湖区小麦-玉米轮作模式下不同施肥措施调控氮磷养分流失研究

针对我国南水北调东线过水区南四湖富营养化问题,利用沿湖流域典型种植模式——小麦-玉米轮作体系,选择材料易获取的几种施肥措施,采用田间原位安装淋溶水采集器和地表水径流池收集水样,室内分析不同处理防控氮磷养分流失的效果。结果表明:各施肥措施在作物不同茬口均能降低氮磷养分的随水流失,不同模式防控养分流失效果有差异;氮径流损失中,硝态氮占主要比例,玉米季和小麦季分别为82.7%~86.4%和94.2%~96.5%,而淋溶途径中硝态氮比例略有下降;径流为氮损失的主要途径,玉米茬口氮损失比例占轮作周年的67.0%~71.4%;磷径流损失中可溶性磷和颗粒磷比例相当,而淋溶磷以可溶性磷为主;淋溶途径损失的磷养分比例稍高,仍以玉米茬口总磷损失为主,占54.4%~63.1%;防控氮磷流失结合周年作物产量,玉米上使用减量控释氮肥或优化施肥配合秸秆还田、小麦上优化施肥或使用减量控释氮肥是相对理想的养分运筹搭配模式。     

施氮量对潮土区冬小麦-夏玉米轮作农田氮磷淋溶的影响

潮土是我国华北地区主要土壤类型之一,潮土区是我国冬小麦-夏玉米作物的主要产区,研究不同施氮量潮土氮磷淋溶特征对于指导区域农田面源污染防控具有重要意义。本研究设置3个施肥处理,即传统施氮(CON)、优化施氮(OPT)和优化再减氮(OPTJ),利用田间渗漏池法,研究潮土冬小麦-夏玉米轮作农田硝态氮及总磷淋溶特征。结果表明:2016—2018年,冬小麦-夏玉米轮作周年不同施肥处理90cm土层年淋溶水量79.0～102.5 mm,不同淋溶事件间土壤淋溶液硝态氮浓度波动较大, CON、OPT和OPTJ处理单次淋溶事件硝态氮浓度分别为18.9～208.7(平均为72.7) mg·L~(-1)、9.0～99.2 (平均为33.8) mg·L~(-1)、4.7～55.5 (平均为15.4) mg·L~(-1)。本研究区域冬小麦-夏玉米轮作模式的氮素淋溶风险较高,磷素淋溶风险较低。传统施氮处理(CON)下农田硝态氮的平均淋溶量和表观淋失系数分别为66.4 kg·hm~(-2)和10.3%,而总磷(TP)为0.06 kg·hm~(-2)和0.04%。氮肥减施会显著降低氮素淋失,OPT和OPTJ处理的氮素淋溶减排率可达56.3%和78.9%。两个年度CON、OPT和OPTJ处理硝态氮平均表观淋失系数分别为10.3%、6.2%和4.9%,随着施氮量的增加,硝态氮淋失系数动态增加。氮淋溶具有较大的年际变化,降雨量高的2018年比降雨少的2017年硝态氮淋溶量多57.0%。两个年度CON、OPT和OPTJ处理总磷平均淋溶量分别为0.06 kg·hm~(-2)、0.06 kg·hm~(-2)和0.08 kg·hm~(-2)。适量减施氮肥会增加作物产量, OPT处理的作物产量是CON处理的1.08倍。然而,过量减施则会带来减产风险, OPTJ处理氮肥减施56%,作物产量比CON处理降低2.0%～8.1%。总之,潮土区农田硝态氮淋溶风险较大,适量减施氮肥能够在保证作物产量的基础上显著降低氮素淋失损失。     

