添加碳源、磷和石灰对红壤氮素矿化和硝化作用的影响

用培养试验研究了添加碳源、磷和石灰石粉对第四纪红色粘土及红砂岩母质上发育的不同侵蚀程度的红壤以及经培肥后红壤的矿化和硝化作用的影响。结果表明 :上述 3个因子对矿化作用的影响较大 ,添加碳源表现出土壤矿质氮的净生物固持 ;在低磷红壤上增施磷能有效地促进红壤氮素的矿化 ;添加石灰石粉也能有效地促进 pH较低的红壤氮素的矿化。培肥后的红壤矿化和硝化作用明显增强 ,添加磷和石灰石粉进一步促进了培肥红壤矿化率和硝化率的提高。但施用石灰石粉和磷并未提高未经培肥的侵蚀红壤的硝化作用     

施入~(15)N标记氮肥在长期不同培肥土壤的残留及其利用

采用盆栽试验和短期矿化培养相结合的方法,研究了施入15N标记氮肥(+N)及其与秸秆配施(+1/2N+1/2S)在3种长期(19年)不同培肥土壤(即:No-F,长期不施肥土壤;NPK,长期施用NPK化肥土壤;MNPK,长期有机无机肥配施土壤)中的残留及其矿化和作物吸收特性。结果表明,第一季小麦收获后,+1/2N+1/2S处理下三供试土壤和+N处理下的NPK和MNPK土壤残留肥料氮(残留15N)中有82.6%~95.1%以有机态存,而+N处理下No-F土壤残留15N有47.7%以矿质态存在。经过28 d矿化培养后,与NPK土壤相比,MNPK土壤氮素净矿化量显著增加,增幅为39%~49%;NPK和MNPK土壤残留肥料氮(残留15N)矿化量为1.23~1.90 mg kg-1,占总残留15N的2.78%~5.53%,均显著高于No-F土壤。与+N处理相比,+1/2N+1/2S处理显著提高了3供试土壤氮素净矿化量,但两施肥处理对NPK和MNPK土壤残留15N矿化量无显著影响。+N处理下No-F土壤残留15N的利用率为20%,显著高于NPK(9%)和MNPK(12%)土壤。两种施肥处理下,MNPK土壤残留15N的利用率均显著高于NPK土壤。短期培养期间土壤氮素矿化量和第二季小麦生育期作物吸氮量呈显著性正相关,而残留15N矿化量和第二季小麦吸收残留15N量间无显著性相关关系。长期有机无机配施可以提高土壤残留肥料氮的矿化量及有效性。     

种植水稻和长期施用无机肥对红壤氨氧化细菌多样性和硝化作用的影响

以中国科学院红壤生态试验站发育于第四纪红黏土的植稻红壤为研究对象,研究了长期种植水稻和施用无机肥对土壤β-变形杆菌纲中氨氧化细菌多样性和硝化作用的影响。原始红壤改种水稻13年后,氨氧化细菌16SrDNA的DGGE条带数量增加,条带谱与原始红壤的差异较大,相似性为61%,说明种植水稻后土壤氨氧化细菌群落结构发生了变化。PCR-DGGE方法研究结果也显示,长期施用无机氮肥的处理(NP、NPK和NK),DGGE带谱相似性较高,达到73%,硝化率和硝化势均高于未施用氮肥的处理。逐步回归分析显示硝化率和硝化势均随着土壤脲酶活性的提高而显著增加。推测尿素可提高土壤水解氮含量,使土壤脲酶活性提高,促进硝化细菌的生长,进而提高硝化率和硝化势。     

不同水分和氮肥水平对冬小麦吸收肥料氮的影响

田间微区条件下用15N研究了不同水分和氮肥水平对冬小麦氮素吸收及化肥氮的去向。结果表明 ,4次灌水省肥处理的全氮吸收量高于节水省肥处理 ,节水常规施肥量处理的全氮吸收量高于省肥处理 ,但小麦籽粒氮素收获指数降低。 4次灌水处理的肥料氮损失率提高 ,氮肥当季利用率和土壤残留率均低于 2次灌水的相应氮肥处理。同一水分条件下 ,常规施肥量处理的氮肥当季利用率和土壤残留率低于省肥处理 ,损失率提高。等量氮肥不同施肥方法间的比较 ,全部基施处理的损失率下降 ,肥料氮回收率高于分次施肥处理     

