Spatial Distribution of Soil Organic Matter and Nutrients in the Pear Orchard Under Clean and Sod Cultivation Models

The soil organic matter and nutrients are fundamental for the sustainability of pear production, but little is known about the spatial distribution of soil organic matter and nutrients in a pear orchard. With the soil of the pear （cv. Dangshansu on P.betulifolia Bunge. rootstock） orchard under clean and sod cultivation models as test materials, the experiment was conducted to evaluate spatial variability of soil organic matter （SOM）, total nitrogen （STN）, total phosphorus （STP）, total potassium （STK）, available nitrogen （SAN）, and available potassium （SAK） in and between rows at different soil depths （0-60 cm）. The SOM, STN, STP, STK, SAN and SAK of the different soil layers under the two tillage models were different in the vertical direction. The SOM, STN, STP and SAN in the 0-20 cm soil layer were higher than those in the 20-40 and 40- 60 cm soil layers. The STK of 40-60 cm soil layer was higher than that in the 0-20 and 20-40 cm soil layers. The STK increased with the depth of soil in the vertical direction in the clean cultivated pear orchard. Variability of the SOM, STN, STP, STK, SAN and SAK of sample sites in between rows of the same soil layer was found in the pear orchard soil in the horizontal direction under clean and sod cultivation management systems, except that STK of all sites did not show the difference in identical soil layers in the pear orchard under clean cultivation. The sod cultivation model improved the SOM, STN, and STK in the 0-20 cm soil layer in the pear orchard, and the three components increased by 12.8, 12.7 and 7.3% compared to clean cultivation, respectively. The results can be applicable to plan collection of orchard soil samples, assess orchard soil quality, and improve orchard soil management practices.

Effects of clipping on dry matter production and nutrients in the fernland of Hong Kong

The dry matter production and its nutrient amounts varied significantly with time and period from April to June was a favourable season for plant growth. Dry matter production declined significantly with clipping. Especially, repeated cutting of high frequencies for the long term had a severe effect on dry matter production. However, N, P, and K amounts in dry matter production did not significantly decline because the concentrations of N, P, and K in the plants increased with clipping. Repeated cutting for long term is a reason why net primary production has been depressed in the most of upland areas of southern China.

茭虾共作对土壤氮磷含量和茭白干物质积累及氮磷钾吸收分配的影响

为探究茭白种养模式的施肥策略,设置茭虾共作(ZC)、茭白单作(Z)2个处理,研究茭虾共作对土壤氮磷含量、茭白产量和茭白干物质积累及氮磷钾吸收分配的影响。2021-2022年的研究结果显示,茭虾共作模式较茭白单作模式采茭期土壤中全氮、全磷、速效磷的含量分别提高了10.85%~38.89%、5.45%~13.79%、6.19%~61.79%,净茭产量提高了5.10%~19.54%,采茭期茭白茎、叶、净茭的干物质积累量分别增加14.41%~16.58%、10.28%~15.15%、10.57%~21.45%。2021年茭虾共作处理较茭白单作处理在采茭期叶的氮含量显著增加了25.74%,但在孕茭期茎中磷含量显著减少了16.76%;2022年氮肥减量、减量投喂下,茭虾共作处理较茭白单作处理在孕茭期茎的氮含量显著减少了23.75%,在分蘖期叶中磷含量显著减少了12.08%,2a全生育期同一器官的钾含量在2个处理间差异不显著。对于养分积累,2021年茭虾共作处理在分蘖期叶的氮、磷、钾积累量较茭白单作处理分别减少26.04%、27.27%、30.11%,但在采茭期茎的氮、钾积累量和叶的氮、磷积累量较茭白单作处理分别增加18.80%、38.41%和44.77%、35.71%;2022年在氮肥减量、饲料减量投喂下,茭虾共作处理在采茭期叶的磷积累量和茎的钾积累量较茭白单作处理显著增加30.0%和30.77%。关于养分分配,2种处理的茭白在孕茭期和采茭期氮素的分配均以茎、叶为主,而磷、钾元素的分配均以茎为主,茎分配比例在42%~66%。对于养分转运,2021年2种处理茭白的根、茎、叶在氮、磷转运上大多为表现为“库”器官,而在钾转运上大多表现为“源”器官;2022年氮肥减量、减量投喂下,茭白的根、茎、叶在氮、磷、钾转运量上大多表现为“源”器官。因此,在茭虾共作模式中适当减少肥料、饲料的投入,能促进形成合理的源库关系,有利于茭白产量的形成。

