酸性水稻土有机磷分组法的探讨

本文研究了Ｂｏｗｍａｎ－Ｃｏｌｅ土壤有机磷有效性分组法应用于酸性水稻土所存在的若干问题。并在该法的基础上提出了一种改进法。结果表明：改进法比Ｂｏｗｍａｎ－Ｃｏｌｅ法能更好地将易矿化的（如ＲＮＡ，磷脂等），中度易矿化的（如植酸钙）和难矿化的（如植酸铁）有机磷化合物区分开来。改进法所测的结果比Ｂｏｗｍａｎ－Ｃｏｌｅ法提高了活性有机磷的数量和中度活性有机磷的质量，增加了稳定性有机磷应有的数量，改善了ＨＡ     

长期施肥条件下潮土耕层有机磷含量与组分的变化研究

以15年肥料长期定位试验为基础,采用Bowman-Cole有机磷分组方法,研究长期施肥对潮土耕层有机磷组分及其变化的影响.结果表明:耕层有机磷含量相对较低,有机磷总量为22.35～66.95 mg·kg-1,占土壤全磷的4.47%～9.86%.各组分中以中度活性有机磷为主要部分,占有机磷58.93%～82.40%.长期施肥对土壤各组分有机磷含量产生明显影响,与对照CK相比,PK处理活性有机磷和中度活性有机磷增加,NP处理活性有机磷和中度活性有机磷减少,两处理间差异显著.施用有机肥显著增加耕层土壤中度稳定性有机磷含量.耕层土壤碱性磷酸酶与中稳定性有机磷呈显著正相关.     

石灰性土壤有效硒浸提剂和浸提条件研究

采用外源硒加入土壤中得到硒污染土壤,6种有效硒的浸提剂NaHCO3、KH2PO4、K2SO4、EDTA、AB-DTPA和DTPA＋TEA＋CaCl2的最佳浸提时间和土液比进行了筛选,并通过盆栽试验对所选择的土壤有效硒浸提剂进行生物学校验,以找出石灰性土壤有效硒提取适宜的浸提剂及其浸提条件。结果表明,NaHCO3、KH2PO4、K2SO4、EDTA、AB-DTPA和DTPA＋TEA＋CaCl26种浸提剂有效硒浸提量都随着浸提土液比的减小而增大,且随浸提时间的增长而增大。其中NaHCO3和KH2PO4最佳土液比为1/15,振荡时间90min;K2SO4和AB-DTPA的最佳土液比为1/15,振荡时间60min;EDTA和DTPA＋TEA＋CaCl2的最佳土液比则为1/20,振荡时间30min。6种浸提剂在各自最佳的提取条件下提取的土壤有效硒量与白菜地上部分硒含量达极显著正相关,但土壤有效硒的提取量以DTPA＋TEA＋CaCl2及K2SO4最少,只占KH2PO4、AB-DTPA及EDTA提取量的14%～48%,故不适用于作为石灰性土壤有效硒的提取剂。NaHCO3适用于土壤硒含量高于5mg·kg^-1的石灰性土壤有效硒提取。KH2PO4、AB-DTPA及EDTA3种浸提剂既可提取土壤中水溶态硒,亦可提取部分的吸附态硒,提取硒数量较多,过程简单,重复性好,都可作为石灰性土壤有效硒提取的浸提剂。     

长期施肥对红壤性水稻土有机磷组分的影响

以19年肥料长期定位试验为背景,应用Bowman和Cole的有机磷分组方法,对红壤性水稻土有机磷组分及其变化进行了研究。结果表明:红壤性水稻土耕层有机磷含量较高,为225.93～322.47mgkg-1,占土壤全磷的28.59%～42.34%。土壤有机磷各组分中以中度活性有机磷含量最高,平均为134.80mgkg-1,占有机磷总量的51 58%;中度稳定性有机磷(92.46mgkg-1)占35.38%;高度稳定性有机磷(20.35mgkg-1)占7.79%;活性有机磷含量最低(13.67mgkg-1),占5.23%;长期施肥对土壤各组分有机磷量产生影响,耗磷处理,主要是中度活性有机磷和活性有机磷下降,降低量以CKNK处理。施磷主要促进中度稳定性有机磷和高度稳定性有机磷的增加,增加幅度以NPK+OMPNPK处理。不同施肥措施对土壤有机磷和无机磷库的耗竭或积累速度是不同的,耗磷条件,土壤有机磷/无机磷的比值上升,施磷使有机磷/无机磷比值下降.土壤供磷强度与有机磷/无机磷的比值呈显著负相关(r=-0.9497* ,r0.05=0.878)。     