氮磷肥减施对露地蔬菜农田氮磷淋溶及蔬菜产量的影响

过量氮磷肥施用导致菜田氮磷淋溶严重,对水环境及人体健康产生较大威胁。本研究在河南蔬菜种植区选取典型露地菜田,采用田间渗漏池法,研究洋葱、甘蓝菜田氮磷肥减施后氮磷淋溶及蔬菜产量变化。试验设置常规施肥(NP),常规氮磷肥减量20%(JNP1),常规氮磷肥减量40%(JNP2)。结果表明:通过氮磷肥减施,JNP1和JNP2处理淋溶液总氮、可溶性总氮、硝态氮浓度比常规平均降低12.9%、18.2%和20.5%。JNP1处理总氮、可溶性总氮和硝态氮淋溶量分别比常规处理降低5.3%、11.9%和10.3%。JNP2处理总氮、可溶性总氮和硝态氮淋溶量比常规处理分别显著降低33.6%、36.2%和32.6%(P <0.05)。所有处理硝态氮平均淋溶量占总氮淋溶量60.1%,占可溶性总氮淋溶量的79.0%。两个蔬菜季氮积累量236.0～256.1 kg hm-2,磷积累量25.3～29.9 kg hm-2。氮磷肥减施后,蔬菜的产量略有降低,不同处理差异并不显著。     

重庆市农田氮磷流失系数初探

结合重庆市农业生产的实际情况,在全市设置监测点12个,以一个种植季为监测周期,采集每次降雨后产生的径流和淋溶水,测定其产生量和氮、磷浓度,测算出氮磷流失系数。结果表明,氮主要以地下淋溶途径流失进入水体,磷主要是以地表径流途径流失进入水体。各监测点总氮流失系数在0.011%~10.82%之间,总磷流失系数在0.013%~0.894%之间。氮的流失以硝态氮为主,最高占总氮流失的61.214%。从地表径流看,氮磷流失系数与地面坡度、施肥量成正相关,坡度越高、施肥量越大,氮磷流失系数就越大。从地下淋溶看,养分流失主要受土壤性质的影响,砂质土壤在灌溉或者降雨后,更容易造成养分的流失。     

不同施肥处理对三峡库区柑橘园土壤氮磷淋失影响

在2017年8月利用原状土柱模拟淋溶试验对三峡库区秭归县柑橘园土壤的氮磷淋溶流失进行研究,探讨不同施肥处理对土壤氮、磷淋失的影响,为三峡库区农业面源污染的防控提供理论依据。试验设置6个处理,分别为不施肥处理(T0)、减量施肥(T1)、常量施肥(T2)、增量施肥(T3)、常量复合肥A施肥(T4)和常量复合肥B施肥(T5)。结果表明:(1)不同施肥处理下,柑橘园土壤淋滤液中总氮(TN)、总磷(TP)、硝态氮(NO_3~-—N)和铵态氮(NH_4~+—N)的淋溶浓度范围分别为37.16~163.07,0.61~6.69,27.54~79.38,2.37~7.10mg/L。(2)施肥量和施肥种类皆为土壤中氮磷淋溶的影响因素。在相同施肥种类下,土壤氮磷淋溶浓度随施肥量增加而显著增加,但施肥量高到一定程度后,淋溶浓度增长幅度会降低。在相同施氮量下,硝态氮的淋失受施肥种类影响最大,铵态氮最小。(3)在土壤淋滤液中,硝态氮为可溶性氮主要淋失形态,其淋失量占TN淋失量的比率为29.72%~46.18%,NH_4~+—N淋失量的比重为1.09%~2.05%。从研究结果推论,常量复合肥A施肥处理更有利于肥料氮向供植物吸收可溶性氮转化并降低施肥后土壤中氮素累积的风险。     

