Quercetin content in field-cured onions (Allium cepa L.): effects of cultivar, lifting time, and nitrogen fertilizer level

Variation in quercetin content was investigated in field-cured onions (Allium cepa L.) that had been supplied with different nitrogen fertilizer levels and lifted at different developmental stages. Quercetin content varied significantly between years and was well correlated to global radiation in August. Field curing generally resulted in significant increases in quercetin content compared to levels at lifting. Nitrogen fertilizer level did not affect quercetin content, suggesting that nitrogen leakage from soil may be minimized without effects on flavonol content. Lifting time had minor effects on quercetin content in field-cured onions. Cultivar differences in quercetin content were significant but not consistent in all years. Quercetin content increased significantly less in dark environments compared to field curing, but some quercetin synthesis occurred regardless of light. Field curing with or without foliage still attached did not affect quercetin content, suggesting that no transportation from the foliage to the scales occurred.     

Effect of nitrogen species supply and mycorrhizal colonization on organosulfur and phenolic compounds in onions

The aim of the present study was to test whether variations in the root environment affect the content of health-related organosulfur compounds, total phenolic compounds, and flavonol glycoside concentrations in onions. For this purpose, greenhouse-grown onions ( Allium cepa L.) were either inoculated with a commercial arbuscular mycorrhizal inoculum or a sterile inoculum and were provided with two NH(4)(+):NO(3)(-) ratios as a nitrogen source. Onion growth, arbuscular mycorrhizal colonization rate, sugars, and nutrient element concentrations were also quantified. The plant antioxidant activity and quercetin monoglucoside and organosulfur compound concentrations increased with dominant nitrate supply. Furthermore, mycorrhizal colonization increased the antioxidant activity and also concentrations of the major quercetin glucosides. The present study provides clear evidence that antioxidant activity, quercetin glycosides, and organosulfur compounds can be increased in sufficiently supplied onion plants by dominant nitrate supply or application of arbuscular mycorrhizal fungi. This was probably due to increased precursor production and induced defense mechanisms.     

Population size and specific potential of P-mineralizing and -solubilizing bacteria under long-term P-deficiency fertilization in a sandy loam soil

The effects of organic manure, mineral fertilizer (NPK), and P-deficiency fertilization (NK) on the individual biomass of young wheat plants, arbuscular mycorrhizal (AM) colonization in wheat root systems, population sizes of soil organic phosphorus mineralizing bacteria (OPMB) and inorganic phosphate solubilizing bacteria (IPSB) as well as soil P-mineralization and -solubilization potential were investigated in a long-term (18-year) fertilizer experiment. The experiment included five treatments: organic manure, an equal mixture of organic manure and mineral fertilizer, fertilizer NPK, fertilizer NK, and the control (without fertilization). Plant biomass, population sizes of soil OPMB and IPSB were greatly increased (P<0.05) by the application of organic manure and slightly increased by the balanced application of mineral fertilizer, while undiminished AM colonization in wheat root system was only observed in the case of the NK treatment. Compared to balanced fertilization, P-deficiency fertilization resulted in a significant increase (P<0.05) of OPMB-specific mineralization potential (soil P-mineralization potential per OPMB cell) and highest IPSB-specific solubilization potential (soil P-solubilization potential per IPSB cell), suggesting that OPMB and IPSB are likely more metabolically active in P-deficiency fertilized soils after long-term fertilizer management, and mycorrhizal plants are more dependent on AM in P-poor soils than in P-fertilized soils. Our results also showed the different effects of mineral fertilizer versus organic manure on soil P-mineralization and -solubilization potentials, as well as specific potentials of OPMB and IPSB in arable soils.     