旱地土壤微生物磷测定方法研究

介绍了国外关于土壤微生物磷测定方法的研究进展 ,讨论了常用的几种方法所存在的问题 ,介绍了主要操作过程要求。对我国 5种主要母质类型的土壤 (pH 3 .3～ 7.4,1molL- 1KCl)的对比研究表明 ,我国土壤采用氯仿熏蒸、0 .5molL- 1NaHCO3在 1∶2 0土水比提取测定无机磷 (Pi)、并以同时测得的培养土壤微生物的磷的回收率作为计算常数得到的结果最佳。测定的大多数南方土壤的微生物磷占土壤全磷的比例小于 1 .5 % ,微生物碳磷比值大于 3 0∶1 ,反映南方土壤磷的生物活性较低 ,土壤微生物对磷的作物供应调节能力不强。     

新鲜土样和改进ASI浸提剂对土壤有效养分测试的影响

通过分析基于风干土样和新鲜土样、ASI（Agro Services International Inc., ASI）浸提剂和改进ASI浸提剂进行测量的土壤有效养分含量的相关性,探索一种基于新鲜土样和联合浸提剂进行土壤有效养分测试的方法。结果表明,利用ASI浸提剂测量的北京潮土新鲜土样的NO3--N和NH4+-N、有效P、K、Ca、Mg、Cu、Fe、Mn、Zn、有机质含量、及pH值,与风干土样的测量值均呈显著的线性相关关系,经该线性方程回归检验的测量相对误差小于5%～9%;利用改进ASI浸提剂测量的新鲜土样和风干土样的NH4+-N、有效P、K、Ca、Mg、Cu、Fe、Mn、Zn含量与基于ASI浸提剂测量的也呈显著的线性相关关系,经该线性方程回归检验的测量相对误差小于5%～8%。因此,基于新鲜土样和改进ASI浸提剂测量石灰性土壤有效养分含量是可行的,可为车载式土壤养分检测提供一种快捷的土样浸提前处理方法。     

不同浓度硫酸盐对水稻土中异化铁还原过程的影响

研究不同电子受体之间的竞争关系对揭示厌氧水稻土中微生物作用导致的氧化还原过程变化机理具有重要的理论意义。本研究采用土壤泥浆厌氧培养、人工合成氧化铁体系接种土壤浸提液厌氧培养及接种铁还原菌纯培养等试验方法,通过向培养体系中添加SO24-,探讨了硫酸盐作为竞争电子受体对不同铁还原体系中Fe（Ⅲ）还原的影响。结果表明,在2种水稻土的泥浆培养过程中,Fe（Ⅲ）还原速率均随着SO24-浓度增加而降低,但Fe（Ⅱ）的最终累积量却较对照处理有明显的增加。添加硫酸盐对Fe（Ⅲ）还原速率（k）的影响表现为：石灰性水稻土〉酸性水稻土;而最终Fe（Ⅱ）累积增加率则为：酸性水稻土〉石灰性水稻土。由接种不同水稻土浸提液的培养试验看出,添加SO24-后Fe（Ⅲ）还原受到显著的抑制,但随着培养时间延长Fe（Ⅲ）还原反应依然可以进行,并且Fe（Ⅱ）累积量最终达到与CK相同的水平。在接种铁还原菌的纯培养试验中,添加SO24-对供试的4株铁还原菌的Fe（Ⅲ）还原过程并未产生抑制效应,表明铁还原菌本身并不受硫酸盐的影响。     

污水灌溉对林地土壤中磷的数量与形态影响

为避免城市生活污水携带的N、P进入水体,新西兰罗托鲁阿市处理后的污水直接喷灌至Whakarewarewa森林,同时建立污水灌溉林地处理系统长期定位试验地,以评价林地生态系统对污水携带营养物质的同化能力。为了解长期污水灌溉对土壤中P的数量、形态、环境的影响,对该灌溉系统中的土壤进行了剖面采样分析。结果表明:土壤TP(全磷)、Olsen P、M3P(Mehlich-3 P)在所有灌溉区的表层土壤(0～10 cm)均有显著(p<0.05)增加,部分指标的显著增加达深层土壤。随灌溉进入土壤的P大多被保存在上层土壤(0～40 cm)中。土壤中各形态的磷所占比例因长期污水灌溉而改变,灌溉前占优势的NaOH Po(以NaOH浸提得到的有机磷)经长期灌溉后被NaOH Pi(以NaOH浸提得到的无机磷)所取代,上层土壤WSP(水溶性磷,Wa-ter-soluble P)变化明显。以Olsen P 60 mg kg-1和M3P 150 mg kg-1为环境临界值可预测土壤剖面中P的淋失危机,WSP可望成为适用更广的土壤P淋失环境危机预测指标。     

