不同施肥条件下旱地红壤磷素固定及影响因素的研究

以Langmuir曲线测出的Xm值（最大吸磷量）为指标，对不同施肥条件下红壤旱地土壤的吸磷能力变化特征及影响磷素吸附的主要因素进行了研究。结果表明：施用磷肥能显著降低土壤的最大吸磷量，其中。施用厩肥的土壤Xm值最小。有机质是影响土壤吸磷能力的一个重要因素，随着有机质含量的升高，土壤吸磷能力减小；活性铝也是影响磷素吸附的重要因素，随活性铝含量增加，磷素吸附能力增加；活性铁的影响不显著；pH对红壤旱地吸磷能力影响也不显著。通过因子分析得到，有机质含量对土壤吸附磷素的能力影响最大。在生产上，磷素最大吸附量Xm值可以作为初步判断土壤需施磷肥量大小的依据。这些可为红壤地及的褴毒施用研有档供理论依据和实践指导。     

施肥措施对水旱轮作条件下灌淤土磷素形态的影响

  目的  研究水旱轮作条件下灌淤土磷素形态的变化特征,为宁夏引黄灌区作物施肥调控土壤磷素有效性提供科学依据。  方法  在水稻-玉米轮作体系下,设不施氮肥（T0）、常规施肥（T1）、优化施氮（T2）、70%优化施氮 + 30%有机肥氮（T3）、80%优化施氮 + 20%有机肥氮（T4）、秸秆还田 + 70%优化施氮 + 30%有机肥氮（T5）、秸秆还田 + 80%优化施氮 + 20%有机肥氮（T6）7个试验处理,通过田间小区定位试验研究了不同施肥措施对灌淤土全磷、速效磷和无机态磷含量的影响。  结果  在水旱轮作过程中,不同施肥措施对各季作物土壤全磷含量和旱地玉米速效磷含量影响不明显,但秸秆还田配施化肥和有机肥（T5、T6）能提高耕层土壤速效磷含量,水稻季和玉米季最高含量分别达56.4 mg kg?1和40.4 mg kg?1。由水田改为旱作后,不同施肥措施下土壤速效磷含量平均降低了7.6 ~ 18.1 mg kg?1。水田条件下不同施肥措施对无机磷含量均有显著影响（铝结合态磷除外）;旱作条件下不同施肥措施对铝结合态磷、铁结合态磷、闭蓄态磷含量均有显著影响,但对交换态磷、钙结合态磷含量影响不大。水田或旱作条件下,闭蓄态磷和钙结合态磷都是灌淤土无机磷的主要赋存形态。  结论  在宁夏引黄灌区水旱轮作体系下,有机无机肥配施秸秆还田是灌淤土磷素有效化调控的最有效手段,且在水稻季的调控效应最明显。     

水稻旱作条件下土壤水分对红壤磷素的影响

通过温室盆栽和大田试验研究旱作水稻在施用中量磷肥条件下,土壤水分对红壤中几种磷的含量和动态的影响。研究表明:土壤水分水平和采样时间对红壤全磷、有效磷、有机磷和不同形态的无机磷含量都有极显著的影响,且相互间的交互作用明显。栽种水稻后总体来说,土壤全磷、有机磷和O-P含量均有一定的提高,有效磷和Al-P、Fe-P、Ca-P含量则下降;土壤中不同形态无机磷含量为O-P>Fe-P>Al-P>Ca-P;大田和盆栽实验相比,在4种形态的无机磷、全磷和有机磷的排列顺序、演变趋势等方面基本一致,但有效磷则出现相反的结果,同时,大田试验土壤中各种磷的含量要比盆栽试验高得多,表明盆栽条件下,由于根系密度大,使土壤磷素消耗更快。     