Nutrient availability and corn growth in a poultry litter biochar‐amended loam soil in a greenhouse experiment

Nutrient‐rich biochar produced from animal wastes, such as poultry litter, may increase plant growth and nutrient uptake although the role of direct and indirect mechanisms, such as stimulation of the activity of mycorrhizal fungi and plant infection, remains unclear. The effects of poultry litter biochar in combination with fertilizer on mycorrhizal infection, soil nutrient availability and corn (Zea mays L.) growth were investigated by growing corn in a loam soil in a greenhouse with biochar (0, 5 and 10 Mg/ha) and nitrogen (N) and phosphorus (P) fertilizer (0, half and full rates). Biochar did not affect microbial biomass C or N, mycorrhizal infection, or alkaline phosphomonoesterase activities, but acid phosphomonoesterase activities, water‐soluble P, Mehlich‐3 Mg, plant height, aboveground and root biomass, and root diameter were greater with 10 Mg/ha than with no biochar. Root length, volume, root tips and surface area were greatest in the fully fertilized soil receiving 10 Mg/ha biochar compared to all other treatments. The 10 Mg/ha biochar application may have improved plant access to soil nutrients by promoting plant growth and root structural features, rather than by enhancing mycorrhizal infection rates.     

施肥结构对砂质潮土有机质及氮磷钾养分变化的影响

通过在砂质潮土上10年长期定位试验,研究了不同施肥结构对作物产量和土壤有机质及N、P、K等养分在土体中变化的影响。结果表明,单施N肥小麦减产21.1％～34.3％,玉米则增产155.9％～209.7％;单施P肥小麦增产29.3％～39.7％,玉米减产50.4％～63.0％;而N、P肥配施小麦、玉米分别增产3.43～5.79倍和3.04～4.23倍。施有机肥能显著提高作物产量和土壤养分含量,而N、P肥单施或配施仅能维持较低有机质水平,且土壤K耗竭严重。单施N肥N素易于下淋,而N、P肥配施有利于N在土壤上层的保持。有机肥配施N肥或N、P肥是较好的施肥结构。     

小麦根蘖发育和产量对耕作和追氮方式以及施氮量的响应

  【目的】  黄淮平原小麦生产中大量施用氮肥,探讨不同耕作和施肥方式对小麦根蘖发育的影响,以期实现减氮不减产并提高氮肥利用率的目标。  【方法】  2016—2018年连续两个种植年度,以半冬性中熟小麦品种矮抗58为材料,采用裂裂区设计试验方法,主区为施氮量 (240 、180 kg/hm2),副区为耕作方式 (旋耕、深耕),副副区为追肥方式 (撒施、隔行开沟追肥、隔二行开沟追肥),研究了小麦根系生长和生理活性、主茎和分蘖发育动态与成穗、籽粒产量和氮肥利用率。  【结果】  小麦不同生育时期单株次生根数、根系活力、单位面积茎蘖数、叶面积指数 (LAI) 均随施氮量降低而降低。与旋耕相比,深耕条件下小麦生育中、后期单株次生根数和单位面积茎蘖数增多、根系活力提高、LAI增大。生育后期,隔行开沟追肥的单株次生根数、根系活力、单位面积茎蘖数和LAI最高,撒施次之,隔二行开沟追肥最低。减量施氮较常规施氮籽粒产量降低了2.41%,氮肥偏生产力、氮肥吸收效率和氮肥内在利用率分别增加了29.67%、25.69%和2.29%。与旋耕相比,深耕条件下籽粒产量增加了5.60%,氮肥偏生产力和氮肥吸收效率分别提高了4.48%和8.47%。不同追肥方式中,隔行开沟追肥的籽粒产量最高,氮肥偏生产力和氮肥吸收效率显著提高,较撒施分别提高了3.62%、3.98%和7.38%,较隔二行开沟追肥分别提高了5.93%、6.34%和12.93%。  【结论】  深耕可提高生育中、后期小麦单株次生根数、根系活力和单位面积茎蘖数。常规施氮 (纯氮240 kg/hm2) 结合深耕 (深度25～30 cm)、隔行开沟追肥,可获得最高小麦产量;减施25%氮肥 (180 kg/hm2) 会导致籽粒产量降低,但结合深耕并采用隔行开沟施肥方式,可显著提高氮肥利用率,部分降低减氮所造成的产量损失,是获得高产高效的最佳组合。     

