水氮配合对绿洲沙地农田玉米产量、土壤硝态氮和氮平衡的影响

在黑河中游边缘绿洲沙地农田研究了不同的水氮配合对玉米产量、土壤硝态氮在剖面中的累积和氮平衡的影响.结果表明,施氮处理较不施氮处理产量增加48.22%～108.6%,施氮量超过225 kg hm-2,玉米产量不再显著增加.受土壤结构影响土壤硝态氮在土壤中呈"W"型分布,即土壤硝态氮含量在0～20 cm、140～160 cm和260～300 cm土层均出现峰值,并随施氮量增加,峰值增高.在常规高灌溉量处理硝态氮含量峰值最高值出现在260～300 cm土层,节水25%灌溉处理硝态氮含量峰值最高值出现在土壤表层0～20 cm土层.在常规高灌溉量处理0～300 cm土层中200～300土层硝态氮累积量所占比例最高,介于27.56%～51.86%之间;节水25%灌溉处理在0～300 cm土层中100～200土层硝态氮累积量所占比例最高,介于32.94%～38.07%之间;表明低灌溉处理下土壤硝态氮在土壤浅层累积较多,而高灌溉处理使更多的硝态氮淋溶至土壤深层.与2006年相比,2007年不施氮处理0～200 cm土层土壤硝态氮含量和积累量均明显减少;而施氮处理变化很小,在低灌溉处理甚至表现出硝态氮含量和积累量增加,表明施氮是土壤硝态氮累积的主要来源,而灌溉则使硝态氮向土壤深层淋溶.0～200 cm 土层土壤硝态氮累积量平均介于27.66～116.68 kg hm-2、氮素表观损失量平均介于77.35～260.96 kg hm-2,和施氮量均呈线性相关,即随施氮量增加,土壤硝态氮累积量和氮素表观损失量均增加,相关系数R2介于0.79～0.99之间,相关均显著.随施氮量增加,玉米总吸氮量和氮收获指数增加,氮的农学利用率降低,而灌溉的影响较小.施氮量超过225 kg hm-2时,地上部植株氮肥吸收利用率和籽粒氮肥吸收利用率开始有降低趋势.所以,在沙地农田,节水10%～25%的灌溉水平和225 kg hm-2的施氮水平可以在避免水肥过量投入的基础上减少土壤有机氮淋溶对地下水造成的污染威胁.     

The effect of deep placement and surface application of nitrogen fertilizers at different light intensities on growth and yield of wetland rice

Summary Lowland rice (RD 3) was cultivated in containers of clay soil submerged with 5 cm water under controlled conditions in the phytotron. Deep placement of urea supergranules 5 cm in the soil significantly enhanced both plant growth and fertilizer efficiency when the plants were cultivated under high light intensity (70 Wm^–2). At the highest urea level grain yield increased 119% above the control level, while growth and fertilizer efficiency was not as high when deep placement of calcium nitrate was used.The application of urea prills and calcium nitrate (18.4g Nm^–2) in two split doses on the soil surface increased grain yield as much as 91% above the control level. At the lower nitrogen concentration (9.2 g N m^–2), the urea prills were more efficient than calcium nitrate as indicated by the grain yield. The height of those plants fertilized by surface application was affected by the concentration and not the type of fertilizer. The number of tillers, however, was significantly higher on urea fertilized plants.When the rice plants were cultivated under low light intensity 930 Wm^–2), neither the nitrogen fertilizers nor the method of application had a significant effect on growth and yield.     

