不同农田管理措施对土壤有机磷影响的研究进展

综述了土壤有机磷种类、来源、含量、分布及影响因素.重点介绍了不同耕作方式、秸秆还田、施用无机磷肥及有机肥对土壤有机磷变化的影响.开垦、轮作有利于土壤有机磷下降;秸秆还田、施用有机肥提高土壤有机磷含量,但由于有机物性质不同,有机磷组分转化不同.施用无机磷肥后,有部分无机态磷转化为有机态.外源有机酸、磷酸酶有利于有效性低的有机磷组分向有效性高的组分转化.     

持续六年施用不同磷肥对稻田土壤磷库的影响

以草甸棕壤稻田为研究对象,采用磷素分级方法研究持续6年施用不同磷肥对稻田土壤磷库组成及磷有效性的影响,明确最有效培肥稻田土壤的磷肥品种。结果表明,持续6年施用不同磷肥土壤无机态磷占土壤磷库的65.64%~81.30%,有机态磷占土壤磷库的18.70%~34.36%;施用不同磷肥均可增加土壤无机磷含量,其中施用磷酸二铵、重钙、过磷酸钙等常规无机磷肥土壤有机磷含量显著增加。施用包膜或含有机酸磷肥的土壤有机磷含量显著低于施用常规无机磷肥土壤。施用包膜或含有机酸磷肥可显著提高磷有效性,施用包膜重钙效果最好。含有机酸磷肥尽管能活化磷素,但也会导致养分流失。施用包膜或含有机酸磷肥是提高土壤磷素库容的有效措施。     

温度对土壤吸附有机肥中可溶性有机碳、氮的影响

可溶性有机碳、氮(Soluble organic carbon or nitrogen,SOC和SON)可被土壤吸附.土壤可溶性有机碳、氮组分复杂,土壤对可溶性有机物吸附的不均一性会导致可溶性有机物组分的变化,大部分疏水性化合物被吸附,而亲水性化合物被释放进入溶液中[1].因此,可溶性有机碳、氮在土壤中的吸附,直接影响其在土壤-水系统中的迁移和行为[2-3].林地土壤中含有相当数量的可溶性有机养分,因此,关于林地土壤对可溶性有机养分的吸附特性,国外研究者已开展了不少研究.研究表明,可溶性有机碳吸附特性与土壤性质如pH、表面积、有机碳、铁铝氧化物和黏粒含量等因素有关[4-5].关于农业土壤对可溶性有机碳的吸附特性的影响,国内也开展了一些研究,主要集中在pH、铁铝氧化物含量等对吸附影响方面[6-9].     

有机无机肥配合对土壤磷素吸附、解吸和迁移特性的影响

通过32P示踪、薄层层析和土柱淋洗研究了经过四季不施磷肥、施用纯无机磷肥以及有机无机磷肥3种处理对土壤磷素迁移的影响。结果表明:有机无机肥配合处理的土壤磷吸附亲和力常数和最大吸附量显著低于化肥处理,磷累积解析量高于化肥处理,而32P在薄层板的迁移距离显著高于化肥及对照处理;淋洗试验中有机无机肥配合处理土壤中的32P最先在淋洗液达到13.1mL时出现,而化肥及对照的32P则分别在淋洗液达19.0和19.8mL时出现;在淋洗液体积达到50mL时,对照、化肥及有机无机肥配合处理淋出的32P总量分别为总加入量的1.6%、8.4%和9.8%。有机无机肥配合可以减少土壤磷素的固定,增强磷在土壤中的移动,提高磷的有效性。     