外源氮在中、低肥力红壤中的转化与去向研究

采用盆栽15N示踪技术,研究了外源化肥氮和有机氮在中、低肥力红壤中的转化过程及其在土壤团聚体中的分配特征。结果表明:无论是低肥力还是中等肥力红壤上,化肥与有机肥配施都能显著增加土壤硝态氮、微生物生物量碳、氮及酶活性,且显著提高氮肥在土壤中的残留率,减少氮肥损失。相同施氮条件下,小麦生育期内中等肥力红壤上微生物生物量碳、氮及硝态氮含量分别相当于低肥力土壤的1.8、1.3和2.0倍。中等肥力红壤上尿素的施入对小麦生育期土壤硝态氮无影响,而低肥力红壤上施用尿素使土壤硝态氮含量提高了5.7倍。施肥可以显著提高低肥力红壤上小麦的地上部吸氮量,相当于不施肥的2.1~3.3倍,但对于中等肥力红壤,不同施氮条件对小麦的地上部吸氮量无明显影响。施入有机肥可以显著增加土壤各粒级团聚体中外源氮的残留量,是单施化肥的2.1~5.0倍。与单施化肥氮相比,有机氮或与有机肥配施的化肥氮优先进入到大团聚体中,而外源氮在微团聚体和粉粘粒中的残留与分配并无明显差异。本研究说明有机肥或化肥与有机肥配施能有效降低氮肥的损失,提高氮肥在土壤中的保存,特别是对于中等肥力的土壤,有机肥的配合施用对于后季作物的生长具有重要意义。     

水生植物堆肥替代部分氮肥提高水稻产量与稻田土壤肥力

为评价太湖流域水生植物堆肥对水稻产量及稻田土壤肥力效应,在太湖流域典型稻田连续进行4a的田间定位试验,比较在等氮条件下不同比例的水生植物有机堆肥替代处理(有机氮替代率分别为0、20％、40％、60％、80％和100％)引起的水稻籽粒产量、产量构成因子、氮磷钾吸收量以及土壤碳氮含量和pH值变化.结果表明:与单施尿素相比,水生植物有机堆肥与尿素配施利于水稻产量的提高,并随着有机肥替代率增加,水稻产量呈先增后降;当有机肥替代率达40％和60％时产量最高.单施有机肥和单施尿素处理水稻籽粒产量相当.单施有机肥显著降低了有效穗数,有机肥和尿素配合施用则可减轻甚至消除这一效应;有机肥替代率在40％和60％时,有效穗数、穗粒数和结实率均较高.随着有机肥施用量增加,水稻秸秆氮浓度降低,籽粒氮浓度无影响;水稻磷浓度和吸收量均无显著差异;有机肥与尿素配施均显著提高了秸秆钾吸收量,有机肥替代率在80％时可显著提高籽粒钾吸收量.表层土壤全氮和有机碳含量及土壤pH值均与有机肥替代率呈显著正相关关系.有机肥-尿素配施处理下土壤全氮和有机碳均较4a前显著提高.有机肥替代率为80％和100％,土壤pH值较试验前土壤分别显著升高.由此可见,水生植物有机肥与尿素配施可以提高太湖稻作区水稻产量,增加土壤有机质含量和减缓土壤酸化程度,可作为太湖稻作区一项环保型施肥技术.     

长期施有机肥对耕地棕壤团聚体及钙素分布的影响

为了探明施有机肥对耕地棕壤团聚体及钙素分布的影响,以长期定位施肥近30年的耕地棕壤为研究对象,采用干筛法进行土壤团聚体分级,系统研究了单施有机肥及有机肥配施氮磷肥对耕地棕壤团聚体及不同形态钙素分布的影响。结果表明:与不施肥对照相比,施有机肥可增加1~2mm粒级团聚体含量,且随有机肥施入量的增加而增加,最高增加了66.68%;与单施有机肥相比,配施氮磷肥则降低了1~2mm粒级团聚体含量;与对照相比,单施及配施有机肥均降低了0.25~1 mm粒级团聚体含量,降幅最高达15.20%。单施及配施有机肥均提高了全土的全钙含量,其中单施高于配施,最高为施高量有机肥处理,增幅达11.67%;单施有机肥处理以1~2 mm粒级团聚体的全钙含量最高,配施氮磷肥后以0.053~0.25mm的最高;与对照相比,单施及配施有机肥均增加了各粒级团聚体水溶性钙含量;单施有机肥提高了土壤交换性钙含量,配施氮磷肥却相反;单施及配施有机肥处理均增加了全土酸溶性钙含量。相关性分析显示,耕地棕壤各级团聚体的全钙含量是影响各形态钙素分布的重要因素。因此,长期施有机肥不仅增加了耕地棕壤较大粒级团聚体含量,且可增加较大粒级团聚体的钙素含量。     

