不同水、氮供应条件下夏玉米养分累积动态研究

在遮雨棚内进行了微区试验,采用不同水、氮素供应研究了玉米N、P、K吸收累积动态。结果表明,植株生物量和N、P、K吸收量,随生育期延长而持续增加;而植株的N、P、K含量,则呈下降趋势。植株生物量和N、P、K吸收量随时间的变化,可用S曲线方程描述。玉米生长期间干物质与养分吸收并非同一速率,前期上升快,至最高峰后缓慢下降。在N、P、K三要素中,N、K吸收速率高,上升快,下降也快;P吸收速率低,上升慢,下降亦慢。养分最大吸收速率出现的时间以K最早,N次之,P最晚。但三者均早于干物质最大累积速率出现的时间。水分和氮素供应增加养分最大吸收速率及养分吸收量,也可增加生育前期的养分含量,但不改变养分累积变化趋势和养分吸收速率的变化趋势。水分和氮素供应促进了营养体养分向子粒的运转,提高了养分在子粒中的分配比例,从而提高了子粒产量。     

CO2浓度升高、氮和水分对春小麦养分吸收和土壤养分的效应

研究了 2种CO2浓度水平 ,2种土壤水分处理和 5种N肥施用水平对春小麦 (TriticumaestivumL cv DingxiNo. 8654)养分吸收和土壤速效养分的影响。结果表明 ,高CO2浓度 (700 molmol-1)明显降低春小麦对氮(N)的吸收 ,低N时降低更为明显 ,但对磷 (P)、钾 (K)吸收的影响不明显。小麦对N、P、K吸收 ,干旱处理明显比湿润处理低。CO2浓度增高对土壤速效N的影响与土壤水分状况有关。湿润处理 ,CO2浓度增加的处理速效N量比当前CO2浓度的处理低 ;而干旱处理 ,施N 50、100、150mgkg-1时 ,速效N则较高。高CO2 浓度对土壤速效P、K量的影响不明显 ,而低N和水分不足 ,土壤速效P、K量较高     

不同供氮水平对夏玉米养分累积、转运及产量的影响

通过田间小区试验,研究了高肥力土壤上施N.125、250、375.kg/hm2对夏玉米生物量、子粒产量、N、P、K养分累积动态、及氮肥表观利用率、养分转运的影响。结果表明,不同施氮量只影响夏玉米不同生育时期养分的阶段累积量,而对累积趋势基本无影响。植株生物量及N、P、K养分累积量随生育期的延长而增加,且它们的累积趋势相似,都呈S型曲线。各处理的子粒产量在7000～7700.kg/hm2之间,只有N250处理增产达显著水平;氮肥表观利用率在10%～18%之间,随施氮量的增加略有降低。施氮可提高子粒中的氮素累积量,而对磷的累积量影响不大。随着施氮量的增加,氮素的转运量、转运效率及其在子粒中的比例都降低,磷的转运与氮表现出类似的趋势。综合考虑产量、氮肥利用率、养分转运及环境污染等因素,该地区夏玉米的推荐施氮量应控制在125.kg/hm2以内。     

长期施肥对红壤旱地玉米生物量及养分吸收的影响

基于江西进贤旱地长期施肥定位试验田,研究不同施肥模式下玉米不同器官的生物量、养分吸收与分配及其与土壤养分的关系.结果表明:(1)长期施用化肥导致土壤pH值下降,不合理施肥使土壤养分含量有不同程度的下降,有机无机肥配施能有效缓解土壤酸化,显著提高土壤有机碳和有效养分含量.(2)与对照相比,N处理降低了玉米籽粒、穗轴、秸秆和根茬的生物量,而均衡施肥(NPK、2NPK)及有机肥处理(NPKOM、OM)使玉米籽粒增产1.1～2.9倍,并提高了其他器官的生物量.土壤酸碱度、有机质及N、P养分对玉米籽粒的产量影响显著,土壤K养分对玉米生物量影响相对较小.(3)玉米对N的吸收主要集中在籽粒和秸秆,分别占总吸N量的41.8％～61.3％和30.3％～48.4％,P在籽粒中的吸收量高达61.8％～73.9％,K的吸收主要集中在秸秆,占总吸K量的51.4％～67.9％.有机无机肥配施模式则显著促进了作物各器官对养分的吸收和提高作物产量.作物养分的收获指数为P＞N＞K.     