Movement of nitrate,chloride, and potassium in a sandy loam soll

Summary This study was conducted to measure the movement of nitrogen, chloride, and potassium in a sandy loam soil under field conditions and with controlled sprinkle irrigation. After 62.5 mm of water was applied, soil nitrate measurements indicated 67 per cent of the applied N fertilizer was lost from the upper 105 cm of the soil profile. Following a cumulative irrigation of 112.5 mm of water, 82 per cent of the applied N was lost. Since the chloride movement and redistribution was almost identical to the nitrate movement pattern, it would seem plausible that most of the nitrates were lost from the upper part of the soil by leaching. The potassium movement involved the redistribution of exchangeable K from the 0–8 cm soil zone into the 8–15 cm zone and with some buildup of K occurring in the 15–30 cm soil layer. re]19741126 rv]19751111     

Crop performance, nitrogen and water use in flooded and aerobic rice

Irrigated aerobic rice is a new system being developed for lowland areas with water shortage and for favorable upland areas with access to supplementary irrigation. It entails the cultivation of nutrient-responsive cultivars in nonsaturated soil with sufficient external inputs to reach yields of 70–80% of high-input flooded rice. To obtain insights into crop performance, water use, and N use of aerobic rice, a field experiment was conducted in the dry seasons of 2002 and 2003 in the Philippines. Cultivar Apo was grown under flooded and aerobic conditions at 0 and at 150 kg fertilizer N ha^–1. The aerobic fields were flush irrigated when the soil water potential at 15-cm depth reached –30 kPa. A ¹⁵N isotope study was carried out in microplots within the 150-N plots to determine the fate of applied N. The yield under aerobic conditions with 150 kg N ha^–1 was 6.3 t ha^–1 in 2002 and 4.2 t ha^–1 in 2003, and the irrigation water input was 778 mm in 2002 and 826 mm in 2003. Compared with flooded conditions, the yield was 15 and 39% lower, and the irrigation water use 36 and 41% lower in aerobic plots in 2002 and 2003, respectively. N content at 150 kg N ha^–1 in leaves and total plant was nearly the same for aerobic and flooded conditions, indicating that crop growth under aerobic conditions was limited by water deficit and not by N deficit. Under aerobic conditions, average fertilizer N recovery was 22% in both the main field and the microplot, whereas under flooded conditions, it was 49% in the main field and 36% in the microplot. Under both flooded and aerobic conditions, the fraction of ¹⁵N that was determined in the soil after the growing season was 23%. Since nitrate contents in leachate water were negligible, we hypothesized that the N unaccounted for were gaseous losses. The N unaccounted for was higher under aerobic conditions than under flooded conditions. For aerobic rice, trials are suggested for optimizing dose and timing of N fertilizer. Also further improvements in water regime should be made to reduce crop water stress.     

Root distribution in relation to soil nitrogen availability in field-grown tomatoes

Tomato root growth and distribution were related to inorganic nitrogen (N) availability and turnover to determine 1) if roots were located in soil zones where N supply was highest, and 2) whether roots effectively depleted soil N so that losses of inorganic N were minimized. Tomatoes were direct-seeded in an unfertilized field in Central California. A trench profile/monolith sampling method was used. Concentrations of nitrate (NO₃ ^-) exceeded those of ammonium (NH₄ ⁺) several fold, and differences were greater at the soil surface (0–15 cm) than at lower depths (45–60 cm or 90–120 cm). Ammonium and NO₃ ^- levels peaked in April before planting, as did mineralizable N and nitrification potential. Soon afterwards, NO₃ ^- concentrations decreased, especially in the lower part of the profile, most likely as a result of leaching after application of irrigation water. Nitrogen pool sizes and rates of microbial processes declined gradually through the summer.Tomato plants utilized only a small percentage of the inorganic N available in the large volume of soil explored by their deep root systems; maximum daily uptake was approximately 3% of the soil pool. Root distribution, except for the zone around the taproot, was uniformly sparse (ca. 0.15 mg dry wt g^-1 soil or 0.5 cm g^-1 soil) throughout the soil profile regardless of depth, distance from the plant stem, or distance from the irrigation furrow. It bore no relation to N availability. Poor root development, especially in the N-rich top layer of soil, could explain low fertilizer N use by tomatoes.     