硝酸钾配施有机肥对早熟禾生长及养分吸收的影响

早熟禾草坪在盐碱土壤上建植3~4年后会发生明显的退化,研究园林养护中采用硝酸钾配施有机肥的方式为其提供营养,对促进植株生长和提高坪用质量具有重要意义。试验设置在城市绿化带中,设置空白对照(K1)、硝酸钾化肥对照(K2)、化肥+发酵饼肥(K3)、化肥+腐殖酸复混肥(K4)4个处理,每个处理3次重复,研究了早熟禾生长和养分吸收变化。结果表明:K3与K1相比,在7~10月有利于提高早熟禾干物质积累量、含水量、叶绿素a、叶绿素b和类胡萝卜素含量,显著提高了植株氮、磷、钾吸收量;K3与K2相比,在8~9月显著提高了干物质积累量,7月和10月显著提高了叶绿素b和类胡萝卜素含量,8~10月提高了氮磷钾养分吸收量;K3与K4相比,在7~9月提高了干物质积累量,7~10月显著提高了叶绿素b和类胡萝卜素含量,促进了氮磷钾营养元素的吸收。综合分析认为,硝酸钾配施发酵饼肥为适宜施肥处理。

有机无机复混肥料对水稻产量及养分吸收利用的影响

为了提高水稻肥料利用率,减少化肥施用量,研究有机无机复混肥的施用效果,设置不施肥(CK)、常规施肥(普通复合肥,氮肥分次施用)(FFP)、等养分有机无机复混肥(一次性施肥)(T1)、等养分有机无机复混肥(氮肥分次施用)(T2)、90%养分有机无机复混肥(氮肥分次施用)(T3)、80%养分有机无机复混肥(氮肥分次施用)(T4)共6个处理,研究有机、无机肥配施对水稻产量及氮磷吸收利用的影响。各处理花后干物质积累量对籽粒贡献率(62.7%~68.5%)均高于干物质转运量对籽粒贡献率(31.5%~37.3%);各处理的实际产量表现为T2>T1>FFP>T3>T4>CK,与FFP处理相比,T2和T1处理增产6.6%和2.2%,T3和FFP处理产量无显著差异;成熟期各处理水稻植株地上部氮素和磷素吸收积累量在籽粒部分占比达到65%和70%以上,与FFP处理相比,T1处理氮磷肥吸收利用率、氮磷肥农学利用率和氮磷肥偏生产力分别增加了8.9%和12.9%、0.9%和3.2%、0.9和3.2 kg·kg^(-1),T2处理氮磷肥吸收利用率、氮磷肥农学利用率和氮磷肥偏生产力分别增加了1.6%和1.6%、2.6%和9.6%、2.6和9.6 kg·kg^(-1),T3和T4处理与FFP处理差异不显著。有机、无机肥配施能提高氮磷养分吸收利用率,在氮磷钾总养分相同的情况下,一次性施用有机无机复混肥更有利于提高水稻氮磷吸收,在氮肥分次施用情况下,有机无机复混肥增产效果更明显,适当减肥不会降低水稻产量,还可以减少稻田养分残留。

