添加生物炭对灌淤土土壤养分含量和氮素淋失的影响

灌淤土是宁夏引黄灌区的主要土种,当地大引大排的灌溉方式不仅造成土壤养分淋失,而且会引起水体污染。本文采用室内土柱模拟降雨淋滤方式,设置1500g灌淤土分别添加1%、2%、5%、10%生物炭4个处理,观测淋滤后土柱中的养分状况和淋溶液中氮素含量,以不加生物炭为对照,研究添加生物炭对土壤养分含量和氮素淋失的影响。结果表明:(1)添加生物炭后土壤pH、全盐以及全磷含量未发生变化,土壤中全氮、速效磷和速效钾含量随着生物炭添加量的增大而显著增加;(2)添加生物炭处理与对照相比均极显著降低了土壤淋溶液的硝态氮含量和淋溶损失量(P0.01),以2%生物炭添加处理效果最好,比对照减少了49%的淋溶损失。(3)铵态氮的淋失峰值随生物炭添加量的增大而延后,但仅添加生物炭10%的处理显著减少铵态氮的淋溶损失量(P0.05),比对照减少了18%,其它处理则显著增加了铵态氮的淋溶损失量(P0.05),这一效果是否与生物炭种类有关,还需进一步探讨。     

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。     

减磷施肥配施生物炭对南方酸性稻作土壤磷素形态的影响

针对南方酸性稻作土壤专性吸附和固定磷素能力强的问题,采用微区试验,以正常施磷(75 kg/hm²)不施生物炭为对照,探讨不同磷肥水平(P2O5 75、60、45、30 kg/hm²)和生物炭配施(40、60、80 t/hm²)对土壤不同形态磷素含量的影响。结果表明：(1)减磷施肥配施生物炭后全磷、有效磷、树脂磷、碳酸氢钠无机磷及稀盐酸磷的含量显著增加,残留态磷的含量显著降低。(2)磷肥水平≥45 kg/hm²时,配施生物炭处理的全磷和有效磷含量较对照分别显著提高17.1%～46.7%和32.5%～76.3%。(3)磷肥水平≥45 kg/hm²时,配施生物炭处理的树脂磷和碳酸氢钠无机磷的含量较对照分别显著增加50.8%～160.3%和36.1%～118.3%。(4)减磷施肥导致氢氧化钠有机磷含量较对照下降38.4%～39.8%;处理间氢氧化钠无机磷的含量无显著差异。(5)配施生物炭后稀盐酸磷含量较对照显著提高57.9%～352.1%;减磷施肥处理的浓盐酸有机磷含量显著低于正常施磷...     

长期秸秆还田对潮土土壤各形态磷的影响

基于黄淮海低平原区潮土上33年长期肥料定位试验,采用蒋柏藩―顾益初的石灰性土壤无机磷分级方法,研究冬小麦―夏玉米轮作中长期不同氮磷用量下秸秆还田对土壤全磷、有效磷(Olsen-P)及各形态无机磷的影响。结果表明:黄淮海低平原区潮土上冬小麦―夏玉米轮作中P2O5用量0~240 kg hm~(-2),随磷肥用量的增加,土壤全磷、Olsen-P、无机磷总量及无机磷中Ca2-P、Ca8-P、Al-P和Fe-P均显著增加,O-P和Ca10-P无显著变化;当土壤输入磷量低于作物输出磷量时,无论秸秆还田与否,土壤全磷、无机磷总量、Olsen-P和无机磷中除Ca8-P外的其他各形态磷均无显著变化;当土壤输入磷量高于作物输出磷量时,随秸秆用量的增加土壤全磷、Olsen-P和无机磷中的Ca2-P、Ca8-P、Al-P均显著增加,其中以Olsen-P增幅最大,无机磷中以Ca2-P增幅最大,其次为Ca8-P,再次为Al-P;土壤磷素盈余和亏缺量与土壤中各磷形态含量均呈显著正相关关系。     