湖南双季稻田不同氮磷施用量的径流损失

研究双季稻田不同施肥量处理的氮磷降雨径流损失规律,对于指导双季稻合理施肥、保护水环境具有重要的现实意义。本研究采用田间试验结合径流小区监测方法,对湖南双季稻田不同氮、磷施用量的径流损失进行了研究。结果表明,单次径流事件中径流水的氮、磷含量随施肥量的增加而增大;基肥和追肥后10d内发生的3次径流事件中径流水的氮磷含量较高,其中总氮含量最高达10.880mg.L-1,总磷含量最高为0.202mg.L-1;铵态氮和硝态氮是稻田总氮径流损失的主要形态,水稻生长前期以铵态氮为主,后期则以硝态氮为主;可溶性磷占总磷比例为11.0%~94.0%;整个双季稻期间不同施肥量处理的总氮流失量为3.710~7.290kg.hm-2,流失系数为1.870%~3.771%,总磷流失量为0.200~0.320kg.hm-2,流失系数为0.327%~0.966%;氮、磷流失量与其施用量存在极显著的线性正相关,相关系数分别为0.978和0.997。氮、磷流失系数随氮、磷施用量增加而下降。适当减少双季稻田氮磷施用量能有效控制稻田的氮磷径流损失量,减小对地表水质的威胁。     

控释肥对坡地农田地表径流氮磷流失的影响

2010年5-9月降雨季,在鲁中山区种植春花生的坡地农田中进行野外降雨径流观测试验,研究了不同坡度下,施用普通复合肥(CCF)和纯控释肥(CRF)对地表径流液和径流泥沙中铵态氮、硝态氮、可溶性磷、颗粒态氮和磷、总氮和总磷的影响。结果表明,花生生长前期,与CCF相比,施用CRF的坡地地表径流中可溶性养分流失含量较低,其中铵态氮含量低5.0%~74.2%,硝态氮含量低3.9%~37.0%,可溶性磷含量低7.1%~94.1%;CRF处理径流中颗粒态氮和磷含量在花生生长前期低于CCF处理,花生生长后期CRF处理径流液总氮、总磷含量高于CCF处理;在整个监测期内,CRF处理径流中总氮和总磷含量低于CCF处理。不同坡度下,随着坡度的增大,CCF和CRF的径流养分流失量变化为15°>10°>5°>0°,表明在坡地条件下,CRF能维持作物生长后期较高土壤养分含量,有利于提高氮磷的利用效率,减少雨季氮磷地表径流养分流失,降低农业面源污染。     

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。     

天然降雨条件下水稻田氮磷径流流失特征研究

采用具有单排单灌的试验小区,对水稻田在多次天然降雨条件下形成的径流中氮磷的流失特征进行了研究。结果表明,几次降雨径流的累积量中总氮的最高浓度达到22.15mg/L,总磷的浓度达4.84mg/L,可溶态氮是天然降雨径流流失氮素的主要形态,约占总氮的70%～92%,尤其是硝态氮,约占总氮的40%～80%,而径流流失中氨态氮的浓度较小,仅占总氮浓度的3.4%～27%,颗粒态磷在径流流失磷素中占到较大的比重,可达76%～79%;几次降雨事件中总氮的累积流失负荷约在0.23～0.80kg/hm2,总磷的累积流失负荷约在0.07～0.15kg/hm2,两者都小于当季施肥量的1%;降雨和施肥是影响氮磷素径流输出的主要因子,对降雨、施肥量、氮磷素输出负荷运用二元一次方程进行拟合,结果表明相关性达到了显著性水平。     

苕溪流域茶园不同种植模式下地表径流氮磷流失特征

为探讨苕溪流域不同种植模式下茶园地表径流氮磷养分流失特征,于2010年5-10月对等高种植和顺坡种植2种种植模式下茶园地表径流水样进行取样测定,分析径流水样中的氮磷元素各指标的含量、形态特征及其随时间的变化规律。结果表明:无论是顺坡种植还是等高种植,茶园径流中氮素各指标含量的峰值均出现在6月底或7月初,茶园径流中磷素各指标含量的峰值出现在6月底、7月初或9月初。在整个监测时期内,等高种植茶园径流中总氮、硝氮、铵氮含量分别比顺坡种植茶园低8.54%～43.01%,4.05%～46.70%,5.92%～33.19%,但2种种植模式间不存在显著差异;等高种植茶园径流水中总磷、可溶态总磷、颗粒态磷的含量分别比顺坡种植低8.51%～31.07%,0.39%～17.91%,8.45%～36.86%,2种种植模式之间径流水中总磷、颗粒态磷含量存在极显著差异,可溶态磷含量不存在显著差异。无论是顺坡种植还是等高种植,硝态氮均为茶园氮素地表径流流失的主要形态,颗粒态磷则是茶园磷素地表径流流失的主要形态。总的来说,等高种植模式能有效地截留茶园氮磷营养元素,防止其随地表径流流失。     