引黄灌区连续减施化肥对春小麦产量稳定性的影响

【目的】探索宁夏引黄灌区连续减施化肥对土壤氮、磷、钾养分供应及春小麦产量的影响,并分析影响产量稳定性的因素,为化肥合理减施、春小麦高产稳产提供理论依据。【方法】以宁春4号春小麦为供试作物,2019-2022年连续4年开展化肥减施田间定位试验,试验设置常规施肥(CF,N 270 kg·hm^(-2)、P_(2)O_(5)150 kg·hm^(-2)、K_(2)O 75 kg·hm^(-2))、减量施肥下限(RF1,N 180 kg·hm^(-2)、P_(2)O_(5)45 kg·hm^(-2)、K_(2)O 30 kg·hm^(-2),与传统施肥相比减N 33.3%、减P_(2)O_(5)70.0%、减K_(2)O 60.0%)、减量施肥上限(RF2,N 225 kg·hm^(-2)、P_(2)O_(5)75 kg·hm^(-2)、K_(2)O 45 kg·hm^(-2),与传统施肥相比减N 17.0%、减P_(2)O_(5)50.0%、减K_(2)O 40.0%)及不施肥(CK)处理,分析春小麦生育期间气候因素,播前土壤水分含量,播前和收获期土壤矿质态氮、速效磷、速效钾含量,收获期春小麦地上部干物质累积量、籽粒产量及产量构成因素的差异及相互关系。【结果】2019-2022年播前土壤水分含量存在年际差异,其中2022年的较低,平均值仅为19.5%;除2020年受施肥处理显著影响外,其余年份各施肥处理之间无显著差异。播前和收获期土壤矿质态氮、速效钾和速效磷含量均以常规施肥(CF)处理较高,RF2处理次之,且两者之间无显著差异,而RF1处理的趋于降低。2019年,地上部干物质累积量和产量均以CF处理最高,分别为23261.7和9449.0 kg·hm^(-2),较RF2处理增幅分别为2.8%-4.5%和3.2%-16.0%,而2020-2022年均以RF2处理较高,但与CF处理之间无显著差异,且4年籽粒产量表现最稳定;从年际变化来看,所有施肥处理的公顷穗数、千粒重、产量均呈逐年下降的趋势,因此施肥量并不是造成产量年际差异的主要原因,而是与播前土壤水分、降水量、气温、湿度和风速有密切关系,其中2022年产量的降低主要与较低的播前土壤水分、灌浆期的干热风现象及氮肥基追比的改变有关。【结论】宁夏引黄灌区连续适量减施化肥(N225 kg·hm^(-2)、P_(2)O_(5)75 kg·hm^(-2)、K_(2)O 45 kg·hm^(-2),相对常规施肥减N 17.0%,减P_(2)O_(5)50.0%,减K_(2)O 40.0%)不会显著降低土壤氮、磷、钾的供应能力,且一定程度上提高了春小麦公顷穗数、穗粒数和千粒重,促进地上部干物质量向籽粒的转移和积累,从而趋于提高春小麦的籽粒产量。但是,春小麦产量受降雨、风速、湿度等气候因素和土壤墒情、连作障碍、氮肥追施比等的影响而存在年际差异,其中,气温、相对湿度和风速是影响小麦产量差异的主要因素,其对施肥效果的影响需做进一步研究。

施钾量对玉米钾素吸收、转运及产量的影响

为研究玉米群体干物质、产量、养分吸收转运对钾素的响应。于2018—2019年在宁夏银川平吉堡开展田间试验,设6个钾肥用量,依次为0、60、120、180、240、300 kg/hm^(2)。结果表明:施钾显著提高了玉米干物质积累、钾素吸收转运及利用效率,以施钾量为180 kg/hm^(2)条件下最好,成熟期干物质积累量较对照提高了3.04%~13.80%,穗钾素积累量较对照提高32.17%~42.57%。施钾处理下钾素转运量提高了20.28%~68.73%,钾转运率提高了10.16%~30.37%,转运养分对籽粒贡献率提高了20.40%~67.71%。180 kg/hm^(2)较其他施钾处理,钾素吸收利用效率提高了20.09%~247.97%,钾素农学利用率提高了37.47%~221.27%,产量提高了6.99%~18.14%。综合考虑玉米产量、养分积累与转运及肥料利用等因素,本试验条件下以施钾量为180 kg/hm^(2)较为适宜。

松嫩平原不同类型土壤剖面形态描述及其性状分析

土壤剖面观察及描述是土壤分类的基础工作,而各层次性状分析是土壤健康评估的重要参考指标。以松嫩平原为主要研究区域,选取4种不同类型土壤:黑钙土(HGT)、厚层黑土(HHT)、薄层黑土(BHT)、风沙土(FST),在垂直和水平两种空间尺度上开展剖面对比调查工作。调查结果指出,4种土壤中HHT和BHT质地最为黏重,而FST质地最轻。另外,除FST外,其他3种土壤随土层深度增加砂粒含量逐渐升高,HGT、HHT、BHT分别升高了21%、125%、122%,质地逐渐变轻。土壤剖面颜色随土层深度增加而逐渐加深,HHT剖面整体颜色较其他土壤相比较深。土壤pH随土层深度加深呈逐渐升高的趋势,HGT、HHT、BHT、FST分别提高了58%、44%、22%、37%,HHT土体pH显著高于其他土壤类型(P<0.05)。土壤有机碳(SOC)随剖面深度增加呈下降的趋势,HGT、HHT、BHT、FST中SOC含量分别降低了21%、41%、26%、23%,其中HHT在0~60 cm土层中SOC含量显著高于其他类型土壤。土壤养分含量随剖面深度加深同样呈逐渐降低的趋势,4种类型土壤中碱解氮、速效钾和有效磷含量随土层加深分别降低了38.1%~68.2%、46.3%~98.3%和100%。综合分析,在垂直空间尺度上,土壤随深度增加发育程度减弱,有机质及养分含量降低,表层土壤酸化现象显著。在水平空间尺度上,厚层黑土的发育程度高于其他类型土壤。

