Fate of fertilizer nitrogen applied to grassland. I. Field leaching results

Results are presented from a 3 year investigation into nitrate leaching from isolated 0.4 ha grassland plots fertilized with 250, 500 and 900 kg N ha^?1 a^?1. Cumulative nitrate leaching over the 3 years was equivalent to 1.5%, 5.4% and 16.7% of the fertilizer applied at 250, 500 and 900 kg N ha^?1 rates respectively. Over a whole drainage season, mean nitrate leachate concentrations at 250 kg N ha^?1 did not exceed 4 mgl^?1, although maximum values of 13.3 mgl^?1 were observed. In contrast, at 900 kg N ha^?1, the mean nitrate leachate concentration in two of the years exceeded 90 mgl^?1. Mineral nitrogen balances constructed for the 1979 growing season indicated that leaching at 250 kg N ha^?1 was low because net mineralization of soil organic nitrogen was small, and crop nitrogen uptake almost balanced fertilizer application. Although the pattern of nitrate leaching suggested that by-passing occurred in the movement of water down the soil profile, it was not possible to confirm this using simulation models of leaching. Possible reasons for this, including the occurrence of rapid water flow down gravitationally drained macropores, are discussed.     

Fate of fertilizer nitrogen applied to grassland. II. Nitrogen-15 leaching results

Results are presented from a 3-year investigation into nitrate leaching from grassed monolith lysimeters treated with double (¹⁵NH₄¹⁵NO₃) or single (¹⁵NH₄NO₃) labelled ammonium nitrate at three rates, 250, 500 and 900 kg N ha^?1 a^?1. Over the 3 years of the experiment, 0.14%, 3.1% and 18.1% of the applied fertilizer was recovered in the leachate at 250, 500 and 900kg N ha^?1 respectively. This represented 9%, 39% and 75% of the overall nitrate leaching at the three application rates. A significant proportion of the fertilizer leached as nitrate at the three application rates was derived, via nitrification, from the fertilizer ammonium. Increasing fertilizer applications caused a rise in the leaching of both soil and fertilizer derived nitrogen, although whether the increase reflected a true priming effect was not clear.     

主要农田生态系统氮素行为与氮肥高效利用研究

氮肥在我国农业生产中发挥了重要作用 ,但氮肥的不合理施用也带来了一些负面影响 ,氮肥施用不合理、利用率低 ,不仅导致氮素的大量损失、造成了浪费 ,而且还对生态环境产生不良影响 ,使农田氮素成为重要的污染源之一 ,同时过量施用氮肥还严重影响了农产品品质。针对氮肥施用存在的问题 ,国内外已经开展了大量的基础研究。国家自然科学基金委员会多年来也资助了与农田生态系统氮素行为与氮肥高效利用研究相关的一些课题 ,为进一步系统开展本领域的综合研究奠定了基础。 2 0 0 2年 ,国家基金委针对氮肥施用中存在的科学问题设立了题为主要农田生态系统氮素行为与氮肥高效利用的重大项目 ,以期在国内外研究基础上 ,围绕农田生态系统氮素行为与氮肥高效利用 ,对我国主要农田生态系统中氮素的行为、作物高效利用氮肥的生理和遗传机制及调控作物高效利用氮肥的理论与方法等前沿科学问题开展跨学科的系统研究 ,为改变我国氮肥利用率低的局面提供理论依据。     

控释氮肥在淹水稻田土壤上的去向及利用率

通过土壤渗漏装置、微区和田间小区试验,研究了15N标记控释氮肥在淹水稻田土壤上氮素的去向和利用率。结果表明,施用控释氮肥能明显地降低氨挥发、淋失和硝化—反硝化的损失。控释氮肥处理的氨挥发量比尿素降低54.0%,氮淋失量降低32.5%。尿素的硝化—反硝化损失量占施入氮量的34.5%,而控释氮肥的只占2.0%;控释肥料与尿素氮在0—80cm土层中的残留率相近。控释氮肥一次性全量作基肥施入土壤,水稻的氮肥利用率平均为65.6%,比尿素(基肥+追肥)高出32.2个百分点。控释氮肥的农学效率显著地高于尿素。     