生物炭与有机肥、无机肥配施对采煤塌陷区复垦土壤理化性状的影响

为了研究施用生物炭对采煤塌陷复垦土壤的熟化效果,以山西省晋城市采煤塌陷复垦区土壤为研究对象,连续3年采用生物炭与有机肥、无机肥配施等方式研究其对复垦土壤主要理化性状的影响。结果表明:不同施肥处理均不同程度改善了土壤的理化性状,有机肥配施生物炭处理明显降低了复垦土壤容重(降幅10%),提高了土壤孔隙含水率(增幅7.14%),但对土壤pH影响不明显。有机肥处理和无机肥处理的土壤全氮、全磷含量差异不显著;无机肥配施生物炭处理与单施无机肥处理相比,速效磷增加了8.33%,速效钾增加了6.34%,增幅较明显,对碱解氮影响则不明显。有机肥配施生物炭,土壤细菌、真菌、放线菌数量增幅不明显;无机肥配施生物炭,真菌数量增幅最为明显(11.7%)。有机肥、无机肥配施生物炭处理玉米产量分别提高了3.03%和2.70%,生物炭的增产作用有限。因此,在复垦土壤上施用生物炭后可以提高有机肥和无机肥的培肥效果,单施生物炭效果不明显。     

秸秆及其生物炭对土壤碳库管理指数及有机碳矿化的影响

以河南省粮食主产区壤质潮土和砂土为研究对象,通过盆栽试验和室内恒温培养试验,研究了生物炭与不同腐殖化程度的传统有机物料(秸秆和腐熟鸡粪)单施及配施对壤质潮土和砂土有机碳储量、活性及碳库管理指数的影响,并进一步比较了小麦秸秆直接还田和制炭还田对土壤有机碳矿化的影响,以及生物炭对土壤原有有机碳矿化的调控作用。结果表明:相同添加量下,生物炭对土壤有机碳含量的提升效果优于秸秆和腐熟鸡粪,在壤质潮土和砂土上分别较对照提升了63.15%和115.62%。另外,生物炭显著增加了土壤稳态碳含量和土壤碳库指数(CPI),但降低了土壤碳素有效率(SC)和碳库活度指数(AI),对土壤易氧化有机碳(POXC)和碳库管理指数(CMPI)无显著影响,添加秸秆显著增加了2种土壤POXC含量、基础呼吸和CPMI。进一步通过室内恒温培养试验发现,秸秆可在培养前期(0～37天)大幅度提升2种类型土壤有机碳矿化速率和累积矿化量,秸秆制炭还田对土壤有机碳矿化无显著影响。此外生物炭对土壤原有有机碳矿化的调控作用受其施用量、外源活性有机碳输入和土壤类型的影响,高量生物炭(2%)对非秸秆还田土壤有机碳矿化表现出较强的负激发效应,而低量生物炭(0.55%)对秸秆还田土壤有机碳矿化表现出较明显的负激发效应。因此,从"固碳减排"角度考虑,秸秆制炭还田是更合理的利用方式,且应根据土壤施肥管理措施和土壤类型考虑生物炭的施用量,添加质量比为2%的生物炭可显著抑制土壤原有有机碳矿化,降低CO_2排放,但应避开秸秆快速腐解期施用。     

