不同缓控释肥对鲜食玉米产量、品质及氨挥发的影响

采用田间试验,设置不施氮对照(CK)、常规施肥(U)、增效尿素(DU)、包膜尿素(CU)、缓控释掺混尿素(CDU)共5个处理,研究了常规施肥(240 kg N·hm^-2)和不同缓控释肥料一次性减量施用(180 kg N·hm^-2)对鲜食玉米产量、品质与土壤无机氮变化和氨挥发的影响。结果表明: U处理氨挥发总量最高,追肥是产生氨挥发损失的重要因素;与U处理相比,DU、CU、CDU处理氨挥发减排78%～81%。收获后U处理80～100 cm土层硝态氮浓度最高,为51.6 mg·kg^-1,氮淋溶风险较高,而DU、CU、CDU处理同土层硝态氮含量均较低,降低了淋溶风险。与U处理相比,减氮25%的3个缓控释肥处理没有减产,并增加了籽粒维生素C、可溶性糖和蛋白质含量;缓控释肥处理之间,DU处理的氮肥农学效率和经济效益最高。综上,减量施用新型缓控释肥可以实现鲜食玉米稳产提质,显著降低氨挥发损失和硝态氮淋失风险。与成本较高的树脂包膜控释肥相比,双效抑制剂增效肥(DU)成本低、制作便捷,是鲜食玉米专用肥的较好选择。     

控释配方肥氮素在芥菜连作期的去向和平衡

采用小型渗漏计,在施用水溶性肥料及其与控释肥料组成的控释配方肥条件下,研究了3个生长季连作芥菜的吸氮量、N₂O排放损失、氮素淋溶损失、氮素残留和其他损失量.结果表明： 在含25%控释氮素的控释配方肥处理下,芥菜的吸氮量逐季增加,后期显著高于水溶性肥料处理.水溶性肥料处理的N₂O累积排放量和氮素淋溶损失量明显高于控释配方肥处理,各肥料处理氮素淋失的形态均以NO₃^--N为主.相对于水溶性肥料,控释配方肥能改变氮素的去向,氮素吸收利用率提高75.4%,土壤残留增加76.0%,淋溶损失和其他表观损失分别减少27.1%和66.3%.施用控释配方肥是减少氮素各种形式损失、显著提高氮肥利用率的有效途径,控释肥料是氮素养分高效利用的环保型肥料.     

15N标记水稻控释氮肥对提高氮素利用效率的研究

本文应用^15N示踪技术研究了水稻对空控释氮肥和尿素氮吸收利用效率的影响以及氮的去向,结果表明：施肥后11天内,水稻控释氮肥和尿素的NH3挥发损失分别占施入氮量的0.69%和1.81%,NH3的挥发损失在施肥后第5天时达到最大值,此后逐渐降低。水稻控释氮肥和尿素氮的淋溶损失分别占施入氮量的0.95%和1.02%,水稻控释氮肥氮的淋溶损失在水稻整个生长期间均比较平缓,施肥后40天时略有上升,此后又缓慢降低。用氮素平衡帐中的亏缺量和缺量扣除氨的损失量后计为硝化-反硝化损失量的结果表明,水稻控制氮肥氮的硝化-反硝化损失量占施氮量的3.46%,而尿素氮在硝化-反硝化损失量却高达37.75%,肥料氮在土壤中的残留主要集中在0～35cm的土层中,达91.4%-91.5%,残留在35cm以下土层中的氮甚微,水稻控制氮肥残留在土壤中的氮量略高于尿素处理。水稻控释氮肥利用率高达73.8%,比尿素高出34.9%,水稻控释氮肥氮利用率高的原因是因氮从颗粒中缓慢释放、受淋溶、氨挥发、尤其受硝化-反硝化途径损失的氮较少。在施等氮量的条件下,施用水稻控制氮肥的稻谷产量比尿素的增产25.5%,达到p=0.05的显著水平。     