对间隙淋洗长期通气培养条件下黄土高原土壤供氮能力的评价

采用间隙淋洗长期通气培养法,通过对黄土高原物理化学性质差异较大的10种农田土样起始矿质氮、起始提取态总氮、起始可溶性有机氮,以及培养期间淋洗矿质氮、淋洗总氮、可溶性有机氮含量及其与作物吸氮量关系的研究,分析并评价黄土高原主要农田土壤氮素矿化能力以及包括和不包括培养淋洗可溶性有机氮对土壤供氮能力的影响。结果表明,供试土样起始可溶性有机氮平均为N 23.9 mg/kg,是起始提取态总氮的28.8%,土壤全氮的2.4%。在通气培养淋洗总氮中,可溶性有机氮所占比例不高,经过217 d通气培养,淋洗出的可溶性有机氮平均为N 28.8mg/kg,占淋洗总氮量的19.8%。相关分析表明,淋洗可溶性有机氮量与第1季作物吸氮量相关不显著,但与连续2季作物总吸氮量显著相关。淋洗矿质氮、淋洗总氮与两季作物总吸氮量的相关系数明显高于与第一季作物吸氮量的相关系数;与第一季作物吸氮量达显著相关水平,与连续两季作物吸氮量达极显著相关水平。总体上看,可溶性有机氮和土壤全氮、土壤微生物氮不能作为反映短期可矿化氮的指标;间隙淋洗通气培养淋洗液中淋洗矿质氮、淋洗总氮是评价可矿化氮的较好指标,不仅适宜于第一季作物,而且也适用于对连续两季作物土壤供氮能力的评价。     

西瓜根系分泌酸性磷酸酶对有机肥营养的响应

有机肥营养对西瓜品质具有提升效果,但根系对有机肥中养分的吸收机制尚不完全清楚,尤其对磷素的利用机制。本研究关注西瓜根系分泌酸性磷酸酶活性对有机肥施用的响应。采用模拟西瓜根系分泌物的方法研究有机酸对有机肥中可溶性全磷和有效磷含量的影响;采用砂培的方法,研究有机肥中的磷替代化肥磷时西瓜根系分泌酸性磷酸酶活性的响应;采用田间试验研究有机肥替代化肥以及有机肥不同施用量对西瓜根际酸性磷酸酶活性、西瓜磷营养、产量和品质的影响。结果表明,有机肥中水浸提可溶性全磷含量为6.9 g?kg~(-1),可溶性无机磷含量为525.1 mg?kg~(-1),可溶性全磷中无机磷占7.6%,有机磷占92.4%,可溶性有机磷需经过水解后才能被根系吸收。有机肥中磷替代化肥磷时,西瓜根系和根际土壤酸性磷酸酶活性均显著提高,西瓜茎、叶中磷含量提高。施用三倍有机肥时西瓜根际土壤有效磷含量和西瓜产量提高。因此,有机肥中磷替代化肥磷时,西瓜通过提高根系分泌酸性磷酸酶的活性而提高利用有机磷的能力。     

水稻秸秆施用后土壤溶解性有机碳的变化与土壤CO_2排放

为了进一步认识水稻秸秆还田后土壤有机碳固定机制,以浙江两种典型水稻土淡涂泥、青紫泥为研究对象,并以不加秸秆为对照,研究秸秆施用下土壤溶解性有机碳(Dissolved Organic Carbon,DOC)含量以及CO_2产生速率的动态变化,以及秸秆分解产生DOC在土壤中的吸附作用。结果表明,添加秸杆显著增加了土壤CO_2排放,总矿化碳量表现为10%>5%>2%>CK;土壤CO_2产生速率的变化与DOC含量变化具有高度一致性,都表现为先快速上升-急剧下降-缓慢下降-趋于稳定的变化模式,两者呈显著正相关(P<0.01),但在石英砂处理中两者则无明显相关性。DOC吸附实验表明随着秸秆分解时间延长,所产生的DOC在土壤中的吸附作用增强。pH和本底DOC较低的青紫泥对DOC具有更强的吸附作用,其CO_2排放速率和总矿化碳量均显著低于淡涂泥,青紫泥更有利于秸秆还田有机碳的保留和稳定。该结果表明秸秆分解前期产生DOC主要以CO_2形式释放,分解后期产生DOC更倾向于土壤有机碳固定,增加土壤对DOC的吸附作用有利于土壤固碳。     

