【作者】 薛巧云；

【导师】 林咸永；

【作者基本信息】 浙江大学 ， 植物营养学， 2013， 博士

【摘要】 随着我国规模化畜禽养殖业的迅速发展,畜禽粪便排放量急剧增加。畜禽粪便由于含有丰富有机质和氮、磷等养分,在改良土壤结构、提高土壤肥力和提供作物营养等方面具有重要的作用。但是,近年来的研究表明,大量施用有机肥在满足作物氮素营养需要的同时,其供磷量常常远超过作物的需磷量而导致土壤磷素积累,进而增加由于地表径流、土壤侵蚀、淋溶等途径造成的水体污染风险。虽然关于施用有机肥后土壤磷素形态、含量和转化特征已有不少的研究报道,但是关于农艺措施和环境条件对石灰性土壤磷素迁移转化和流失风险的影响尚缺乏系统的研究。本论文以石灰性土壤为研究对象,采用室内模拟试验与田间原位观测方法相结合,运用化学测试和微生物分子生态学技术,较系统地研究了长期施用有机肥对石灰性土壤磷素积累、转化和迁移的影响、降水强度和有机肥用量对休闲期石灰性土壤磷素淋失的影响、石灰性土壤磷素吸附特性及其与流失风险的关系、不同磷源对石灰性土壤磷素有效性及其微生物群落结构的影响以及长期冻融交替循环对石灰性土壤磷素形态转化及其微生物群落结构的影响。取得的主要结果如下：1.在北京市顺义区采集了3种土地利用方式(菜地、农田、林地)下,0-200cm内不同土层石灰性土壤样品,研究了长期大量施用有机肥(8-15y)对不同土地利用方式下石灰性土壤磷素积累、转化和迁移的影响。结果表明,3种土地利用方式下,土壤中磷酸钙型磷占全磷比例最大,残留态磷次之,有机磷最低,占全磷比例不足5%。长期大量施用有机肥显著增加土壤无机磷含量,其中,活性无机磷增幅显著高于稳定性无机磷。施用有机肥的耕层土壤(0-20cm)中,土壤有效磷(POIs)和磷饱和度(DPS)水平均分别高于临界值60mg Pols kg-1和30%DPS,增加土壤磷素流失风险。底土中(20-200cm) DPS值均低于临界值,通过淋溶途径造成的土壤磷素流失风险较低。因此,长期大量施用有机肥不仅导致磷在表层土壤积累,而且提高土壤活性磷水平,从而增加土壤磷素流失风险；3种土地利用方式中以菜地土壤磷素流失风险最大。2.采用短期(53d)渗漏计试验,在北京市顺义区北郎中养殖场原位观测了模拟降水强度和有机肥用量对休闲期石灰性雏形土磷素淋溶的影响。结果表明,降水和施用有机肥均会引起土壤磷素向下迁移,并主要富集在4-10cm土层。强降水条件下,土壤水溶性磷含量显著低于弱降水土壤,前者渗漏液中活性磷(DRP)和全磷(TP)含量均显著高于后者；休闲期未施用有机肥处理也存在磷素淋溶,施用有机肥处理尤为显著,53d后渗漏液中DRP和TP分别达1.83、7.46mg L-1根据水溶性磷(Pw)与土壤磷饱和度DPSCaM3和DPS(Ca+Mg)M3关系所确定的土壤磷素淋失DPSCaM3和DPS(Ca+Mg)M3临界值分别为18.9%和14.1%。供试土壤中,0-30cm土层土壤的DPS值均高于上述临界值,存在磷素淋失的风险；相反,30-40cm土层土壤DPS值均低于上述临界值,土壤磷素淋失风险较低。可见,在作物种植期施用有机肥导致土壤磷素积累的情况下,无论降水强度高低或休闲期施用有机肥与否,均存在不同程度的磷素淋失风险,高强度降水和施用有机肥则显著增加休闲期土壤磷素淋失的潜能,大型养殖场附近的农田在休闲期可否进行畜禽粪便的土地消纳需根据土壤磷素状况而定。3.采集了75个土壤基本性质、磷素水平差异较大的典型石灰性土壤样品,系统研究了土壤固磷能力与理化性质间的关系,以期建立石灰性土壤磷素流失评价体系。结果显示,采用较为简便的单点吸附所获得的土壤磷素吸附量(PSCl50)可替代多点吸附所获得的磷最大吸附量(Xm)以表征供试土壤的磷素固定能力,并可依据土壤磷饱和度(DPS)方程DPS(%).[PM3/(0.039CaM3+0.462MgM3)]计算石灰性土壤的DPS(DPS(CaM3+MgM3)).在此基础上,通过分段线性拟合DPS(CaM3+MgM3)和水溶性磷(Pw)的关系得出供试石灰性土壤磷素流失的DPS(CaM3+MgM3)和速效磷(Pols)的临界值分别为28.1%和49.2mg kg-1。本研究综合考虑土壤磷水平和吸附特征所构建的预测石灰性土壤磷素流失风险的指标体系,克服了以往沿用酸性土壤中常用方法所建立的指标体系,存在难以准确评价石灰性土壤磷素流失风险的缺点,得出的临界值可为石灰性土壤磷素流失风险预测以及科学施肥管理提供理论依据。4.采用室内培养方法,研究了不同磷源(猪粪、堆肥和化肥)对石灰性土壤供磷水平的影响及其机制。结果表明,施用3种磷源均显著提高土壤速效磷含量和土壤磷素释放能力,化肥处理尤为显著。随着培养时间的延长,施用化肥土壤速效磷水平显著下降,施用猪粪和堆肥土壤的速效磷水平却没有显著变化。施用猪粪可显著提高土壤真菌、细菌特征脂肪酸和总磷脂脂肪酸含量、真菌特征脂肪酸/细菌特征脂肪酸比值以及磷酸酶活性,对放线菌特征脂肪酸含量没有影响；施用堆肥显著提高土壤总磷脂脂肪酸含量和碱性磷酸单酯酶活性,对土壤真菌、细菌和放线菌特征脂肪酸含量以及酸性磷酸单酯酶和磷酸二酯酶活性均没有影响；施用化肥对真菌、细菌和放线菌特征脂肪酸以及总磷脂脂肪酸的含量没有影响,显著降低土壤磷酸酶活性。因此,不同磷源均可提高土壤供磷水平,但化肥处理显著高于猪粪和堆肥处理,化肥处理显著降低土壤磷酸酶活性却对土壤微生物群落结构没有明显影响；但猪粪和堆肥可通过提高土壤磷酸酶活性或磷脂脂肪酸含量以促进有机磷水解,保证土壤磷素的持续供应。5.采用室内培养方法,研究了长期冻融交替循环(53个循环,共计424d)对石灰性土壤磷素形态转化、释放特征的影响及其机制。结果显示,长期冻融交替处理下,土壤微生物生物量碳和生物量磷以及土壤细菌特征脂肪酸含量显著降低,土壤磷酸二酯酶活性显著提高,而真菌特征脂肪酸和放线菌特征脂肪酸含量以及磷酸单酯酶活性的响应特征同时受土壤磷水平的影响；土壤活性磷含量及其占全磷比例显著提高,土壤中有机磷含量及其占全磷比例却显著降低；土壤磷素的释放受到显著抑制,且以高磷土壤尤为明显。因此,释放土壤微生物生物量磷、改变微生物群落结构以及提高土壤磷酸酶活性而促进有机磷水解是冻融交替循环提高土壤活性磷水平的主要机制。更多还原

【Abstract】 Intensive livestock and poultry production systems have generated large quantities of manures, which are readily available and abundant sources of nutrients for crop production worldwide. The land application of manure for the purpose of conditioning the soil and fertilizing crops is a common practice in the world. However, repeated land application of manures to meet crop nitrogen (N) needs can cause the buidup of large amounts of phosphorus (P) in the soil profile, leading to the risk of P loss to water bodies by runoff, erosion or leaching. Previous studies showed that P forms, quantities and migration of P are strongly influenced by manure application, however, effects of agronomic practices and environmental factors on P translocation, transformation and loss potential haven’t been clearly studied. Incubation experiments and in situ field experiments were performed on calcareous soils using chemical testing and microbial molecular ecology technique. This study aimed