控释肥料与普通氮肥混施对春白菜产量、品质和氮素损失的影响

在京郊露地生产条件下,研究了控释肥料与速效化肥混配施用对春白菜产量、品质、氨挥发、土壤硝态氮累积和淋失的影响.结果表明：与习惯施肥处理（施N 300 kg·hm^-2）相比,控释肥料与普通化肥按纯氮比2∶1混配施用（共施N 150 kg·hm^-2）没有造成白菜减产,并显著降低了菜叶中硝酸盐和有机酸含量;与半量施肥处理(施N 150 kg·hm^-2)相比,控释肥与化肥混施处理产量和叶片硝酸盐含量无显著差异.控释肥与化肥混施处理提高了白菜氮肥利用率,减少了N₃-N淋失量和氨挥发总量.白菜收获后,控释肥与化肥混施处理在20～40、60～80、80～100 cm土层的NO₃^--N含量显著低于习惯施肥处理.     

不同施肥模式调控沿湖农田无机氮流失的原位研究——以南四湖过水区粮田为例

为探索山东南四湖沿岸麦玉轮作区玉米季内减少土壤无机氮素淋溶和径流损失的施肥策略,降低其对湖区水质产生的潜在威胁,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结合室内分析不同形态氮含量的方法,研究了不同施肥模式下无机氮素淋溶和径流损失特征。结果表明：土壤淋溶水量及地表水径流量与降水呈显著正相关关系,其水量受秸秆类物质还田的影响;硝态氮(NO3--N)与铵态氮(NH4 -N)随地表水径流损失的浓度及总量均明显高于淋溶水,由径流方式损失的氮素占2/3以上,是氮素以水溶液形式流失的主要途径;淋溶和径流均以NO3--N损失为主(径流损失中NO3--N占总量的82.9%-90.8%,淋溶损失中NO3--N占63.5%-72.9%),地表径流水NO3--N浓度对水质有较大影响,但土壤淋溶水NO3--N浓度对地下水污染不构成威胁;农民习惯施肥处理在玉米整个生育期淋溶和径流氮损失最高。在保证玉米产量前提下,降低氮素流失造成湖区的污染,平衡施用氮磷钾肥、施用控释氮肥、有机替代无机和秸秆还田等措施均可在沿南四湖区农田使用。     

长期施用有机物料下黑土氮素有效性及其与作物产量的关系

利用长期定位施肥试验,于2011年采样研究长期施用不同有机物料(秸秆、有机肥)对东北黑土氮素有效性的影响,并分析氮供应与作物生物量及产量的关系.结果表明:化肥配施有机肥、化肥配施低量秸秆均可显著提高黑土农田土壤无机氮和硝态氮含量,进而提高作物产量;尽管化肥配施高量秸秆提高了土壤氮矿化速率,但可能由于硝态氮淋溶或者其他形式的氮素损失或转化,与化肥配施低量秸秆处理相比,化肥配施高量秸秆下土壤无机氮量并没有增加.可见,适量施用有机物料对提高土壤氮素有效性、提高作物产量及保护环境具有重要意义.     

关中地区小麦/玉米轮作农田硝态氮淋溶特点

通过田间原位淋溶装置研究了不同施氮量和秸秆覆盖对关中地区小麦/玉米轮作农田90cm深处硝态氮(NO3--N)淋溶量、0～1m土层硝态氮累积及作物产量和氮平衡的影响.试验设不施氮(N1,0kg·hm-2·a-1)、常规施氮(N2,471kg·hm-2·a-1)、推荐施氮(N3,330kg·hm-2·a-1)、减量施氮(N4,165kg·hm-2·a-1)、增量施氮(N5,495kg·hm-2·a-1)和推荐施氮+秸秆覆盖(N3+S)6个不同施肥处理.结果表明:NO3--N淋溶量随施氮量的增加而增大,氮肥的过量施用及秸秆覆盖易造成NO3--N淋溶.N3+S处理90cm处年NO3--N流失量最大,为22.32kg·hm-2,施肥造成的氮流失量为16.44kg·hm-2,比相同施氮量不覆盖处理(N3)高158.9%.NO3--N主要累积在20～60cm土层,年施氮量330kg·hm-2(N3)时,秸秆覆盖与否不影响NO3--N的剖面分布.各施肥处理对作物产量没有显著影响,但减量施氮处理(N4)有减少作物产量的趋势.在本试验条件下,推荐施肥量(小麦施氮150kg·hm-2,玉米施氮180kg·hm-2)在保证作物产量的同时,可减少土壤NO3--N的淋溶和累积.     