The contribution of soil organic matter fractions to carbon and nitrogen mineralization and microbial community size and structure

The aims of this study were to: (i) assess the impact of hay and fertilizer application on organic matter (OM) fractions (dissolved organic matter (DOM), light fraction organic matter (LFOM, <1.0 g cm⁻³), heavy fraction OM (HFOM, <1.7 g cm⁻³)), carbon (C) and nitrogen (N) cycling processes and microbial community size and structure, and (ii) quantify the role of OM fractions to C and N cycling. Soil was collected in 2001 from a field experiment to which grass hay (1996) and/or fertilizer (1995 and 1999) had previously been applied. DOM-C (P<0.05) and DOM-N (P=0.07) were significantly higher in control and fertilized soil than hay and hay+fertilized soil. LFOM and HFOM C and N contents and C/N ratios were significantly (P<0.05) higher in hay+fertilized and hay amended soil than in control and fertilized soil. Potentially mineralizable-N (PMN), microbial biomass-C (MB-C), microbial biomass-N (MB-N) and microbial respiration (CO₂) were not affected by fertilizer and/or hay application. Gross N mineralization (Gross Min) and gross nitrification (Gross Nit) rates were significantly (P<0.05) higher in fertilized, hay, hay+fertilized soil than control soil. However, there was no significant difference between treatments in gross N immobilization rates. Results reported here highlight the importance of a labile fraction of the DOM pool to N and C cycling as its removal significantly (P<0.05) reduced PMN, MB-N, Gross Min and Gross Nit compared with whole soil in most or all treatments. In soil where DOM+LFOM were removed PMN was significantly (P<0.05) lower, but MB-C, Gross Min and Gross Nit was significantly (P<0.05) higher than in DOM removed soil. This suggests that LFOM plays an important role as a sink for mineral-N. Total soil phospholipid fatty acid (PLFA) concentration was significantly (P<0.05) higher in hay amended than control, fertilized and hay+fertilized soil. Principal components analysis was able to clearly discriminate between control, fertilized, hay+fertilized and hay amended soil. Soil amended with hay or fertilizer had a microbial community structure which differed from that of the control or hay+fertilized soils. Redundancy analysis with Monte Carlo permutation tests revealed that PLFA profiles were strongly correlated to differences in Gross Min, Gross Nit, MB-N, MB-C, MB-C/N ratio, total soil C and total soil C/N ratio. The results of this research suggest that changes in microbial structure are related to aspects of soil C and N pools and cycling.     

有机肥和化肥长期施用对土壤活性有机氮组分及酶活性的影响

本文以中国农业科学院山东禹城长期定位施肥试验为平台,研究了长期施用有机肥和化肥26年后对土壤活性氮库不同组分［颗粒有机氮（POM-N）、 可溶性有机氮（DON）、 微生物量氮（SMBN）及轻组有机氮（LFOM-N）］及土壤酶活性的影响。结果表明,与不施肥相比,长期施肥显著提高了土壤全氮、 颗粒有机氮、 可溶性有机氮、 微生物量氮以及轻组有机氮的含量,长期施有机肥效果好于化肥,施用高量有机肥效果好于施用常量有机肥。常量施用量下,50%有机肥和50%化肥配施处理其土壤全氮和活性有机氮库各组分含量与高量化肥处理的相当。长期施化肥处理土壤全氮及活性有机氮库各组分含量随施肥量的增加而显著增高。POM-N对土壤全氮的贡献率最高,且明显受施肥方式的影响,LFOM-N对土壤全氮的贡献率不随施肥方式的改变而变化。长期施肥处理土壤脲酶、 碱性磷酸酶和蔗糖酶活性显著增加,它们之间及与土壤全氮、 速效磷及有机碳含量间呈现显著或极显著相关性,脲酶活性与土壤各活性氮组分间也存在显著或极显著相关性; 但长期施肥后土壤过氧化氢酶的活性低于不施肥     

