Stickstoff- und Kaliumbilanzen bei Anbau von Chrysanthemen (Dendranthema-Grandiflorum-Hybriden) im Plant Plane Hydroponic Verfahren

Nitrogen and Potassium Balances in Chrysanthemum (Dendranthema-Grandiflorum) Hybrids Grown in a Plant Plane Hydroponic Cultivation System Chrysanthemum (Dendranthema Grandiflorum) hybrids were grown in a non-recirculating plant plane hydroponic system with fleece mat (polyester 80 gm^?2) to investigate possible potassium and nitrogen losses from the system. Cuttings were planted either in January (WI) or July (SO). Nutrient solution was applied in two ways: (a) at increasing (0.6 rising to 1.7 mS cm^?1), (b) at constant (1.5 mS cm^?1) electrical conductivity. The nutrient balance sheets showed that there was no detectable loss of potassium under any treatment. There was a large difference in cumulative nitrogen deficit between January (59 ± 8.5 kg ha^?1 N) and July (142 ± 20 kg ha^?1 N) plantings, equivalent to 22 and 31 % of the input. Mode of nutrient supply (a) or (b) did not affect this cumulative N deficit. Nitrogen loss was proportional to cumulative nitrogen supply with a mean rate of 344 g kg^?1 N. It is assumed that gaseous N losses were caused by nitrification and/or denitrification.     

Einfluß von Düngemaßnahmen auf die Stickstoffauswaschung bei mehrjährigem Silomaisanbau

Influence of fertilization on nitrogen leaching after cultivation of maize for silage over four successive seasons In a field trial, nitrogen leaching from soil was determined between February 1983 and May 1986 by analyzing soil water from 50, 80 and 110 cm below the soil surface every 14 days. On a Stagno-gleyic Luvisol, maize after maize was cultivated over four successive seasons. Nitrogen was applied either minerally in spring according to N_min or as a semiliquid cattle manure. The time of application (autumn and/or spring), application rate and use of nitrification inhibitor dicyandiamide (DCD) were varied. Under very low N-fertilization (underground fertilization only), nitrate nitrogen losses by leaching dropped from 100 kg N/ha in the first year to 33 kg N/ha in the 3^rd. Nitrogen leaching from the various treatment plots depended on the maize growth and rainfall conditions. Because of an intensive and long lasting seepage of gravitational water, nitrogen leaching from the root zone ranged from 113 to 208 kg N/ha during the fall and winter seasons of 1983/84 and 1984/85. Under the more balanced infiltration conditions of the leaching period 1985/86, and after a high yield of maize in 1985, losses due to leaching were reduced to values between 69 to 108 kg N/ha. Under these experimental conditions (deliberately high quantities of semiliquid cattle manure; DCD-application in autumn) no reduction in nitrogen losses could be proved due to the addition of dicyandiamide.     

北京郊区冬小麦/夏玉米轮作体系中氮肥去向研究

采用田间微区15N示踪试验研究了肥料氮在冬小麦、夏玉米当季和后茬的去向。结果表明 ,在供试土壤的肥力水平和生产条件下 ,N 120kg/hm2 的施肥水平已经达到了较高产量 ,再增加氮肥施用量作物产量不再增加 ;其氮肥利用率和残留率均显著高于施氮量为N 360kg/hm2,损失率则远低于后者 ;在一季作物生长后仍有 20.9%～48.4%肥料氮残留于 0～100cm土层 ,这些残留的肥料氮在后茬的利用率不足 8% ,至施肥后第 2或第 3茬作物 ,仍有部分肥料氮残留于土壤。在低施氮量时 ,肥料氮以NO3--N残留的量很低 ,在高施氮量时 ,残留氮除以有机态、微生物态氮形式存在外 ,以NO3--N形式存在的比例也很高 ;在氮素损失途径中 ,淋洗损失可能占有相当重要的地位。     

Effect of nitrogen fertilization and irrigation on soil microbial activities and population dynamics — a field study