有机质、石灰、磷酸盐和淹水对红壤中铝形态的影响

研究了有机质，施用石灰和磷酸盐，以及淹水培育对红壤铝形态的影响。结果表明，用Ｈ２Ｏ２去除有机质，施用石灰和磷酸盐，以及淹水培育，使土壤ｐＨ升高，交换态铝减少，吸附态无机羟基铝增加。而施用腐殖酸使土壤ｐＨ降低，交换态铝增加，有机配合态略有上升。     

山东主要土类有机质及其与供磷特性的关系

山东省3大土类中棕壤的有机质含量最高,平均为10.69g kg-1,其次为褐土和潮土;高产农田的有机质含量平均为10.9g kg-1,高于中低产田。相关分析结果表明,土壤的主要养分含量中有机质含量与土壤有效磷含量的密切正相关,进一步分析表明,土壤的有机质含量与土壤全磷、有机磷、有效磷、磷酸化酶活性和土壤微生物转化难溶性磷的强度均呈正相关,而与磷吸附最大缓冲容量MBC、固磷百分率、解吸能Qm呈负相关;逐步回归结果表明有机质对棕壤中的中度活性有机磷MLOP、潮土中的Ca2-P、褐土中的A l-P、高产农田中的A l-P,中低产田的Fe-P均显著的正相关;而且这种相关性均是高产农田大于中低产田。有机质不仅直接丰富了高产农田的磷库,而且通过提高磷酸化酶的活性,降低土壤磷的吸附、固定,促进解吸,增加了土壤磷的有效性。     

施用秸秆对土壤可溶性有机碳氮及矿质氮的影响

为了研究施用秸秆对土壤可溶性有机碳氮及矿质态氮含量的影响,设置CK（对照）,M₂,M₄,M₆共4个处理,处理中每100 g干土中加入秸秆量分别为0,2,4,6 g。在室温为25℃、土壤含水量为田间持水量的70%的条件下进行培养试验,分别在15,30,45,60,105,150 d时,采取各处理中的土壤样品,观测土壤可溶性有机碳氮及矿质氮的动态变化。结果表明:4个处理的土壤可溶性有机碳、氮具有相同的变化趋势,表现为随着培养时间的推移,先增加,再减小,然后经过一段时间的波动后趋于平稳。在培养的整个过程中,M₄与M₆处理的土壤可溶性有机碳、氮明显高于CK中的含量,表明了施用秸秆可以促进土壤可溶性有机碳氮的累积。在相同时间段内,各处理之间铵态氮含量无明显差异,与对照相比,加入秸秆后,土壤中硝态氮的含量明显下降。     

The effect of soil type on phosphorus sorption capacity and desorption dynamics in Irish grassland soils

Abstract. The phosphorus (P) sorption and desorption dynamics of eleven major agricultural grassland soil types in Ireland were examined using laboratory techniques, so that soils vulnerable to P loss might be identified. Desorption of P from soil using the iron-oxide paper strip test (Pfeo), water extractable P (Pw) and calcium chloride extractable P (Pcacl₂) depended on soil P status in all soils. However, soil types with high organic matter levels (OM), namely peat soils (%OM >30), had lower Pfeo and Pw but higher Pcacl₂ values compared to mineral soils at similar soil test P levels. Phosphorus sorption capacity remaining (PSCr) was measured using a single addition of P to soils and used to calculate total P sorption capacities (PSCt) and degree of P saturation (DPS). Phosphorus sorption capacities correlated negatively with % OM in soils indicating that OM may inhibit P sorption from solution to soil. High organic matter soils exhibited low P sorption capacities and poor P reserves (total P, oxalate extractable P) compared to mineral soils. Low P sorption capacities (PSCt) in peat soils were attributed to OM, which blocked or eliminated sorption sites with organic acids, therefore, P remained in the soil solution phase (Pcacl₂). In this work, peat and high organic matter soils exhibited P sorption and desorption characteristics which suggest that these soils may not be suitable for heavy applications of manure or fertilizer P owing to their low capacities for P sorption and storage.     