有机无机肥配施对潮土麦田肥力和冬小麦产量的影响

【目的】研究不同施肥方式对黄淮海潮土区麦田肥力和冬小麦氮素利用效率和产量的影响,为该区域优化施肥措施、合理利用有机肥资源和保障作物高产提供理论支持和技术指导。【方法】基于天津潮土区连续12年的施肥处理定位试验,设置施肥处理为对照(CK,不施肥)、单施有机肥(M)、化肥减量50%配施有机肥(MF_(1))、常量化肥配施有机肥(MF_(2))、单施化肥处理(F)。【结果】与对照相比,施肥处理均能显著提高麦田土壤有机质和碱解氮、速效磷、速效钾含量,且有机无机肥配施处理提升土壤肥力效果最好。与对照相比,M、MF_(1)、MF_(2)和F处理土壤有机质增幅分别为92%、48%、78%和20%。MF_(1)处理孕穗-成熟期叶片氮素含量显著降低,促进氮素向籽粒的转移,提高氮素利用效率,显著提高穗粒数和千粒重,进而起到增产作用。MF_(1)、MF_(2)处理冬小麦产量分别达到6467和6345 kg/hm^(2),较F处理提高12%和9%。【结论】施用化肥115 kg/hm^(2)、有机肥15000 kg/hm^(2)的配施模式能够较常规模式降低化肥投入15%,并保持冬小麦产量稳定,可作为黄淮海平原潮土区冬小麦农田的推荐施肥技术。

西凉湖沉积物重金属及营养元素分布特征及污染评价

以西凉湖沉积物为研究对象,利用地累积指数法和潜在生态风险指数法评估其重金属元素的污染情况,利用综合污染指数法和有机污染指数法评价其氮、磷元素及有机质的污染情况。结果表明,西凉湖沉积物整体受到重金属污染水平较低,Cu、Zn、As、Hg污染情况在空间分布上相似,少数点位Cd、Ni、Hg元素达中度或重度污染,归因于养殖饲料和交通运输。西凉湖沉积物中氮、磷元素污染评价结果显示,磷元素污染情况相对较轻,80%的点位处于中度污染水平;氮元素污染情况严重,所有点位均达重度污染;氮、磷元素的综合评价中所有点位均达重度污染。有机污染指数法评价结果显示,所有点位有机污染指数均大于0.50,达重度污染水平。结合氮、磷元素的评价结果,将外源污染归因于西凉湖曾经过度发展渔业造成的营养输入。

2008~2022年我国湖泊有机质相关指标时空演变

基于2008~2022年中国湖泊长时间序列水质数据,采用Mann—Kendall检验(M-K检验),Pearson相关分析以及主成分分析(PCA)等对有机质及相关营养指标在长时间序列上的变化规律,空间异质性特征及指标之间的相关关系进行研究.结果表明:2008~2022年,全国湖泊溶解氧(DO)浓度以每年0.19mg/L的速度增加(P<0.001),从2008年的7.09mg/L增加至2022年的10.04mg/L,高锰酸盐指数(COD-Mn)浓度从5.86mg/L下降至3.17mg/L,表明我国湖泊水环境质量整体改善.然而,化学需氧量(COD),COD-Mn,生化需氧量(BOD5)等近年来出现波动性变化且有增加趋势.相关性分析结果表明,COD-Mn与总磷(TP),氨氮(NH3-N)以及叶绿素(Chla)均呈现显著正相关性(r>0.50, P<0.05);BOD5与TP呈现显著正相关性(r=0.61, P<0.05);COD与TP(r=0.80,P<0.05)以及Chla(r=0.61,P<0.05)显著正相关,表明TP浓度和叶绿素浓度可能是影响我国湖泊有机质变化的关键因素.在空间尺度上,COD,COD-Mn与BOD5等有机质相关指标为影响全国湖泊水质空间异质性特征的主要因素,且有机质浓度较高的湖泊地理分布较为明显,主要集中于蒙新湖区和云贵高原湖区.