铲草和施肥对降香黄檀与印度檀香混交林土壤氮素矿化淋溶的影响

珍贵树种降香黄檀与印度檀香混交种植是当前华南地区人工林发展的一种重要模式.本研究设置对照(不做处理)、铲草、施肥、铲草+施肥4个处理,研究抚育措施对林地土壤净矿化速率、净硝化速率、净铵化速率和氮素淋溶速率的影响.结果表明:4个处理0~10 cm土层在春、秋季有最大净氮矿化速率,分别为18.92、18.13 mg·kg^-1·month^-1;在春、秋季有最大硝化速率,分别为20.35、18.85 mg·kg^-1·month^-1;夏、冬季有最大铵化速率,分别为0.22、0.26 mg·kg^-1·month^-1;秋季的氮素淋溶最严重,为15.98 mg·kg^-1·month^-1,全年最大淋溶为86.69 mg·kg^-1.铲草、施肥、铲草+施肥都在一定程度上抑制了土壤氮的净矿化和硝化速率,铲草、施肥、铲草+施肥处理年氮矿化量分别下降26.2%、16.1%、6.3%,年氮硝化量分别下降17.1%、16.6%、1.4%,同时也抑制了土壤铵态氮的累积.铲草、施肥、铲草+施肥处理全年氮素淋溶量依次减少25.2%、8.6%、6.1%.相对于铲草、施肥、铲草+施肥抚育措施,季节因素对土壤氮素矿化和淋溶过程的影响更显著.铲草、施肥、铲草+施肥措施在一定程度上抑制了土壤氮素硝化和铵化过程,减少了土壤氮素的矿化和淋溶损失量,有利于土壤肥力的保存和氮素的累积.     

26年长期施肥对土壤微生物量碳、氮及土壤呼吸的影响

研究长期小麦连作施肥条件下土壤微生物量碳、氮,土壤呼吸的变化及其与土壤养分的相关性。以陕西长武长期定位试验为平台,应用氯仿熏蒸-K2SO4提取法、碱液吸收法和化学分析法分析了长达26a不同施肥处理农田土壤微生物量碳、微生物量氮和土壤呼吸之间的差异及其调控土壤肥力的作用。长期施肥及种植作物,均能提高土壤微生物量碳、氮含量,尤其是施用有机肥,土壤微生物量碳、氮含量高于单施无机肥的处理,土壤呼吸量也提高15.91%—75.73%,而施用无机肥对于土壤呼吸无促进作用。土壤微生物生物量碳氮、土壤呼吸与土壤有机质、全氮呈极显著相关。长期有机无机肥配施可以提高土壤微生物量碳氮、土壤呼吸,氮磷肥与厩肥配施对提高土壤肥力效果最好。微生物量碳氮及土壤呼吸可以反映土壤质量的变化,作为评价土壤肥力的生物学指标。     