钢渣与生物质炭配合施用对红壤酸度的改良效果

采用厌氧热解方法制备污泥生物质炭和花生秸秆炭,研究了钢渣和生物质炭单独施用及配合施用对红壤酸度的改良效果,结果表明,钢渣、花生秸秆炭和污泥生物质炭均含有一定量的碱性物质,向红壤中添加钢渣和生物质炭可以中和土壤酸度,提高土壤pH,增加土壤交换性盐基阳离子含量,降低土壤交换性铝含量.90天培养实验结束时,这3种改良剂分别使土壤pH相对对照提高1.10、0.72和0.48.钢渣与花生秸秆炭配合施用对土壤酸度的改良效果最好,使土壤pH相对对照提高2.14,单施污泥生物质炭的改良效果最小.钢渣和生物质炭含一定量的养分元素,添加钢渣和生物质炭可以同时改善土壤肥力.钢渣含丰富的钙,添加钢渣使土壤交换性钙含量增幅最大,相对对照增加4.5倍;添加花生秸秆炭使土壤交换钾增加最显著,相对对照约增加7倍;污泥生物质炭含丰富的磷,添加污泥生物质炭使土壤有效磷增加最显著,相对对照增加5.4倍.添加钢渣和2种生物质炭均显著提高了土壤交换性镁含量,将钢渣与生物质炭配合施用,土壤交换性镁含量的增幅更大.由于钢渣和2种生物质炭的碱含量和养分含量各有特点,因此可以根据土壤酸度状况和养分含量选择将钢渣与不同生物质炭配合施用,以达到既能最大限度中和土壤酸度又能补充土壤所必需养分的目的.     

生物炭对宁夏引黄灌区水稻产量及氮素利用率的影响

【目的】氮是作物生长发育所需的主要营养元素,随着宁夏引黄灌区农业生产集约化程度不断提高,氮肥投入亦不断增加,由此导致的土壤板结及氮素利用率低等问题日益突显。鉴于生物炭在改良土壤及提高氮肥利用方面的潜在可行性,本文通过大田试验研究添加不同用量生物炭对水稻产量和氮素利用率的影响,为生物炭在该地区的应用提供参考和依据。【方法】以宁夏灌区具有代表性的集约化水稻田为研究对象,以宁粳43号水稻为试验材料,采用裂区试验设计,施氮量设常规施氮量(N 300,N 300 kg/hm2)和不施氮(N0)2个水平;生物炭设高量炭(C3,9000 kg/hm2)、中量炭(C2,6750 kg/hm2)、低量炭(C1,4500 kg/hm2)和不施炭(C0)4个水平。旨在明确添加生物炭对灌淤土基本理化性质、水稻产量及氮素利用率的影响。【结果】1)添加生物炭种植一季水稻后对灌淤土土壤含水量没有明显影响,土壤p H值亦没有发生明显变化。2)施加氮肥情况下,C3处理较C0处理可显著提高灌淤土全氮、全磷和速效钾含量,但对速效磷含量没有影响,C2和C3处理下土壤全氮、全磷、速效磷和速效钾都没有明显差异,但二者全氮和速效钾含量要显著高于C1处理;不施肥情况下,除C3和C2处理显著增加土壤速效钾含量外,其余处理对土壤养分含量没有影响。3)生物炭和氮肥配施可以显著增加水稻籽粒产量,并随生物炭用量(4500 9000 kg/hm2)增加而增高,增产率在15.26%44.89%之间,水稻籽粒产量与生物炭用量呈显著正相关关系(r=0.962),水稻株高和穗粒数也随生物炭用量增多而增加,同时,水稻地上部总吸氮量随生物炭用量增加而增加,C3处理较C0处理提高66.27 kg/hm2,各处理之间差异显著;不施氮肥情况下,添加生物炭(4500 9000kg/hm2)对水稻籽粒产量没有显著影响,对水稻产量构成因素的影响亦不明显,C1和C2处理可以显著提高水稻地上部总吸氮量,但C3处理对总吸氮量影响不明显,同时各施炭处理之间无显著差异。4)生物炭和氮肥配施时,氮肥农学效率和氮肥利用率均表现为随生物炭用量增加而增加,C3较C0处理氮肥农学效率提高10.87 kg/kg,氮肥利用率提高22.09个百分点。【结论】生物炭和氮肥配施可以提高宁夏引黄灌区水稻产量,本试验以施用9000kg/hm2(C3)的生物炭产量最高(增产率达44.89%),同时水稻株高和穗粒数也随生物炭用量增多而增加,生物炭和氮肥配施,氮肥农学效率和氮肥利用率随生物炭用量增加而增加;不施氮肥情况下,添加生物炭对水稻产量没有显著影响,对水稻产量构成因素的影响亦不明显。。     