Response of nitrogen use efficient sorghums to nitrogen fertilizer

Little information is available on the response of grain sorghum [Sorghum bicolor (L.) Moench] genotypes differing in nitrogen (N) use efficiency (NUE) (g DM g N^‐1) to added N fertilizer. Such knowledge is important for reducing the reliance upon fertilizer N. A dryland field experiment was conducted in 1993 and 1994 at Mead, NE evaluating the agronomic responsiveness of 13 sorghum genotypes differing in NUE to three N rates (0, 50 and 100 kg N ha^‐1) and also to determine physiological factors that contribute to improved NUE. The experiment was conducted on a fine montmorillonitic, mesic, Typic Argiudoll soil. Total N at maturity, dry matter, and grain yield were used to calculate NUE terms. Genotype differences were found for all measured variables both years, but no N rate by genotype effects were significant. Nitrogen fertilizer enhanced plant N contents and grain yield, but decreased NUE for total biomass and grain production. An early freeze in 1993 markedly reduced the later maturing genotype grain yields which, in turn, influenced NUE group comparisons. All genotypes in the study attained their full yield potential in 1994. The linear response to N rate of the N non‐responsive group was significantly less than the moderately responsive or N responsive group. High NUE sorghums had greater yields than low NUE types averaged over N levels only in 1994 since Naga White, a high NUE type, did not reach maturity in 1993. There was no difference in the linear response to N between these two groups. A linear increase in grain yield with increasing N rate was significantly greater for hybrids than lines. The results suggest that specific selection for high NUE sorghums will not diminish responsiveness to applied N.     

The application timing of nitrogen fertilizer

This paper is concerned with factors affecting a farmer's decision concerning the timing of nitrogen ferilizer application. These factors include the expected nitrogen loss associated with different application times, the expected seasonal fluctuations in nitrogen fertilizer prices and operating costs, and the perceived risk of not being able to apply nitrogen fertilizer during the growing season. This paper shows that a split application of nitrogen fertilizer is an optimal strategy for both risk-neutral and risk-averse cotton farmers in the United States if there is a possibility that they may be unable to apply nitrogen fertilizer after planting. Furthermore, a risk-averse cotton farmer relative to a risk neutral farmer will apply more nitrogen fertilizer prior to planting.The authors are with the Economic Research Service, U.S. Department of Agriculture, Washington, DC. The views expressed are those of the authors and do not necessarily represent the policies of the U.S. Department of Agriculture or the views of other U.S. Department of Agriculture staff members. They would like to thank the anonymous referees for useful suggestions. Senior authorship is not assigned.     

Environmentally friendly slow-release nitrogen fertilizer

To sustain the further world population, more fertilizers are required, which may become an environmental hazard, unless adequate technical and socioeconomic impacts are addressed. In the current study, slow-release formulations of nitrogen fertilizer were developed on the basis of natural attapulgite (APT) clay, ethylcellulose (EC) film, and sodium carboxymethylcellulose/hydroxyethylcellulose (CMC/HEC) hydrogel. The structural and chemical characteristics of the product were examined. The release profiles of urea, ammonium sulfate, and ammonium chloride as nitrogen fertilizer substrates were determined in soil. To further compare the release profiles of nitrogen from different fertilizer substrates, a mathematical model for nutrient release from the coated fertilizer was applied to calculate the diffusion coefficient D. The influence of the product on water-holding and water-retention capacities of soil was determined. The experimental data indicated that the product can effectively reduce nutrient loss, improve use efficiency of water, and prolong irrigation cycles in drought-prone environments.     