Dissolved organic matter sorption by mineral constituents of subsoil clay fractions

The retention of dissolved organic matter in soils is mainly attributed to interactions with the clay fraction. Yet, it is unclear to which extent certain clay‐sized soil constituents contribute to the sorption of dissolved organic matter. In order to identify the mineral constituents controlling the sorption of dissolved organic matter, we carried out experiments on bulk samples and differently pretreated clay‐size separates (untreated, organic matter oxidation with H₂O₂, and organic matter oxidation with H₂O₂ + extraction of Al and Fe oxides) from subsoil horizons of four Inceptisols and one Alfisol. The untreated clay separates of the subsoils sorbed 85 to 95% of the dissolved organic matter the whole soil sorbed. The sorption of the clay fraction increased when indigenous organic matter was oxidized by H₂O₂. Subsequent extraction of Al and Fe oxides/hydroxides caused a sharp decrease of the sorption of dissolved organic matter. This indicated that these oxides/hydroxides in the clay fraction were the main sorbents of dissolved organic matter of the investigated soils. Moreover, the coverage of these sorbents with organic matter reduced the amount of binding sites available for further sorption. The non‐expandable layer silicates, which dominated the investigated clay fractions, exhibited a weak sorption of dissolved organic matter. Whole soils and untreated clay fractions favored the sorption of ”︁hydrophobic” dissolved organic matter. The removal of oxides/hydroxides reduced the sorption of the lignin‐derived ”︁hydrophobic” dissolved organic matter onto the remaining layer silicates stronger than that of ”︁hydrophilic” dissolved organic matter.     

连续种植蔬菜对潮土磷素水平的影响

Soil P status, inorganic P fractions, and P sorption properties were studied using sandy fluvo-aquic horticultural soils, which are high in organic matter content for vegetable production in comparison with a soil used for grain crop production in Zhengzhou, Henan Province, China. P fractions, Olsen-P, and OM were determined at different depths in the soil profile and sorption isotherm experiments were performed. Most P in excess of plant requirements accumulated in the topsoil and decreased with soil depth. Total P, inorganic P, and OM concentrations increased with continued horticultural use. Olsen-P concentrations in the 0-20 cm depth of horticultural soils were 9 to 25 times higher than those of the grain crop soil. A linear transformation of the Langmuir equation showed that the P adsorption maximum (491.3 mg P kg^-1) and the maximum phosphate buffering capacity (162.1 L kg^-1) for 80-100 cm were greater in the grain crop soil than the horticultural soils. Thus, the most immediate concern with excess P were in areas where heavy P fertilizer was used for vegetable crops and where soil P sorption capacities were low due to sandy soils and high organic matter content.     

Labile organic matter fractions as early‐season nitrogen supply indicators in manure‐amended soils

Soil test indicators are needed to predict the contribution of soil organic N to crop N requirements. Labile organic matter (OM) fractions containing C and N are readily metabolized by soil microorganisms, which leads to N mineralization and contributes to the soil N supply to crops. The objective of this study was to identify labile OM fractions that could be indicators of the soil N supply by evaluating the relationship between the soil N supply, the C and N concentrations, and C/N ratios of water extractable OM, hot‐water extractable OM, particulate OM, microbial biomass, and salt extractable OM. Labile OM fractions were measured before planting spring wheat (Triticum aestivum L.) in fertilized soils and the soil N supply was determined from the wheat N uptake and soil mineral N concentration after 6 weeks. Prior to the study, fertilized sandy loam and silty clay soils received three annual applications of 90 kg available N (ha · y)^?1 from mineral fertilizer, liquid dairy cattle manure, liquid swine manure or solid poultry litter, and there was a zero‐N control. Water extractable organic N was the only labile OM fraction to be affected by fertilization in both soil types (P < 0.01). Across both test soils, the soil N supply was significantly correlated with the particulate OM N (r = 0.87, P < 0.001), the particulate OM C (r = 0.83, P < 0.001), and hot‐water extractable organic N (r = 0.81, P < 0.001). We conclude that pre‐planting concentrations of particulate OM and hot‐water extractable organic N could be early season indicators of the soil N supply in fertilized soils of the Saint Lawrence River Lowlands in Quebec, Canada. The suitability of these pre‐planting indicators to predict the soil N supply under field conditions and in fertilized soils from other regions remains to be determined.     