In a field experiment, net nitrogen (N) mineralization and immobilization were studied in relation to: 1) population dynamics and activities of N-metabolizing soil microbial communities, 2) changes in substrate-induced respiration (SIR) and 3) potential urease acitvity. Nitrogen fertilization (80 kg NO₃-N ha^-1) without irrigation induced additional N mineralization up to 280 kg N ha^-1. Net N-mineralization was weakly correlated to cell numbers of ammonifying and NH₄⁺-oxidizing microorganisms. Potential urease activity, respiration activity, and substrate-induced respiration activity were not correlated with the amount of mineralized nitrogen. Irrigation significantly increased potential urease activity of the soil microflora. Substrate induced respiration activity and basal respiration activity of the soil microflora were highest in the unfertilized and non irrigated treatment. But greatest differences were detected between the two sampling dates. NO₂^--oxidizing and ammonifying microbial populations increased, while populations of NH₄⁺-oxidizing and denitrifying microorganisms decreased with time. The results of this study demonstrate the interaction of nitrogen fertilizer application and irrigation on population dynamics of N-transforming soil microorganisms and microbial activities under field conditions. Detailed microbiological investigations of this type improve our understanding of nitrogen transformations in soil and suggest possible reasons of nitrogen losses, so that N fertilizer can be used more effectively and N losses be reduced.     

Maize (Zea mays L.) Grain Yield Response to Methods of Nitrogen Fertilization

ABSTRACT

In the developing world, fertilizer application is commonly achieved by broadcasting nutrients to the soil surface without incorporation. A commonly used nitrogen (N) source is urea and if not incorporated, can sustain N losses via ammonia volatilization and lower crop yields. This study evaluated the effect of planting, N rate and application methods on maize (Zea mays L.) grain yield. An experiment with a randomized complete block design (nine treatments and three replications) was established in 2013 and 2018 in Oklahoma. The planting methods included; farmer practice (FP), Oklahoma State University hand planter (OSU-HP), and John Deere (JD) mechanical planter. Side-dress N application methods included; dribble surface band (DSB), broadcast (BR), and OSU-HP. Nitrogen was applied at the rate of 30 and 60 kg ha^?1 as urea and UAN at V8 growth stage. On average, planting and applying N at 60 kg ha^?1 using OSU-HP resulted in the highest yield (11.4 Mg ha^?1). This exceeded check plot yield (5.59 Mg ha^?1) by 104%. Nitrogen application improved grain yield by over 57% when compared to the 0-N check (8.77 Mg ha^?1). Mid-season N placement below the soil surface using OSU-HP makes it a suitable alternative to improve grain yield.     

Nitrogen losses from outdoor pig farming systems

Abstract. Nitrogen losses via nitrate leaching, ammonia volatilization and nitrous oxide emissions were measured from contrasting outdoor pig farming systems in a two year field study. Four 1‐ha paddocks representing three outdoor pig management systems and an arable control were established on a sandy loam soil in Berkshire, UK. The pig management systems represented: (i) current commercial practice (CCP) ‐ 25 dry sows ha^?1 on arable stubble; (ii) ‘improved’ management practice (IMP) ‐ 18 dry sows ha^?1 on stubble undersown with grass, and (iii) ‘best’ management practice (BMP) 12 dry sows ha^?1 on established grass. Nitrogen (N) inputs in the feed were measured and N offtakes in the pig meat estimated to calculate a nitrogen balance for each system. In the first winter, mean nitrate‐N concentrations in drainage water from the CCP, IMP, BMP and arable paddocks were 28, 25, 8 and 10 mg NO₃ l^?1, respectively. On the BMP system, leaching losses were limited by the grass cover, but this was destroyed by the pigs before the start of the second drainage season. In the second winter, mean concentrations increased to 111, 106 and 105 mg NO₃‐N l^?1 from the CCP, IMP and BMP systems, respectively, compared to only 32 mg NO₃‐N l^?1 on the arable paddock. Ammonia (NH₃) volatilization measurements indicated that losses from outdoor dry sows were in the region of 11 g NH₃‐N sow^?1 day^?1. Urine patches were identified as the major source of nitrous oxide (N₂O) emissions, with N₂O‐N losses estimated at less than 1% of the total N excreted. The nitrogen balance calculations indicated that N inputs to all the outdoor pig systems greatly exceeded N offtakes plus N losses, with estimated N surpluses on the CCP, IMP and BMP systems after 2 years of stocking at 576, 398 and 264 kg N ha^?1, respectively, compared with 27 kg N ha^?1 on the arable control. These large N surpluses are likely to exacerbate nitrate leaching losses in following seasons and make a contribution to the N requirement of future crops.     

