灌溉与旱作条件下长期施肥塿土剖面磷的分布和移动

利用12年长期定位试验研究了灌溉和旱作条件下不同施肥处理对土土壤剖面全磷与有效磷(Olsen-P)分布和移动的影响。结果表明,土施磷后主要累积在耕层,极大地提高了0—20cm土层全磷与Olsen-P含量。旱作条件下,施用磷肥或化肥配施有机肥提高了100cm以上土体全磷与Olsen-P含量;而化肥配合有机肥,Olsen-P含量在100—300cm土壤剖面中都高于对照(不施肥)和化肥处理。灌溉条件下,与旱作有相同趋势,但磷钾、有机肥配施氮磷钾处理,全磷和Olsen-P不仅在0—300cm剖面中高于对照和氮磷钾处理,而且也高于旱作条件下的相同处理。土上存在磷素的淋失。     

灌溉与旱作条件下长期施肥(土娄)土剖面磷的分布和移动

利用12年长期定位试验研究了灌溉和旱作条件下不同施肥处理对(土娄)土土壤剖面全磷与有效磷(Olsen - P)分布和移动的影响.结果表明,(土娄)2土施磷后主要累积在耕层,极大地提高了0-20cm土层全磷与Olsen - P含量.旱作条件下,施用磷肥或化肥配施有机肥提高了100cm以上土体全磷与Olsen - P含量; 而化肥配合有机肥,Olsen - P含量在100-300cm土壤剖面中都高于对照(不施肥)和化肥处理.灌溉条件下,与旱作有相同趋势,但磷钾、有机肥配施氮磷钾处理,全磷和Olsen - P不仅在0-300cm剖面中高于对照和氮磷钾处理,而且也高于旱作条件下的相同处理.(土娄)土上存在磷素的淋失.     

不同有机培肥方式对红壤性水稻土磷素的影响

基于红壤性水稻土有机肥长期定位试验,分析了红壤双季稻种植模式下,不施肥、NPK、紫云英+猪粪+化肥、紫云英+猪粪+秸秆+化肥、紫云英+秸秆+化肥处理耕层土壤全磷、Olsen-P、磷素有效性和磷素利用率35年的变化特征,以及Olsen-P与水稻产量的响应关系。结果表明:不施肥处理土壤全磷含量显著降低,有效磷含量及磷素有效性略微下降。配施猪粪显著提高全磷、Olsen-P含量和磷素有效性,但显著降低磷肥利用率,增加磷的环境污染风险。化肥配合紫云英及稻草还田处理土壤全磷、有效磷含量以及磷素有效性保持稳定,但显著提高磷肥利用率。Olsen-P的产量农学阈值为16.36 mg kg-1。     

长期不同施肥模式红壤性水稻土磷素变化

【目的】研究红壤性水稻土长期不同施肥模式下耕层土壤有效磷含量与全磷含量的变化特征,以及有效磷含量与累积磷盈亏的关系,分析不同形态磷肥对土壤磷素有效性影响的差异,找出最有效的红壤性水稻土磷素培肥施肥方式。【方法】供试土壤取自1981~2012年在江西进行的红壤双季稻稻田长期定位试验。试验自始至终保持水分、农药等日常田间管理与当地习惯相同,统一水稻品种并定期更换。试验设5个处理:施氮钾肥(NK);氮磷钾化肥(NPK);两倍氮磷钾化肥(NPK2);早稻氮磷钾化肥配施紫云英,晚稻氮磷钾化肥配施猪粪(NPKM);长期不施肥(CK)。分析了耕层土壤有效磷含量和全磷含量计算了有效磷增量与累积磷盈亏的相互关系。【结果】试验32年后对照土壤磷年均亏缺22.7 kg/hm2,有效磷含量在低水平下维持平衡;NK处理磷素年均亏缺27.9kg/hm2,显著高于不施肥处理,全磷含量缓慢降低32年累计降低了8.6%,有效磷含量呈持平趋势。NPK、NPK2、NPKM处理土壤磷素均有盈余,年均盈余量分别为33.3、39.0、41.0 kg/hm~2,全磷含量分别增加了32.1%、89.4%、165.1%,有效磷含量分别增加了2.2、6.9、15.3倍,年上升速率分别为0.30、1.18、1.79 mg/kg,有效磷增量与累积磷盈余呈显著正相关。NPK化肥配施有机肥处理不仅提高土壤有效磷及全磷的含量,还显著提高磷素有效性。水稻产量增加量随累积磷投入量和有效磷的增加而增加,前期增加较快后期增加较慢,有效磷含量具有明显的拐点,其值超过20 mg/kg后产量就增加缓慢。【结论】红壤性水稻土在双季稻种植模式下,长期不施磷肥处理土壤全磷含量缓慢降低,有效磷含量可维持低水平下的平衡。施磷处理土壤全磷含量,有效磷含量以及磷素有效性均呈上升趋势且无机磷肥与有机磷肥配施处理上升最快。无机磷肥与有机磷肥配合施用在提高土壤全磷含量的同时也提高磷素的有效性。土壤有效磷超过20 mg/kg后相对产量提高缓慢。氮磷钾化肥与有机肥配合施用是提高耕层土壤磷素库容和提高磷素活化能力的有效措施。     

