Ca8-P, Fe-P and Al-P had positive increasement. By adding organic acid and manure into soil, percentages of W-P and Ca2-P increased which indicated higher phosphorus availablility. This changing energy depended on the additives. They had a decreasement which followed as manure>oxalic acid>citric acid.The movement of phosphorus also differed in soils.In this paper, phosphorus migrated to 57.5 mm in paddy soil while the distance was 42.5 mm in calcareous soil. Concentration of water-extractable phosphorus, available phosphorus and acid-extractable phosphorus quickly decreased with the distance to fertilization site increased. Most phosphorus were quickly fixed in these two soils and the fixation was more efficient in paddy soil which indicated lower availablility. By adding oxalic acid into the fertilizer, fixation of soil was decreased and the amount of phosphorus that was migrated increased. However the additive didn’t effect the movement distance. Coated fertilizer that was studied in this paper had extremly low release rate in soil that only about 20% nutrient was released in 120 days which caused a short movement distance. Furthermore, the slow releasement of phosphorus would strengthen the fixation by soil.The transformation and movement were effected by the temperature. In this paper, three temperatures were studied. The nutrient moved to about 57.5 mm under 5 degree centigrade,57.5 mm under 20 degree centigrade and 42.5 mm under 35 degree centigrade. Adding oxalic acid obviously didn’t change the movement distance under these three temperatures. With the increase of temperature, concentration of water-extractable phosphorus and available phosphorus in soil decreased. Adding oxalic acid in all temperature treatments weakened the fixation by soil and increased the migrate amount especially in low temperature. Coated fertilizer released faster in high temperature but did not release more even after 120 days. Under 35 degree centigrade, the coated fertilizer treatment had high percent of water-extractable phosphorus and available phosphorus and had low fixation by soil.Submerging the soil obviously effected the transformation and movement of phosphorus in soil. In this study, comparing two water contant situation(60% soil water contant and fully submerge), the movement distance had obvious difference which was 57.5 mm in 60% soil water contant and was 65 mm in fully submerge situation. When soil was fully submerged in water, phosphorus moved further than in 60% soil water contant situation while the soil available phosphorus and water-extractable phosphorus were lower than in 60% soil water contant situation which indicated decreasing bioavailablility of soil phosphorus. Adding oxalic acid into the two experiments did not obvious increase the movement distance but increased the phosphorus availablility in 60% soil water contant situation while the negative result was observed in fully submerged situation. In these two experiments, coated fertilizer also released only about 20% after 120 days and had the same movement distance.更多还原