Effects of organic matter addition on phosphorus availability to flooded and nonflooded rice in a P‐deficient tropical soil: a greenhouse study

Addition of organic matter (OM) to flooded soils stimulates reductive dissolution of Fe(III) minerals, thereby mobilizing associated phosphate (P). Hence, OM management has the potential to overcome P deficiency. This study assessed if OM applications increases soil or mineral fertilizer P availability to rice under anaerobic (flooded) condition and if that effect is different relative to that in aerobic (nonflooded) soils. Rice was grown in P‐deficient soil treated with combinations of addition of mineral P (0, 26 mg P/kg), OM (0, ~9 g OM/kg as rice straw + cattle manure) and water treatments (flooded vs nonflooded) in a factorial pot experiment. The OM was either freshly added just before flooding or incubated moist in soil for 6 months prior to flooding; blanket N and K was added in all treatments. Fresh addition of OM promoted reductive dissolution of Fe(III) minerals in flooded soils, whereas no such effect was found when OM had been incubated for 6 months before flooding. Yield and shoot P uptake largely increased with mineral P addition in all soils, whereas OM addition increased yield and P uptake only in flooded soils following fresh OM addition. The combination of mineral P and OM gave the largest yield and P uptake. Addition of OM just prior to soil flooding increased P uptake but was insufficient to overcome P deficiency in the absence of mineral P. Larger applications of OM are unlikely to be more successful in flooded soils due to side effects, such as Fe toxicity.     

紫色土可溶性有机碳的吸附-解吸特征

选择代表性的酸性、中性和石灰性紫色土为实验材料,采用平衡吸附和动力学吸附法研究了紫色土对可溶性有机碳（DOC）的吸附-解吸特征,分析了土壤理化性质与DOC吸附量之间的关系。结果表明,紫色土对DOC的吸附容量呈以下顺序：酸性紫色土〉中性紫色土〉石灰性紫色土。石灰性紫色土对DOC的解吸率明显高于酸性、中性紫色土,其迁移淋失问题值得重视。紫色土对DOC的吸附过程包括快速吸附和慢速吸附2个阶段,0~0.5 h内吸附速率最大,随后吸附速率逐渐减小,4~6 h内基本达到吸附平衡。土壤pH值、有机质、粘粒和活性铁铝氧化物含量是影响土壤DOC吸附量与解吸率的重要因素。通径分析表明,土壤理化性质对DOC吸附量的直接作用系数大小顺序为活性铝含量〉土壤pH值〉有机质,对DOC解吸率的直接作用系数大小顺序为活性铁含量〉粘粒〉有机质。多元线性回归模型能较好地预测土壤对DOC的吸附及解吸的变化。     

土壤残渣有机质与固定态铵之间的关系

采集了全国不同类型的土壤40个,分析了土壤全氮、有机质、固定态铵、剩余有机质（KOBr处理后的土壤有机质）、残渣有机质（KOBr-HF处理后的土壤有机质）含量.结果表明,以2∶1型粘粒矿物为主土壤的残渣有机质含量与固定态铵含量之间呈极显著正相关（r=0.831^＊＊）,晶格之间存在的有机质（即残渣有机质与剩余有机质之差值）含量则与固定态铵含量之间也呈极显著正相关（r=0.832^＊＊）,而以1∶1型粘粒矿物为主土壤的残渣有机质含量和晶格有机质含量与固定态铵含量不相关;土壤剩余有机质、残渣有机质的含量分别为2.59 g kg^-1、3.70 g kg^-1,分别占土壤有机质的10%和16%.土壤残渣C/N比（平均值为16.69）明显高于原土壤（平均值为5.37）.     