长期不同施肥对南方黄泥田磷库及其形态的影响

基于福建黄泥田长期定位施肥试验,研究不同施肥对土壤有效磷、 全磷演变及磷库组分的影响。结果表明,双季稻年份,各施肥处理土壤有效磷与全磷含量呈年际上升趋势,单季稻年份则呈年际下降趋势,而不施肥（CK）则均呈下降趋势,尤其是有效磷,较试验前土壤下降了64.9%。试验第26年,与 CK相比,化肥（NPK）、 化肥+牛粪（NPKM）、 化肥+秸秆还田（NPKS）处理的土壤总无机磷（TIP）含量增加了46.2%~114.2%、 总有机磷（TOP）含量增加了16.0%~41.8%、 全磷（TP）含量增幅为29.2%~73.8%,均达到显著差异水平,其中均以NPKM处理增幅最大。与试验前土壤相比,CK处理的土壤无机磷总含量降低,但有机磷总含量增加,其中无机磷以Al-P组分的耗竭速率相对最大,而有机磷以中等稳定性组分增幅相对最大; 与CK相比,施肥处理均提高了Al-P与Ca-P在全磷中的比例,而降低了各有机磷组分在全磷中的比例; 与试验前土壤相比,各处理总无机磷/总有机磷 (TIP/TOP) 的比值均呈下降趋势,但施肥的降幅较低,尤其是NPKM处理,TIP/TOP比值与有机质含量呈显著正相关。黄泥田不论施肥与否,土壤中有机磷含量均呈增加的趋势,NPKM处理对提高土壤有效磷、 无机磷、 有机磷库含量最为明显,但NPKS与NPK处理的无机磷库与有机磷库组分含量无明显差异。拟合方程显示,双季稻栽培模式下土壤有效磷含量为17.56 mg/kg、 单季稻栽培模式下有效磷含量为16.94 mg/kg时,作物产量可达最高。     

三种物料及其施用比例对汞污染土壤养分的影响

通过室内培养试验,研究了3种物料(中药渣生物有机肥、秸秆生物炭、凹凸棒土)不同施用比例[0 (CK)、1.5%、3%和6%]对汞污染土壤全氮、有效磷和速效钾含量的影响。结果表明,培养60 d后,施用中药渣生物有机肥和秸秆生物炭均可明显提高土壤全氮、有效磷和速效钾含量,且土壤全氮、有效磷和速效钾含量均随施用比例增加而提高;施用凹凸棒土可有效降低土壤有效磷含量,但对土壤全氮和速效钾含量的影响不明显。可见,中药渣生物有机肥和秸秆生物炭可有效提高汞污染土壤肥力水平,但凹凸棒土对土壤肥力的影响尚不明确。     

Use of phosphorus vectors to monitor changes in soil phosphorus

Abstract

A study was conducted to evaluate the use of P vectors to predict the amount of P required on a yearly basis to maintain a constant solution‐solid phase P relationship in an irrigated calcareous and a dryland acid soil. Irrigated potato‐spring barley and dryland spring pea spring‐barley crop rotations established at the two locations. Mono‐calcium phosphate (0–45–0) was applied annually at five levels, ranging from 0–4 times estimated crop removal. Phosphorus vectors were determined on soil samples by equilibration with standard P solutions. Yields tended to increase with added P on the calcareous soil; however, significant responses were not recorded at either location. Consequently, critical P vectors were not established. A constant solution‐solid phase P relationship was maintained by addition of P equal to that removed by the crop on the calcareous soil. A constant solution‐solid phase P relationship was not maintained on the acid soil.     