at evaluating the impact of manure application on phosphorus accumulation, translocation and transformation in a calcareous soil under different land use, studying the effects of rainfall and manure application on phosphorus leaching in field lysimeters during fallow season, deriving sorption indices for the prediction of potential phosphorus loss from calcareous soils, to study effects of phosphorus addition on phosphorus availability and microbial community structure, and to explore the effects of freeze-thaw cycles on phosphorus forms and translocation and microbial community structure. The main results were listed as follows:(1) Soil samples under different cropping systems (Vegetable, Cereal, and Tree) were collected to a depth of200-cm to evaluate the effect of manure application on soil P forms and quantities. It was shown that soil calcium bound P was the most abundant P fraction, followed by the residual P. Organic P only accounted for less than5%of total P in most of the soils. Manure application increased the levels of inorganic P (Pi), with higher proportions of Pi in labile forms than stable forms. After manure application for8-15yr, available P (Pois) and DPS values of the0-20cm layer in all sites exceeded the threshold for Olsen P (60mg kg-1) and DPS (30%) and the risk of P loss by runoff is expected to significantly increase. The DPS values were generally lower than30%below20cm, indicating a minimal risk of P loss via leaching Tom deeper soil. The results indicated that in typical peri-urban areas of the North China Plain,;he on-going practice of manure application not only caused P accumulation on topsoil, but also ncreased labile P, thus leading to high P loss potential, with the highest P loss risk found in vegetable soil.(2) A short-term field lysimeter experiment (53d) was performed to evaluate the effect of rainfall (low, high) and manure application (0,43kg P ha-1) on phosphorus (P) leaching from a calcareous soil in the fallow season. Our results showed that the P loading, irrespective of different extractions, was found below40cm in all treatments and P was most concentrated in the4-10cm soil layer. High rainfall enhanced P leaching and consequently led to lower water P (Pw) and higher leachate dissolved reactive P (DRP) and total P (TP) than low rainfall. Furthermore, P leaching was observed regardless of manure application, with the highest leachate DRP (1.83mg L"1) and TP (7.46mg L-1) concentrations found at the end of experiment (day53).Observed P leaching loads during fallow season (53d) varied between0.08and1.21kg ha-1. The thresholds of degree of P saturation (DPS) indicating P leaching were identified at18.9%DPSCaM3and12.9%DPS(Ca+Mg)M3, respectively. In this study, the DPSCaM3and DPS (Ca+Mg)M3values exceeded the corresponding thresholds in the upper30-cm soil layer but did not reach the thresholds at30-40cm. Nevertheless, the leachate DRP and TP indicated soil P leaching. The results showed that intensive rainfall could significantly increase P leaching from manure application. Moreover, P leaching could occur in fallow season even in the absence of manure input, which should be assessed by not only soil P sorption capacities, but also soil fertilization history and hydrologic conditions. Implementation of soil P level evaluation is critical before spreading manure on land to avoid P pollution. Cost effective and applicable soil test methods are required to generate environmental indicators to classify agricultural lands for risk of P loss, providing basis to safe manure disposal.