灌溉方式和施氮量对棉田氮肥利用率及损失的影响

在田间条件下,研究不同灌溉方式(滴灌和漫灌)和不同施氮水平(0、240、360、480kg N·hm-2)对棉田氮肥利用率及损失的影响,并定量分析了氮肥被植株吸收、土壤硝态氮残留,以及氨挥发、硝态氮淋溶损失、硝化反硝化损失等氮素循环转化途径.结果表明:滴灌棉花籽棉产量、植株吸氮量和氮肥利用率均显著大于漫灌.漫灌土壤硝态氮残留量显著高于滴灌;在不同施氮量处理中滴灌土壤氨挥发损失量占肥料氮施用量的比例为0.06％～0.14％,且显著高于漫灌;滴灌和漫灌硝态氮淋溶损失量占肥料氮施用量的比例分别为4.4％和8.8％,与漫灌相比,滴灌能显著降低淋溶水中硝态氮淋失量;滴灌和漫灌肥料氮的硝化-反硝化损失量分别占肥料氮施用量的17.9％和16.8％.硝态氮淋溶和硝化-反硝化损失是新疆棉田氮素损失的主要途径.     

一次性施肥技术对水稻-油菜轮作系统氮素淋失特征及经济效益的影响

一次性施肥技术是指在作物根际附近只进行一次基施肥的新技术,具有简化施肥管理、降低劳动成本等优点,但其对环境的影响如氮素淋失等仍需进一步分析.本研究以长江中下游地区典型的水稻-油菜轮作模式为例,设置了空白对照(CK)、农民习惯施肥(FP)、优化施肥(OPT)、一次性基施尿素(UA)、一次性基施控释肥(CRF)5个处理,采用地下淋溶原位监测的方法,获取了不同处理下水稻-油菜轮作系统土壤90 cm深度处氮素(N)淋失特征,评估了一次性施肥技术对氮素淋失的影响,并综合分析了其经济效应.结果表明: 油菜季和水稻季土壤渗漏液中氮素的主要形态不同,油菜季渗漏液中以NO₃^--N为主,水稻季渗漏水中NO₃^--N和NH₄⁺-N各占约50%.从整个轮作周期看,氮素淋失主要发生在水稻季,与FP、OPT和UA相比,CRF氮淋失总量分别显著减少33.7%、20.8%和20.7%;但各施肥处理对油菜季氮素淋失影响不显著.在相同施氮量的条件下,与OPT相比,UA不仅保证油菜和水稻均稳产,而且使油菜季氮肥农学效率显著提高了15.1%,但是没能提高水稻季氮肥农学效率;CRF水稻产量和氮肥农学效率均差异不显著,但油菜产量和氮肥农学效率分别显著提高10.7%和18.9%.经济效益上,与OPT相比,UA和CRF处理油菜分别增收3660和3048 元·hm^-2,水稻分别增收3162和2220元·hm^-2.因此,对于长江中下游典型种植系统而言,综合考虑对氮素淋失、作物产量和经济效益的影响,一次性基施控释肥技术能在保证作物稳产或增产、提高农民经济效益的同时显著降低氮淋失量,是未来水稻-油菜轮作系统值得推荐的一种生产技术.     

脲酶／硝化抑制剂对土壤有效态氮、微生物量氮和小麦氮吸收的影响

研究了脲酶抑制剂(NBPT)、硝化抑制剂(DCD)及二者组合在草甸棕壤上施用对尿素态N转化及土壤总有效态N、微生物量N的影响．结果表明,尿素配施NBPT、DCD及抑制剂组合能够增加尿素水解后土壤NH4^+含量2％-53％。显著降低了氧化态N的浓度,抑制了土壤中铵态N的氧化,增加土壤总有效N34％-44％,小麦吸N量增加0．26％-6．79％。其中以脲酶抑制剂与硝化抑制剂组合的效果最明显．抑制剂施用增加了微生物在小麦生长初期对有效态N固持,有利于后期土壤有效态N的矿化．     

Fate of 15N-labelled fertilizer applied to spring barley grown on soils of contrasting nutrient status