氮钾肥施用次数对夏直播棉花干物质积累、产量和养分利用率的影响

【目的】探究氮钾肥施用次数对棉花的影响,为进一步提高长江流域棉区夏直播棉花产量提供参考。【方法】于2021―2022年开展大田试验,采用裂区设计,主区为钾肥(210 kg·hm^(-2))施用次数:K1[播种前(PP)100%]和K2[PP 50%+见花(FF)0 d 50%];副区为氮肥(210 kg·hm^(-2))施用次数:N2[PP 20%+FF 0 d 80%]、N3[PP 20%+FF 0 d 60%+FF 21 d 20%]和N4[PP 10%+FF 0 d 50%+FF 7 d 30%+FF 21 d 10%]。分析不同处理对棉花干物质积累与分配、氮钾积累与分配、产量及其构成因素和养分利用率的影响。【结果】K2N3处理下棉株和源、流、库器官拔秆期的干物质质量和氮、钾积累量以及干物质快速积累期的持续时间和平均积累速率均低于K2N4处理,但干物质以及氮钾向库器官的分配比例较K2N4处理高。K2N3处理可获得较高的籽棉产量和皮棉产量,较K1N2处理(产量最低)分别显著提高31.4%和31.9%,进一步增加施氮次数(K2N4处理)没有显著提高棉花产量。K2N3和K2N4处理的氮肥和钾肥偏生产力无显著差异,但二者均显著高于其他处理。主成分分析结果显示棉花产量的差异主要来源于铃数,促进干物质和氮钾养分向库器官分配有利于提高棉花产量。【结论】长江流域棉区麦后直播棉花,2次施钾配合3次施氮能促进棉株对氮钾的吸收,促进干物质和氮钾养分向库器官分配,增加铃数,提高棉花产量。

减氮配施微生物菌剂对烤烟干物质和氮磷钾养分积累的影响

为明确减氮配施微生物菌剂对烤烟干物质和氮磷钾养分的调控效应,以‘云烟87’为例,设计施肥模式、微生物菌剂的双因素试验,比较不同处理的烤烟干物质积累与分配、氮磷钾养分积累与分配及肥料利用效率差异,采用η2值分析施肥模式、微生物菌剂及其互作对烤烟干物质和氮磷钾养分积累及肥料利用效率的贡献率。结果表明,减氮配施微生物菌剂可提高烤烟干物质和氮、磷、钾养分积累量,提高氮、磷、钾肥干物质积累效率、利用效率和吸收效率,提高氮肥烟叶生产效率。施肥模式、微生物菌剂及其互作对干物质积累贡献率分别为41.90%、29.34%、28.76%,对氮积累贡献率分别为41.98%、27.49%、30.53%,对磷积累贡献率分别为34.63%、34.47%、30.90%,对钾积累贡献率分别为24.17%、32.95%、42.87%。南方多雨烟区,采用减少基肥比例和基肥穴施的减氮施肥模式,并配施微生物菌剂,可提高烟叶干物质和养分积累及提高肥料利用效率,有利于促进稻茬烤烟早生快发。

修复连作大蒜土壤生产力衰退的有机质补偿方案与初步机理

针对山东省金乡县品牌大蒜主产区长期连作大蒜田中土壤有机质亏缺和大蒜产量连年衰减的典型问题,以不同比例的有机肥替代化肥作为有机质补偿方案,研究了有机肥替代化肥对大蒜产量和土壤障碍的修复效果。试验选取了大于25年连作历史的代表性田块,以未种植大蒜的麦田作为非连作田块对照,设置常规化肥施肥(CF)、以氮(N)为基准进行有机肥替代化肥25%(M25)、50%(M50)和100%(M100)四个处理。结果表明,在长期大蒜连作土壤中,有机替代处理对大蒜的产量衰退具有显著的当季修复效果,增产幅度可达20%,同时改善了土壤中的氮素养分供应状态和土壤大于2 mm团聚体的比例;其中25%有机替代率(M25)具有较佳的经济效益;而在土壤有机质未出现亏缺的非连作土壤中,有机替代处理并无直接的增产效果。综上,本研究明确了增施有机肥仅在土壤有机质出现明显亏缺的连作大蒜土壤中可通过促进大颗粒土壤团聚体的形成和提升全生育期土壤有效态养分的固持能力,进而对连作大蒜土壤生产力的退化具有显著的修复效果。该研究对缓解连作体系中的类似土壤退化问题和维持土壤生产力的可持续性,具有有益的借鉴作用。