夏玉米和冬小麦秸秆对石灰性土壤磷吸附特性及磷素形态的影响

本文对夏玉米秸秆(MR)和冬小麦秸秆(WR)单施或者与P肥混施(在等P量条件下)对石灰性土壤P的吸附特性及其形态转化进行了为期15周的室内模拟培养研究,结果表明,无论是MR和WR单施,还是秸秆与P肥混施,都可以减少土壤对P的吸附量,提高土壤P的活性,其中秸秆单施处理的活性无机磷(Pi)和有机磷(Po)(NaHCO3-P或者NaOH-P)提高较大,夏玉米秸秆单施时,比对照(CK)增加Pi、Po的量分别达6.0、5.6mgkg-1(NaHCO3-P),增加NaOH-Po为12.7mgkg-1。并通过Langmuir方程求得P的最大吸附量(b)、P吸附结合能常数(k)、P素最大缓冲量(MPBC)、标准需P量(SPR)的值,进一步说明了两种秸秆均可使土壤对P的吸附能力降低,增加土壤中P的活性。     

农牧交错带土壤磷素动态研究

对海拔2600～3000m农牧交替带不同退化程度的草原、草原开垦后土壤磷素变化进行了系统研究。退化草原包括:轻度(LDP),中度(MDP)和重度(HDP)3种类型,耕种土壤开垦年限从1至50年不等,土壤样品取自甘肃省7县市18个地点,主要土壤类型为黑钙土。通过进行磷的分级发现,草原开垦后土壤有机磷组分明显下降。种植8、16、41年后土壤有机磷分别下降8%、20%和36%;区域性土壤分析结果亦表明,耕种30年以上的土壤有机磷平均下降35%。有机质矿化,土壤侵蚀后由于耕作措施造成的底土与表土混合,以及无机磷肥的施用使得耕种土壤中Ca-P明显增加。NaOH浸提的潜在活性有机磷,随着草原退化程度的增加和耕作年限的延长有递减的趋势。活性有机磷与总有机磷显著相关(R2=0.63),而活性有机磷的多寡与耕种和施肥明显相关。     

酸性土壤磷分级新方法建立与生物学评价

土壤磷分级方法可用于估算土壤有效磷数量、不同土壤磷组分库数量及其对土壤有效磷的补充能力。以云南赤红壤、黄红壤及湖北棕红壤为供试材料,运用张守敬方法、蒋柏藩方法及本文提出的新方法,对三种酸性土壤和其石灰改良后的土壤磷进行分级研究,探讨石灰改良对酸性土壤磷组分数量及其生物有效性的影响。结果表明:Ca2-P、Al-P和Fe-P是酸性土壤主要的有效磷源,O-P(闭蓄态磷)也是潜在有效磷源,土壤中活性有机磷库相对比较稳定,可转化为高活性有效磷源供植物吸收利用。与两种经典磷分级方法相比,新方法将O-P划分为O-Al-P和O-Fe-P,O-Fe-P较好地反映了石灰处理与对照之间的土壤磷植物有效性差异。     

Bowman-Cole土壤有机磷分组法的探讨

采用Bowman-Cole法的几种浸提剂和浸提步骤大体上可将矿化难易不同的几种有机磷化合物区分开来.采用该法所测得的土壤有机磷四种组分,其矿化速率有随土壤有机磷组分活性增强而增加的趋势.因此,该法能用来监测土壤有机磷对植物有效性的高低.     

Phosphorus forms and enzymatic hydrolyzability of organic phosphorus in soils after 30 years of organic and conventional farming

Lower P‐input levels in organic than conventional farming can decrease soil total and available P, which can potentially be resupplied from soil organic P. We studied the effect of 30 y of conventional and organic farming on soil P forms, focussing especially on organic P. Soil samples (0–20 cm) were taken in a field experiment with a nonfertilized control, two organic systems receiving P inputs as animal manure, and two conventional systems receiving only mineral P or mineral P and manure. Soils were analyzed for total, inorganic, organic, and microbial P, by sequential P fractionation and by enzyme additions to alkaline soil extracts. Samples taken prior to starting the experiment were also analyzed. Average annual P balances ranged from –20 to +5 kg ha^–1. For systems with a negative balance, labile and moderately labile inorganic P fractions decreased, while organic and stable inorganic P fractions were hardly affected. Similar quantities and proportions of organic P extracted with NaOH‐EDTA were hydrolyzed in all soils after addition of an acid phosphatase, a nuclease, and a phytase, and enzyme‐stable organic P was also similar among soils. Thus, neither sequential fractionation nor enzyme addition to alkaline soil extracts showed an effect of the type of applied P (manure vs. mineral) on organic P, suggesting that organic P from manure has largely been mineralized. Thus far, we have no indication that the greater microbial activity of the organic systems resulted in a use of stable P forms.     