施磷对不同质地棉田土壤磷素有效性及磷肥利用率的影响

为阐明施磷对不同质地棉田土壤磷素有效性及磷肥利用率的影响,以盆栽试验为基础,在不同质地(粘土、壤土、砂土)上设计5个磷素水平(P0、P150、P300、P600、P1200)研究棉田磷素状况和棉花磷素积累及磷肥利用率。结果表明:不同质地棉田土壤有效磷含量在苗期和蕾期均随施磷量的增加而增加,苗期时粘土、壤土、砂土的土壤有效磷含量在P1200处理下与对照相比分别增加了80.94%、85.78%、94.41%,蕾期则分别增加了76.82%、85.10%、94.20%。苗期时,土壤全磷含量分别在粘土P600、壤土P1200、砂土P600处理下达到最大值;蕾期时粘土、壤土和砂土的全磷含量均在P1200处理达到最大值,土壤磷素活化系数在苗期时表现为粘土砂土壤土,蕾期磷素活化系数在粘土和砂土基本呈持续递增状态,最大值与对照(P0)相比分别增加了34.22%、85.71%。植物整株干物质积累在不同土壤质地表现为粘土砂土壤土。植物全磷含量则是壤土略低于粘土,砂土最低。棉花整株磷素积累量在不同土质上表现为粘土最高,壤土次之,砂土最低,且分别在P600、P300、P600处理时达到最大值。不同磷水平下,磷肥表观利用率在3种土壤质地上表现不同,粘土、壤土、砂土分别在P150、P300、P600时达到最大值,与P0相比分别提高了16.84%、29.19%、10.68%。同一磷水平下不同土壤质地磷素生理利用率表现为砂土壤土粘土。因此,在生产中应针对土壤质地合理施磷,粘土土质下棉田施磷量应控制在约150 kg/hm~2,壤土土质应控制在150～300 kg/hm~2,砂土土质施磷量总体应控制在300～600 kg/hm~2,才能促进土壤中磷的有效性和棉花磷素吸收,从而提高磷肥利用率。     

Rapid microbial phosphorus immobilization dominates gross phosphorus fluxes in a grassland soil with low inorganic phosphorus availability

Gross phosphorus (P) fluxes measured in isotopic dilution studies with ³³P labeled soils include the biological processes of microbial P immobilization, remineralization of immobilized P and mineralization of non-microbial soil organic P. In this approach, isotopic dilution due to physicochemical processes is taken into account. Our objectives were to assess the effect of inorganic P availability on gross P mineralization and immobilization in soil under permanent grassland, and to relate these fluxes to soil respiration, phosphatase activity and substrate availability as assessed by an enzyme addition method. We used soils from an 18-year-old grassland fertilization experiment near Zurich, Switzerland, that were collected in two treatments which differed only in the amount of mineral P applied (0 and 17 kg P ha⁻¹ yr⁻¹ in NK and NPK, respectively). Water-extractable phosphate was low (0.1 and 0.4 mg P kg⁻¹ soil in NK and NPK, while hexanol-labile (microbial) P was high (36 and 54 mg P kg⁻¹ soil in NK and NPK). Extremely fast microbial P uptake under P-limited conditions in NK necessitated the use of a microbial inhibitor when determining isotopic dilution due to physicochemical processes. At the higher inorganic P availability in NPK, however, isotopic exchange parameters were similar in the presence and absence of a microbial inhibitor. Phosphatase activity was higher in NK than in NPK, while soil respiration, water-extractable organic P and its enzyme-labile fraction were not affected by P status. Together, the results showed that inorganic P availability primarily affected microbial P immobilization which was the main component of gross P fluxes in both treatments. Gross P mineralization rates (8.2 and 3.1 mg P kg⁻¹ d⁻¹ for NK and NPK) during the first week were higher than reported in other studies on arable and forest soils and at least equal to isotopically exchangeable P due to physicochemical processes, confirming the importance of microbial processes in grassland soils.     