自然降雨下玉米秸秆堆沤还田对滇中小流域坡耕地氮素流失的影响

为探究自然降雨下不同堆沤方式秸秆还田对小流域坡耕地径流泥沙及氮素流失的影响,以滇中二龙潭流域坡耕地为研究对象,设置9种不同玉米秸秆堆沤方式,分别为CK及8种处理,各处理包括2种秸秆还田量(0.75,1.5 kg/m^2)、2种秸秆粒度(1,5 cm)、2种秸秆堆沤方式(水或水与尿素堆沤),研究烤烟坡耕地产流产沙及氮素流失特征。结果表明:(1)在4场具有典型产流的降雨中,施用较高秸秆还田量(1.5 kg/m^2)和粗颗粒秸秆(5 cm),均可有效减少坡耕地产流产沙量(10.06%~38.60%和10.07%~38.60%);(2)施用较低秸秆还田量(0.75 kg/m^2)、粗颗粒秸秆(5 cm)及未添加尿素堆沤的秸秆径流TN、NO3--N浓度低于施用高秸秆还田量(1.5 kg/m^2)、细颗粒秸秆(1 cm)及添加尿素堆沤的处理(1.96%~32.79%和3.97%~40.89%);(3)各处理下NO3--N/TN、NH4+-N/TN、PN/TN分别为63.64%~86.18%,5.31%~13.86%和5.33%~25.80%,表明坡耕地地表径流氮素主要流失形式为NO3--N,溶解态氮是径流中的主要氮素污染物;(4)施用较低秸秆还田量(0.75 kg/m^2)、粗颗粒(5 cm)秸秆、未加尿素堆沤的秸秆,泥沙TN流失浓度降低(16.87%~48.15%);(5)施用较高秸秆还田量、粗颗粒秸秆及未添加尿素堆沤可有效降低滇中坡耕地氮素的流失风险(0.32%~35.05%和54.52%~77.23%)。TN径流和泥沙流失中,以径流输出为主,占TN流失量的50.09%~71.67%。为了减少该流域氮素流失量,可选择施用较高秸秆还田量(1.5 kg/m^2)和粗颗粒(5 cm)秸秆,并依据烤烟不同生长期的吸收情况和土壤养分情况等选择少量或不添加尿素堆沤进行秸秆还田。     

Effect of Salinity and Nitrogen Application on Growth,Chemical Composition and Some Biochemical Indices of Pistachio Seedlings (Pistacia Vera L.)

To study the effect of nitrogen and salinity on growth and chemical composition of pistachio seedlings (cv. ‘Badami’), a greenhouse experiment was conducted. Treatments consisted of four salinity levels [0, 800, 1600, and 2400 mg sodium chloride (NaCl) kg^?1 soil], and four nitrogen (N) levels (0, 60, 120, and 180 mg kg^?1 soil as urea). Treatments were arranged in a factorial manner in a completely randomized design with three replications. The highest level of nitrogen and salinity decreased leaf and root dry weights. Nitrogen application significantly increased the concentration of shoot N and salinity suppressed shoot N concentration. Salinity and nitrogen fertilization increased shoot and root sodium (Na), calcium (Ca), and magnesium (Mg) concentrations. Nitrogen application increased proline concentration and reducing sugar content. Although salinity levels increased proline concentration a specific trend on reducing sugars content was not observed.     