有机肥无机肥配施对稻田氨挥发和水稻产量的影响

在南方红壤区双季稻田进行田间试验,研究等氮、磷、钾量条件下,有机无机肥配施对稻田氨挥发及水稻产量的影响。结果表明,有机无机肥配合施用能显著地降低稻田氨挥发,减少氮素损失,提高氮肥利用率。单施化肥(尿素),其氨挥发损失达37.8%,而单施有机肥和有机无机肥各半配合施用,氨挥发损失分别为0.7％-1.0％和7.2％-18.2％。田间氨挥发持续的时间,早稻约在施肥后20d,晚稻为9-10d。虽然有机无机肥各半配合施用的水稻产量与单施化肥的相近,均比对照提高约70％,但前者的氮损失少,其氮肥利用率为34.9％,高于化肥处理(33.2％)和有机肥处理(28.0%)。有机无机肥配合施用对提高水稻产量和降低氮肥环境负效应的综合效应最佳。     

冬小麦节水灌溉制度下不同施氮量的氮素平衡

用15N示踪技术研究了节水灌溉条件下冬小麦对不同施氮量的氮素吸收和氮素平衡 ,并比较了两种灌溉制度下小麦对节肥施氮量的吸收动态。结果表明 ,与常规施氮量处理相比 ,节水灌溉条件下节肥施氮量处理的氮肥损失率降低 ,氮肥当季利用率和土壤残留率提高 ;基施氮肥的利用率高于追施氮肥 ;土壤肥料氮的残留率在 2 9%～ 41 %之间 ,分布于 1m土层中 ,其中60 %以上集中在 0～ 2 0cm土层 ;在整个小麦生长季内 ,肥料氮并没有淋洗到 1 30m以下。节肥施氮量在常规灌溉下的当季利用率比在节水灌溉下降低 1 6 6%。     

化肥有机肥配合施用下双季稻田氮素形态变化

为揭示有机无机肥配合施用下稻田氮素的动态及迁移特征,在湘南双季水稻农作区第四纪红土发育的红黄泥稻田上进行了连续6年田间试验。通过比较不施氮肥（PK）、施用有机肥猪粪（M）、化肥（NPK）及有机肥化肥配合（NPKM）,研究稻田表层全氮、无机氮动态变化,不同层次（25—30、55—60、85—90 cm）土壤溶液无机氮动态,耕层土壤无机氮动态等。结果表明,NH4+-N是红壤双季稻田无机氮素存在的主要形态,施用化学肥料处理（NPK）施肥后1～3 d表面水NH4+-N浓度占全氮比例可达0.5～0.9,有机肥处理（M）为0.3左右。不同层次土壤溶液及其土壤氮素浓度呈现一致的特征,即施肥后短期内出现浓度峰值随后迅速下降,且随着往下推移,氮素峰值出现时间延长,表层水全氮及无机氮在施肥后1～2 d出现浓度高峰,耕层土壤及25—30 cm土壤溶液无机氮浓度高峰约在施肥后3～5 d。化肥有机肥配施有利于水稻稳产高产,年产量达12.2 t/hm2,比不施氮肥的对照产量（7.3 t/hm2）增加68%;土壤有机质6年提升18.5%,显著高于化肥。施用有机肥（M）及有机无机肥配合（NPKM）显著降低了稻田表层水全氮及不同层次土壤溶液和耕层土壤NH4+-N峰值浓度,提高水稻产量和培肥土壤,有利于减少当前氮肥过量施用带来的环境负荷。     