贵州草海耕地土壤与农作物中DDTs和HCHs残留及污染特征

采集草海流域周边成熟期整株农作物及土壤样品,分析测试其中DDTs和HCHs的含量,对比研究了土壤和作物中DDTs和HCHs污染水平及其在作物中富集能力。结果表明：研究区域土壤中HCHs和DDTs残留检出率均为100％,残留范围分别为0．06～16．66μg·kg^-1和0．08-39．77μg·kg^-1,土壤中HCHs和DDTs的残留量均小于国家土壤环境质量一级标准;三种农作物中DDTs、HCHs及∑（DDTs,HCHs）残留量差异显著,HCHs含量最高的是玉米,DDTs和（DDTs,HCHs）最高的是马铃薯;三种农作物中HCHs和DDTs残留的风险系数均为1．1,属于低度风险,农作物中DDTs、HCHs及∑（DDTs,HCHs）的安全指数IFSc均小于1,DDTs和HCHs残留量对三种农作物安全影响的风险是可以接受的。     

陇陕片预警减灾工作的成效与做法

自 1991年长江上游水土保持重点防治区滑坡、泥石流预警系统运作以来 ,陇南陕南片成功预报和处理滑坡、泥石流险情 10 3处 ,保护人口 11 6 8万 ,避免经济和财产损失 11879 6 5万元 ,取得了良好的社会效益。主要做法及经验是 :依靠各级政府 ,健全预警网络 ;广泛深入宣传 ,增强防灾意识 ;健全管理制度 ,落实岗位职责 ;强化技术培训 ,提高业务技能 ;加强检查指导 ,现场解决问题 ;及时调查险情 ,做好技术服务 ;预防治理结合 ,注重减灾实效。     

Changes in yield and gas exchange parameters in Festulolium and alfalfa grown in pure sowing and in mixture under drought stress

Crop performance and yield are the results of genotypic expression as modulated by continuous interaction with the environment. Among environmental factors, water is globally one of the most limiting for crop production. Water resources in the world are steadily diminishing and in many areas, including Poland, more frequent periods of drought are being observed. The aim of the study was to compare the yields and gas exchange parameters of Festulolium hybrid (Festulolium braunii (K. Richt) A. Camus) and alfalfa (Medicago?×?varia T. Martyn) under different levels of soil moisture (well-watered conditions and drought stress) and cultivation method (pure stand and mixture). The study has shown that all the measured parameters were affected by drought stress. Net photosynthetic rate, transpiration rate, stomatal conductance and dry mass yield were significantly lower under drought stress than under well-watered conditions in all treatment types. Alfalfa grown in a pure sowing showed the strongest reaction to stress, while hybrid Festulolium grown in mixture showed the weakest. It was also found that under stress, grass assimilated CO₂ and evaporated water much more intensively in mixture cultivation than in pure sowing. Higher water use efficiency (WUE) was observed in alfalfa and Festulolium growing in mixture only in the first year of the study.     

Cadmium Effects in Sunflower: Membrane Permeability and Changes in Catalase and Peroxidase Activity in Leaves and Calluses