玉米种植密度对大豆玉米带状复合种植体系干物质养分积累与转运的影响

为探索大豆玉米带状复合种植模式下适宜的玉米种植密度,通过田间试验,研究大豆玉米带状复合种植模式(3+2)下,玉米种植密度(52500、60000和67500株·hm^(-2),分别以SM1、SM2和SM3表示)和玉米单作(MM,种植密度60000株·hm^(-2))对大豆玉米带状复合种植体系产量及玉米干物质、养分积累和转运的影响。结果表明,与单作相比,带状复合种植体系玉米产量降低5.25%~14.30%,其中SM2产量与MM差异未达显著水平,但带状复合种植体系总产值显著提高10.80%~16.71%。在复合种植模式下,与SM1和SM3相比,SM2显著提高玉米穗粒数和百粒重,延长干物质快速积累的时间,提高干物质积累最大增长速率,促进花后干物质向籽粒中转运,提高养分吸收,产量分别较SM1和SM3提高10.56%和9.67%。综上,相比较玉米单作,大豆玉米带状复合种植(3+2模式)可实现“玉米不减产或稍减产,多收一季豆”;在大豆玉米带状复合种植模式下,大丰30系列玉米的种植密度在60000株·hm^(-2)左右时可作为晋南小麦玉米一年两熟轮作区合理的密度选择,实现稳产高效。本研究可为晋南小麦玉米一年两熟轮作区推广大豆玉米带状复合种植及提高我国大豆自给率提供理论依据。

秸秆粉碎技术对土壤环境及作物生长的提升机理

秸秆粉碎技术是指将农田或农作物种植后残留的秸秆、稻草等植物秸秆进行机械粉碎处理,在有效处理秸秆的同时秸秆中的有机物质和养分为土壤提供营养,有助于改善土壤质量。该文分析了秸秆粉碎对土壤环境的影响,包括改善土壤结构、增加土壤有机质和提高土壤保水保肥能力等方面的正面影响。同时探讨了秸秆粉碎技术可能带来的负面影响,如对土壤微生物和生物多样性的影响等,阐述了秸秆粉碎对作物生长中提供养分、改善土壤温度、减轻土壤压实等方面的作用机理,并结合实际案例和研究成果,总结秸秆粉碎技术在提升土壤环境质量和促进作物生长方面的重要意义和发展趋势,研究内容旨在对农业生产具有重要意义。

温州市水稻土壤pH值和养分特征与分级的调查分析

掌握耕地土壤养分状况是保障粮食生产和耕地质量建设的重要内容。该研究在2021—2022年采集了温州市6 477个水稻土耕层样品,分析了土壤pH值、有机质、水解氮、速效磷和速效钾含量,并根据第二次土壤普查分级标准对土壤养分分级进行了评价,为水稻土合理施肥和耕地质量管理提供科学依据。结果显示,温州市水稻土土壤pH值平均为5.61,酸性土壤(pH值4.5~5.5)占比达48.43%,与第二次土壤普查结果比较,土壤呈现明显的酸化趋势。土壤有机质、水解氮、速效磷和速效钾平均含量分别为33.30 g·kg^(-1)、123.49 mg·kg^(-1)、67.93 mg·kg^(-1)和162.36 mg·kg^(-1)。总体上,土壤有机质和水解氮以很丰富-中等等级为主体;速效磷和速效钾含量很丰富-丰富等级之和的占比分别为51.58%和38.11%,但仍有较大比例的土壤存在缺磷和缺钾问题,缺乏-极缺乏之和的比例为32.85%和40.32%。与第二次土壤普查结果比较,温州市水稻土有机质平均含量保持稳定,速效磷和速效钾含量均有显著的提高,平均分别比第二次土壤普查时提高了430%和68.25%。不同行政区的土壤pH值、有机质、水解氮、速效磷和速效钾含量和分级存在明显差异。分析表明,温州市水稻土肥力的主要障碍因子是土壤酸化,土壤磷富集和缺乏共存,土壤缺钾明显。因此,水稻土施肥应实现减氮施肥,阻控土壤酸化;根据养分区域分布规律平衡施肥,维持土壤养分平衡。