长期定位施肥对碱性紫色土磷素迁移与累积的影响

在25年稻麦轮作长期定位施肥试验点上,开展了碱性紫色土水旱轮作种植制不同施肥处理土壤剖面全磷、速效磷迁移和累积以及耕层土壤全磷、速效磷随时间的变化规律研究。结果表明,单施无机磷肥土壤磷可迁移至100 cm土层,Olsen-P可迁移至40 cm土层。有机无机磷肥配施不但使土壤磷可迁移至相同深度,且迁移量更大,Olsen-P可迁移至60 cm土层。耕作25年后,施磷处理土壤耕层磷素随时间的变化显著,MNPK处理耕层土壤全磷含量年增长率为0.033 g/kg,Olsen-P的年增长率为2.56 mg/kg。试验表明,连续数年施用足量磷肥后,作物施磷量可根据具体情况酌减,以节约磷肥资源和提高磷肥利用率;施用有机肥促进了磷素从耕层向底层的迁移,是造成土壤磷素迁移的一个重要因素。     

施肥与覆膜对棕壤Olsen-P剖面分布及动态变化的影响

利用沈阳农业大学长期定位试验站裸地和覆膜的不同施肥处理（不施肥、单施氮肥、有机肥、有机无机肥配施）及其附近不同土地利用方式，探讨了不同施肥处理和覆膜对整个生长季的棕壤Olsen-P剖面（0—100 cm）分布及动态变化的影响。结果表明，耕地棕壤各施肥处理土壤剖面Olsen-P含量均表现为0—20 cm和60—100 cm大于20—60 cm；而自然草地、自然林地棕壤Olsen-P含量则随深度加深（0—100 cm）而逐渐增多。施用有机肥或有机无机肥配施处理的Olsen-P含量在60 cm土层以上均远大于不施肥或单施氮肥处理；覆膜后不施肥、有机肥、有机无机肥配施处理土壤0—40 cm土层的Olsen-P含量略有降低（0—20 cm土层有机肥处理除外），但差异未达到显著水平。说明施有机肥或有机无机肥配施，是补充土壤Olsen-P的有效措施；但施肥时应深施以补充表层以下土壤Olsen-P含量。覆膜未对本研究的棕壤Olsen-P含量产生显著的负面影响。     

长期不同施肥处理水稻土磷素在剖面的分布与移动

稻麦轮作黄泥土施肥试验始于1980年,共布置不施肥、纯化肥、有机肥(猪粪或菜籽饼)、化肥加有机肥、氮肥加秸秆、氮肥加有机肥加秸秆等14种处理。2003年11月麦季取土壤样品分析结果表明:(1)与无肥处理相比,施磷处理和有机肥处理耕层土壤全磷(TP)含量皆有显著增加,并且表现出向下迁移的迹象,有机肥配施NPK化肥处理土壤磷的迁移可达30 cm深度,其余施磷处理均至25 cm。(2)大部分施磷处理在表层0~25 cm内无机磷(I-P)总量发生显著性变化,Ca2-P由于其溶解性强可迁移到30 cm以下,Al-P、Fe-P、Oc-P(闭蓄态磷)的迁移可达25 cm,Ca8-P至20 cm;Ca10-P含量只在有化肥P输入的6个处理的0~15 cm耕层土壤中有显著性增加。(3)土壤有机磷(O-P)含量的变化小于无机磷的变化,只有无机磷配施有机肥的3个处理和仅施PK化肥的处理,其耕层土壤有机磷发生显著性增加。     