福建山地红壤土壤磷素资源的研究

对福建省山地红壤磷素资源进行了研究,结果表明:福建山地红壤磷素主要由无机磷组成,无机磷组成以闭蓄态磷(O-P)含量最高,其次为磷酸铁磷(Fe-P),再其次为磷酸铝磷(Al-P);有机磷组成比例大小为中等活性有机磷中等稳定性有机磷高稳定性有机磷活性有机磷。随着纬度(北纬)的降低,山地红壤的闭蓄态磷(O-P)含量占全磷含量比例的平均值增加,而Fe-P、Al-P则减少;随着纬度的降低,山地红壤有机磷占全磷的比重以及绝对量均逐渐降低,土壤有效磷含量以及活性有机磷和中等活性有机磷比例呈逐步下降趋势,中等稳定和高稳定有机磷呈逐步升高趋势。土壤各无机磷组分的含量与有机质含量、pH值、阳离子交换量存在负相关,土壤有机磷的含量与有机质含量、阳离子交换量呈极其显著的正相关。土壤有机磷组分与有效磷相关密切的顺序为:活性有机磷中等活性有机磷中等稳定性有机磷高稳定性有机磷;O-P与有效磷呈极其显著的负相关,Al-P和Fe-P与有效磷正相关,但未达显著程度。     

长期施肥对旱地红壤团聚体磷素固持与释放能力的影响

在中国科学院红壤生态试验站26年的旱地红壤长期肥料定位试验中,选取无机肥试验区的NPK、NK处理,有机无机肥配施试验区的对照(CK)、CK+稻秆(RS)、CK+花生秸秆还田(PS)、CK+绿肥(FR)及CK+猪厩肥(PM)等7个肥料处理土壤,采用湿筛法逐级提取并得到粒级依次为2 mm、2~1 mm、1~0.25 mm与0.25~0.053 mm的团聚体土壤样品;通过室内分析获得了土壤及各粒级团聚体的全磷(TP)、有效磷(Available P)、水溶性磷(CaCl_2-P)、土壤磷素吸持指数(PSI)及土壤磷素饱和度(DPS)等指标值,并探讨了上述测定指标间的相关关系。结果表明:长期施用磷肥可有效保持旱地红壤的供磷水平,配施猪厩肥可显著增加旱地红壤及大小团聚体的TP、有效磷及CaCl_2-P含量、降低土壤PSI并显著增大旱地红壤DPS,加大了旱地红壤磷素的流失风险;随着土壤中1 mm粒级团聚体数量的增多,旱地红壤磷素储量显著增加,磷素固持能力显著下降,土壤磷释放潜能随之增大。由DPS、有效磷及CaCl_2-P的分段线性拟合方程可以推断得出,当旱地红壤中有效磷为168~260 mg kg~(-1)时或DPS28%,土壤磷素具有潜在流失风险;当有效磷≥260 mg kg~(-1)或DPS≥28%,土壤磷素具有极高的流失风险,应立即停止施用磷肥尤其是有机磷肥,并重新调整施肥方案,以避免土壤磷素流失及其对水体环境的污染。     

定植3,13,34年热带胶园的土壤磷素形态变化和有效性研究

采用Hedley磷素分级方法研究了定植3，13，34年热带胶0－20cm深的土壤磷素形态，结果表明：在不施肥条件下，随着定植年限的增加，土壤磷素总量（∑P）基本保持不变，但土壤中的无机磷（∑Pi）增加了273％，有机磷（∑Po）降低了55％。并且发现，残留磷（Residual P）在长期耕作条件下是无铲的。由于土壤有机磷的矿化，使土壤磷素有效性水平降低。     

长期施肥下红壤旱地磷素有效性影响因子的冗余分析

以长期施肥(1988~2014年)的红壤旱地为研究对象,以全磷(TP)、有效磷(Bray-P)为响应变量,土壤p H值、大小粒级团聚体组成比例(PSAi)、铁铝氧化物、阳离子交换量(CEC)、分形维数(D)等指标为解释变量,借助于冗余分析(RDA)方法探讨各指标变量与红壤旱地TP和Bray-P含量变化的相关关系。研究结果表明,长期施磷或配施猪粪均可显著增加红壤旱地TP和Bray-P含量,而配施作物秸秆无显著影响。冗余分析发现,土壤p H、CEC、D、铁铝氧化物含量及粒级为0.25~0.05、0.001~0.005与<0.005 mm的团聚体分布比例(PSA2、PSA4与PSA5)等土壤测试值是影响红壤旱地磷素有效性的主控因子,其中,p H和CEC的影响作用最大。可见,通过长期施肥改善土壤的酸性环境,提高土壤阳离子交换量,是提高红壤旱地磷素有效性的关键。     