控制性分根交替灌溉下氮形态对番茄生长、果实产量及品质的影响

以高产大果型西红柿品种中研988为材料,采用分根培养的方法,研究了控制性分根交替灌溉(APRI)条件下,不同氮素形态(硝态氮、铵态氮)对番茄生长、产量及果实品质的影响.结果表明: 同一灌溉方式或下限处理下,铵态氮对番茄植株前期生长有利,而硝态氮促进番茄植株后期生长,并促进果实产量增加.在APRI同一灌水下限下,硝态氮处理可提高果实维生素C含量及糖酸比,提高营养品质.同一氮素形态供应下,APRI番茄的株高和叶面积均小于正常灌溉(CK),但灌水下限为60%田间持水量(θ_f)的APRI处理番茄茎粗在生长后期有所增加.在同一氮素形态下,与CK相比,APRI各处理的产量均下降,其中灌水下限在40%θ_f的APRI处理产量下降了22.4%～26.3%;而灌水下限在60% θ_f的APRI处理仅下降了5.3%～5.4%,下降幅度相对较小,而品质显著提高,并具有明显的节水效果.因此,控制灌水下限在60%θ_f、供应硝态氮的APRI处理为番茄高产、优质、节水的最佳处理.
     

Denitrification losses from a natural grassland in the Basque Country under organic and inorganic fertilization

Denitrification losses from a poorly drained clayey loamy soil under natural pasture were measured over a two-year period using the acetylene inhibition technique. Plots received two different applications of fertilizer as calcium ammonium nitrate or cow slurry (a total of 145–290 kg N ha^–1 in 1991 and 120–240 kg in 1992). In the first year, N losses in the mineral treatments were about 4 times greater than losses in the slurry treatments. In the second year losses in the slurry treatments increased in such a way that losses in the higher slurry application became similar to those for the two mineral treatments. Soil nitrate was the factor producing differences between treatments. In this way, N mineralization in periods between fertilizations coinciding with high soil water contents was responsible in the second year for the increase in N losses in the slurry treatments. Denitrification rates greater than 0.1 kg N ha^–1 day^–1 occurred at soil water contents > 33 % (air filled porosity < 26 %) and soil nitrate contents > 1 mg N kg^–1 dry soil. Spring and autumn were the seasons of highest risk of denitrification because of N fertilizations coinciding with periods of soil saturation with water. Winter losses were low, but this is a period when there is a risk of denitrification in wetter seasons, particularly for a slurry application management.     

Effect of Rural Sewage Irrigation Regime on Water-Nitrogen Utilization and Crop Growth of Paddy Rice in Southern China

Reclaimed water irrigation has become an effective mean to alleviate the contradiction between water availability and its consumption worldwide. In this study, three types of irrigation water sources (rural sewage’s primary treated water R1 and secondary treated water R2, and river water R3) meeting the requirements of water quality for farmland irrigation were selected, and three types of irrigation water levels (low water level W1 of 0–80 mm, medium water level W2 of 0–100 mm, and high water level W3 of 0–150 mm) were adopted to carry out research on the influence mechanismS of different irrigation water sources and water levels on water and nitrogen use and crop growth in paddy field. The water quantity indicators (irrigation times and irrigation volume), soil ammonium nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃⁻-N), rice yield indicators (thousand-grain weight, the number of grains per spike, and the number of effective spikes), and quality indicators (the amount of protein, amylose, vitamin C, nitrate and nitrite content) of rice were measured. The results showed that, the average irrigation volume under W3 was 2.4 and 1.9 times of that under W1 and W2, respectively. Compared with R3, the peak consumption of rice was lagged behind under R1 and R2, and the nitrogen form in 0–40 cm soil layers under rural sewage irrigation was mainly NH₄⁺-N. The changes of NO₃⁻-N and NH₄⁺-N in the 0–40 cm soil layer showed the trend of declining and then increasing. The water level control only had a significant effect on the change of NO₃⁻-N in the 60–80 cm soil layer. Both irrigation water use efficiency and crop water use efficiency were gradually reduced with the increase of field water level control. The nitrogen utilization efficiency under rural sewage irrigation was significantly higher than that under R3. Compared with the R3, rural sewage irrigation could significantly increase the yield of rice, and as the field water level rose, the effect of yield promotion was more obvious. It was noteworthy that the grain of rice under R1 monitored the low nitrate and nitrite content, but no nitrate and nitrite was discovered under R2 and R3. Therefore, reasonable rural sewage irrigation (R2) and medium water level (W2) were beneficial to improve nitrogen utilization efficiency, crop yield and crop quality promotion.