施肥与覆膜对棕壤Olsen-P剖面分布及动态变化的影响

利用沈阳农业大学长期定位试验站裸地和覆膜的不同施肥处理(不施肥、单施氮肥、有机肥、有机无机肥配施)及其附近不同土地利用方式,探讨了不同施肥处理和覆膜对整个生长季的棕壤Olsen-P剖面(0—100.cm)分布及动态变化的影响。结果表明,耕地棕壤各施肥处理土壤剖面Olsen-P含量均表现为0—20.cm和60—100.cm大于20—60.cm;而自然草地、自然林地棕壤Olsen-P含量则随深度加深(0—100.cm)而逐渐增多。施用有机肥或有机无机肥配施处理的Olsen-P含量在60.cm土层以上均远大于不施肥或单施氮肥处理;覆膜后不施肥、有机肥、有机无机肥配施处理土壤0—40.cm土层的Olsen-P含量略有降低(0—20.cm土层有机肥处理除外),但差异未达到显著水平。说明施有机肥或有机无机肥配施,是补充土壤Olsen-P的有效措施;但施肥时应深施以补充表层以下土壤Olsen-P含量。覆膜未对本研究的棕壤Olsen-P含量产生显著的负面影响。     

长期轮作施肥棕壤磷素对磷盈亏的响应

【目的】 研究长期轮作施肥条件下棕壤磷素盈亏状况及其与土壤磷素的关系,为棕壤科学施用磷肥提供理论依据。 【方法】 玉米?玉米?大豆轮作长期施肥定位试验始于1979年,设不施磷肥 (CK)、施氮磷肥 (NP)、施氮磷钾肥 (NPK)、低量有机肥配施氮磷肥 (M1NP)、低量有机肥配施氮磷钾肥 (M1NPK)、高量有机肥配施氮磷肥 (M2NP) 和高量有机肥配施氮磷钾肥 (M2NPK),共7个处理。测定1979—2015年不同施肥处理土壤Olsen-P和全磷含量,计算了土壤磷的盈亏状况,分析了全磷和有效磷与累积磷盈亏之间的关系。 【结果】 CK处理土壤磷素水平处于亏缺状态,平均土壤年亏缺磷为9.0 kg/hm2;磷肥处理 (NP和NPK) 和有机肥配施磷肥处理 (M1NP、M1NPK、M2NP和M2NPK) 土壤磷素均处于盈余状态,且M2NP和M2NPK盈余较多。所有施肥处理的有效磷增量与土壤累积磷盈亏均呈极显著相关关系 (P < 0.01),CK处理土壤每亏缺磷100 kg/hm 2,Olsen-P下降0.84 mg/kg;磷肥及有机肥磷肥配施处理每盈余磷100 kg/hm2,Olsen-P上升范围为1.97～7.23 mg/kg。除CK外,所有施肥处理土壤全磷增量与累积磷盈亏均呈极显著相关关系 (P < 0.01)。土壤每盈余磷素100 kg/hm 2,各施肥处理全磷增加范围为0.03～0.04 g/kg。 【结论】 磷肥投入是影响棕壤全磷和有效磷水平的关键因素。长期轮作不施磷肥,棕壤磷素亏缺;长期轮作施用化学磷肥 (年均投入P₂O₅ 70 kg/hm2) 和磷肥有机肥配施 (年均投入P₂O₅ 126～182 kg/hm2),棕壤磷素有盈余,增施高量有机肥的盈余量高于增施低量有机肥,高于单施磷肥。磷肥配施有机肥提升棕壤有效磷的速率高于单施磷肥。      