有机无机肥配施对菜地土壤氮素径流流失的影响

利用田间小区试验,研究了无机肥配施不同用量有机肥对菜地土壤氮素径流流失的影响.结果表明,施肥显著增加菜地土壤氮素径流流失量.单施无机肥处理总氮、硝态氮和铵态氮流失量均最高,分别为4.20,1.22,2.30kg/hm2.配施有机肥可降低不同形态氮流失量,且随有机肥配施量增加而显著降低.配施高量有机肥处理总氮、硝态氮和铵...     

长期不同施肥潮土活性有机氮库组分与酶活性对外源牛粪的响应

【目的】研究不同施肥制度下潮土中活性有机氮库及酶活性对新添加有机物料的响应机制,可深入理解不同施肥制度培肥土壤、提高土壤基础地力的机理。【方法】供试土壤采集于从1986年开始的长期定位试验处理,包括CK (不施肥)、OF (常量有机肥)、CF (常量化肥)、OCF (常量有机无机配施) 4个处理。通过室内恒温培养试验,研究添加等氮量牛粪后长期不同施肥潮土有机氮库组分(微生物量氮、可溶性有机氮和颗粒有机氮)含量及土壤酶(α-葡萄糖苷酶、β-葡萄糖苷酶、β-木糖苷酶、纤维二糖水解酶、磷酸酶、过氧化物酶和酚氧化酶)活性的变化特征。【结果】首先,无论添加牛粪与否,土壤全氮、可溶性有机氮和颗粒有机氮含量均随培养时间呈上升趋势或与初始时期差异不显著;添加牛粪的长期不施肥与施化肥处理土壤微生物量氮含量显著低于相同处理不添加牛粪的土壤微生物量氮含量。其次,培养结束后,添加牛粪增加了长期不同施肥潮土全氮、可溶性有机氮和颗粒有机氮含量,分别提高了5.43%~15.49%、5.83%~69.42%及9.75%~42.29%,却降低了土壤微生物量氮含量16.91%~62.10%。另外,施肥、添加牛粪及其交互作用对土壤酶活性具有显著影响(P <0.05);无论添加牛粪与否,不同施肥处理土壤氧化酶(过氧化物酶和酚氧化酶)活性显著低于不施肥处理,不同施肥处理的土壤水解酶活性却呈现不同的变化趋势。不添加牛粪情况下,长期施肥显著提高了除β-葡萄糖苷酶以外的土壤水解酶活性;其中与长期不施肥处理相比,长期施用化肥土壤β-木糖苷酶和β-纤维素酶分别提高了208.74%和180.75%。添加牛粪情况下长期施用有机肥土壤β-葡萄糖苷酶和β-纤维素酶比不施肥分别提高了201.40%和308.04%;冗余分析(redundancy analysis,RDA)显示,添加与不添加牛粪条件下土壤酶活性的关键环境驱动因子不同,在不添加牛粪时为可溶性有机氮,添加后其关键驱动因子为全氮和可溶性有机氮。【结论】不同施肥制度下土壤微生物量氮、可溶性有机氮、颗粒有机氮与土壤全氮之间呈显著正相关;室内好气培养条件下,添加牛粪显著提高了长期不同施肥潮土的全氮、可溶性有机氮、颗粒有机氮含量,却显著降低了土壤微生物量氮含量;不同施肥制度下土壤酶活性差异显著,牛粪的添加改变了影响长期不同施肥潮土酶活性的关键环境因子。     