长期有机养分循环利用对红壤稻田土壤供氮能力的影响

通过15年的田间定位试验结合盆栽试验,研究了长期有机养分循环利用和不同化肥配施对红壤稻田土壤供氮能力的影响。结果表明,土壤有机碳、全氮、微生物生物量氮(MB-N)和土壤氮的矿化量与生物吸氮量有极显著的正相关关系,是良好的土壤供氮能力指标。长期有机养分循环利用或配合化肥施用能显著提高土壤有机碳、全氮含量和氮的矿化量,提高幅度分别为20.1%4～0.9%、0.460～.60.g/kg和55.0%(6周);明显提高土壤MB-N含量,提高幅度平均为70.3%。长期纯化肥处理对土壤碳、氮库的积累和氮的矿化量的提高作用甚微。盆栽试验表明,长期施用氮肥和氮、磷、钾肥土壤供氮量提高量极小,与长期不施肥相比提高幅度分别为2.1%和6.2%,而有机养分循环利用能显著提高土壤供氮量,提高幅度为33.7%8～9.0%。随着有机养分循环利用和NPK肥配合程度的提高,土壤供氮量提高幅度呈上升的趋势。     

长期施用有机物料对旱地红壤磷组分及磷素有效性的影响

针对中亚热带第四纪红黏土发育的红壤旱地,建立了玉米单作系统等碳量投入有机物料的田间试验,利用不同的磷分级方法研究了不同有机物料施用对土壤磷组分的影响,构建了不同磷组分的含量与土壤全磷及有效磷之间的回归方程,明确了不同磷组分对土壤磷活化系数(PAC)及磷肥(表观和经济)利用率的影响。连续7a的试验结果表明:施用有机物料可以增加土壤PAC和磷肥利用率,并以秸秆猪粪9︰1配施(NPKS/M)处理效果最佳,显著高于常规施肥处理(NPK);施用有机物料显著提升了土壤有机磷含量,且与土壤有效磷含量显著正相关,其对土壤PAC及磷肥(表观和经济)利用率影响显著。施用有机物料通过影响土壤有机碳、全氮、碱解氮、交换性K~+以及交换性Al~(3+)含量影响土壤磷的有效性。     

长期施氮和秸秆还田对小麦-玉米轮作体系土壤氮素平衡的影响

在陕西关中小麦-玉米轮作区,通过4年田间定位试验研究了长期施氮和秸秆还田对作物产量、氮肥利用率、0-100 cm土层无机氮残留及体系氮平衡的影响.结果显示,施氮能显著提高作物产量,小麦、玉米4年平均产量增幅分别为64.1％和48.8％,均随施氮量的增加先增加后减小.优化施肥小麦、玉米氮肥用量较农民习惯施肥分别减少了27.3％和55.6％,但连续4年作物产量没有显著降低.秸秆还田随种植年限的推移其增产效果逐渐明显.轮作体系作物累计氮肥利用率逐年升高,前8季作物达33.3％～56.6％,说明氮肥后效明显.施氮增加了0-100 cm土层无机氮残留,且N03--N残留明显高于NH4+-N,并与年施氮量表现出显著的正相关关系,秸秆还田对无机氮残留影响不明显.体系氮平衡表明,随施氮量增加,作物累计氮素吸收先显著增加后增幅不变,而残留Nmin和表观损失均显著增加.秸秆还田措施下,作物累计氮素吸收和氮肥利用率分别增加了13.0％和26.2％,氮素表观损失和损失率均降低了22.9％,但对残留Nmin和表观残留率的影响不显著.     