An assessment of various pools of organic phosphorus distributed in soil aggregates as affected by long-term P fertilization regimes

The phosphorus (P) forms in long-term fertilization determine the fate and transport of P in soil. However, the fate of various pools of organic P of added P in the long-term measured with sequential chemical fractionation is not well-understood. Four soil physical aggregates (>250, 125–250, 63–125 and <63 μm) from 0- to 20-cm depth after 35 years of long-term fertilization treatments including control (CK), nitrogen and phosphorus fertilizer (NP) and NP combined with farmyard manure (NPM) under continuous winter wheat were separated using settling tube apparatus. Results showed that the application of long-term P fertilization had no apparent effects on promoting the mass proportion of soil aggregates except for >250 μm, where the NP and NPM treatments significantly increased the mass proportion by 60% and 70% over CK, respectively. Compared with CK, P fertilizer (NP and NPM) treatments significantly increased organic P (Po) contents in each size aggregate. In particular, mean labile Po increased by 35% and 246%, moderately labile Po by 125% and 161%, nonlabile Po by 105% and 170% and total Po (TPo) by 101% and 178%, respectively, under NP and NPM treatments, respectively. There was a significant correlation between soil organic carbon (SOC) and Po fractions. SOC was exponentially positively correlated with labile Po but linearly positively correlated with moderately labile Po, nonlabile Po and TPo fractions among soil aggregates. A reduced C:Po ratio (<100) in soil aggregates among treatment indicates a large amount of available P accumulated in soils, and soil P loss risk in the study site is still high. Our results show that the Po pool measured by sequential chemical fractionation may represent an important, yet often overlooked, source of P in agriculture ecosystems. According to the result, long-term mineral P fertilizer combined with organic amendments better sustains soil structural stability in large aggregates, contributing more Po availability in the moderately labile P followed by labile P in soil aggregates.     

长期施肥对旱地土壤有机磷及其组分的影响

通过15年长期定位试验,采用Bowman和Cole提出的土壤有机磷分级方法,研究了不同耕作施肥措施对旱地耕层土壤有机磷及其组分的影响。结果显示旱地土壤各个处理的活性有机磷含量低,占有机磷总量的比例低于3.6%,中活性有机磷为有机磷的主体,约占有机磷总量的73.37%-91.54%。休闲、撂荒及磷肥与其它肥料配合使用,均增加了耕层土壤的中活性有机磷含量,增加了中稳性有机磷含量及其比重;休闲、撂荒及磷钾提高了高稳性有机磷含量及比重,而氮磷钾及其与有机肥配合处理则降低了高稳性有机磷的含量。尽管不同耕作施肥管理均影响旱地土壤有机磷含量,但是施用有机肥对有机磷的增加贡献最大;撂荒与休闲相比,前者更有利于土壤有机磷的积累。     

湖南稻田土壤有机磷组分的施磷效应、季节变化及生物有效性研究

为探明施用磷肥对湖南稻田土壤有机磷组分的影响、有机磷组分的季节变化及其有效性,以湖南省5种不同母质发育的稻田土壤为供试土壤,通过盆栽试验,研究了稻田土壤有机磷组分的施磷效应、在植稻期间的动态变化及其生物有效性。结果表明,施用磷肥可以使土壤中活性有机磷得到较大的增加,而对活性有机磷、中稳性有机磷和高稳性有机磷影响较小。在施磷和不施磷条件下,土壤有机磷的变化主要是中活性有机磷,而其余3种形态有机磷在水稻生长期间几乎保持不变。不管土壤是否施用磷肥,土壤有效磷与有机磷总量总是呈极显著相关,说明土壤有机磷的确是植物可以利用的有效磷源;在早稻生长期间土壤各形态有机磷的生物有效性的大小顺序为:中活性有机磷中稳性有机磷高稳性有机磷活性有机磷;在晚稻生长期间土壤各形态有机磷的生物有效性一般随水稻生育期不同而不同。     

