分区平衡施肥技术对氮肥利用率和土壤养分平衡的影响

本文的研究结果表明，分区平衡施肥技术能明显提高氮肥利用率，在小麦和玉米上分别平均提高12.7和14.2个百分点。该技术能使养分盈亏趋于合理，分区平衡施肥的氮素平衡盈余显著低于习惯施肥，有利于减少氮素损失及其对环境的污染；磷素平衡盈余则明显高于习惯施肥，有利于改善土壤磷素状况；钾素平衡存在一定程度的亏缺，需通过增加无机、有机钾源来调节土壤钾素平衡。     

河西农田养分投入产出平衡的长期定位研究

通过长期定位试验和作物养分含量分析,确定了河西地区小麦、玉米生产上测土配方施肥的可靠养分吸收参数,系统研究了河西灌区农田主要养分投入产出状况.连续24 a研究结果表明,长期连施化肥(NP,NPK)土壤氮素投入产出盈余率前期(1982-1990年)为8.6%～19.1%,最高时期(1997-2005年)的表观盈余率平均为29.0%～48.5%,扣除氮素损失后为负平衡;磷素化肥投产始终为正平衡,平均盈余率为57.4%～68.3%.钾素化肥投入不抵作物携带量,投产为负平衡.平均盈余率为-58.7%.说明连施化肥氮、钾养分投入不足.有机肥与化学肥料长期配合平衡施用(MNP,MNPK),氮素平均盈余率56.3%～61.5%,扣除氮素损失后为正平衡,盈余率平均为9.4%～10.9%;磷素投产为正平衡,平均盈余率高达249.9%～265.7%;钾素投产为负平衡,平均亏缺19.9%.有机肥连施钾素亏缺45.0%.增施化学钾肥,适量减少化学磷肥,保持氮素化肥投入水平,配施有机肥是科学的平衡施肥技术.     

不同施肥模式下春玉米养分吸收利用和土壤养分平衡研究

通过三年定位试验,研究了吉林省春玉米主产区(公主岭和乾安)农民习惯与优化施肥模式对玉米产量、养分吸收利用、土壤养分变化及收支平衡的影响。结果表明,公主岭和乾安优化施肥玉米产量较农民习惯施肥分别增产6.8%~9.2%和6.3%~12.9%,差异均达显著水平(P<0.05)。与农民习惯施肥相比,公主岭和乾安优化施肥肥料吸收利用率分别提高46.9%和26.4%、农学利用率分别提高45.9%和32.6%、偏生产力分别提高35.2%和22.5%,差异均达显著水平(P<0.05)。优化施肥30~90 cm土壤无机氮含量和0~40 cm土壤有效磷含量均低于农民习惯施肥,0~40 cm土壤速效钾含量高于农民习惯施肥。与试验起始时相比,农民习惯施肥30~90 cm土壤无机氮含量与0~40 cm土壤有效磷含量均有明显提高,0~30 cm土壤无机氮含量和0~40 cm土壤速效钾含量下降。而优化施肥处理0~90 cm土壤无机氮含量,0~40 cm土壤有效磷含量和速效钾含量变化幅度较小。玉米收获期土壤氮、磷、钾养分表观平衡估算结果表明,优化施肥和农民习惯施肥土壤氮、磷素均出现盈余,钾素亏缺。与农民习惯施肥相比,公主岭和乾安优化施肥处理氮盈余量分别下降86.3%和93.3%,磷盈余量分别下降98.1%和92.1%,钾亏缺量分别下降16.5%和34.0%。综上所述,农民习惯施肥模式使土壤氮素和磷素大量残留,钾素亏缺,而优化施肥模式在提高产量和肥料利用率的同时,降低了氮、磷的损失和钾的亏缺。     