不同施肥处理对白菜的物质积累与养分吸收的影响

研究了在洞庭湖平原的冲积性菜园土条件下,不同施肥结构对白菜生育期间的物质积累与白菜对N,P,K养分的吸收规律以及土壤有效N,P,K养分的动态变化.结果表明,不同处理白菜的产量相差较大,各施肥处理比不施肥对照平均增产达33.1%,但各施肥处理之间产量差异不显著.白菜对N,P,K养分的吸收都是在移栽30 d以后的生长中、后期,与其地上部生物产量的积累规律一致.专用肥处理和有机无机肥配施处理明显促进白菜对N,P,K养分的吸收.从而提高白菜对肥料养分的利用率.当地习惯施肥处理的N,P施用量明显过大,浪费肥料,也对当地水体及环境造成污染.其施K量明显低于白菜一季的总吸钾量,既影响白菜产量和品质,也造成土壤K素的耗竭.根据不施肥对照和4个平衡施肥处理白菜地上部分的养分吸收总量结果,以白菜对肥料N,P,K的当季利用率分别为40%,25%和60%计算,供试土壤条件下白菜一季所需N,P_2O_3,K_2O的施用量分别为195.25 kg/hm~2,145.60 kg/hm~2,228.53 kg/hm~2.其N:P_2O_5: K_2O值为1:0.75-1.17.     

菌肥减施对结球甘蓝养分吸收及利用的影响

为探讨功能菌型复合肥及化肥减量条件下栽培蔬菜的养分吸收特性及利用特征,在露地和大棚种植体系下,以结球甘蓝为试验材料,采用田间小区试验研究不同养分配比功能菌型复合肥及减量施用对结球甘蓝物质积累、养分吸收及肥料利用率的影响。结果表明,不同种植体系下,施肥处理对结球甘蓝生长后期干物质累积及N、P、K养分吸收速率,收获期N、P、K累积及肥料利用率效应显著。与常规施肥处理相比,露地和大棚种植体系下施用功能菌型复合肥处理结球甘蓝收获期干物质累积量分别增加2.4%~5.7%和4.9%~10.8%,N肥吸收利用率分别增加10.8~35.4和9.4~57.6个百分点。减量25%功能菌型复合肥处理较等量处理结球甘蓝N累积量分别增加2.6%~2.7%(露地)和4.4%~10.8%(大棚),P累积量分别增加1.6%~1.9%(露地)和7.0%~8.2%(大棚),K累积量分别增加1.5%~2.3%(露地)和0.9%~2.0%(大棚)。结球甘蓝各生育阶段对N、K(露地)吸收速率变化表现为结球-收获期>莲座-结球期>苗期-莲座期,而对P、K(大棚)吸收速率变化表现为莲座-结球期>结球-收获期>苗期-莲座期。施用功能菌型复合肥在一定程度上能有效增加不同种植体系中结球甘蓝植株N、P、K养分吸收速率及养分累积,从而提高蔬菜的肥料利用效率。总体而言,在不同种植体系下,施用不同养分配比功能菌肥可有效提高结球甘蓝的物质积累、养分吸收及肥料利用率,且适宜减量施用能进一步增加其作用效果,但应根据土壤肥力特征、作物需肥特性及栽培管理模式合理地进行选择施用。     