     

不同施氮量下灌水量对小麦耗水特性和氮素分配的影响

研究了不同施氮量条件下灌水量对高产小麦耗水特性和氮素分配利用的影响。设置4个施氮水平:0kg·hm-2(N0)、120kg·hm-2(N1)、210kg·hm-2(N2)和300kg·hm-2(N3),在每个施氮水平下设置4个灌水量处理:不浇水(W0)、底墒水+拔节水(W1)、底墒水+拔节水+开花水(W2)、底墒水+拔节水+开花水+灌浆水(W3),每次灌水量60mm。结果表明:(1)在N0水平下W0处理日耗水量以拔节至开花期最高,在N1水平下,拔节至开花期日耗水量与开花至成熟期的无显著差异。同一施氮水平下,小麦开花后总耗水量、耗水模系数和日耗水量随灌水量的增加而提高,但产量随灌水量的增加先升高后降低。(2)同一施氮水平下,成熟期W1处理20—140cm各土层土壤含水量低于W2和W3处理,140—200cm土层土壤含水量与W2处理无显著差异;W1处理0—40cm土层土壤硝态氮含量及植株氮素在籽粒中的分配比例高于W2和W3处理,100—140cm土层土壤硝态氮含量及植株氮素在营养器官中的分配量和分配比例低于W2和W3处理。表明灌溉底墒水和拔节水的W1处理,促进了小麦对20—140cm土层土壤水的吸收利用,减少了土壤硝态氮向100cm以下土层的淋溶,而且有利于营养器官中氮素向籽粒的再分配,水分和氮素利用效率较高。(3)在试验条件下,施纯氮210kg·hm-2、灌溉底墒水和拔节水的N2W1处理,籽粒产量最高,水分利用效率和氮素利用效率较高,可供生产中参考。     

管道输液滴干对核桃生长、果实的影响

为了探索核桃提质增效新途径,该研究采用管道输液滴干技术,对‘辽核’核桃树进行水、肥、药一体化管理,将管道输液滴干处理与土壤施肥处理、常规管理进行对比,测定叶片 SPAD 值、叶面积、新梢长度、新梢粗度、干周、土壤含水量、单株产量、单果重、出仁率、黑果率等指标。结果表明：管道输液滴干处理的叶片SPAD 值比土壤施肥处理和常规管理分别提高了28.37％和53.23％;核桃叶片叶面积值分别提高了18.27％和51.54％;新梢长度分别提高了7.03％和13.73％;新梢粗度分别提高了21.92％和27.14％;干周分别提高了20.52％和24.28％;0~20 cm 土层的土壤含水量分别增加了8.66％和8.52％;单株产量分别提高了21.62％和73.08％;单果重分别提高了14.55％和23.53％;出仁率分别提高了11.45％和12.37％;黑果率分别降低了88.76％和91.55％。这说明管道输液滴干技术可以促进树体生长,提高核桃产量和果实品质以及抗病性,降低果实的黑果率,确保核桃丰产稳产。该研究结果能达到既节水、省工,又高效利用肥料、农药,提高核桃产量和品质的目标,从而为管道输液滴干技术在果木生产上的推广应用提供了依据。     