长期定位施肥对旱作塿土小麦产量、养分效率及养分平衡的影响

本文以20年塿土冬小麦-夏休闲轮作体系长期肥料定位试验为平台,探讨小麦产量、肥料利用效率及养分平衡对长期不同施肥模式的响应。试验包括7种施肥模式:不施肥(CK)、单施氮肥(N)、氮磷(NP)、氮钾(NK)、磷钾(PK)、氮磷钾(NPK)、有机肥与氮磷钾化肥配施(MNPK)。结果表明,同时施入氮肥和磷肥处理的小麦产量上升趋势显著,年均增产幅度为219~265 kg hm-2。施氮肥处理土壤氮素盈余,施磷肥处理土壤磷素盈余。以N和NK氮素盈余最多,年均盈余分别为88 kg hm-2和66 kg hm-2,MNPK土壤磷素盈余达到107 kg hm-2。同时施入氮磷肥处理(NP、NPK)显著提高了氮(磷)肥的累积表观利用率、农学效率和偏生产力,MNPK仅显著提高了氮肥的累积表观利用率、农学效率和偏生产力。除了PK和MNPK外的其它处理,土壤钾素均呈亏缺状态,以NP亏缺最严重,达到103 kg hm-2a-1。施钾肥对钾肥累积表观利用率、钾肥农学效率以及钾肥偏生产力均没有明显影响。20年后,土壤有机质、全氮、速效磷和速效钾含量均以MNPK最高。旱作塿土合理的施肥措施为氮磷配合或有机肥配合氮肥。     

农田肥料投入监测与养分平衡分析

通过 15年对农田肥料投入与产出的定点监测 ,得出了如下几个结论 :有机肥投入量减少较快 ,平均年递减率达 9.3% ;农田氮素投入过剩 ,化学氮素中稻和棉花田增加了 89.8% ;磷素基本达到平衡 ;而钾素投入严重不足 ,1999年四种作物钾素平均亏缺 10 8.9kg/ hm2 ,从而导致农田速效钾含量下降过快 ,平均年下降 2 .7mg/ kg。在今后的施肥中应加大平衡施肥技术的推广力度 ,利用各种途径增施有机肥 ,使农业走上持续稳定发展的道路。     

农田肥料投入监测与养分平衡分析

通过15年对农田肥料投入与产出的定点监测，得出了如下几个结论；有机肥投入量减少较快，平均年递减率达9.3%；农田氮素投入过剩，化学氮素中稻和棉花田增加了89.8%；磷素基本达到平衡；而钾素投入严重不足，1999年四种作物钾素平均亏缺108.9kg/hm^2，从而导致农田速效钾含量下降过快，平均年下降2.7mg/kg，在今后的施肥中应加大平衡施肥技术的推广力度，利用各种途径增施有机肥，使农业走上持续稳定发展的道路。     

山东省肥料施用与养分平衡状况研究

对山东省1952年以来肥料的施用情况和养分平衡状况进行了分析,结果表明:山东省自1952年以来,化学肥料用量逐步增加,有机肥用量逐渐减少;2002年有机肥用量仅占肥料施用总量的35.50%,其中有机氮肥、磷肥和钾肥分别占氮、磷、钾肥用量的26.09%、34.55%和57.60%,而化学肥料用量占肥料施用总量的64.50%,其中无机氮、磷、肥占氮、磷、钾肥的比例分别为73.91%、65.45%和42.68%,化学肥料用量明显高于有机肥;而且全省137个县市之间养分分配极不平衡,单位耕地面积化肥用量相差数千倍。进一步对全省氮、磷、钾投入产出状况进行分析发现,氮素从1982年开始盈余,每年盈余的氮素在30万吨左右;磷素从1972年开始盈余,2002年盈余高达134.64万吨;自1952年以来,钾素一直处于亏缺状态,目前每年亏缺60万吨左右。     

浅析兴国县农田养分现状及调整对策

本研究选择８０年第二次土壤普查取样点为背景，在原取样点再次取样分析，同时收集全县有关农田养分收支状况进行对比，结果表明，农田养分来源氮供应以有机肥和化肥基本各占一半，而磷素供应基本上以化肥为主。农田氮素基本平衡，磷素有机质略有盈余，钾素则明显亏缺。１７年间农田养分有增有减，其中束效钾反而下降３１．９％，ＰＨ下降近１个单位。为此，特提出下世纪初调整兴国农田养分的对策；一是调整化肥结构，协调氮磷施肥比     