长期不同施肥红壤磷素特征和流失风险研究

为探索长期施肥对红壤磷素吸附固持的影响,分析不同施肥土壤磷流失风险及影响因素。在南方丘陵区红壤上开展了持续25年的长期定位试验,处理包括:不施肥(CK)、施氮肥(N)、施磷肥(P)、施钾肥(K)、施氮磷钾肥(NPK1)、施2倍量氮磷钾肥(NPK2)、单施有机肥(OM)和氮磷钾配施有机肥(MNPK)。研究了不同施肥下土壤全磷、Olsen-P、Mehlich1-P、CaCl2-P含量及磷吸持指数(PSI)、磷饱和度(DPS)的变化,探讨不同施肥处理土壤对磷的吸附和解吸特征,并分析了土壤磷指标与土壤有机碳、pH、CEC之间的关系。结果表明:长期施用化学磷肥有利于补充土壤磷素,特别是土壤全磷,并使Olesn-P和Mehlich 1-P有增加趋势,而对CaCl2-P影响不显著;施用化肥对DPS影响不显著,单施磷会降低PSI,低量氮磷钾提高了PSI,高量氮磷钾处理与对照差异不显著;长期施用有机肥(猪粪)土壤全磷增加,而Olsen-P、Mehlich 1-P和CaCl2-P则大幅累积, PSI显著降低, DPS显著增加。长期施用化肥处理土壤对新添加磷的吸附较强,长期施用有机肥降低了土壤对新添加磷的吸附;土壤全磷、Olsen-P、Mehlich1-P、CaCl2-P、PSI、DPS及最大吸附容量(Qm)与土壤pH、CEC、土壤总有机碳(TSOC)、土壤水溶性有机碳[冷水提取水溶性有机碳(CWSOC)和热水提取水溶性有机碳(HWSOC)]间相关性较高;土壤磷指标和土壤有机碳、pH、CEC指标之间存在典型相关关系,第1对和第2对典型变量的典型相关系数分别为0.997和0.951,达显著水平。研究表明,施用有机肥是调节土壤磷的供给和保持的重要措施,土壤水溶性有机碳和pH可能是反映红壤磷素供应和流失的关键指标。     

Comparison of Organic and Inorganic Phosphorus Fractions in an Established Buffer and Adjacent Production Field

Abstract

Since the U.S. Department of Agriculture's Conservation Reserve Program was established in 1985, thousands of acres of cropland have been converted to conservation buffers. The distributions of soil phosphorus (P) in various organic and inorganic fractions in a buffer and an adjacent crop production field were compared. Most of the extractable inorganic P (32 to 39%) in both the crop field and the buffer was present in the calcium (Ca)‐P fraction. Levels of the most labile P fractions were higher in the cropped area; however, more P was in the iron (Fe)‐P fraction in the buffer (23 vs. 18%). There were few differences among organic P fractions between the buffer and crop field. Soil sampling depth had a significant effect on the distribution of P. Differences between the cropped area and the buffer were less significant as depth increased. These results suggest that care should be taken in choosing sampling depths when relating P fraction distribution to potential P loss.     

磷素活化剂对红壤磷形态及有效性影响的研究

在我国南方红壤中加入不同的磷活化剂进行培养试验,结果显示:磷活化剂提高了土壤有效磷含量,不同活化剂的活化能力不同。相关分析和通径分析结果表明,磷活化剂的活化能力大小顺序为:低分子有机酸钠钙盐>腐植酸>腐植酸钠>脲基甲酸乙酯;磷活化剂可以提高红壤中的Al-P、Ca-P和Fe-P等无机磷含量,其中Al-P和Ca-P与有效磷均达到极显著水平,而Fe-P作用效果不显著,可以通过影响Al-P和Ca-P来间接影响有效磷,磷活化剂会抑制土壤中O-P的生成。     

Soil and Compost Type Affect Phosphorus Leaching from Inceptisol,Ultisol, and Andisol in a Column Experiment

A column leaching experiment using three soils (Inceptisol, Ultisol, and Andisol) and seven livestock manure composts that had different characteristics was conducted for 19 weeks to investigate the interactive effects of composts and soils on the phosphorus (P) leaching potential of compost-amended soils and to identify the principal variables that affect P leaching. Cumulative total P leaching (TP_cum) tended to increase with increasing total and available P concentration in the soils. Among various compost properties, total P concentration was positively correlated with TP_cum from the compost-amended soils, except for the Andisol, which has a high P-sorption capacity. There was no significant relationship between TP_cum and water-extractable P concentration of the composts, suggesting that total P rather than inorganic P concentration of composts may be successfully used in predicting P leaching potential from compost-amended soils except for soils that have a high P-sorption capacity, as in Andisol.     