Rapid decomposition of phytate applied to a calcareous soil demonstrated by a solution 31P NMR study

myo‐Inositol hexakisphosphate (phytate) is widely regarded as an abundant form of soil organic phosphorus (P) in many soils. Its abundance is believed to be because of its resistance to microbial degradation. We examined the fate of phytate added to a calcareous soil as a solution at a concentration of 58 mg P kg⁻¹, with and without the addition of wheat straw. The soil was incubated for 13 weeks, with phytate concentrations determined at 0, 1, 4, 7 and 13 weeks using NaOH‐EDTA soil extraction followed by ³¹P nuclear magnetic resonance (NMR) spectroscopy. The phytate concentration declined rapidly, with 18% (phytate + wheat straw) and 12% (phytate) of the initial phytate remaining after 13 weeks. This coincided with an increase in the proportion of orthophosphate relative to total NaOH‐EDTA extractable P (from 65 to 81%) and a small increase in α‐ and β‐glycerophosphate concentration, providing evidence for the microbial degradation of phytate. The decrease in phytate concentration was consistent with a first‐order decay with a half‐life for phytate of 4–5 weeks. This study demonstrates that in the calcareous soil examined, phytate was not highly stable, but a potentially biologically available form of P. In order to quantify the concentration of P species, we developed an improved method of spectral deconvolution. This method accounted for a broad signal (3.5–6.5 ppm) in the monoester region of the spectra that represented up to 23% of the total extractable P. We found that when this broad signal was not included, phytate concentrations were over‐estimated by up to 54%.     

不同灌溉和施肥模式对稻田磷形态转化和有效性的影响

为阐明不同灌溉和施肥模式对水稻磷吸收和利用效率、稻田土壤磷形态转化特征的影响及其对土壤磷素有效性的贡献,该研究以杂交籼稻中浙优1号为供试材料,设常规淹灌（Conventional Flooding,CF）、干湿交替（Alternate Wet and Dry irrigation,AWD）2种灌溉模式,以及不施肥（CK）、常规尿素（Ureal,100%PU）、常规尿素减氮20%（80% of Urea,80%PU）、缓控释复合肥减氮20%+生物炭（80% of Control-Released Fertilizer+Biochar,80%CRF+BC）和稳定性复合肥减氮20%+生物碳（80% of Stable Fertilizer+Biochar,80%SF+BC）5种施肥模式,对比分析了不同灌溉和施肥模式下水稻产量、磷吸收效率、稻田土壤磷有效性及土壤磷形态变化特征。1）与CF相比,AWD灌溉模式下80%CRF+BC和80%SF+BC处理水稻产量显著高于100%PU和80%PU处理（P<0.05）;2）AWD灌溉显著增加了成熟期80%SF+BC处理水稻穗部磷累积量,且80%CRF+BC与80%SF+BC处理水稻各器官磷累积量、磷吸收效率与磷肥偏生产力均显著高于80%PU处理;3）AWD灌溉显著提高80%CRF+BC和80%SF+BC处理土壤有效磷、无机磷、有机磷含量与磷活化系数,以及土壤各形态无机磷和0～15 cm 土壤中活性有机磷（Moderately Labile Organic Phosphorus,MLOP）、活性有机磷（Labile Organic Phosphorus,LOP）含量,且其含量均显著高于两组尿素处理;4）相关分析表明,土壤中稳态有机磷（Moderately Resistant Organic Phosphorus,MROP）、LOP、MLOP和Al-P是土壤有效磷的主要决策因子,O-P（闭蓄态磷）和Ca-P是有效磷的主要限制因子。通过适宜的水肥管理提高MROP、LOP、MLOP含量可能是提高土壤有效磷的潜在有效途径。AWD灌溉模式下,生物炭配施稳定性复合肥/缓控释肥能通过调控土壤磷形态转化和磷素活化提高稻田磷有效性,进而提高水稻磷吸收累积和磷素利用效率。研究结果可为通过不同水肥管理模式提高水稻磷利用效率提供理论依据。     

Soil organic phosphorus fractions in response to long-term fertilization with composted manures under rice–wheat cropping system

Present investigation evaluates the effect of organic fertilization (OF), integrated nutrient management (INM) practice, and recommended dose of chemical fertilization (CF) on changes in soil organic phosphorus (P) and its fractions under rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system. The 4-year experiment (2009–2013), under split-plot design, showed that OF did not increase the total P or total organic P content of soil under either of the test crops. However, OF maintained the higher level of labile organic P and moderately labile organic P in soil under wheat the moderately stable organic P and highly stable organic P was highest in paddy soil under CF practices (11.34 and 7.77 μg g^?1, respectively) followed by wheat. The P concentration in organically grown rice or wheat grain was increased significantly compared with their CF counterparts. The productivity economics for rice and wheat crops showed INM fertilization to be more economical than OF.