黄土高原旱地长期施肥对小麦养分吸收和土壤肥力的影响

通过定位试验研究了长期施肥对小麦子粒、秸杆养分吸收和土壤肥力变化的影响。结果表明,合理施用化肥不但增产幅度大,还在一定程度上增加了小麦N、P、K养分浓度。单施氮、单施磷肥能增加小麦子粒和秸杆的N、P、K吸收量,氮磷肥配施增加效果显著,其子粒吸收N、P、K增加了153.2%、157.1%和162.4%。施有机肥能补充土壤中的N、P、K含量,增加小麦子粒中的养分含量,使品质有大幅度的提高。单施磷肥的土壤有机质、全P、速效P含量增加,土壤全N、速效N含量减少,N素亏缺。氮磷肥配施加剧了土壤K的亏缺。有机肥培肥作用显著,有机肥和氮、磷肥配施的土壤有机质、全N、全P、速效N、速效P和速效K分别增加了69.0%5、7.5%、54.8%、73.1%、830.5%和119.1%。     

不同产量水平的玉米田养分利用效应比较

采用大田试验方法,在不同土壤肥力水平和不同管理措施导致产量水平明显不同的玉米田中,对植株对氮、磷、钾养分的吸收、运转及利用效应进行了分析比较。结果表明,玉米对N、P吸收呈双峰趋势变化,吸收高峰均为拔节—大喇叭口期和灌浆—成熟期,K呈单峰吸收,但高产田和常规田出现在大喇叭口—吐丝期,低产田K吸收高峰提前至拔节—大喇叭口期。与常规田和低产田相比,高产田玉米对N、P、K养分的累积量、玉米营养体贮藏N、P、K养分的运转量和运转率,以及玉米营养体N、P养分向籽粒的转移效率均明显提高,但单位养分的生产效率以及氮、钾养分的生理效率降低。     

施肥对红壤地区直播油菜生长、产量及养分吸收的影响

2009～2010年在江西典型红壤地区设置直播油菜氮磷钾硼肥田间试验,研究施肥对直播油菜生长发育、籽粒产量及N、P、K养分吸收与累积的影响。结果表明,红壤上直播油菜各施肥处理中以NPKB处理的籽粒产量和施肥效益最高,分别为1 722 kg/hm2和1 469元/hm2,而N、P、K、B任何一种养分缺乏均影响油菜的正常发育和籽粒产量。本试验条件下,红壤直播油菜的养分限制因子为P>B>N>K。施肥对直播油菜N、P、K养分的吸收和累积有明显影响,各养分间存在相互影响和制约的关系,NPKB处理最有利于养分吸收及累积,其氮、磷、钾肥吸收利用率分别为29.3%、59.5%和89.1%,均为最高。红壤地区直播油菜的高产应积极推广氮磷钾硼肥平衡配施措施,并实行氮、钾肥分次施用。     

氯对白菜幼苗的生长及养分吸收的影响

采用土培实验，研究了外源氯（CK，低氯，中氯，高氯）对大白菜 [Brassica campestris L. ssp. Pekinesis (Lour)Olsson]幼苗叶绿素含量、根系活力以及对N、P、K养分吸收、累积的影响。结果表明:低浓度氯处理对大白菜幼苗没有明显的影响。中氯和高氯处理，都显著降低了白菜幼苗生物量、叶绿素含量和根系活力。随着氯浓度的升高，白菜幼苗叶片和根Cl-含量显著升高，中氯处理Cl-累积量最高，过量的氯降低了N、P、K养分在白菜幼苗体内的累积。氯胁迫抑制作物根系活力和光合作用从而减少主动养分的有效供应是造成生物量降低的主要原因。     