制种玉米连作恒量施磷对灌漠土与潮土中磷素利用的影响

[目的]研究恒量外源磷施用对玉米种子生产的影响,为合理施磷提供依据。[方法]通过大田定位与实验室分析相结合,选用河西走廊石灰性潮土及灌漠土定位施肥。[结果]制种玉米连作8a,恒量磷二铵525kg/(hm^2·a)施用,除无机态二钙磷(Ca_2-P)外,2种不同土类总磷(T-P)、速效性磷(Av-P)、总无机磷(T-IP)、总有机磷(T-OP),以及其他各分级无机、有机磷组分均显著增加。无机磷占全磷总量65.2%~70.2%,有机磷占全磷总量6.5%~11.4%。无机磷中十钙磷(Ca₁₀-P)>八钙磷(Ca8-P)>铝磷(Al-P)>铁磷(Fe-P)>闭蓄态磷(O-P)。有机磷中活性有机磷(MLO-P)>高稳性(HRO-P)>中稳性有机磷(MROP)>活性有机磷(LO-P)。随连作年限增加,灌漠土Ca₁₀-P在连作第5a达到最大,Al-P,O-P均持续增加;潮土Ca₁₀-P持续增加,Fe-P,O-P在连作第5a达到最大,磷增加量为3.94%~37.28%。0—60cm土层,两种土类无机磷各组分含量均呈现由表层至下层递减特点,但不同分级磷在不同土层所占比例不同,Ca₁₀-P,Al-P,O-P,MRO-P底聚,Ca_2-P,HRO-P表聚,制种玉米连作生产8a,磷肥最大表观利用率为4.89%,磷素活化系数<2%,外源磷肥以174.3kg/(hm^2·a)残余在土壤中。[结论]制种玉米连作,总磷转化率低,磷素移动缓慢,大部分以溶解性较低的磷素形态在土壤表层积累,但随连作年限增加,土壤对磷素的固持及转化率下降,表现底聚趋势,对生态环境健康存在极大风险,应减量或停止施磷。潮土磷肥施用应采取更加合理措施。     

Crop use and profile distribution of phosphorus in soils that developed on mafic rocks in southern Portugal

The phytoavailability of soil phosphorus (P) depends on the different forms in which it occurs and how these forms change after the application of P fertiliser to the soil. Forms of P in the A, B and C horizons of eleven pedons that developed on mafic rocks were characterised by a fractionation method before and after fertilisation with single superphosphate, and a micropot experiment was conducted to assess the short-term use of P fertiliser by rye (Secale cereale L.). The main sources of P to the crop were (i) phosphate adsorbed on mineral surfaces and pedogenic Fe, Al or Ca phosphates in the A horizon and (ii) Ca-phosphates in B and C horizons. In the C horizons, poor in Fe/Al phases and clay, the precipitated Ca-P showed low solubility, resulting in a reduction in shoot biomass. The apparent P recovery by rye was similar in the A (36%) and B (29%) but decreased in the C (15%) horizons. The partial factor productivity (g g^?1) decreased from the A (58) to B (11) and C (5) horizons. P phytoavailability decreased with increasing profile depth because the transformation of P fertiliser to poorly soluble Ca-P forms increased with depth.     

The equivalence of the Calcium‐Acetate‐Lactate and Double‐Lactate extraction methods to assess soil phosphorus fertility

A large variety of extraction methods are used worldwide for the estimation of “plant‐available P” in soils. In Germany, the standard extractants are Calcium‐Acetate‐Lactate (CAL) and Double‐Lactate (DL). Until now there is no validated transformation procedure available and studies on the comparability of both methods have reported conflicting evidence. The uncertainty about the equivalence of CAL‐P and DL‐P hinders a direct comparison of the P fertility status and P fertilizer recommendations across Germany. Based on 136 datasets for soil samples from an interlaboratory comparison program and three P fertilization field trial sites, for which plant‐available P had been determined by both the CAL and DL method, we assessed the comparability of both extraction methods and derived simple and multiple regression equations to transform DL‐P into CAL‐P values. On average, DL extracted 30% more P than CAL. However, this strongly depended on soil pH and carbonate content. A simple linear regression model explained 70% of the variance. However, if simple linear regression models were fitted to pH‐specific samples (pH range 4.5 to 7.0) the R² increased to 0.96. Based on an independent validation dataset (n = 48) we demonstrated that such pH‐specific models were more accurate than models that did not consider pH when transforming DL‐P to CAL‐P values. Multiple regression results showed that out of soil pH, C_org, N_t, and C : N ratio, only soil pH improved the model. The transformation equations in this study provide a step towards an improved comparability of P fertility status assessments of soils across Germany.     