石灰组配土壤改良剂抑制污染农田水稻镉吸收

为达有效地调控污染稻田水稻糙米对Cd吸收,该研究选取湖南省长株潭地区的湘潭、醴陵和株洲3处不同Cd污染程度田块,研究石灰配施海泡石、钙镁磷肥、有机肥对水稻Cd吸收和累积的影响。结果表明,施用石灰及其组配改良剂均可明显提高土壤pH值,有效降低土壤中酸提取态Cd含量和水稻中Cd含量。与不施用改良剂相比,石灰配施海泡石或有机肥、配施海泡石和有机肥,Cd污染稻田土壤pH值平均升高1.08,0.96和0.93个单位,酸提取态Cd质量分数分别平均降低20.6%,15.6%和21.2%。石灰配施海泡石、有机肥或钙镁磷肥处理下在轻度Cd污染田块中糙米Cd含量较对照分别显著降低了48.3%,46.7%和34.2%,石灰配施有机肥、钙镁磷肥或钙镁磷肥和有机肥处理下在中度Cd污染田块中糙米Cd含量较对照分别显著降低了52.8%,47.8%和37.5%,石灰配施钙镁磷肥和有机肥、有机肥或海泡石处理下在重度Cd污染田块中糙米Cd含量较对照分别显著降低了51.2%,44.6%和42.5%,均低于食品安全国家标准中糙米限量值0.2 mg/kg(GB2762-2017)。相关分析表明,土壤中酸提取态Cd含量与水稻根、茎叶和糙米中Cd含量呈显著正相关关系(P0.05),说明土壤酸提取态Cd含量是影响糙米对Cd吸收的关键因素之一。上述结果说明,石灰配施海泡石、有机肥或钙镁磷肥+有机肥可有效调控污染稻田土壤中Cd进入水稻,实现水稻安全生产。     

长期施用有机肥对水稻产量和氮磷养分利用效率的影响

以长三角地区典型土壤类型青紫泥为背景土壤,研究连续7年有机肥不同施用量和化肥减量条件下水稻产量、氮磷吸收累积特性和氮磷利用效率,并对影响水稻氮磷吸收利用效率的原因进行分析。结果表明,与纯化肥处理相比,施用有机肥处理在不同程度上增加了水稻产量,其中以处理C4(30 t·hm~(-2)有机肥+1/2常量化肥)增加比例最大,为5.67%。当有机肥单施用量达60 t·hm~(-2)时,水稻产量比纯化肥处理增加5.56%,地上部氮磷累积均高于其它各处理,其中,氮累积尤为明显,增加比例为16.5%~25.4%。有机肥不同用量配合化肥减量施用时水稻地上部氮磷转运量、生理利用效率与纯化肥处理间无明显差异。然而,当单施有机肥用量达60 t·hm~(-2)时,氮转运量明显增加,生理利用效率明显降低,磷生理利用效率亦有所降低,但不如氮明显。水稻氮磷生理利用效率降低的主要原因是长期大量施用有机肥使土壤养分含量增加特别明显,可能超过利于水稻利用的浓度范围。另外,土壤矿质元素铵态氮在水稻生长过程中含量过高也与之紧密相关。     

Mycorrhizal colonization and nutrition of wheat and sweet corn grown in manure‐treated and untreated topsoil and subsoil

Dry bean yields (Phaseolus vulgaris L.) were raised to similar levels as the topsoil by manure application to eroded or leveled Portneuf silt loam soil (coarse‐silty mixed mesic Durixerollic Calciorthid). Only soil organic matter and zinc (Zn) content of leaf tissue were correlated with improved yields. Manure application increased mycorrhizal colonization and Zn uptake in pot experiments with dry bean which would explain the increased yields in the field. A field study was conducted to see if similar effects of manure and mycorrhizal colonization could be observed in field grown spring wheat (Triticum aestivum L.) and sweet corn (Zea mays L.). This study was conducted on existing experiments established in the spring of 1991 at the USDA‐ARS farm in Kimberly, Idaho, to study crop rotation/organic matter amendment treatments on exposed subsoils and focused on mycorrhizal colonization as related to topsoils and subsoils treated with conventional fertilizer (untreated) or dairy manure. Mycorrhizal root colonization was higher with untreated than with manure‐treated wheat and sweet corn. Root colonization was also higher in subsoil than in topsoil for wheat, but there were no differences between soils for sweet corn. Shoot Zn and manganese (Mn) concentrations generally increased with increased root colonization for both species (except between soils with corn Mn contents). Wheat shoot potassium (K) concentration was increased by manure application, but the affect declined with time, was the opposite of colonization and was not observed with sweet com. Phosphorus (P), calcium (Ca), magnesium (Mg), iron (Fe), and copper (Cu) concentrations either were not influenced or were erratically affected by mycorrhizal colonization. Yields of wheat were highest for manure‐treated subsoil and topsoil compared to untreated soils. Mycorrhizal colonization was different between conventional and manure‐treated soils and between topsoil and subsoil and these differences increased Zn and Mn uptake, but they did not explain the improvement in wheat yields obtained with manure application.     