氮肥减施对稻-麦轮作体系作物氮素吸收、利用和土壤氮素平衡的影响

田间试验研究了稻-麦轮作体系中减施氮肥对作物氮素吸收、利用和土壤氮素平衡的影响。结果表明,与当地习惯施肥(小麦:N 225 kg/hm2,基肥与分蘖肥各半;水稻:N 210 kg/hm2,基肥和分蘖肥为3∶2)相比,减氮20%～30%处理产量并没有降低,而氮肥当季利用率、氮素农学利用率以及氮素偏因子生产力则有所增加;而且,氮肥分次追施,能增加子粒产量,并减少氮肥成本。虽然减氮20%～30%处理0—40 cm土层无机氮含量较习惯施肥处理降低,但是并没有降低植株地上部对氮素的吸收。在小麦和水稻收获期,减施氮肥处理0—100 cm土壤无机氮残留量低于习惯施肥处理;且稻-麦轮作系统中氮的表观损失主要发生在水稻季。初步认为,在长江中下游平原稻-麦轮作体系氮素过量施用地区,第一个轮作周期减施氮肥20%～30%不仅不影响产量,而且可提高氮素利用率,有利于保护环境。     

Yield,N Uptake and N Utilization of Early Maturing,Drought and Striga-Tolerant Maize Varieties under Low N Conditions

Performance under sub-optimal nitrogen (N) conditions, of early maturing maize cultivars bred for tolerance to drought and Striga parasitism in the Nigerian savanna is not known. This study evaluated the tolerance of selected early maturing drought and Striga-tolerant maize cultivars to low N conditions in Northern Nigeria. The cultivars were evaluated at 30 and 100 kg N ha^?1. The varieties were compared with an improved maize cultivar that is not tolerant to drought and Striga. Maize grain yield was 26% higher at 100 kg N ha^?1 than at 30 kg N ha^?1 in 2010 and 161% higher100 kg Nha^?1 than at 30 kg Nha^?1 in 2011. The drought and Striga-tolerant varieties produced consistently higher yields than the non-drought-tolerant variety particularly at 30 kg Nha^?1. These cultivars also accumulated higher amount of N, had higher N-uptake efficiency or N-utilization efficiency than the non-drought-tolerant variety ACR 95 TZE-COMP4 C3. Grains yield at low nitrogen rate was associated with high ears m^?2, high dry matter accumulation, high grains m^?2, suggesting that these traits are linked to low-N tolerance. The good performance of the drought-tolerant maize varieties under low N suggests that varieties developed for drought tolerance may be tolerant to low-N conditions.     

OPTIMAL N FERTILIZATION,USING TOTAL AND MINERAL N,AFFECTING CORN (ZEA MAYS L.) GRAIN N UPTAKE

Measurement of total and mineral nitrogen (N), resulted by the presence of soil organic matter, would make the more precise determination of N fertilization possible with respect to the amounts of N absorbed by crop grains. Such a test requires a wide range of soil properties and observations. Accordingly, in a three-year experiment, grain N uptake and soil total and mineral N were determined using different analytical methods (standard laboratory and the N-Trak quick method). The other experimental treatments consisted of sampling time (seeding and postseeding where plants were about 30 cm tall), sampling depths (0–30 and 30–60 cm) as well as the condition of samples (wet or dry). Using regression equations the effects of N fertilization and soil total and mineral N on the uptake of grain N was investigated. Accordingly, the proposed N test predicted the optimum N fertilizer amounts of 236 to 271 kg ha^?1 for corn production.     

Influence of Long-term Tillage,Straw, and N Fertilizer Management on Crop Yield,N Uptake,and N Balance Sheet in Two Contrasting Soil Types