An experiment with ¹⁵N-labelled fertilizer was superimposed on the Rothamsted Hoosfield Spring Barley Experiment, started in 1852. Labelled ¹⁵NH₄ ¹⁵NO₃ was applied in spring at (nominal) rates of 0, 48, 96 and 144 kg N ha^-1. The labelled fertilizer was applied to microplots located within four treatments of the original experiment: that receiving farmyard manure (FYM) annually, that receiving inorganic nutrients (PK) annually and to two that were deficient in nutrients: applications were made in two successive years, but to different areas within these original treatments. Maximum yields in 1986 (7.1 t grain ha^-1) were a little greater than in 1987. In 1987, microplots on the FYM and PK treatments gave similar yields, provided enough fertilizer N was applied, but in 1986 yields on the PK treatment were always less than those on the FYM treatment, no matter how much fertilizer N was applied. In plots with adequate crop nutrients, about 51% of the labelled N was present in above-ground crop and weed at harvest, about 30% remained in the top 70 cm of soil (mostly in the 0–23 cm layer) and about 19% was unaccounted for, all irrespective of the rate of N application and of the quantity of inorganic N in the soil at the time of application. Less than 4% of the added fertilizer N was present in inorganic form in the soil at harvest, confirming results from comparable experiments with autumn-sown cereals in south-east England. Thus, in this experiment there is no evidence that a spring-sown cereal is more likely to leave unused fertilizer in the soil than an autumn-sown one. With trace applications (ca. 2 kg N ha^-1) more labelled N was retained in the soil and less was in the above-ground crop. Where P and K were deficient, yields were depressed, a smaller proportion of the labelled fertilizer N was present in the above-ground crop at harvest and more remained in the soil.Although the percentage uptake of labelled N was similar across the range of fertilizer N applications, the uptake of total N fell off at the higher N rates, particularly on the FYM treatment. This was reflected in the appearance of a negative Added Nitrogen Interaction (ANI) at the highest rate of application. Fertilizer N blocked the uptake of soil N, particularly from below 23 cm, once the capacity of the crop to take up N was exceeded. Denitrification and leaching were almost certainly insufficient to account for the 19% loss of spring-added N across the whole range of N applications and other loss processes must also have contributed.     

不同氮肥喷涂吡啶对夏玉米田氮素利用及土壤N2O排放的影响

为减少土壤N₂O排放,提高作物氮素利用,采用田间试验法研究了不同氮肥用量喷涂一定比例的吡啶(0、180、270、360 kg N·hm^-2)对夏玉米生育期内土壤N₂O排放和氮素表观损失、籽粒产量及氮素利用的影响.结果表明:不同氮肥用量下喷涂吡啶的土壤N₂O排放主要集中在播种-苗期和拔节-抽雄期,基肥和追肥后均会出现显著的土壤N₂O排放通量高峰.随氮肥用量增加,玉米产量不断增加,但270和360 kg N·hm^-2间无显著差异,2种施氮量下的玉米分别净增收5209和5426元·hm^-2.与不施氮肥比,各施氮处理下的玉米籽粒吸氮量提高幅度为109.6%～134.1%.各处理间的氮肥农学效率和氮肥利用率均以氮肥喷涂吡啶270 kg N·hm^-2较大,而土壤氮素表观损失较小.氮肥喷涂吡啶在270 kg N·hm^-2时玉米增产增收,氮肥利用效率较高,土壤N₂O排放和氮素表观损失较少,是一种较为合理的氮肥调控施用技术.     

Turnover of residual 15N-labelled fertilizer N in soil following harvest of oilseed rape (t Brassica napus L.)