玉/豆和玉/薯模式下氮肥运筹对玉米氮素利用和土壤硝态氮残留的影响

过量施用氮肥造成的环境问题日益严重,氮肥合理使用已成为人们研究的热点.本文研究了西南玉米两种主要套作模式下氮肥运筹对玉米氮素利用和土壤硝态氮残留的影响.结果表明：连续分带轮作种植玉/豆模式后,玉米收获期植株中的氮素积累较玉/薯模式平均提高了6.1%,氮收获指数增加了5.4%,最终使氮肥利用效率提高4.3%,氮素同化量提高了15.1%,氮肥偏生产力提高了22.6%;玉米收获后硝态氮淋溶损失减少,60～120 cm土层中硝态氮残留玉/豆模式较玉/薯模式降低了10.3%,而0～60 cm土层中平均提高了12.9%,有利于培肥地力,两年产量平均较玉/薯模式高1249 kg·hm^-2,增产22%;增加施氮量提高了植株氮素积累,降低了氮肥利用率,显著提高了表层土壤中硝态氮的累积,60～100 cm土层中硝态氮的累积量在0～270 kg·hm^-2处理间差异不显著,继续增加施氮量会显著增加土壤硝态氮的淋溶;氮肥后移显著提高了土壤0～60 cm土层硝态氮的积累.两种模式下施氮量和底追比对玉米氮素吸收和硝态氮残留的影响结果不一致,玉/豆模式以施氮180～270 kg·hm^-2、按底肥∶拔节肥∶穗肥=3∶2∶5的施肥方式有利于提高玉米植株后期氮素积累、氮收获指数和氮肥利用效率,减少了氮肥损失,两年最高产量平均可达7757 kg·hm^-2;而玉/薯模式在180 kg·hm^-2、按底肥∶穗肥=5∶5的施肥方式下,氮素积累利用及产量均优于其他处理,两年平均产量为6572 kg·hm^-2,可实现两种模式下玉米高产、高效、安全的氮肥管理体系.
     

氮硅添加对青藏高原高寒草甸土壤氮矿化的影响

为了解全球气候变化背景下氮沉降对土壤氮矿化的影响及硅添加对土壤氮矿化的促进作用, 该试验设置不同浓度的氮肥单独添加(0、20、40、60 g·m ^-2, 分别为对照CK、N20、N40、N60)以及与硅肥配施(硅酸4 g·m ^-2, Si4), 测定不同处理下0-20、20-40、40-60 cm土层土壤硝态氮含量、铵态氮含量、净硝化速率、净氨化速率以及净矿化速率。结果显示: (1)单独添加氮肥, 各土层土壤硝态氮和铵态氮含量均随处理浓度的增加而增加, 0-20 cm土层N20、N40、N60处理下土壤硝态氮和铵态氮分别较CK增加63.48%、126.04%、247.03%和80.66%、152.52%、244.56%; 随着土层深度增加, 土壤硝态氮、铵态氮含量均有下降, 20-40、40-60 cm土层较0-20 cm土层硝态氮含量分别平均减少53.90%、76.05%, 铵态氮含量分别平均减少48.62%、68.23%。(2)土壤净硝化速率、净氨化速率及净矿化速率随着氮肥浓度增加均呈上升趋势。相同氮肥添加浓度下, 土壤净硝化速率、净氨化速率和净矿化速率随着土层深度增加逐渐下降(除CK外)。(3)与单独添加氮肥比较, 氮硅肥配施, 土壤氮含量有显著提高, 在0-20 cm土层硝态氮和铵态氮较CK分别增加98.78%、192.62%、330.16%和99.96%、195.82%、306.32%, 20-40、40-60 cm土层也有类似趋势。同时, 氮硅配施促进了土壤氮矿化行为, 在0-20 cm土层, N60Si4处理下的土壤净硝化速率、净氨化速率较单独施氮时分别增加35.88%、27.41%。以上结果表明, 与单独氮肥添加相比, 氮硅配施不但能提高土壤氮含量, 而且能促进土壤氮的矿化作用, 对大气氮沉降有一定的缓解作用。     