Mechanisms preventing oxidative burst in cells exposed to high metal concentrations are crucial for cell survival. In this report, sunflower (Helianthus annuus L.) was used as a model species to investigate: (a) how cadmium (Cd) affects plant defense pathways (in particular, those involved in preventing oxidative stress), and (b) whether antioxidative enzymes of plants and of in vitro cell culture (calluses) have similar responses to Cd exposure. For this experiment, plants (grown hydroponically on Long Ashton medium) and calluses (grown on Murashige and Skoog medium) were exposed for three weeks to different Cd concentrations (0, 5, 50, and 500 μ M). Solute and electrolyte leakage increased significantly with the increase in Cd concentration in the external medium and in exposed leaves, and less in exposed calluses. Cadmium exposure also reduced significantly soluble protein contents in both leaves and calluses. The activities of catalase and peroxidase decreased significantly in 50 and 500 μ M-exposed leaves compared with the control, but increased in 5 μ M-exposed calluses, decreasing in the calluses exposed 500 μ M Cd. The decrease in antioxidative enzymes activities is congruent with the decrease in membrane integrity and suggests that calluses develop antioxidant mechanisms that respond better to Cd stress than do leaves. On average, 100% of plants exposed for 21 d to 500 μ M and 95% of plants exposed for 45 d to 50 μ M Cd were dead. After 45 d, only 53% of 50 μ M-exposed calluses had died. These surviving calluses were maintained on 50 μ M for six months. Six-month-old exposed calluses had higher activities of peroxidase and catalase when compared with control calluses, as well as lower membrane degradation. These data show that calluses are more tolerant than plants to Cd exposure, and that antioxidant mechanisms under Cd exposure may differ between the two cell systems and vary with time.     

Fungal abundance and diversity in earthworm casts and in uningested soil

Earthworm casts and adjacent uningested soil from 30 different locations were compared to determine the abundance and diversity of fungal species. The casts contained larger fungal populations (g^-1 dry soil weight) and numbers of fungal species than the soil. Variations in these parameters between casts and soil were statistically significant (P=0.05). Fungal populations and the number of fungal species in casts and soil also varied significantly (P=0.05) between samples from different locations. A total of 27 fungal species were recorded from the casts and soil. Indices of dominance (0.084 casts; 0.14 soil) and general diversity (2.53 casts; 2.02 soil) demonstrated that the casts displayed more diverse fungal flora than the soil. The diversity of fungal species increased in earthworm casts after passing through the earthworm gut.     

云南省开展水土保持的做法与成效

云南省各级党政领导重视和支持水土保持 ,积极出台有关法规、政策 ,为搞好水土保持工作提供了保障。治理中坚持高起点要求 ,有力地推动了水保产业化建设。适应市场经济要求 ,大力发展水土保持专业户、重点户 ,调动社会各方面力量参与水土流失治理开发。介绍了具体的做法、成效及今后做好水保工作的思路。     

1,4-Dimethoxyglucobrassicin in Barbarea and 4-hydroxyglucobrassicin in Arabidopsis and Brassica

A novel indole glucosinolate, 1,4-dimethoxyglucobrassicin (1,4-dimethoxyindol-3-ylmethylglucosinolate), was isolated as the desulfo derivative from roots of the P-type of Barbarea vulgaris ssp. arcuata, and its structure was determined by spectroscopy including 2D NMR spectroscopy. 4-Hydroxyglucobrassicin (4-hydroxyindol-3-ylmethylglucosinolate) was isolated as the desulfo derivative from green siliques (fruits) of Arabidopsis thaliana and identified by comparison of its (1)H NMR spectrum with the spectrum of the known desulfoglucosinolate from Brassica napus. The delayed elution of desulfo indole glucosinolates from the DEAE Sephadex column used in sample preparation was examined, and the diode-array UV spectra of desulfo indole glucosinolates were measured, to ensure a reliable determination of 1,4-dimethoxyglucobrassicin and 4-hydroxyglucobrassicin with the existing analysis method based on the HPLC of desulfoglucosinolates. 1,4-Dimethoxyglucobrassicin was not detected in 10 other Arabidopsis, Brassica, and Barbarea species, indicating an evolutionarily recent mutation in the indole glucosinolate biosynthesis in B. vulgaris ssp. arcuata type P.     