苗期干旱胁迫下施氮对玉米氮素吸收和土壤生物化学性质的影响

研究苗期干旱胁迫下施氮对东北春玉米氮素吸收利用和土壤生物化学性质的影响,为区域玉米养分管理与逆境调控提供依据。研究设置水、氮二因素盆栽试验,土壤水分包括3个水平:田间持水量的30%(W0),50%(W1)和70%(W2);施氮量包括2个水平:不施氮(N0)和施氮0.24 g/kg(N1),测定不同水氮条件下玉米苗期的植株干重和氮素吸收、根际和非根际土壤的化学性质、微生物量碳、氮(MBC、MBN)及土壤酶活性。结果表明:干旱胁迫显著降低玉米苗期植株干重和氮素吸收量,其中W0条件降幅最大(分别为51.1%,43.8%)。施氮促进各水分条件下植株生长,且与水分存在显著交互作用,W2条件下施氮后植株干重和氮素吸收量的增幅最高(分别为53.7%,83.2%)。干旱胁迫提高植株的水分利用效率,但降低氮肥利用效率。施氮显著提高W2条件植株的水分利用效率,但干旱条件下则无显著影响。水、氮及其交互作用对土壤性质的影响较为复杂。总体上,苗期干旱胁迫暂时提高了根际和非根际土壤pH,显著增加根际土壤的铵态氮和硝态氮含量。MBC、MBN对干旱胁迫的响应在根际与非根际土壤之间存在相反趋势,根际土壤随干旱程度增加而提高,非根际土壤则随之下降。土壤酶活性方面,干旱胁迫显著影响根际土壤的硝酸还原酶和亚硝酸还原酶活性。施氮增加所有水分条件下根际和非根际土壤的pH和铵态氮、硝态氮含量,其中根际土壤的增幅高于非根际土壤。施氮显著增加各水分条件下根际和非根际土壤的MBC、MBN、脲酶和硝酸还原酶活性,但显著降低根际和非根际土壤亚硝酸还原酶活性。水氮交互作用显著影响根际土壤的亚硝酸还原酶、非根际土壤的脲酶、亚硝酸还原酶和FDA水解酶活性。根际、非根际土壤各生物化学性质之间均存在显著的相关关系,而且根际土壤除土壤亚硝酸还原酶外的各指标均与植株氮素吸收和氮肥利用效率呈正相关。苗期干旱显著抑制玉米植株生长和氮素吸收,并对土壤生物、化学性质造成显著影响。施氮对植株和土壤性质的影响在不同水分条件下存在差异,而且植株表现与土壤生物、化学性质之间存在显著相关关系。     

生物硝化抑制剂——一种控制农田氮素流失的新策略

农业生产中氮肥的施用是影响全球氮素循环的一个重要因素,在促进作物增产的同时,也对生态环境产生了重要的影响。由于铵态氮肥在旱地中很容易经过硝化作用转变为硝态氮,其中一小部分为植物所吸收,而大量的硝态氮被淋失,或经反硝化作用进入大气,造成土壤氮素严重损失。自然界中一些植物的根系能够分泌抑制硝化作用的物质,被称为生物硝化抑制剂,因而可以显著提高土壤氮素利用率。本文阐述了有关生物硝化抑制剂的由来、分泌调节、作用机制及其应用潜力,并探讨了其在农业生产中氮素高效管理等方面的应用前景。     

Accumulation of Nutrients in Above and Below Ground Biomass in Response to Ammonium Sulphate Addition in a Norway Spruce Stand in Southwest Sweden

The effects of ammonium sulphate (NS) on the accumulation of nutrients in above and below ground biomass and soil were studied in a Norway spruce stand in south-west Sweden during 1988–1993. Ammonium sulphate addition resulted in nitrogen accumulation with 326 and 16 kg ha^?1 in above and below ground biomass, respectively. Corresponding figures for the control plots (C) were 34 and 3 kg ha^?1. Nitrogen accumulation in forest floor of NS was 266 kg ha^?1 and 47 kg ha^?1 in mineral soil. About 70% of added sulphate by fertiliser was retained in NS plots (482 kg S ha^?1) of which 274 kg ha^?1 was adsorbed in the mineral soil. The sulphate addition resulted in increased leaching of nitrogen, magnesium, calcium and sulphur. It is suggested that the spruce stand at the study site has a high capacity to accumulate nitrogen with a high above ground production. The high input of ammonium sulphate may in the long run result in increased losses of cations to ground water.     