The effect of soil phosphorus on particulate phosphorus in land runoff

Accumulation of surplus phosphorus (P) in the soil and the resulting increased transport of P in land runoff contribute to freshwater eutrophication. The effects of increasing soil P (19–194 mg Olsen‐P (OP) kg⁻¹) on the concentrations of particulate P (PP), and sorption properties (Q_max, k and EPCo) of suspended solids (SS) in overland flow from 15 unreplicated field plots established on a dispersive arable soil were measured over three monitoring periods under natural rainfall. Concentrations of PP in plot runoff increased linearly at a rate of 2.6 μg litre⁻¹ per mg OP kg⁻¹ of soil, but this rate was approximately 50% of the rate of increase in dissolved P (< 0.45 μm). Concentrations of SS in runoff were similar across all plots and contained a greater P sorption capacity (mean + 57%) than the soil because of enrichment with fine silt and clay (0.45–20 μm). As soil P increased, the P enrichment ratio of the SS declined exponentially, and the values of P saturation (P_sat; 15–42%) and equilibrium P concentration (EPCo; 0.7–5.5 mg litre⁻¹) in the SS fell within narrower ranges compared with the soils (6–74% and 0.1–10 mg litre⁻¹, respectively). When OP was < 100 mg kg⁻¹, P_sat and EPCo values in the SS were smaller than those in the soil and vice‐versa, suggesting that eroding particles from soils with both average and high P fertility would release P on entering the local (Rosemaund) stream. Increasing soil OP from average to high P fertility increased the P content of the SS by approximately 10%, but had no significant (P > 0.05) effect on the P_sat, or EPCo, of the SS. Management options to reduce soil P status as a means of reducing P losses in land runoff and minimizing eutrophication risk may therefore have more limited effect than is currently assumed in catchment management.     

Pear seedling response to phosphorus in a phosphorus‐fixing soil

Abstract

The effect of P on growth of ‘Bartlett’ pear (Pyrus communis L.) seedlings was evaluated on the P‐fixing, Parkdale soil (Vitrandepts) from Oregon, USA. The P treatment levels were 0.03, 0.04, 0.06, 0.09, 0.15, 0.25, and 0.40 mg P/L of soil solution, based on a P‐sorption isotherm. At age 145 days, the dry weight response to P was significant. Seedlings required 0.25 mg P/L for maximum growth. This corresponds to 723 mg P/kg soil based upon the P‐sorption isotherm. Standard P soil tests did not accurately predict seedling response to P. About one‐half of the soil P was in the chemisorbed fraction.     

Evaluation of phosphorus availability from three phosphorus sources in Nigerian soils

Abstract

In an attempt to search for a cheaper source of phosphorus (P), both for direct application and industrial use, three P fertilizers were evaluated in incubation and greenhouse studies. Indigenous Sokoto rock phosphate (SRP) imported, Togo rock phosphate (TRP), and conventional single superphosphate (SSP) were applied on three soil types namely Oxisol, Ultisol, and Alfisol at rates ranging from 0–800 mg P kg^‐1 soil. Evaluation of the P sources was conducted for 12 weeks in incubation study, and five weeks in the greenhouse using maize as test crop. Evaluation of direct application of SSP and SRP on an oxic paleudult was carried out in the field for three years. The results of incubation studies revealed in general, that P availability increased as fertilizer rates increased. The P availability was, however, greater when SSP was applied on the Alfisol than on the Oxisol and Ultisol. The rock phosphates on the other hand were more efficient on acid soils than on soils neutral in pH. Optimum P availability from the fertilizers was observed to occur predominantly between four and eight weeks of incubation. In the greenhouse study, SSP gave the highest cumulative P uptake and optimum rate of application was 200 mg P kg^‐1 soil, while optimum rate for rock phosphate was 400 mg P kg^‐1 soil. The agronomic effectiveness (EA) of the rock phosphates was about 40% relative to SSP on the Alfisol. The EA, however, for TRP and SRP was 120% and 160%, respectively, on the Oxisol, while on the Ultisol, SRP was equally effective as SSP and TRP had 65% effectiveness. The results of the field trial indicated that the SRP had 54%, 83%, and 107% agronomic effectiveness of SSP, respectively, in the first, second, and third year of cropping. Optimum rate for SSP and SRP application was considered to be 50 and 75 kg P₂O₅ ha^‐1, respectively.     