(3) Seventy five soils mostly from Northern China were analyzed for developing techniques to evaluate soil phosphorus (P) sorption capacity (PSC) and determine critical soil P levels to predict P loss potential for calcareous soils. Strong correlation was found between PSC150and St (r2=0.89, p<0.001). The sum of αCaM3and βMgM3as an index of PSC (PSC(CaM3+MgM3)) was most closely related to the maximum amount of P sorbed (Smax) as given by the sum of St and soil initial P setting α=0.039and β=0.462(r2=0.80, p<0.001). The degree of P saturation (DPS) was thereafter calculated from PSC(CaM3+MgM3)(DPS(CaM3+MgM3)), to which Olsen P (Pols) was significantly correlated (r2=0.82, p<0.001). In a split-line regression from Pw against DPS(CaM3+MgM3)(r2=0.87, p<0.05), a change point was identified at28.1%DPS(CaM3+MgM3), which was equivalent to49.2mg kg-1Pols and corresponded to a Pw concentration of8.8mg kg-1. After the change point, a sharp increase in Pw was observed. Our results reveal a new approach to approximating DPS from CaM3and MgM3for calcareous soils without the need to generate a Smax. We conclude that in the absence of an environmental soil test criteria for P, the DPS(CaM3+MgM3) and Pois could be used to predict P loss potential from calcareous soils. (4) An incubation experiment was performed to study the effects of different phosphorus additions (swine manure, compost and fertilizer). Results showed that the three P additions can increase Olsen P (Pols) content and enhance P release, with the significant effect found under fertilizer addition. As time prolonged, Pols concentration decreased with fertilizer addition, while there was no change with manure and compost additions. Phospholipid fatty acid analysis (PLFA) revealed that manure greatly increased fungal, bacterial and total PLFA biomass, fungal/bacterial ratio, and phosphatase activities, while actinomycetes were not affected. Besides, compost greatly increased total PLFA biomass and alkaline phosphomonoesterase activity, whereas, biomass of fungal, bacterial and actinomycetes, acid phosphomonoesterase or phosphosdiesterase activities were not influenced. For fertilizer addition, fungal, bacterial and total PLFA biomass didn’t change, while phosphatase activities were decreased. Therefore, P availability could be increased by different P additions, with the most significant increase observed with fertilizer. Moreover, fertilizer could decrease phosphatase activities and have no effect on microbial community structure, however, manure and compost can favor organic P hydrolysis by increasing phosphatase activities and PLFA biomass, thus providing sustainable P supply.(5) An incubation experiment was carried out to study the effects of long-term freeze thaw cycles (FTCs)(53cycles,424d) on phosphorus (P) transformation, release characteristics and corresponding mechanism. Our results showed that microbial biomass carbon (C) and P as well as bacterial biomass were significantly reduced by FTCs, while phosphosdiesterase activity was increased and the responses of fungal and actinomycetes biomass as well as phosphomonoesterase activities to FTCs were affected by soil P levels. Furthermore, labile P concentration and the proportion in total P (TP) were significantly increased by FTCs, while the organic P (Po) content and the proportion in TP were obviously decreased. Soil P release characteristics showed that P release was reduced by FTCs, especially in high P soils. Therefore, FTCs could enhance Po hydrolysis by releasing soil biomass P, shifting microbial community structure and increasing phosphatase activities, thus improving soil P availability.更多还原