肯尼亚和中国农业资源投入与农业单产水平变化

当前，肯尼亚和中国在生产足够粮食以保障粮食安全方面都面临着严峻的挑战。尤其是对于肯尼亚而言，因为其2100年预测的人口将达到2018年的1.4倍，且其粮食生产在过去并没有大幅度的改善。而中国近些年粮食生产能力显著提高。本文系统分析了肯尼亚和中国农业资源投入、种植业和畜牧业单产水平的历史变化，以及农业资源投入与产量之间的关系，为肯尼亚粮食危机和消灭贫困提供更多的理论支撑。研究结果表明，在20世纪60年代，肯尼亚耕地、草地和降水等自然资源人均占有量比中国高2~3倍，且人均食物能量和蛋白质供应显著高于中国。当前，肯尼亚人均资源拥有量仍高出中国约30%，但是其人均食品供应和粮食自给率却远低于中国平均水平。这是由于与肯尼亚相比，中国在种植业和畜牧业长期持续的投入，大幅度地增加了种植业和畜牧业能量或蛋白质单产水平。1961-2017年，中国和肯尼亚作物蛋白的平均单产分别增加282%和44%。中国的数据表明，种植业和畜牧业单产水平与肥料、精饲料、机械和农药的投入具有显著正相关性；农牧业生产结构对单产水平的变化影响也很大，如种植业中蔬菜和水果播种面积占比，畜牧业中单胃动物饲养占比等。总的来说，农业资源投入和农业结构对生产力的提高都有很大的影响，这可能是肯尼亚提高农业生产力的潜在选择。     

Aorta and liver changes in rats fed cholesterol-containing and raw vegetable-supplemented diets: experiments in vitro and in vivo

The aim of this investigation was to compare the liver and aorta changes in rats fed cholesterol-containing diets and the possible improvement when diets would be supplemented with frequently used raw vegetables. The phenolic compounds of three vegetables in methanol-water (1:1) fraction were characterized using electrospray ionization mass spectra (ESI-MS). Results showed that the content of polyphenols, flavonoids, quercetin, flavanols, tannins, and ascorbic acid varied for garlic and white and red onions ranging from 6.68 to 18.08 mg GAE/g DW, 490.4-701.0 μg CE/g DW, 281.2-1100.0 μg, 32.40-41.30 μg CE/g DW, 2.88-3.12 mg CE/g DW, 1.87-2.33 mg AA/g DW, 1388.2-1442.3 μg CGE/g DW, respectively. The radical scavenging capacities (μM TE/g DW) for the same investigated vegetables for ABTS, FRAP, CUPRAC, and DPPH assays ranged from 48.78 to 92.42, 9.41-28.56, 3.06-10.41, and 6.49-23.42, respectively. Good correlations were observed between the phenolic contents and the radical scavenging capacities of the vegetables. The interaction between BSA and quercetin, BSA and garlic and onions extracts was measured by 3-dimensional fluorescence (3D-FL) and Fourier transform infrared (FT-IR) spectroscopy. The highest polyphenol content was found in methanol/water fraction of onions and garlic; therefore, for the investigation of in vitro interactions with BSA only polyphenols of this fraction were used. For in vivo studies, 30 male Wistar rats were divided into 5 groups each of 6 and named Control, Chol, Chol/Garlic, Chol/OnionRed, and Chol/OnionWhite. During 6 weeks, the rats of all 5 groups were fed a basal diet (BD). The rats of the Control group were fed the BD only. The BD of the Chol group was supplemented with 10 g/kg of nonoxidized cholesterol (NOC). Each of the other three groups was supplemented with 10 g/kg of NOC and 500 mg of raw fresh garlic, 500 mg of raw fresh red onion, and 500 mg of raw fresh white onion on 1 kg of body weight for Chol/Garlic, Chol/OnionRed, and Chol/OnionWhite diet groups, respectively. In order to detect the changes in the liver and aorta, a histological procedure was applied, and the liver enzymes were determined and compared. It was found that the main changes vs the Control group were in the liver of rats fed the cholesterol-containing diet without vegetable supplementation. Significantly less histological changes in the liver and lower level of liver enzymes vs those of the Chol group were detected in rats of the Chol/Garlic group (P < 0.05). The interaction between the polyphenol extract of garlic and BSA in vitro showed its strong ability comparable with that of quercetin to quench the intrinsic fluorescence of BSA. In conclusion, all studied vegetables showed protective effects, but raw garlic supplemented with cholesterol-containing diets significantly prevented the aorta and liver damages of rats.