连续施用生物炭对棕壤磷素形态及有效性的影响

【目的】土壤磷有效性差、磷肥利用率低是农业发展的主要限制因素之一。生物炭作为新型土壤改良剂，其独特的理化性质会影响磷素形态及有效性。本研究通过分析连续施用不同用量生物炭对棕壤不同形态磷素含量及变化规律，探讨各形态磷对棕壤磷素有效性的贡献，以期明确生物炭对棕壤磷素有效性的作用，为其合理农用提供理论依据。【方法】本试验研究对象为连续5年增施生物炭的玉米连作棕壤，共设5个处理:不施肥(CK)、单施化肥氮磷钾(NPK )、1.5 t/hm2生物炭 + 氮磷钾(C1NPK)、3 t/hm2生物炭 + 氮磷钾(C2NPK) 和6 t/hm2生物炭 + 氮磷钾(C3NPK)，采用蒋柏藩、顾益初土壤无机磷分级、Bowman-Cole土壤有机磷分级方法测定不同形态磷含量，研究不同用量生物炭配施化肥对棕壤磷素形态及有效性的影响。【结果】连续5年施用生物炭可显著提高棕壤全磷、有效磷含量及磷活化系数；明显提高了棕壤Ca₂-P、Ca₈-P、Al-P、Fe-P、LOP(活性有机磷)、MLOP(中活性有机磷) 含量，降低了MROP(中稳性有机磷) 含量；在磷组分中，MLOP、O-P分别占棕壤有机磷、无机磷比例最大，为64.32%、28.43%。施用生物炭显著提高了Ca₂-P、Ca₈-P占无机磷比例；Al-P与有效磷含量相关系数最大为0.945，LOP、Al-P、MROP对有效磷的直接通径系数较大，分别为0.318、0.285、–0.261；Al-P、HROP(高稳性有机磷) 对有效磷的决策系数分别为0.295和–0.130，是棕壤有效磷的主要决策因子和主要限制因子。【结论】施用生物炭可以促进棕壤磷素积累并提高其活性；施用生物炭条件下，Al-P、LOP是棕壤磷素的活跃组分，提高Al-P含量、限制HROP含量是生物炭提高棕壤磷素有效性的主要途径。     

长期施肥对旱地红壤磷素饱和度的影响

磷素饱和度(Degree of phosphorus saturation, DPS)能够有效评估土壤磷素的流失潜能及地表水磷富营养化问题,可用于评价土壤磷素环境风险。DPS值通常由酸性草酸铵提取态磷(Pox)与提取态铁铝(Feox, Alox)的摩尔质量比除以校正常数(Corrected constant,α)计算得到,而α是通过建立土壤饱和吸磷量与影响土壤磷吸附的土壤特征值间的相关关系而计算得到的数值;α的取值大小(常取0.5)会直接影响到DPS的准确估算。因此,本文以中国科学院红壤生态实验站(28°04′～28°37′N,116°41′～117°09′E)为依托,以长期施肥(1988～2014年)的旱地红壤为研究材料,通过两种计算方法得到了土壤的DPS值,分析了校正常数α=0.5在长期施肥的旱地红壤DPS计算中的适用性,并确定了长期施肥旱地红壤DPS计算中α的适用性阈值。研究结果表明:校正常数α=0.5虽适用于长期施肥旱地红壤DPS的估算,但易导致旱地红壤DPS的过高估算;对比计算发现,长期施肥旱地红壤DPS计算时,校正常数α的最适取值范围为0.71～0.81。但是,不同环境背景下旱地红壤DPS计算公式中校正常数α的适应性阈值仍需进一步校正与验证,从而提高红壤区土壤磷素环境风险评估的准确性。     