Relation between soil P test values and mobilization of dissolved and particulate P from the plough layer of typical Danish soils from a long‐term field experiment with applied P fertilizers

Accumulation of phosphorus (P) in agricultural topsoils can contribute to leaching of P which may cause eutrophication of surface waters. An understanding of P mobilization processes in the plough layer is needed to improve agricultural management strategies. We compare leaching of total dissolved and particulate P through the plough layer of a typical Danish sandy loam soil subjected to three different P fertilizer regimes in a long‐term field experiment established in 1975. The leaching experiment used intact soil columns (20 cm diameter, 20 cm high) during unsaturated conditions. The three soils had small to moderate labile P contents, expressed by water‐extractable P (3.6–10.7 mg/kg), Olsen P (11–28 mg/kg) and degree of P saturation (DPS) (25–34%). Mobilization of total dissolved P (TDP) increased significantly (P < 0.05) from the intact soil columns with increasing labile P, whereas the increase in particulate P (PP) with increasing labile P content was modest and statistically insignificant. We found concentrations up to 1.5 mg TP/L for the plough layer of this typical Danish sandy loam soil. This highlights that even a moderate labile P content can be a potential source of TDP from the plough layer, and that a lower concentration margin of optimum agronomic P levels should be considered.     

氮磷配施对苹果幼苗生长、土壤无机磷形态和磷素利用的影响

以矮化苹果砧木M9T337幼苗为试材,设置4个氮水平(N 0,150,300,450 mg/kg,分别以N0、N1、N2、N3表示)和2个磷水平(P_2O_5 100,200 mg/kg,分别以P1、P2表示),研究了氮磷配施对苹果砧木幼苗生长、土壤无机磷形态转化和磷素吸收利用的影响,以期为果园磷肥高效利用提供参考依据。结果表明,不同氮磷配施显著影响M9T337幼苗生物量及根系形态,以N2P2处理效果最佳,其次为N1P2处理。植株磷素积累量及磷肥利用率分别在N2P2、N2P1处理下达到最大值,同一磷水平下适量增氮可促进幼苗对磷素的吸收,有效提高植株磷肥利用率。高氮处理(N3P1、N3P2)显著抑制幼苗对土壤磷素的吸收,不利于砧木幼苗的生长。土壤有效磷(Olsen—P)含量主要受施磷量的影响,在N2P2处理下达到最大,为27.86 mg/kg;土壤碱性磷酸酶活性则在N2P1处理下最大,为2.12 mg/(g·d)。与单施磷肥相比,氮磷配施增加土壤中可供植物吸收利用的Ca_8—P、Al—P所占土壤磷库的比例,降低植物难以吸收利用的Ca_(10)—P比例,Ca_2—P的比例也有所降低;随施氮量的增加,Ca_8—P、Al—P呈现先增加后减小的趋势,均在N2P2处理下达到最大值,Ca_(10)—P随施氮量的增加呈现逐渐降低的趋势,而Fe—P、O—P含量在不同施氮量下则无明显变化趋势。合理的氮磷配施可通过改变土壤无机磷库组成,提高土壤磷素有效性,促进砧木幼苗的生长和对土壤磷素的吸收。     

Corn and Soybean Grain Phosphorus Content Relationship with Soil Phosphorus,Phosphorus Fertilizer,and Crop Yield

Most fertilizer phosphorus (P) rate recommendations for the north-central United States are based on combination of a critical soil-test P value and a mass-balance calculation of fertilizer P required to maintain critical soil-test P. Accurate estimates of grain P removal are an essential component of P mass-balance calculation. Current north-central extension service guidelines recommend that estimates of corn and soybean grain P removal should be calculated using constant grain P concentrations. We reviewed research from the north-central region to determine the extent to which variation in grain P concentration accounts for differences in crop P removal and to determine whether predictions of grain P concentration can be improved through consideration of soil-test P, crop yield, and fertilizer P application. We found that soil-test P, grain yield, and fertilizer P are predictor variables that may significantly improve estimates of grain P concentration for corn and soybeans.     

Soil Phosphorus Fractions in a Sandy Typic Hapludaft as Affected by Phosphorus Fertilization and Grapevine Cultivation Period

The purpose of this study was to quantify the phosphorus (P) fractions in phosphate-fertilized sandy soils under grapevines. Soil was sampled from a grassland site and two vineyards (13 and 31 years old) in the State Rio Grande do Sul, Brazil, from the layers 0–5, 5–10, 10–15, 15–20, and 20–40 cm deep. The samples were prepared and P fractions were assessed by chemical fractionation. Phosphate fertilization of the vineyard soils increased P contents to a depth of 40 cm, especially in the more recalcitrant fractions but detectable in the more labile fractions as well, which are plant available and may increase the risk of environmental contamination. Phosphate fertilizers and the period of grapevine cultivation had little effect on the levels of organic P forms, whereas cover crops in vineyards could be an appropriate strategy to increase or maintain the levels of soil organic matter and the levels of organic P over the years.