长期施肥下潮土全氮、碱解氮含量与氮素投入水平关系

通过长期肥料定位试验,对不同施肥处理下潮土全氮和碱解氮含量演变特征及其与氮素投入水平的关系进行研究。结果表明,不施氮肥处理,土壤全氮和碱解氮含量基本保持平衡或者缓慢增加;长期施用化学氮肥处理,土壤全氮和碱解氮含量均有所增加;施用有机肥和秸秆还田处理,土壤全氮和碱解氮含量均显著提高。单施化学氮肥处理每投入氮素1 kg/hm2,土壤全氮含量增加0.017 mg/kg;而氮磷钾化肥配施有机肥和氮磷钾化肥并秸秆还田处理每投入氮素1 kg/hm2,土壤全氮含量分别增加0.049和0.035 mg/kg。施氮磷钾处理每投入氮素1 kg/hm2,土壤碱解氮含量增加0.001 mg/kg;而化肥配施有机肥或玉米秸秆处理每投入氮素1 kg/hm2,土壤碱解氮含量均增加0.004和0.004 mg/kg。总的来说,施用化学氮肥、有机肥配施化肥及秸秆还田处理增加氮素投入量均可以提高土壤全氮及碱解氮含量,且有机肥配施化肥及秸秆还田处理优于单施化肥。综上所述,增施有机肥及秸秆还田对于提升土壤肥力及实现农业可持续发展具有深远意义。     

长期定位施肥下黑土呼吸的变化特征及其影响因素

阐明长期不同施肥下的土壤呼吸特征及其影响机制对黑土区固碳减排研究至关重要。该研究基于1990年开始的国家土壤肥力与肥料效益监测网站-吉林省公主岭市黑土监测基地,选取不施肥(CK)、单施氮磷钾肥(NPK)、无机肥配施低量有机肥(NPKM1)、1.5倍的无机肥配施低量有机肥(1.5(NPKM1))、无机肥配施高量有机肥(NPKM2)和无机肥配施秸秆(NPKS)6个处理,明确了长期不同施肥下土壤总呼吸和异养呼吸的季节变化特征,并分析了土壤温度、水分、微生物量碳氮、铵态氮、硝态氮与土壤呼吸和异养呼吸的关系。结果表明:长期有机无机肥配施可以显著提高土壤有机碳、全氮、土壤速效磷、有效钾的含量和土壤活性有机碳库组分含量(P0.05);与不施肥相比,长期有机无机肥配施和无机配施秸秆处理分别显著增加土壤呼吸及异养呼吸碳累积排放量56.32%~86.54%和70.01%~100.93%;根系呼吸对土壤呼吸的整体贡献为23.68%~34.30%;相关分析表明,土壤呼吸速率和异养呼吸速率与土壤温度极显著正相关(P0.01),与土壤含水率呈显著负相关(P0.01),土壤温度可以分别解释土壤呼吸和异养呼吸变化的42.79%和39.61%;土壤微生物量碳氮、土壤硝态氮均与土壤呼吸速率和异养呼吸速率极显著相关(P0.01),土壤微生物量碳氮、土壤硝态氮可以分别解释土壤呼吸和异养呼吸变化的78.42%和77.18%,58.33%和56.79%,59.29%和59.14%;土壤铵态氮虽然显著影响土壤呼吸速率(P0.05),可以解释土壤呼吸变化的5.56%,但其对异养呼吸速率的影响不显著。综合来看,微生物量碳对土壤呼吸及异养呼吸的影响最大,而土壤含水率(15%)越高则土壤呼吸越弱;无机配施秸秆处理可以提高土壤碳库组分含量,且作物生育期内土壤呼吸及异养呼吸碳累积释放量均低于等氮量下施用有机肥(NPKM1)的处理,为最佳的农田管理措施。     