长期轮作与施肥对农田土壤磷素形态和吸持特性的影响

通过对黄土旱塬地区长期定位施肥(26a)条件下的不同轮作系统的土壤磷素形态和吸持参数的测定,研究了轮作和施肥对土壤磷素吸持特性和磷素形态的影响,以及土壤磷素吸持参数与磷素形态之间的关系。结果表明,长期轮作与施肥都可以减低土壤磷素的最大吸附量（Qm）,相对于其它轮作和连作,在氮磷（NP）施肥下,小麦-玉米-豌豆轮作可以减低土壤的Qm,在氮磷有机肥（NPM）施肥下,小麦-玉米轮作可以减低土壤的Qm。在施肥相同的条件下,小麦-玉米轮作和小麦-豌豆轮作可以显著增加土壤中各形态无机磷的含量,长期轮作比连作可以增加土壤中的有效磷养分,尤其对Ca2-P的提高效果更为显著。相关分析表明,Qm和磷吸持指数（PSI）与全磷（T-P）、Olsen-P、CaCl2-P、Ca2-P、Ca8-P、Fe-P、Ca10-P和有机磷呈极显著负相关（p＜0.01）,与闭蓄态磷（O-P）呈显著负相关（p＜0.05）,与Al-P关系不显著。土壤有机质（SOM）与Qm、PSI和磷最大缓冲能力（MBC）之间存在极显著负相关关系,与磷吸持饱和度（DPSS）存在显著正相关。通径系数和逐步回归分析表明,在石灰性黑垆土土壤的无机磷形态中,Ca2-P对Olsen-P的贡献最大。     

蔬菜地肥熟表层土壤中各形态磷的可淋洗性研究

肥熟表层是长期培肥形成的富磷表土层.为了解该类土层中积累磷的释放特性,本文选择了酸碱度和质地相差较大的5个代表性肥熟表层土壤样品,采用室内模拟淋洗和磷形态分析方法,研究了该类土层中磷的可淋洗性.结果表明,该类土层有很强的磷释放能力,从中释放出来的磷主要为无机态磷,其占总释放磷的86.68%～94.44%.可释放土壤磷的形态除水溶性磷(H2O-P)外,还有胶体表面吸附的无机磷(NaHCO3-Pi)、钙、镁结合态磷(HCl-P)、有机态P和土壤铁铝氧化物吸附的磷(NaOH-Pi)等形态;在淋洗过程中,H2O-P、NaHCO3-Pi和HCl-P的下降率分别达45.8%～58.1%、30.5%～43.2%和3.6%～49.0%.淋洗过程中磷的稳定性由低到高依次为水溶性磷和NaHCO3-Pi,而后期可能来自HCI-P.     

《中国土壤磷素养分潜力概图》及其说明

《中国土壤磷素养分潜力概图》是以一千万分之一的《中国土壤图》为底图,收集国内有关单位的资料^1-5)(中国科学院南京土壤研究所,1978;熊毅等,1965)整理后编制而成。又缩影成一千八百万分之一。解放以来,我国土壤化学和农业化学工作者,在土壤磷素养分和磷肥方面进行了大量的工作,积累了一定的资料,为编制本图奠定了基础。但由于资料的平衡性和系统性不够,所以编制过程中仍有不少困难,尤其是西部和西北部地区,收集的资料较少,有待进一步补充和修改。     

Isolating the influence of pH on the amounts and forms of soil organic phosphorus

Soil pH influences the chemistry, dynamics and biological availability of phosphorus (P), but few studies have isolated the effect of pH from other soil properties. We studied phosphorus chemistry in soils along the Hoosfield acid strip (Rothamsted, UK), where a pH gradient from 3.7 to 7.8 occurs in a single soil with little variation in total phosphorus (mean ± standard deviation 399 ± 27 mg P kg^?1). Soil organic phosphorus represented a consistent proportion of the total soil phosphorus (36 ± 2%) irrespective of soil pH. However, organic phosphorus concentrations increased by about 20% in the most acidic soils (pH < 4.0), through an accumulation of inositol hexakisphosphate, DNA and phosphonates. The increase in organic phosphorus in the most acidic soils was not related to organic carbon, because organic carbon concentrations declined at pH < 4.0. Thus, the organic carbon to organic phosphorus ratio declined from about 70 in neutral soils to about 50 in strongly acidic soils. In contrast to organic phosphorus, inorganic phosphorus was affected strongly by soil pH, because readily‐exchangeable phosphate extracted with anion‐exchange membranes and a more stable inorganic phosphorus pool extracted in NaOH–EDTA both increased markedly as soil pH declined. Inorganic orthophosphate concentrations were correlated negatively with amorphous manganese and positively with amorphous aluminium oxides, suggesting that soil pH influences orthophosphate stabilization via metal oxides. We conclude that pH has a relatively minor influence on the amount of organic phosphorus in soil, although some forms of organic phosphorus accumulate preferentially under strongly acidic conditions.     