Available Contents of Trace Nutrient Element and Factors Affecting Their Availability in Western Jilin

Based on the assay of the total content and available content of the trace nutrient elements and the soil pH and organic matter of the soil samples,the characteristic of the available content of the trace nutrient elements and their affecting factors are studied. The results show that the available B in western Jilin is in a middle level,the content in Nong'an is higher than that in the others; the available Mn is extremely abundant; the available Cu in Nong'an is obviously higher than other areas,and the content in Da'an differs greatly; the available Zn is in a middle level; the severe shortage of available Mo differs between different areas; and the available Fe is extremely abundant. The available Mn,Cu and Fe have significantly positive correlation with their total content; the available B has significantly positive correlation with pH,and Zn has obviously negative correlation with pH; the available Mn and Fe had significantly positive correlation with soil organic matter.

Changes of Organic Matter, N, P and K Content of Soils in Red Soil Areas Under Long-Term Experiment

The content of organic matter （OM）, nitrogen （N）, phosphorus （P）, and potassium （K） in the three selected soils, including Calcaric Purpli-Orthic Primosols （purple sand-shale parent material）, Dystric Turbi-Anthric Primosols （quaternary red clay parent material） and Typic Udi-Sandic Primosols （granite parent material） were studied under a long-term experiment by using crop straw and inorganic fertilizers at the Hunan Red Soil Experiment Station of Chinese Academy of Agricultural Sciences. The results showed that the contents of OM, N, P and K in the three selected soils increased after 23 years application of crop straw and inorganic fertilizers, but the contents increased much less when crop straw or inorganic fertilizers was applied alone. The nutrient contents in the three soils developed from granite changed more remarkably than those in the soil derived from quaternary red clay and purple sand-shale. It was also found that the contents of OM, N, and P increased slightly in the treatments without applying fertilizers or returning the crop straw to the root bed. Combined application of inorganic fertilizers and crop straw could remarkably increase the contents of OM, alkalihydrolyzable N and available K, the positive correlation between application of organic fertilizers and increase of OM in soil did not always happened, it provided evidence for the relation between appropriate C/N ratio and accumulation of OM in soil. The increase of nutrient content was influenced by the soil properties. By comparing the contents of nutrient in 0-20 cm depth in the three different soils, it was concluded that the most increases of OM, alkali-hydrolyzable N, and available P were observed in Typic Udi-Sandic Primosols with the average increase by 3.03, 27.38, and 21.73 mg kg^-1, respectively. The available K increased in Dystric Turbi-Anthric Primosols with the average increase by 25.82 mg kg^-1, while it decreased in Calcaric Purpli-Orthic Primosols and Typic Udi-Sandic Primosols. It was concluded that the application of inorganic fertilizer and crop straw was important to improve the soil fertility for all of three selected soils. The straw return to the field had played a significant role for enhancement of the soil quality in the study areas. The application of inorganic fertilizer combined with the straw return to the fields could remarkably improve the soil fertility.

Improving Removal Efficiency of Organic Matters by Adding Phosphorus in Drinking Water Biofiltration Treatment

Objective To investigate phosphorus limitation and its effect on the removal efficiency of organic matters in drinking water biological treatment. Methods Bacterial growth potential (BGP) method and a pair of parallel pilot-scale biofilters were used for the two objectives, respectively. Results The addition of phosphorus could substantially increase the BGPs of the water samples and the effect was stronger than that of the addition of carbon. When nothing was added into the influents, both CODMn removals of the parallel biofilters (BF1 and BF2) were about 15%. When phosphate was added into its influent, BF1 performed a CODMn removal, 6.02 percentage points higher than the control filter (BF2) and its effluent had a higher biological stability. When the addition dose was <20μg. L-1, no phosphorus pollution would occur and there was a good linear relationship between the microbial utilization of phosphorus and the removal efficiency of organic matters. Conclusions Phosphorus was a limiting nutrient and its limitation was stronger than that of carbon. The addition of phosphate was a practical way to improve the removal efficiency of organic matters in drinking water biological treatment.