不同用量猪粪对红壤花生坡地水土流失和磷素流失的影响

通过田间径流微区定位试验,以中亚热带3种典型母质(花岗岩、红砂岩、红黏土)发育红壤花生坡地为研究对象,以当地常规化肥用量处理为对照,连续3年研究了在常规化肥用量减半条件下配施6个不同用量腐熟猪粪(猪粪含有0,0.5,1,2,4,8倍的对照处理磷用量)对红壤花生坡地水土流失和磷素流失的影响,以期为典型红壤地区合理施用猪粪提供科学依据。结果表明:化肥减半配施猪粪处理能有效降低红壤坡地的产流产沙,但随着猪粪用量的增加,径流水和泥沙磷含量均呈线性增加,环境风险增大。径流量和泥沙量均为花岗岩红壤红砂岩红壤红黏土红壤。配施3 500kg/(hm~2·a)猪粪,花岗岩红壤的径流量减少了28.0%、泥沙量减少了6.3%,红砂岩红壤的径流量减少了23.2%、泥沙量减少了37.1%;而配施7 000kg/(hm~2·a)猪粪,红黏土红壤的径流量减少了40.7%,泥沙量减少了12.8%。当花岗岩红壤、红砂岩红壤、红黏土红壤的猪粪用量分别达到14 000,28 000,28 000kg/(hm~2·a)时,径流水总磷平均含量超过地表水环境质量标准V类限值。径流水总磷含量为花岗岩红壤红黏土红壤红砂岩红壤,而泥沙总磷含量则为红黏土红壤花岗岩红壤红砂岩红壤。在减半化肥用量条件下花岗岩红壤和红砂岩红壤配施与常规化肥处理等磷量[P含量40kg/(hm~2·a)]的猪粪、红黏土红壤配施2倍常规化肥处理磷含量[P含量80kg/(hm~2·a)]的猪粪,可有效减少水土流失,且3年内不会增加磷素流失风险。     

有机无机肥料配合施用对滨海盐土土壤生物量态氮及土壤供氮特征的影响

采用盆栽试验研究海盐渍化土上蚕粪与无机氮肥（碳铵和尿素）的施用对土壤生物量态氮和土壤供氮特征的影响，指出（１）施肥均能明显地提高土壤生物量态碳和生物量态氮的含量，蚕粪与无机氮肥配合施用比化肥单施或蚕粪单施更能增加土壤生物量态氮含量。（２）土壤生物量态氮是土壤氮素转化的重要环节，也是土壤有效氮的重组成部分；（３）土壤生物量态氮的消长与壤的供氮特征关系极为密切，只要前期有强烈的微生物固持无机氮肥过程，     

肥料混施对赤红壤氮磷淋失特征的影响

采用室内模拟土柱淋洗方法研究了无机复合肥、有机复合肥、猪粪堆肥和花生麸4种肥料单施和两两混施条件下氮磷在赤红壤中的淋失特征。结果表明,各处理总氮淋失率在43.2%～74.8%之间,总磷淋失率在0.01%～0.08%之间,赤红壤中肥料氮淋失严重,肥料磷淋失有限。肥料单施处理的无机氮淋失量和有机氮基本相近,肥料混施处理的无机氮淋失量远高于有机氮;各施肥处理磷的淋失均以颗粒磷为主。肥料混施显著增加铵态氮和无机氮淋失,减少有机氮和总氮淋失。猪粪与复合肥混施减少颗粒磷和总磷淋失,花生麸与复合肥混施则促进颗粒磷和总磷淋失,所有混施处理均减少可溶性磷淋失。肥料混施对赤红壤氮磷淋失特征具有显著的混施效应。     

有机、无机肥料氮在水稻-土壤系统中的转化与分配

在农业生产中,氮肥是决定作物产量的一个重要因素.有关氮肥的施肥方法和增产效果,长期以来已有很多报道,但是,对于有机态氮肥,如绿肥以及有机、无机肥结合施用以后,肥料氮素和土壤氮素在作物—土壤系统中的转化和分配动态研究较少.有机肥和绿肥是我国农业生产中的主要肥源.解放以后,全国开始普遍施用化肥,当前有机、无机肥结合施用已是我国施肥方法中的主要特点.     