滴施不同水溶性磷肥对石灰性土壤磷分布及玉米磷素吸收利用的影响

  【目的】  磷的形态影响着其施入土壤后的移动分布。研究滴灌施肥中不同水溶性磷肥在石灰性土壤中的分布特征及玉米对磷素的吸收和利用,为滴灌玉米生产中的磷肥选择提供理论依据。  【方法】  于2018—2020年在新疆石河子市实验站开展滴灌玉米田间试验,选用玉米品种‘郑单958’作为试验材料。试验共设磷酸脲(UP)、磷酸二氢钾(MKP)、聚磷酸铵(APP)、磷酸二铵(DAP)、磷酸一铵(MAP)、不施磷肥(CK) 6个处理,除CK不施磷肥外,其余处理灌溉量及氮磷钾投入量均相同。玉米开花期和成熟期,分别在滴头下、根系、宽行3个位点,在垂直方向0—10、10—20、20—40 cm处采集土样,测定pH、速效磷和全磷含量。采集玉米地上部植物样品,测定茎、叶、穗器官磷素含量。在完熟期测产,计算磷肥利用效率等指标。  【结果】  与DAP和CK处理相比,UP处理能显著降低0—40 cm土层土壤pH,开花期UP处理土壤pH较CK和DAP分别降低了0.20和0.32个单位,成熟期分别降低了0.24和0.31个单位,MAP、APP和MKP也不同程度地降低了滴头下0—10 cm土层土壤pH。UP处理土壤有效磷在0—40 cm土层的分布最均匀,APP处理10—20 cm土壤速效磷含量显著高于UP和MAP。玉米开花期APP、UP、MAP处理土壤速效磷含量较DAP分别增加了65.47%、44.18%和23.14%,成熟期分别增加了58.08%、40.13%和127.89%。APP处理的玉米穗、叶和总磷素积累量均最高,开花期较DAP分别显著增加了29.22%、43.97%和22.43%,成熟期较DAP分别增加了65.39%、26.63%和50.60%。APP、UP、MAP处理的玉米产量没有显著差异,较DAP分别增产了18.03%、11.64%和9.46%,磷肥利用率分别较DAP增加了29.62个百分点、13.65个百分点和9.93个百分点。APP处理的磷肥偏生产力和磷肥农学效率分别较DAP增加了18.03%和174.96%。相关分析表明,玉米产量和磷素积累量与0—20 cm土层的土壤有效磷含量正相关,与20—40 cm土层土壤速效磷含量负相关或相关性较弱。  【结论】  速效磷的分布与土壤pH的变化高度一致。酸性水溶性磷肥可不同程度地降低玉米根系周围土壤pH,磷酸脲的影响范围可达滴头周围0—40 cm土层,磷酸二氢钾、聚磷酸铵和磷酸一铵仅在滴头周围0—10 cm土层范围内有影响,而磷酸二铵对土壤pH无显著影响。滴施磷酸脲土壤中速效磷在0—40 cm土层中的分布较均匀,其在10—20 cm土层中的速效磷含量低于聚磷酸铵并高于其他磷肥处理。磷肥利用率与10—20 cm土层速效磷含量极显著相关。因此,滴施聚磷酸铵的玉米产量和磷肥利用率高于其它磷肥处理。综合3年试验结果,在新疆滴灌玉米生产中,水溶性磷肥中以聚磷酸铵最优,其次是磷酸脲和磷酸一铵等酸性磷肥,应减少磷酸二铵等碱性磷肥的施用。     