动物粪液中可溶性磷在土壤中的吸附和迁移特性研究

农田土壤施用动物粪肥引入了大量的可溶性有机物、有机磷和无机磷,了解这些可溶性物质在土壤中的相对移动性及它们之间的相互作用有助于指导农田养分管理。本研究从粪液中分离获得含水溶性无机磷、有机磷和有机物（碳）的溶液,选择了具不同质地和有机质含量的4个土壤（含高量有机质的黄筋泥、含低量有机质的黄筋泥、淡涂泥和清水沙）,应用等温吸附和土柱模拟淋洗方法研究了可溶性有机碳、无机磷和有机磷共存条件下,粪液中可溶性有机态磷和无机态磷在土壤中的吸附和迁移特性。吸附试验表明,可溶性有机物（碳）的存在大大降低了土壤对有机态磷和无机态磷的吸附,表明施用液态有机肥比施用化肥具有更大的磷流失风险。供试土壤对无机态磷的吸附强度高于有机态磷,但对二者的吸附量大小为:黄筋泥>淡涂泥>清水沙;并与粘粒含量、氧化铁含量呈正相关。有机质较高的土壤对有机磷的吸附明显低于有机质低的土壤。淋洗试验表明,在供试土壤中,这3种可溶性物质在土壤中吸持(包括生物吸持)的顺序为:可溶性无机磷>可溶性有机碳>可溶性有机磷;有机态磷比无机态磷更易在土壤中迁移。     

Effects of long-term phosphatic fertilizer applications on amounts and forms of phosphorus in soils under irrigated pasture in New Zealand

In this study a detailed sequential fractionation scheme was used to examine the effects of long-term annual applications of phosphatic fertilizer on the amounts and forms of phosphorus (P) in soils under intensively grazed irrigated pasture over a 25 year period (1952–1977). Results showed that increases in soil inorganic and organic P occurred in response to continued P fertilizer addition, although inorganic P decreased with time following the cessation of P fertilizer inputs in the residual fertilizer and control treatments. The rate of organic P accumulation in soils decreased with time, while a marked decline in soil organic P in all treatments between 1971 and 1974 was attributed to increased mineralization as a result of lime addition in 1972. Furthermore, changes in the forms of inorganic P which accumulated in the continually fertilized soils after 1971 were attributed to the combined effects of liming and changes in the chemical nature of applied fertilizer P.     

土壤磷形态组分分级及31P-NMR 技术应用研究进展

农田生态系统中土壤磷形态转化,影响土壤磷对作物的有效供应。土壤磷分为无机磷和有机磷两大部分。化学连续提取法 (chemical sequential fractionation,CSF) 研究土壤磷形态分级,采用不同的化学提取剂,分级提取土壤中组成或分解能力接近的有机无机含磷化合物,是目前表征土壤磷素形态的重要方法。但该方法虽历经改进,仍难以确切反映土壤磷的实际组成,提取的不同磷形态间存在重叠,有机磷和无机磷组分分级存在一定的误差;不同分级磷组分对作物的有效性,需谨慎评估。核磁共振波谱技术 (nuclear magnetic resonance,NMR) 根据核磁共振波谱图上共振峰的位置、强度和精细结构来研究土壤中含磷化合物的分子结构。液相31P-NMR 可以同吋检测出土壤中多种磷组分,如正磷酸盐、磷酸单酯、磷酸二酯、膦酸脂、焦磷酸盐和多聚磷酸盐,识别土壤提取物磷形态,可将有机磷与无机磷分开。本文综述了应用31P-NMR 技术研究土壤磷形态组分的一些进展,总结了样品制备过程、NMR 测试参数及在土壤磷形态转化研究中的应用。二维31P-NMR 技术发展为鉴定分析土壤中更多种类的含磷化合物提供了契机。     