不同施肥管理对红壤性水稻土有机碳、氮形态的影响

A long-term experiment beginning in 1981 in Jinxian County of Jiangxi Province, subtropical China, was conducted in a paddy field under a double rice cropping system with four different fertilization regimes, including 1) no fertilizer as control (CK), 2) balanced chemical N, P, and K fertilizers (NPK), 3) organic manure using milk vetch and pig manure in the early and late rice growing season, respectively (OM), and 4) balanced chemical fertilizers combined with organic manure (NPKM). Samples (0-17 cm) of the paddy field soil, which was derived from Quaternary red clay, were collected after the late rice harvest in November 2003 for determination of total organic carbon (TOC) and total nitrogen (TN) and fractions of organic C and N. Results showed that TOC and TN in the NPKM and OM treatments were significantly higher than those in other two treatments (CK and NPK). Application of organic manure with or without chemical fertilizers significantly increased the contents of all fractions of organic C and N, whereas chemical fertilizer application only increased the contents of occluded particulate organic C (oPOC) and amino acid N. In addition, application of organic manure significantly enhanced the proportions of free particulate organic carbon (fPOC) and oPOC in total C, and those of amino sugar N and amino acid N (P < 0.01) in total N. In contrast, chemical fertilizer application only increased the proportions of oPOC and amino acid N (P < 0.05). There were no significant differences in either contents or proportions of soil organic C and organic N fractions between the NPKM and OM treatments. These indicated that organic manure application with or without chemical fertilizers played the most significant role in enhancing soil organic C and N quantity and quality in the paddy field studied.     

Biological and chemical properties of arable soils affected by long-term organic and inorganic fertilizer applications

 Using soils from field plots in four different arable crop experiments that have received combinations of manure, lime and inorganic N, P and K for up to 20 years, the effects of these fertilizers on soil chemical properties and estimates of soil microbial community size and activity were studied. The soil pH was increased or unaffected by the addition of organic manure plus inorganic fertilizers applied in conjunction with lime, but decreased in the absence of liming. The soil C and N contents were greater for all fertilized treatments compared to the control, yet in all cases the soil samples from fertilized plots had smaller C:N ratios than soil from the unfertilized plots. The soil concentrations of all the other inorganic nutrients measured were greater following fertilizer applications compared with the unfertilized plots, and this effect was most marked for P and K in soils from plots that had received the largest amounts of these nutrients as fertilizers. Both biomass C determined by chloroform fumigation and glucose-induced respiration tended to increase as a result of manure and inorganic fertilizer applications, although soils which received the largest additions of inorganic fertilizers in the absence of lime contained less biomass C than those to which lime had been added. Dehydrogenase activity was lower in soils that had received the largest amounts of fertilizers, and was further decreased in the absence of lime. This suggests that dehydrogenase activity was highly sensitive to the inhibitory effects associated with large fertilizer additions. Potential denitrification and anaerobic respiration determined in one soil were increased by fertilizer application but, as with both the microbial biomass and dehydrogenase activity, there were significant reductions in both N₂O and CO₂ production in soils which received the largest additions of inorganic fertilizers in the absence of lime. In contrast, the size of the denitrifying component of the soil microbial community, as indicated by denitrifying enzyme activity, was unaffected by the absence of lime at the largest rate of inorganic fertilizer applications. The results indicated differences in the composition or function of microbial communities in the soils in response to long-term organic and inorganic fertilization, especially when the soils were not limited. Received: 10 March 1998     

动物粪液中可溶性磷在土壤中的吸附和迁移特性研究

农田土壤施用动物粪肥引入了大量的可溶性有机物、有机磷和无机磷,了解这些可溶性物质在土壤中的相对移动性及它们之间的相互作用有助于指导农田养分管理。本研究从粪液中分离获得含水溶性无机磷、有机磷和有机物（碳）的溶液,选择了具不同质地和有机质含量的4个土壤（含高量有机质的黄筋泥、含低量有机质的黄筋泥、淡涂泥和清水沙）,应用等温吸附和土柱模拟淋洗方法研究了可溶性有机碳、无机磷和有机磷共存条件下,粪液中可溶性有机态磷和无机态磷在土壤中的吸附和迁移特性。吸附试验表明,可溶性有机物（碳）的存在大大降低了土壤对有机态磷和无机态磷的吸附,表明施用液态有机肥比施用化肥具有更大的磷流失风险。供试土壤对无机态磷的吸附强度高于有机态磷,但对二者的吸附量大小为:黄筋泥>淡涂泥>清水沙;并与粘粒含量、氧化铁含量呈正相关。有机质较高的土壤对有机磷的吸附明显低于有机质低的土壤。淋洗试验表明,在供试土壤中,这3种可溶性物质在土壤中吸持(包括生物吸持)的顺序为:可溶性无机磷>可溶性有机碳>可溶性有机磷;有机态磷比无机态磷更易在土壤中迁移。     