不同用量有机肥对陇东旱塬黑垆土磷素形态转化及有效性的影响

以覆盖黑垆土土壤为材料,研究了不同用量有机肥对土壤磷素有效性及不同形态无机磷含量的影响。结果表明:在陇东旱塬黑垆土上施肥能够增加全磷、有效磷含量,有机肥增加效果更明显,且随有机肥施用量的增加而增加。无磷肥输入的氮肥处理区,活性较强的Ca_2-P、Ca_8-P、A1-P和Fe-P含量都有所降低,而较稳定态的O-P和Ca_(10)-P含量则有所提高。与CK相比,有机肥处理随有机肥用量的增加,Ca_2-P、Ca_(10)-P、A1-P含量表现为增加,而Ca_8-P、Fe-P、O-P则相反。同时Ca_2-P与有机质、有效磷显著正相关,与p H值显著负相关。因此,在本试验条件下,从有效态的Ca_2-P和难溶性的Ca_(10)-P含量变化来看,在施等量氮的基础上配施农家肥60 000 kg·hm~(-2)更有利于活化土壤磷和减缓磷吸附,从而提高磷素的有效性。     

长期不同施肥潮土对可溶性有机碳的吸附特征

可溶性有机碳(DOC)吸附影响土壤元素化学行为。为此,本研究采用批处理法研究了DOC在长期不同施肥处理(对照CK、氮N、氮磷NP、氮磷钾NPK、化肥+秸秆还田NPKS、化肥+有机肥NPKM)潮土上的吸附动力学和等温吸附特征。结果表明,猪粪源DOC易于分解,需要添加0.025 mmol(1 mL 25 mmol/L)Na N3抑制其分解,抑制率超过90%。DOC吸附符合准二级动力学方程(R~2≥0.99)。不同施肥处理下,吸附速率常数k及初始速率常数h与平衡吸附Qe都没有显著差异,平均值分别为0.208 kg/(g·h)、1.60 g/(kg·h)和2.77g/kg。吸附等温式可用Langmuir方程很好拟合(R~2≥0.96),吸附容量(最大吸附量)Q_(max)在不同施肥处理下也没有显著差异(平均7.05 g/kg),但在N和NP等非平衡施肥下却保持高的亲合力,半饱和吸附浓度k_d分别为50.2和57.6 mg/L,吸附亲合常数K则分别为0.02和0.017 4 L/mg;相反,在NPKM处理下,显著低的亲合性发生,k_d和K分别为72.94 mg/L和0.013 8 L/mg。研究证明粘粉粒含量控制了不同施肥处理潮土对DOC的吸附;土壤有机碳水平不影响Q_(max),而且高土壤有机碳还降低其吸附亲合性。     

Phosphorus Adsorption and Bioavailability in a Paddy Soil Amended with Pig Manure Compost and Decaying Rice Straw

Phosphorus (P) availability in soil is closely related not only to soil P content but also to soil physicochemical and biological properties, which are closely associated with P sorption and biochemical transformation. The aims of this study were to determine the effects of pig manure compost (PMC) or decaying rice straw (DRS) added to a paddy soil on soil pH, soil organic carbon (SOC), dissolved organic carbon (DOC), acid phosphatase, microbial biomass P, soil test P (Olsen P), and P uptake by rice (Oryza sativa L. cv. ‘Liaoyan’). Phosphorus adsorption characterization affected by PMC‐ or DRS‐derived DOC was also studied. Compared with the control, both PMC and DRS treatments increased soil pH, SOM, DOC, microbial biomass P, and Olsen P, and the activity of acid phosphatase during the 110‐day incubation period. Phosphorus adsorption in soil decreased with DOC extracted from PMC and DRS and was well fit by the Langmuir equation. The Olsen P in the PMC‐ and DRS‐treated soil was correlated with both DOC content and acid phosphatase activity. Both PMC and DRS treatments significantly increased dry‐matter yield and P uptake in rice shoot. In conclusion, the increased P availability in the paddy soil was not only a result of direct P supplied following organic manure incorporation, but also an indirect result of reduction in P sorption on the solid phase of the paddy soil by DOCs which were derived from DRS or PMC.