A comparison of organic and inorganic nitrogen fertilizers: Their nitrate-N and ammonium-N release characteristics and effects on the growth response of lettuce (Lactuca sativa L. cv. Fortune)

The response of pot grown lettuce to inorganic (ammonium nitrate) and organic (dried blood and Protox) N fertilizers was determined at two temperature regimes (15°C day/10°C night and 20°C day/15°C night) and related to the NH₄–N and NO₃–N release characteristics of each material. The N release characteristics of the organic materials matched the N requirements of lettuce more closely than the inorganic fertilizer. However, was rapidly released from the protein based materials such that composts were depleted of available fertilizer N at the same time irrespective of the form supplied. The warmer temperature regimes resulted in a more rapid depletion of the fertilizers due to biological immobilization such that N recoveries in shoots, roots and leachates were reduced. Approximately 20% of the N present in Protox (a material derived from activated sewage sludge, processed to reduce the heavy metal content to minimal levels) appeared to be resistant to microbial degradation and was unavailable to the plants. Therefore, the growth response of lettuce was slightly reduced with Protox compared to the other materials at similar rates of incorporation. The organic materials did not contribute NO₃–N to the plant and small NO₃–N concentrations in petioles were derived from the water used for irrigation. However, NO₃–N levels in plants receiving inorganic ammonium nitrate were initially high but progressively declined as the fertilizer NO₃–N became depleted.     

Soil nutrient dynamics in response to irrigation of a Panamanian tropical moist forest

We measured concentrations of soil nutrients (0–15 and 30–35 cm depths) before and after the dry season in control and dry-season irrigated plots of mature tropical moist forest on Barro Colorado Island (BCI) in central Panama to determine how soil moisture affects availability of plant nutrients. Dry-season irrigation (January through April in 1986, 1987, and 1988) enhanced gravimetric soil water contents to wet-season levels (ca. 400 g kg^–1 but did not cause leaching beyond 0.8 m depth in the soil. Irrigation increased concentrations of exchangeable base cations (Ca²⁺, Mg²⁺, K⁺, Na⁺), but it had little effect on concentrations of inorganic N (NH₄ ^+C, NO₃ ^– and S (SO₄ ^2–). These BCI soils had particularly low concentrations of extractable P especially at the end of the dry season in April, and concentrations increased in response to irrigation and the onset of the rainy season. We also measured the response of soil processes (nitrification and S mineralization) to irrigation and found that they responded positively to increased soil moisture in laboratory incubations, but irrigation had little effect on rates in the field. Other processes (plant uptake, soil organic matter dynamics) must compensate in the field and keep soil nutrient concentrations at relatively low levels.     

The effect of nitrogen fertilizer and irrigation on black point incidence in soft white spring wheat

Agronomic studies were conducted to examine the effect of fertilizer N on black point incidence in Fielder soft white spring wheat (Triticum aestivum L. em Thell.). Black point incidence rose with increases in the amount of N supplied either as fertilizer applied during the growing season in irrigation water or as soil N, specifically nitrate, from fertilizer N application in previous years. A comparison of four different irrigation regimes demonstrated that black point incidence was highest under frequent irrigation (irrigate to field capacity at 75% available moisture) and lowest under conventional irrigation (irrigate to field capacity at 50% available soil moisture). In each irrigation regime, disease incidence increased as N rates were raised from 0 to 120 kg ha^-1. A residual fertilizer-N study demonstrated in 1985 and 1986 that black point incidence generally rose with increasing levels of nitrogen from either preplant applications in the spring or soil nitrate from the previous year. However, additions of fertilizer N were shown to slightly reduce black point incidence at soil nitrate levels above 150 kg ha^-1. A two-year fertilizer N study demonstrated that in treatments receiving the same amount (90 kg ha^-1) of fertilizer N, the amount broadcast as a preplant treatment versus the amount applied in irrigation water in a fertigation treatment had no effect on black point incidence, but all fertilized treatments had significantly higher levels of disease than the unfertilized check.Contribution no. 3879016     