Phosphorus addition enhances gross microbial N cycling in phosphorus-poor soils: a <Superscript>15</Superscript>N study from two long-term fertilization experiments

The tight coupling between nitrogen (N) and phosphorus (P) suggests that P availability may affect soil microbial N dynamics in terrestrial ecosystems. However, how P addition affects the internal N transformations in P-deficient agricultural soil remains poorly understood. We hypothesized that an increase in gross microbial N rates in P-deficient soil should occur after long-term P inputs in agricultural soils. We thus conducted a ¹⁵N pool dilution experiment to quantify the gross microbial N transformation rates after long-term mineral fertilizer applications in an upland fluvo-aquic soil (from Fengqiu with pH 8.55) and upland red soil (from Qiyang with pH 5.49) in China. We found that P addition significantly enhanced the gross N mineralization and immobilization rates when N and K were also applied, probably due to the increased soil total C and N concentrations at both soils. Also, gross nitrification rate was stimulated by P addition, perhaps because of enhanced gross N mineralization rates and associated NH₄⁺ substrate availability. Our results showed that long-term P addition may stimulate soil gross N dynamics and hence increase overall N availability for crops in P-deficient agricultural soils.     

Nitrogen compounds in soil solutions of agricultural land

Plants are capable of taking up nitrogen (N) in both organic and inorganic forms, so the concentrations and relative proportions of different N forms in soils are likely to be important determinants of their N nutrition. Therefore, there is a need for greater knowledge of the N profiles of soils. In the study presented here we examined the potential plant-available N in soils from four sites with various agricultural histories (one recently fertilized), using small tension lysimeters to collect free and bound amino acids and inorganic N forms in solution, with minimal soil disturbance and with intact plants present. Subsequent analysis showed that concentrations of free amino acids ranged from 0.1 to 12.7 μM, whereas concentrations of bound amino acids were on average 50 times higher, and higher than ammonium and nitrate concentrations in all three unfertilized soils. In contrast, nitrate strongly dominated in the fertilized soil. Bound amino acids are likely to represent a potential replenishment pool for free amino acids, so the abundance and rate at which amino acid-containing substances are depolymerized might be important determinants of the availability of free amino acids. Our results highlight the need for further research on the liberation of free amino acids from polymers in agricultural soil, and the importance of bound amino acids as N sources for plants.     

Alkalinity exacerbates phosphorus deficiency in subtropical red soils: Insights from phosphate-solubilizing fungi

Red soils in subtropical regions are often low in available phosphorus (P), a vital plant nutrient. Phosphate-solubilizing microorganisms (PSMs) can release P from phosphate reservoir, making it accessible to plants. However, the complex interactions between PSMs and minerals in red soils are not yet fully understood. In this study, we investigated the effects of Aspergillus niger, a typical phosphate-solubilizing fungus (PSF), on phosphate dissolution in two representative red soils – an acidic soil and an alkaline soil. In the acidic red soil, the fungal abundance reached 3.01 × 10 ⁷ cfu g⁻¹ after a 28-day incubation period, with respiration of ~2000 mg C kg⁻¹. The secretion of oxalic acid promoted P release from inorganic phosphate (from ~1 to 187 mg kg⁻¹). Additionally, the contents of amorphous Fe/Al oxides decreased, which otherwise could have contributed to P sorption in the soil. In contrast, P availability declined in the alkaline red soil after the addition of A. niger, regardless of the P source (inorganic or organic phosphate). Meanwhile, the fungal respiration decreased to ~780 mg C kg⁻¹. Therefore, alkaline red soils with abundant carbonates are susceptible to P deficiency due to both the diminished function of PSMs and strong soil buffering. These findings have important implications for sustainable agriculture on alkaline red soils, as they suggest that the use of PSMs to improve P availability may be limited.