黄淮海平原玉田县和陵县试区粮田土壤养分平衡现状评价

对黄淮海平原玉田县和陵县试区粮田土壤养分平衡现状进行了评价。结果表明 ,玉田县和陵县试区粮田氮素 (N)平衡均处于盈余状况 ,分别为202.1和 189.3kghm-2a-1,其实际平衡盈余率分别达到 64.4%和 71.8% ,较允许平衡亏缺率 (玉田县和陵县试区分别为 - 4.8%和 -23.1%)分别高出 69.2和 94.9个百分点 ,大大超过合理的范围 ,可能会引起环境问题。磷素 (P2O5)平衡亦均处于盈余状态 ,分别为 58.4和 88.4kghm-2a-1,其实际平衡盈余率分别为 57.2%和 84.6% ,较允许平衡盈亏率 (玉田县试区允许盈余 11.1% ,陵县试区允许亏缺-62.3% )分别高出 46.1和 146.9个百分点 ,玉田县试区磷肥的施用基本合理 ,而陵县试区磷肥用量明显偏高 ,未得到合理高效利用。钾素 (K2O)亏缺均较高 ,差异也较大 ,分别为 -50.9和 -115.3kghm-2a-1,其实际平衡亏缺率均低于允许平衡亏缺率 ,两地尤其是陵县试区土壤钾素长期处于亏缺状态 ,将会明显降低土壤的供钾能力。     

稻麦轮作减量施肥技术研究

为实现化肥高效施用和零增长目标,采用稻麦轮作大田定位试验,探讨不同减量施肥模式对稻麦轮作体系作物产量及养分利用效率的影响。试验设置不施肥(T1)、常规施肥(T2)以及等养分条件下有机肥与化肥配施(T3)、T3减20%化肥氮增施氮肥增效剂(T4)、T3减20%化肥磷增施磷素活化剂(T5)以及T3减20%化肥氮磷增施氮肥增效剂+磷素活化剂(T6),共6个处理。结果表明:与常规施肥(T2)相比,各减量施肥处理对稻麦体系作物周年产量影响不显著;T4处理有利于提高氮素和钾素的偏生产力和农学利用率,提高氮素和磷素吸收效率,提高作物磷素总吸收量;T5处理可以明显提高作物磷素总吸收量、磷素利用效率、磷素偏生产力、磷素的农学利用率,提高作物钾素农学利用率和钾素的偏生产力;T6处理可以明显提高作物的氮磷钾的利用效率和农学利用率,提高氮素和钾素的偏生产力;T3处理对作物氮磷素的吸收与利用均无显著影响,显著提高了作物钾素的偏生产力。综合结果表明,有机肥与化肥配施基础上减少20%化肥氮磷增施氮肥增效剂+增施磷素活化剂(T6)模式有利于协调作物养分吸收和稳定作物产量,可作为长江中下游相似生态区域稻麦轮作种植减肥增效的优选模式。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

Responses of native legume desert trees used for reforestation in the Sonoran Desert to plant growth-promoting microorganisms in screen house

Three slow-growing legume trees used for desert reforestation and urban gardening in the Sonoran Desert of Northwestern Mexico and the Southwestern USA were evaluated whether their growth can be promoted by inoculation with plant growth-promoting bacteria (Azospirillum brasilense and Bacillus pumilus), unidentified arbuscular mycorrhizal (AM) fungi (mainly Glomus sp.), and supplementation with common compost under regular screenhouse cultivation common to these trees in nurseries. Mesquite amargo (Prosopis articulata) and yellow palo verde (Parkinsonia microphylla) had different positive responses to several of the parameters tested while blue palo verde (Parkinsonia florida) did not respond. Survival of all tree species was over 80% and survival of mesquite was almost 100% after 10 months of cultivation. Inoculation with growth-promoting microorganisms induced significant effects on the leaf gas exchange of these trees, measured as transpiration and diffusive resistance, when these trees were cultivated without water restrictions.