不同间作播期和密度对甜瓜/向日葵间作系统氮素利用效率的影响

在大田条件下以甜瓜和向日葵为试材,研究两种作物单作和向日葵间作播期(甜瓜伸蔓期、开花坐果期、果实膨大期)、间作密度[高(24 975株·hm~(-2))、中(22 200株·hm~(-2))和低(19 980株·hm~(-2))]对间作系统和两种作物单作的氮素积累量、氮素利用效率和光能利用效率的影响。结果表明,间作显著提高了间作系统甜瓜的氮素累积和利用效率,却降低了向日葵的氮素累积和利用效率。间作甜瓜植株地上部的氮素累积量平均为195.08 kg·hm~(-2),较单作甜瓜(172.61 kg·hm~(-2))提高13.0%,氮素利用效率和氮肥偏生产力均显著高于单作(分别提高40.5%和55.4%)。间作系统向日葵氮素利用效率和氮肥偏生产力较单作降低8.2%和58.4%,而氮素收获指数较单作提高4.9%。在甜瓜伸蔓期、开花坐果期和果实膨大期间作向日葵,间作系统的氮素利用效率较同播期的单作向日葵分别提高43.5%、12.5%和59.8%;果实膨大期间作向日葵,间作系统的氮素利用效率较单作甜瓜提高6.7%。在甜瓜伸蔓期、开花坐果期和果实膨大期间作向日葵,间作系统的氮肥偏生产力较同播期的单作向日葵提高6.5%、32.1%和40.4%,较单作甜瓜分别降低22.5%、10.1%和34.3%;在甜瓜伸蔓期、开花坐果期和果实膨大期间作向日葵,间作系统的氮素收获指数较同播期的单作向日葵分别降低7.2%、7.7%和12.5%。高、中和低3个间作密度下,间作系统的氮素利用效率较同密度甜瓜单作分别降低14.2%、20.4%和13.9%,较向日葵单作分别提高25.2%、20.0%和9.5%,氮肥偏生产力较同密度甜瓜单作降低29.6%、15.6%和21.1%;高密度和低密度间作处理的间作系统氮素收获指数较向日葵单作提高2.7%和1.4%,而中密度间作降低7.6%。间作系统甜瓜的光能利用效率与氮素利用效率呈显著正相关关系,向日葵的光能利用效率与氮素利用效率无显著相关。在河西绿洲灌溉条件下,氮素利用率较高的适宜向日葵间作播期为甜瓜果实膨大期,适宜间作株距为40 cm(密度为24 975株·hm~(-2))。     

平衡减量施肥和行间配植对白茶园氮磷流失的影响

安吉白茶经济效益高,施肥量大,茶园氮磷流失已成为西苕溪流域农业面源污染的主要来源之一.通过2个生长周期的野外径流小区试验连续观测了减量施肥和行间配植乔木控制白茶园氮磷径流损失的效应.试验设置习惯施肥处理(CK)、减氮减磷处理(T1)、减磷+配植合欢处理(T2)和减氮减磷+配植合欢处理(T3)4个处理,各处理重复2次.结...     

Winter wheat fertilizer nitrogen use efficiency in grain and forage production systems

Abstract

Nitrogen use efficiency (NUE) is known to be less than fifty percent in winter wheat grain production systems. This study was conducted to determine potential differences in NUE when winter wheat (Triticum aestivum L.) is grown strictly for forage or grain. The effects of different nitrogen rates on plant N concentrations at different growth stages and on grain yield were investigated in two existing long‐term winter wheat experiments near Stillwater (Experiment 222) and Lahoma (Experiment 502), OK. At both locations in all years, total N uptake was greater when wheat forage was harvested twice (Feekes 6 and flowering) compared to total N uptake when wheat was grown only for grain. Percent N content immediately following flowering was much lower compared to percent N in the forage harvested prior to flowering, indicating relatively large losses of N after flowering. Averaged over locations and years, at the 90 kg N ha^?1 rate, wheat produced for forage had much higher NUE (82%) compared with grain production systems (30%). While gaseous N loss was not measured in this trial, the higher NUE values found in the forage production systems were attributed to harvesting prior to anthesis and the time when plant N losses are known to be greater.     

施用包膜尿素对水稻生长和氮磷流失的影响

施用新型肥料是减少养分径流损失的重要途径。采用田间试验研究了施用包膜尿素对水稻生长和径流氮磷损失的影响,试验设置CK(习惯施肥)、PU1(减磷41%、减氮20%、施普通尿素)、PU2(PU1基础上减氮13%)、UR1(PU2基础上施包膜尿素)和UR2(UR1基础上减氮13%)5个处理。结果表明:PU1和UR1处理水稻氮磷含量与CK处理相近,PU1成熟期氮、磷总积累量比CK增加11.21,2.69kg/hm~2。PU1和UR1处理成熟期地上部生物量和籽粒产量高于CK处理,籽粒产量分别提高7.68%,5.77%。PU1、PU2、UR1和UR2处理径流总磷含量和累积流失量比CK处理低,减少13.18%~21.51%。施用包膜尿素(PU1、PU2)处理径流总氮、铵氮和硝氮含量低于施用普通尿素(CK、UR1、UR2)处理;稻田径流总氮、铵氮和硝氮累积流失量分别减少12.90%~26.91%,54.52%~49.38%和4.03%~15.95%,其中包膜尿素处理铵氮累积流失量显著(P0.05)小于普通尿素处理。施用包膜尿素和优化施肥能促进水稻对氮磷养分的吸收,提高水稻籽粒产量,显著减少稻田氮磷流失量,值得在水稻生产中推广应用。     