施氮量对夏季玉米产量及土壤水氮动态的影响

在黄土高原南部旱地有大量氮素残留背景的田块上,研究了不同氮肥用量对夏玉米生长及对土壤水分、硝态氮、铵态氮累积及其剖面分布的影响。结果表明：适量施氮可以提高作物产量;过量施氮没有表现出增产效果,其氮肥利用率只有3．9％,残留率则高达87．2％。施氮240kghm^-2时,0～200cm土层土壤水分达到593mm,且可以下渗到200cm土层;不施氮和施氮120kghm^-2以小区土壤的蓄水量分别为561和553mm,可下渗到180cm。对矿质态氮而言,施氮量可以显著影响土壤中硝态氮的累积和分布,但对铵态氮的影响较小;施氮0,120,240kghm^-2时．收获期土壤硝态氮累积量分别为78,148,290kghm^-2,硝态氮的下移前沿分别到达60,60,140cm。可见,适量施氮会促进作物对土壤水氮的利用。提高作物生物量和产量;过量施氮导致硝态氮在土壤中大量累积,提高硝态氮随水分淋溶危险;但硝态氮向下层土壤的移动显著滞后于水分。     

根系分区交替灌溉条件下水肥供应对番茄果实硝酸盐含量的影响

为了研究根系分区交替灌溉条件下灌水量和氮、磷、钾肥及有机肥用量对番茄果实硝酸盐含量的影响,采用五元二次正交旋转组合设计,通过盆栽试验,建立了番茄果实中硝酸盐含量与水肥因子的数学模型,并对各单一因素的效应及两两因素的耦合效应进行了分析。结果表明,在其他因子为中间水平时,番茄果实中的硝酸盐含量,随灌水量呈先降低后增加的变化规律;随施氮量和施磷量呈先增加后降低的变化趋势;随有机肥用量呈逐渐增加的趋势;但不受钾肥用量的影响。交互效应表现为,施磷量与有机肥用量、施氮量与施磷量间的相互作用会促使番茄果实硝酸盐含量提高;灌水量与施钾量和有机肥量、施氮量与施钾量间的相互作用有利于降低番茄果实硝酸盐累积。耦合效应表现为,除不施有机肥时随灌水量增加番茄果实硝酸盐含量显著增加外,对于其它任何有机肥及钾肥施用水平,果实硝酸盐含量皆随灌水量增加呈先减小后增加趋势;灌水量高于中水平时,番茄果实硝酸盐含量随着钾肥与有机肥用量的增加而减少。不论施磷量与施钾量如何变化,番茄果实硝酸盐含量皆随施氮量呈现先增加后减小的变化趋势,降低氮肥用量同时提高磷肥用量有利于降低番茄果实硝酸盐累积,而提高施钾量仅在施氮量高于中水平时能显著降低番茄果实硝酸盐含量。适当增加磷肥用量、减小有机肥用量能显著降低番茄果实硝酸盐的累积。     