We studied the fate of ¹⁵N-labelled fertilizer nitrogen in a sandy loam soil after harvest of winter oilseed rape (Brassica napus L. cv. Ceres) given 100 or 200 kg N ha^-1 in spring, with or without irrigation. Our main objective was to quantify the temporal variations of the soil mineral N, the extractable soil organic N and soil microbial biomass N, and fertilizer derived N in these pools during autumn and winter. Nitrogen use efficiency of the oilseed rape crop varied from 47% of applied N in the 100N, irrigated treatment to 34% in the 200N, non-irrigated treatment. However, only in the latter treatment did we find significantly higher fertilizer derived soil mineral N than in the three other treatments which all had low soil mineral N contents at the first sampling after harvest (8 days after stubble tillage). Between 31% and 42% of the applied N could not be accounted for in the harvested plants or 0-15 cm soil layer at this first sampling. Over the following autumn and winter none of the remaining fertilizer derived soil N was lost from the 0–5 cm depth, but from the 5–15 cm depth a marked proportion of N derived from fertilizer was lost, probably by leaching. Negligible amounts of fertilizer derived extractable soil organic and mineral N (<1 kg N ha^-1, 0-15 cm) were found in all treatments after the first sampling.Soil microbial biomass N was not significantly affected by treatments and showed only small temporal variability (±11% of the mean 76 kg N ha^-1, 0- 15 cm depth). Surprisingly, the average amount of soil microbial biomass N derived from fertilizer was significantly affected by the treatments, with the extremes being 5.5 and 3.1 kg N ha^-1 in the 200N, non-irrigated and 100N, irrigated treatments, respectively. Also, the estimated exponential decay rate of microbial biomass N derived from fertilizer, differed greatly (2 fold) between these two treatments, indicating highly different microbial turnover rates in spite of the similar total microbial biomass N values. In studies utilising ¹⁵N labelling to estimate turnover rates of different soil organic matter pools this finding is of great importance, because it may question the assumption that turnover rates are not affected by the insertion of the label.     

Effect of one year rotational set-aside on immediate and ensuing nitrogen leaching loss

This paper reports results from a 3-year field experiment which examined Nitrogen (N) leaching loss from land under various set-aside managements. Four treatments were examined: three ploughed plots which were sown with wheat, ryegrass or maintained fallow; the fourth treatment was unploughed and natural weed growth (volunteers) permitted. The l-year set-aside was followed by two winter wheat test crops. Ceramic suction cups were installed at a depth of 90 cm and used to collect drainage water. N leaching loss was calculated by multiplying drainage volume, calculated from meteorological data, by its inorganic N concentration.Set-aside management significantly affected N leaching loss over the three years. During the set-aside year, the peak nitrate concentration from the unploughed treatment growing volunteer weeds was significantly lower than that from ploughed plots. Of the latter, by the spring, crop (i.e. wheat and ryegrass) assimilation of N significantly reduced N concentration compared to the fallow. The four set-aside treatments had a carry-over effect to the following year (first wheat test crop) resulting in significant differences in N losses. Leaching following the ryegrass treatment was very small and we believe that the grass residues minimised rates of net-N mineralization.The influence of set-aside management continued to the second wheat test crop where N loss was greater under the all wheat rotation because take-all had reduced yield and therefore crop N uptake.     

育秧箱全量施肥对水稻产量和氮素流失的影响

采用育秧箱全量施肥技术,通过2年田间小区试验,研究中量控释氮肥(80 kg N·hm-2)、高量控释氮肥(120kgN·hm-2)和常规施肥(300 kg N·hm-2)处理对水稻产量和氮素流失的影响.结果表明:与常规施肥相比,高量控释氮肥处理的水稻产量未显著降低.常规施肥处理2年平均氮素利用率为33.2％,中量和高量控释氮肥处理的平均氮素利用率分别比常规施肥处理提高26.2％和20.7％.常规施肥处理田面水的总氮含量在施肥后1～3d达最大值,中量和高量控释氮肥处理的高峰期为施肥后7～9d,全生育期内,中量和高量控释氮肥处理田面水的总氮含量均显著低于常规施肥处理.常规施肥处理的氮素渗漏流失主要在分蘖期,中量和高量控释氮肥处理的氮素渗漏流失后移至分蘖-开花期.各处理硝态氮流失量占总氮流失量的59.7％～64.2％,高量控释氮肥处理的总氮净流失量比常规施肥处理减少51.8％.