The potential for volatilization losses of applied nitrogen fertilizers from northern Idaho soils

Abstract

Up to 70% applied ammonium‐based nitrogen (N) fertilizers can be lost by volatilization in agricultural soils. The purpose of this experiment was to determine the effects of fertilizer treatment, water potential, and time on volatilization losses in three northern Idaho soils under laboratory conditions maintained at 25°C. A completely randomized block factorial design with repeated measures (3 soils x 4 fertilizer treatments x 2 soil water potentials x 3 replications‐measured at 0,2,4, 8, and 16 d) was utilized in this study. The four fertilizer treatments consisted of 200 kg N/ha applied as: (1) surface‐applied ammonium nitrate (AN), (2) surface applied ammonium sulfate (AS), (3) surface applied urea (Ysur), and (4) incorporated urea (Uinc). Data were analyzed by SAS‐GLM and Omega squared (ω²) values were used to identify the impact of each main effect and interaction. A 4‐factor interaction of fertilizer treatment (NIT) x soil (SL) K water potential (WP) x time of incubation (IT), four‐3 factor interactions, six‐2 factor interactions and four main effects were found to be significant in this study. Due to the number of significant sources of variation, ω² values were used to assess their relative importance. The soil x fertilizer treatment interaction accounted for 27.3% of the variation in this study. Nitrogen loss after 16 d of incubation from the Usur treatment was 37.8% in the Devoignes silt loam, 18.7% in the Santa silt loam, 4.9% in the Schnoorson silt loam. Volatilization of N from the Uinc and AS treatments was greater in the Devoignes silt loam than the Santa and Schnoorson soils. Conversely, differences in volatilization losses from AN were not observed among the three soils. Fertilizer treatment was the second most important factor accounting for 21.4% of the variability. Losses of 20.5, 2.6, 1.9, and 1.3% were observed for the Usur, Uinc, AS, and AN treatments, respectively. This study demonstrated that: (1) volatilization losses may be significant for surface applications of urea on some Idaho soils; however, incorporation of urea will reduce this hazard, and (2) volatilization losses are minimal when AN and AS are the N fertilizer sources.     

Modelling nitrogen transport and transformation in a transplanted rice field experiment with reduced irrigation

Application of water-saving irrigation technologies in transplanted rice (TPR) cultivation resulted in different soil water regimes compared to traditional flood irrigation and consequent diverse nitrogen transport and losses in paddy fields. In this study, nitrogen transport and transformations in a TPR field under multiple shallow irrigation (MSI) conditions in the Taihu Lake Basin of Eastern China were observed and simulated (Hydrus-1D model) during the 2008 and 2009 seasons based on a previous study. MSI controlled well the depth of floodwater and reduced nitrogen losses substantially through percolation and surface runoff, in particular during the 2008 season with relative less rainfall. Nitrogen balance analysis showed that both denitrification and NH₃ volatilisation were the two major paths of nitrogen loss during the two seasons. Most nitrogen transformations occurred in top soil (0–40?cm) during early-middle seasons. The overall nitrification and denitrification differed slightly between the two seasons but largely between soil depths, averagely 92.7% and 73.0% of respective total in a 120?cm soil profile occurred in 0–40?cm soil, respectively. MSI method coupled with deep applied fertiliser is recommended to substantially reduce nitrogen losses through surface runoff, percolation, and NH₃ volatilisation in TPR fields.     