Field experiments (established in autumn 1979, with monoculture barley from 1980 to 1990 and barley/wheat–canola–triticale–pea rotation from 1991 to 2008) were conducted on two contrasting soil types (Gray Luvisol [Typic Haplocryalf] loam soil at Breton; Black Chernozem [Albic Agricryoll] silty clay loam soil at Ellerslie) in north-central Alberta, Canada, to determine the influence of tillage (zero tillage and conventional tillage), straw management (straw removed [S_Rem] and straw retained [S_Ret]), and N fertilizer rate (0, 50 and 100 kg N ha^?1in S_Ret, and only 0 kg N ha^?1in S_Rem plots) on seed yield, straw yield, total N uptake in seed + straw (1991–2008), and N balance sheet (1980–2008). The N fertilizer urea was midrow-banded under both tillage systems in the 1991 to 2008 period. There was a considerable increase in seed yield, straw yield, and total N uptake in seed + straw with increasing N rate up to 100 kg N ha^?1 under both tillage systems. On the average, conventional tillage produced greater seed yield (by 279 kg ha^?1), straw yield (by 252 kg ha^?1), and total N uptake in seed + straw (by 6.0 kg N ha^?1) than zero tillage, but the differences were greater at Breton than Ellerslie. Compared to straw removal treatment, seed yield, straw yield, and total N uptake in seed + straw tended to be greater with straw retained at the zero-N rate used in the study. The amounts of applied N unaccounted for over the 1980 to 2008 period ranged from 1114 to 1846 kg N ha^?1 at Breton and 845 to 1665 kg N ha^?1 at Ellerslie, suggesting a great potential for N loss from the soil-plant system through denitrification, and N immobilization from the soil mineral N pool. In conclusion, crop yield and N uptake were lower under zero tillage than conventional, and long-term retention of straw suggests some gradual improvement in soil productivity.     

氮肥减量后移对玉米产量和氮素吸收利用及农田氮素平衡的影响

田间试验研究了不同土壤氮素供应水平和底追比例对玉米籽粒产量、土壤硝态氮和农田氮素平衡的影响.与农民习惯施肥(N 240 kg·hm-2,基肥和大喇叭口追肥为1∶2)相比,氮肥减量10％(N 216 kg· hm-2)和20％ (N 192kg·hm-2)处理的玉米产量并没有降低,而氮肥利用效率显著增加.氮肥减量后移可使耕层无机氮供应较好地与作物吸收同步,降低收获期0～100 cm土层的硝态氮积累,减少氮素的田间表观损失,提高氮肥利用效率.在本试验条件下,氮肥减量20％(N 192 kg·hm-2),基追比例1∶3∶1处理的植株产量、地上部植株氮肥吸收利用率、氮肥农学利用率均较高,0～100 cm土层未出现硝态氮明显累积,氮素表观损失量最少,是最佳施氮运筹模式.     

N Cycle, N Flow Trends in Japan, and Strategies for Reducing N2O Emission and NO3^- Pollution

To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, livestock wastes,and municipal and agricultural wastes, with national and international concern about its potential adverse effects on environmental quality and public health. To understand these phenomena and problems, first the nitrogen cycle and the environment are described. Then recent trends for nitrogen cycling through the food and feed system, N2O emissions from fertilized upland and paddy soils, and NO3^- pollution in ground water in Japan are reported. Finally, mitigation strategies in Japan for reducing N2O emission and NO3^- pollution are proposed, including nitrification inhibitors, controlled release fertilizers, utilization of plant species that could suppress nitrification, utilizing the toposequence, government policy, and appropriate agricultural practices. Of all the technologies presented, use of nitrification inhibitors and controlled release fertilizers are deemed the most important with further development of these aspects of technologies being expected. These practices, if employed worldwide, could help reduce the load, or environmental deterioration, on the Earth‘s biosphere.     

不同施氮量对夏玉米产量、氮肥利用率及氮平衡的影响

通过田间小区试验研究了不同施氮量对夏玉米产量、氮肥利用率、硝酸盐淋溶及氮平衡的影响。结果表明,施氮对夏玉米子粒有显著的增产作用,但随施氮量的增加产量变化不大。氮肥利用率在9.2%~22.6%之间,随施氮量的增加而降低。施氮可明显提高0~160 cm剖面土壤NO3--N含量,而且随深度的增加NO3--N含量呈降低趋势,累积峰主要在20~60 cm之间。玉米收获后,随着施氮量的增加氮素的损失量增加,各施氮处理的硝态氮残留量在121~221 kg/hm2之间,以N250处理的残留量最高,残留率近65%。     