菌剂配施有机肥下植物-土壤-微生物生态化学计量特征及内稳性——以内蒙矿区排土场中药复垦模式为例

生态化学计量学是研究生态系统与多重化学元素平衡的有效方法,明确不同施肥制度对植物—土壤—微生物连续体碳、氮、磷含量及其生态化学计量比的影响,可为揭示生态系统养分循环、实现矿山复垦农业系统元素平衡及可持续发展提供参考依据。以武家塔露天煤矿排土场复垦地为研究对象,设置微生物菌剂配施不同有机肥(A1B0、A2B0、A3B0、A1B1、A2B1、A3B1) 6个施肥处理,结合苦参的种植,研究其植物—土壤—微生物碳氮磷特征及内稳性。结果表明：(1)与单施有机肥相比,有机肥配施微生物菌剂对茎叶磷、土壤碳氮磷和微生物量氮影响显著(p<0.05),但对根系养分影响不显著。其中,微生物菌剂与A1有机肥配施下对土壤全磷影响最大,增加90.06%;与A2有机肥配施下,对土壤有机碳和生物量氮影响最大,分别增加104.60%和71.95%;与A3有机肥配施下,对茎叶全磷和土壤全氮影响显著,茎叶全磷减少183.96%,土壤全氮增加29.14%。(2)施肥处理下,相比于茎叶和微生物,苦参根系内稳性较弱,对于外源养分的输入比较敏感。(3)施肥处理下,植物根系养分与土壤及土壤微生物之间相关性较强,因此可通过根系敏...     

秸秆还田与氮肥运筹对土壤水碳氮耦合及作物产量的影响

探究全覆膜双垄沟播栽培下玉米秸秆还田与氮肥运筹对土壤水、碳、氮及作物产量的影响,为内蒙古黄土高原秸秆还田氮肥合理施用和节氮、高效秸秆还田技术研发提供科学依据。对比分析了氮肥习惯施用(FN)、氮肥习惯施用配合秸秆还田(FNS)、氮肥高量施用配合秸秆还田(HNS)、氮肥后肥前移施用(RN)、氮肥后肥前移施用配合秸秆还田(RNS)5种不同耕作措施对玉米农田土壤水分、土壤碳氮、酶活性、微生物量及玉米籽粒产量的影响,并通过相关分析和通径分析进一步揭示土壤理化性质和生物学性质变化规律及其耦合效应,明确秸秆还田玉米田不同氮肥运筹方式下土壤水碳氮演变特征。结果表明,与不还田相比,秸秆还田可显著提高0～100 cm土层土壤水分含量,且玉米秸秆还田与全膜垄沟栽培结合后(FNS、HNS、RNS),二者的协同效应较单一地膜覆盖(FN、RN)增强了土壤纳雨增墒能力,为秸秆的正常腐解提供了适宜水热环境；秸秆还田下不同氮肥运筹处理较对照FN均可显著提高土壤有机质和全氮含量,其中以氮肥后肥前移施用配合秸秆还田和氮肥高量施用配合秸秆还田提升效果最显著,土壤过氧化氢酶、脲酶、蔗糖酶和碱性磷酸酶活性以及微生物量碳、氮明显增加,表现为0～20 cm土层大于20～40 cm土层,秸秆不还田氮肥习惯施用和氮肥后肥前移施用无显著性差异；土壤微生物量碳、氮与土壤酶活性和土壤碳氮呈显著或极显著正相关关系,且土壤微生物量碳、氮对土壤有机质、蔗糖酶、全氮和过氧化氢酶变化较敏感,对土壤性质变化具有一定指示作用。在产量方面,还田处理FNS、HNS、RNS较对照FN分别提高5.30%、10.93%、11.41%,且氮肥的常量投入即可获得较高的氮肥偏生产力。综合土壤因子、玉米产量和氮素利用率来看,秸秆还田条件下可通过调整氮肥的后肥前移平衡土壤碳氮收支,实现节本增产增效,同时提高氮肥利用率,是内蒙古黄土高原地区一种节氮、稳产、增效秸秆还田技术模式。