锡林河流域温带草原土壤的净氮矿化研究

氮素矿化是决定土壤供氮能力的重要过程,也是目前国内外研究的热点。该文采用树脂芯方法测定了内蒙古锡林河流域不同温带草原土壤在雨季期间的净氮矿化率,对树脂芯方法在温带草原的应用效果进行了评价。结果表明,实验期间贝加尔针茅草原、羊草草原和大针茅草原土壤的平均日净氮矿化率分别为0.035、0.120和0.125 kg/(hm²·d);树脂芯方法对草原土壤氮转化过程干扰较小,是自然条件下研究温带草原土壤净氮矿化的有效手段。     

Losses of Solids,Moisture, Nitrogen,Phosphorus, Potassium,Carbon, and Sulfur from Laying-Hen Manure in Storage Facilities

The losses of total solids, moisture, nitrogen (N), phosphorus (P), potassium (K), carbon (C), and sulfur (S) were determined in two storage events of laying-hen manure immediately removed from three different housing systems in Iowa, USA. The three laying-hen houses were conventional cage (CC), enriched colony (EC), and aviary (AV). The houses held a nominal number of 200,000, 46,700, and 50,000 Lohmann LSL lite layers, respectively. The manure collected on belts in each house was cleaned out twice a week. A fraction of the cleaned out manure was transferred to designated storage rooms wherein losses of different components were determined in two storage events. Manure was loaded into the storage rooms over 171 days during the first storage event and over 185 days during the second storage event. The total storage periods were 202 and 245 days, respectively, for the first and second storage events. Manure was weighed, sampled, and analyzed before it was loaded into the storage rooms and at the end of each storage event. Mass balance calculations were used to determine the losses of different components. Statistical analyses show that the nutrient contents, on a wet basis, of manure loaded in CC, AV, and EC storage rooms were significantly different due to the differences in manure moisture contents. However, on a dry basis, they had no significant differences. The fresh manure cleaned out from the EC layer house was drier than that from the other two houses. Loaded-in nitrogen losses in the CC, AV, and EC storage rooms were 24.6, 12.9, and 20.8%, respectively. Nitrogen losses depended on house temperature, manure moisture, and pH. The average losses of loaded-in manure mass, moisture, and total solids during the two storage events were 27.6?±?1.9, 33.8?±?8.3, and 20.8?±?7.0%, respectively. The losses of N, P, K, C, and S were 19.4?±?13.4, 11.7?±?5.6, 10.2?±?6.8, 27.0?±?6.5, and 8.3?±?8.5% of their loaded-in amounts, respectively. The total loss of N, P, K, C, and S was 56% of the total loaded-in solids loss; thereof, the loss of N, P, and K was 7%, and C loss was 48%. The laying-hen-specific losses of N, P, K, C, and S were 0.34, 0.05, 0.08, 3.2 and 0.019 g day^?1 hen^?1, respectively. The results of this research are important for assessing impacts of stored manure on environment and nutrient losses. They can also be used to develop methodologies for the mitigation of the emissions from egg production facilities.     

Nitrate leaching from short-rotation coppice

In the UK, short‐rotation coppice (SRC) is expected to become a significant source of ‘bio‐energy’ over the next few years. Thus, it is important to establish how nitrate leaching losses compare with conventional arable cropping, especially if SRC is grown in Nitrate Vulnerable Zones. Nitrate leaching was measured using porous ceramic cups in each of the three phases in the lifespan of SRC, establishment, harvest and removal and was compared with conventional arable cropping. Nitrogen concentrations were increased in drainage water as soon as the crop cover was destroyed to plant the SRC (peak 70 mg L^?1 nitrate‐N) and increased further (peak 134 mg L^?1 nitrate‐N) on cultivation. Once the coppice crop was established, concentrations returned to a smaller level (average 18 mg L^?1 nitrate‐N). Concentrations were not affected by the harvesting operation, and annual applications of nitrogen (40, 60 and 100 kg ha^?1 N in the first, second and third years, respectively) had little effect. By contrast, concentrations in the arable rotation showed a regular pattern of increase in the autumn, and the average peak value over the 4 years was 54 mg L^?1 nitrate‐N. When the SRC was ‘grubbed up’ and roots removed, the soil disturbance resulted in a flush of mineralization which, combined with a lack of crop cover, led to increased nitrate‐N in leachate (peak 67 mg L^?1 nitrate‐N). In a normal life‐span of SRC (15–30 years), the relatively large nitrate losses on establishment and at final grubbing up would be offset by small losses during the productive harvest phase, especially when compared with results under the arable rotation.