灌溉方法与施氮对土壤水分、硝态氮和小麦生长发育的调控效应

为探明玉米秸秆还田下小麦的合理灌溉与施肥方法,于田间研究了漫灌(FI)、微喷灌(SI)、滴灌(DI)和灌水施氮模式(N₁, 基施纯N 157.5 kg·hm^-2+拔节期施纯N 67.5 kg·hm^-2; N₂, 基施纯N 157.5 kg·hm^-2+拔节期施纯N 45.0 kg·hm^-2+灌浆期施N 22.5 kg·hm^-2)对土壤水分、硝态氮(NO₃^--N)含量和小麦生长发育的影响.结果表明: 灌溉方法和灌水施氮模式共同影响土壤含水量和贮水量的变化.其中,灌溉方法对越冬期和返青期0～60 cm、孕穗期和灌浆期0～160 cm、成熟期100～160 cm土层含水量影响相对较小,对越冬期和返青期80～160 cm、成熟期0～80 cm土层含水量影响大;FI对含水量和贮水量影响最大,DI次之,SI最小;SI和DI的灌水施氮模式中灌水量多,则土层含水量高、贮水量多,变化大.NO₃^--N含量受灌溉方法和施氮的影响,施氮对0～20 cm土层影响大,SI生育期NO₃^--N含量变化大,DI越冬期至孕穗期NO₃^--N含量变化小,此后变化大,FI与DI相反;生育前中期灌水量对NO₃^--N含量影响大,后期施氮对NO₃^--N含量影响大;SI和DI的2种灌水施氮模式中冬前灌水量多的NO₃^--N含量变化大.灌溉方法中SI越冬期总茎数和单株分蘖高,成穗率高,成穗数多,产量、水分利用效率(WUE)和氮素利用效率最高,滴灌次之,漫灌最低;SI和DI中N₁生育期总茎数、成穗数多,但穗粒数和千粒重低,产量、WUE和氮素利用效率低于N₂.因此,玉米秸秆还田后播种小麦,微喷灌代替漫灌生育期灌4水,施足基肥,拔节期和灌浆期分次追氮,是山西南部小麦-玉米一年两熟区小麦节水高产高效栽培模式.     

The Effects of Fertilizers on Rabbiteye Blueberry (<i>Vaccinium ashei</i> Reade.) Root Distribution and Fruit Yield

The root system plays an important role in the growth and development of blueberry. The aim of this study was to assess the impacts of different fertilizers on the root growth and root–yield relationship of blueberry to provide insight into the regulation of root growth and fruit yield by fertilizing from the perspective of the root system. Rabbiteye blueberry variety ‘Britewell’ as the test material, and six fertilizers, including BF, OR, CF, SF, HF, and RT were used in single-factor fertilization experiments to analyze the effects of different fertilizer treatments on the root morphology, root distribution, and fruit yield of blueberry. Fertilization overall increased the root length density and root surface area in most soil layers, and the RT treatment significantly increased the total root length density and total root surface area 98.6% and 98.5%, respectively, compared with a control lacking fertilizer. In addition, the effect of fertilization on the blueberry root system was mainly observed in the 0–20 cm layer. Fruit yield was positively correlated with total root length density and total root surface area, and negatively correlated with average root diameter. In summary, the SF and RT treatments increased the morphological indexes of the root system, particularly in the shallow soil layers, leading to an increase in blueberry fruit yield.     

Effects of Irrigation and Nitrogen on the Performance of Aerobic Rice in Northern China

Aerobic rice is a new production system in which specially-developed varieties are grown under non-flooded, non-puddled, and non-saturated soil conditions. In 2003-2004, irrigation x Nitrogen experiments were carried out near Beijing using variety HD297. Water treatments included four irrigation levels, and Nitrogen treatments included different fertilizer N application rates and different numbers of N splits. The highest yields were 4460 kg/ha with 688 mm of total (rain plus irrigation) water input in 2003 and 6 026 kg/ha with 705 mm of water input in 2004. Because of the quite even distribution of rainfall in both years, the four irrigation treatments did not result in large differences of soil water conditions. There were few significant effects of irrigation on biomass accumulation, but yield increased with the total amount of water applied. High yields coincided with high harvest index and high percentages of grain filling. The application of fertilizer N either reduced biomass and yield or kept it at the same level as 0 N and consistently reduced the percentage grain filling and 1 000-grain weight. With the highest water application, five splits of N gave higher yield than three splits, whereas three splits gave higher yield than five splits with lower water applications.