不同施氮量对夏玉米产量、氮肥利用率及氮平衡的影响

通过田间小区试验研究了不同施氮量对夏玉米产量、氮肥利用率、硝酸盐淋溶及氮平衡的影响。结果表明，施氮对夏玉米子粒有显著的增产作用，但随施氮量的增加产量变化不大。氮肥利用率在9．2％-22．6％之间，随施氮量的增加而降低。施氮可明显提高0-160cm剖面土壤NO3^--N含量，而且随深度的增加NO3^--N含量呈降低趋势，累积峰主要在20—60cm之间。玉米收获后，随着施氮量的增加氮素的损失量增加，各施氮处理的硝态氮残留量在121～221kg／hm^2之间，以N250处理的残留量最高，残留率近65％。     

Kinetics of C and N mineralization, N immobilization and N volatilization of organic inputs in soil

C and N mineralization data for 17 different added organic materials (AOM) in a sandy soil were collected from an incubation experiment conducted under controlled laboratory conditions. The AOM originated from plants, animal wastes, manures, composts, and organic fertilizers. The C-to-N_AOM ratios (η_AOM) ranged from 1.1 to 27.1. Sequential fibre analyses gave C-to-N ratios of soluble (η_Sol), holocellulosic (η_Hol) and ligneous compounds (η_Lig) ranging from 1.1 to 57.2, 0.8 to 65.2, and 3.5 to 25.3, respectively. Very different patterns of net AOM-N mineralization were observed: (i) immobilization for four plant AOM; (ii) moderate mineralization (4-15% AOM-N) for composts; (iii) marked mineralization (11-27% AOM-N) for 1 animal AOM, 1 manure and 2 organic fertilizers; and (iv) high rates of transformations with possible gaseous losses for some N-rich AOM.The Transformation of Added Organics (TAO) model proposed here, described AOM-C mineralization (28 °C, 75% WHC) from three labile (L′), resistant (R) and stable (S) compartments with the sole parameters P′_L and P_S=fractions of very labile and stable compounds of AOM, respectively. Dividing the C-compartments by their C-to-N estimates supplied the remaining N_AOM fraction (RAONF). A P_im parameter split the TAO nitrogen fraction (TAONF=added N-RAONF) into two compartments, immobilized (imN) and inorganic (inorgN) N. A P_im>0 value meant that all the TAONF plus a fraction (P_im−1) of native soil inorganic N was immobilized. Additional N mineralization was predicted when necessary from imN by first order kinetics (constant k_remin). The TAO version with two parameters P_im and k_remin allowed us to predict very different patterns of N mineralization and N immobilization. In a few cases, a further first order kinetic law (constant k_v) was added to predict N volatilization from inorgN. Two hypotheses were tested: (i) η_L′, η_R, η_S (C-to-N of L′, R and S)=η_Sol, η_Hol, η_Lig, respectively, (ii) η_L′=η_R=η_S=η_AOM. The first hypothesis was validated by these data, and the second was a good approximation of the former one. In all the cases, predictions were in good agreement with measured values.     

Availability of N from Casuarina residues and inorganic N to maize, using 15N isotope techniques

 The contribution of N from Casuarina equisetifolia (casuarina) residues to maize with inorganic N (ammonium sulphate) supplementation was studied in a pot experiment using ¹⁵N labelling techniques. A single rate of N application of 100 mg N kg^–1 soil was applied as N-ammonium sulphate in combination with casuarina residues in the proportions 100 : 0; 75 : 25; 50 : 50; 25 : 75 and 0 : 100, respectively. The directly ¹⁵N-labelled casuarina residue and indirect labelling (unlabelled casuarina + ¹⁵N soil) were compared to estimate the proportion and amount of N derived from the residue and fertilizer. The application of ammonium sulphate at a high rate significantly affected shoot dry matter (P<0.05) and likewise reduced the contribution of soil-derived N compared to residues. Total recoveries by maize of residue N and applied fertilizer N averaged 11% and 24%, respectively. Residue and fertilizer use efficiencies were not influenced by the addition of different rates of fertilizer or residue. The estimation of the contribution of N from different sources showed that direct measurement of the ¹⁵N-labelled organic source was more reliable. Received: 10 September 1997