不同滴灌磷肥对棉田土壤磷含量及磷肥利用率的影响

通过田间试验,研究不同磷肥对滴灌棉田土壤有效磷及棉花产量和磷肥利用效率的影响。试验选取5种滴灌用磷肥：磷酸一铵（MAP）、聚磷酸铵（APP）以及大量元素水溶肥固体型（SF）、悬液型（LSF）、清液型（LCF）,并以不施磷肥为对照（CK）,共6个处理。测定土壤有效磷含量以及棉花生长、磷素吸收和产量。结果表明：在一个灌溉施肥周期内,施用清液型水溶肥（LCF）和聚磷酸铵（APP）较其它处理显著增加了土壤有效磷含量;在棉花各生育期,聚磷酸铵（APP）0～20 cm土层土壤有效磷含量较其它处理显著增加,清液型水溶肥（LCF）20～40 cm土层土壤有效磷含量最高,在盛铃期时较聚磷酸铵（APP）显著增加了21.41%;聚磷酸铵（APP）较磷酸一铵（MAP）显著促进了吐絮期棉花茎、叶的干物质及磷素积累量,而清液型水溶肥（LCF）干物质和磷素吸收在棉铃的分配比例最高,分别为64.89%、69.28%;清液型水溶肥（LCF）产量最高,聚磷酸铵（APP）次之,分别较磷酸一铵（MAP）提高了8.97%、2.87%;施用清液型水溶肥（LCF）较其它处理显著提高了棉花的磷肥偏生产力和磷肥农学效率,而聚磷酸铵（A...     

Microbial biomass phosphorus and its significance in predicting phosphorus availability in red soils

Abstract

Red soils are widespread in Southern China and other subtropical regions in the world. An improved management of phosphorus (P) is crucial for sustainable agriculture and environmental quality in red soil regions. Plant‐availability of P in red soils mainly depends on fertilization and biological cycling. Both laboratory analyses and greenhouse experiments were conducted to examine the relationships between plant P uptake, chemical index of P, and microbial biomass P in red soils with different fertility levels. Microbial biomass P ranged from 2.1 to 43 mg kg^‐1 in the red soils and was significantly correlated with total P (r=0.84*), organic P (r=0.87*), or Bray I extractable P (r=0.94**). Extractable P plus organic carbon accounted for >85% of the variation in microbial biomass P in the red soils. The significant relationship between microbial biomass P and extractable P suggests that microbial biomass P has a great potential in predicting P‐supply ability in soil. Greenhouse experiments showed that there were close relationships between ryegrass dry matter yield, plant P uptake or tissue P concentration and microbial biomass P in the red soils. The corresponding correlation coefficients were 0.79*, 0.90*, and 0.91*, respectively. These results imply that microbial biomass P plays an important role in the availability of P to plants, and is a potential biological index of P availability in the red soils.     

施磷量对玉米 -大豆间作根际红壤无机磷形态及磷吸收的影响

通过盆栽模拟试验,探讨不同施磷量对玉米 -大豆间作作物生长及磷吸收的影响,并分析根际红壤中各无机磷形态的变化。结果表明:与单作相比,玉米 -大豆间作显著提高了作物地上部生物量及磷素吸收量,并具有明显的产量优势。与常规施磷水平(P100)下的单作相比,玉米 -大豆间作条件下,磷肥减施 1/2(P50)并未降低作物籽粒产量与玉米的磷吸收量。间作种植显著降低了玉米、大豆根际红壤总无机磷含量,并且无机磷减少量主要以O-P、Fe-P和 Ca-P为主。玉米、大豆根际土壤Fe-P、Al-P、Ca-P与 O-P占土壤总无机磷含量的比例主要受磷水平的调控,而种植模式对玉米和大豆根际土壤中各无机磷形态的比例(除 Fe-P外)均没有影响。在本试验条件下,玉米 -大豆间作通过根系交互作用主要促进土壤中 Fe-P、Ca-P和 O-P的活化来增加玉米与大豆的磷吸收,并具有节约磷肥、维持作物产量和磷吸收的潜力。