不同磷源对设施菜田土壤速效磷及其淋溶阈值的影响

土壤中磷的移动性不仅取决于磷的数量且与磷肥形态有关。了解不同磷源（有机肥和化肥）对设施菜田土壤磷素的影响对于指导科学施肥和面源污染防治至关重要。本文选取河北省饶阳县3种不同磷含量的农田土壤（未种植过蔬菜的土壤、种植蔬菜30年的塑料大棚土壤和种植蔬菜4年的日光温室土壤）为研究对象,采用室内培养试验和数学模型模拟方法研究有机无机磷源对设施菜田土壤磷素的影响,确定无机肥和有机肥源土壤磷素淋溶的环境阈值。结果表明添加有机肥和无机磷肥都会显著增加3种不同种植年限设施菜田土壤速效磷（Olsen-P）和氯化钙磷（CaCl₂-P）含量,但增加速度不同。对于未种植过蔬菜的低磷对照土壤,磷投入量高于50 mg·kg^-1（干土）后,无机肥比有机肥显著提高了土壤Olsen-P含量。对于已种植蔬菜30年的塑料大棚土壤,高磷投入时[300 mg·kg^-1（干土）和600 mg·kg^-1（干土）],无机肥比有机肥显著提高了土壤Olsen-P含量,低于此磷投入量时有机肥和无机肥处理之间没有显著差异。3种不同农田土壤CaCl₂-P的含量所有处理均表现出无机肥显著高于有机肥处理,尤其是在高磷量[>300 mg·kg^-1（干土）]投入时表现更加明显。两段式线性模拟结果表明,设施菜田土壤有机肥源磷素和无机肥源磷素淋溶阈值分别为87.8 mg·kg^-1和198.7 mg·kg^-1。随着土壤Olsen-P的增加,添加无机肥源磷对设施菜田土壤CaCl₂-P含量的增加速率是有机肥源磷的两倍。因此,建议在河北省高磷设施菜田应减少无机磷肥的投入,特别是土壤速效磷高于198.7 mg·kg^-1的设施菜田应禁止使用化学磷肥和有机肥,在土壤速效磷低于198.7 mg·kg^-1的设施菜田应加大有机肥适度替代无机肥技术的推广。     

Dynamics of 15N-labeled ammonium sulfate in various inorganic and organic soil fractions of wetland rice soils

Summary The dynamics of basally applied ¹⁵N-labeled ammonium sulfate in inorganic and organic soil fractions of five wetland rice soils of the Philippines was studied in a greenhouse experiment. Soil and plant samples were collected and analyzed for ¹⁵N at various growth stages. Exchangeable NH₄ ⁺ depletion continued after 40 days after transplanting (DAT) and corresponded with increased nitrogen uptake by rice plants. Part of the applied fertilizer was fixed by 2:1 clay minerals, especially in Maligaya silty clay loam, which contained beidellite as the dominant clay mineral. After the initial fixation, nonexchangeable ¹⁵N was released from 20 DAT in Maligaya silty clay loam, but fixation delayed fertilizer N uptake from the soil. Part of the applied N was immobilized into the organic fraction. In Guadalupe clay and Maligaya silty clay loam, immobilization increased with time while the three other soils showed significant release of fertilizer N from the organic fraction during crop growth. Most of the immobilized fertilizer N was recovered in the nondistillable acid soluble (alpha-amino acid + hydrolyzable unknown-N) fraction at crop maturity. Between 61% and 66% of applied N was recovered from the plant in four soils while 52% of fertilizer N was recovered from the plant in Maligaya silty loam. Only 20% – 30% of the total N uptake at maturity was derived from fertilizer N. Nmin (mineral N) content of the soil before transplanting significantly correlated with N uptake. Twenty-two to 34% of applied N was unaccounted for possibly due to denitrification and ammonia volatilization.