Quantifying soil nitrogen mineralization to improve fertilizer nitrogen management of sugarcane

Intensive use of synthetic nitrogen (N) fertilizers for sugarcane (Saccharum spp.) production presents environmental challenges for water and air quality as well as impacts profitability for producers. Central to these concerns is a widespread reliance on yield-based recommendations that invoke generic models of crop N response but lack any means to account for variations in soil N-supplying power, a critical determinant of fertilizer N need for cereal, fiber, and tuber crops. The work reported herein was designed to ascertain the impact of soil N mineralization on sugarcane response to N fertilization and was carried out in conjunction with eight N-response trials conducted between 2006 and 2010 at field sites in the largest sugarcane-cultivated area in Brazil. Soil samples were utilized in categorizing the sites as highly responsive, moderately responsive, or nonresponsive to fertilizer N, based on two chemical indices of soil N availability, the Illinois Soil Nitrogen Test (ISNT) and direct steam distillation (DSD), and assessments of (1) net mineralization during aerobic incubation for 12 weeks and (2) incubation-induced changes in soil N fractions obtained by acid (total hydrolyzable N, hydrolyzable NH₄ ⁺-N, amino sugar N, and amino acid N) or alkaline (ISNT-N) hydrolysis. Sugarcane varied widely in response to N fertilization, indicating that yield-based recommendations would often under- or overestimate N requirement and thus adversely impact sustainability of sugarcane-based ethanol production. In studies to evaluate feasibility of soil N testing to improve fertilizer N recommendations, mineral N production upon aerobic incubation was accompanied by significant decreases in hydrolyzable NH₄ ⁺-N and ISNT-N, indicating that both fractions were liberating mineralizable forms of soil N. Test values by the ISNT and DSD were highly correlated, and both showed promise for differentiating soil responsiveness to fertilizer N.     

控释氮肥对双季水稻生长及氮肥利用率的影响

为阐明控释氮肥的产量和生态效应,选用N 75和150 kg/hm2两种不同用量的控释氮肥（日本Meister系列）和尿素对比,在南方典型双季稻区第四纪红壤发育的水稻土上进行早稻和晚稻田间试验,观测控释肥氮素田间释放规律及其水稻的生长、产量和氮肥利用率。结果表明,控释氮肥S9和LP70(40%)+LPS100(60%)的氮释放规律分别与早稻、晚稻氮吸收的规律基本一致,且氮累积吸收量与控释肥氮释放率均成显著正相关（相关方程的决定系数R2=0.9764和0.9968）。与N 75kg/hm2用量的尿素相比,早、晚稻施用相同量的控释氮肥分别增产3.6%和9.3%;有效分蘖数和有效穗数明显增加,氮肥利用率分别提高了29.9个百分点和10.4个百分点。施用高氮（N150 kg/hm2）尿素的水稻产量与低氮（N 75 kg/hm2）控释肥相比,差异不显著。控释氮肥N 75kg/hm2用量可以达到尿素N 150kg/hm2的产量水平,氮肥利用率则显著提高,为高产高环境效益的施肥方式。     

有机无机配施体系中有机肥腐熟程度对化肥氮利用率的影响机制

为探究有机肥腐熟度对配施化肥氮利用率的作用机制,利用~(15)N标记技术进行意大利生菜盆栽试验,从堆肥过程中选取不同腐熟度的有机肥[按照种子发芽指数(GI值)为50%、80%和100%进行堆肥的腐熟度区分],研究施~(15)NPK化肥(对照, CK)、~(15)NPK+GI 50%有机肥(GI50)、~(15)NPK+GI 80%有机肥(GI80)、~(15)NPK+GI 100%有机肥(GI100) 4个处理对意大利生菜化肥氮的转化、吸收和利用的影响。结果表明,与CK处理相比,添加有机肥处理意大利生菜生物量、~(15)N吸收量与~(15)N利用率分别显著提高30.5%～56.1%、 40.0%～91.0%和15.5%～41.8%(P0.05), GI80处理较GI50处理生物量、~(15)N吸收量与利用率分别显著提高17.1%、31.8%和35.4%(P0.05), GI100处理较GI50处理生物量、~(15)N吸收量与利用率分别显著提高19.6%、15.8%和22.8%(P0.05)。试验期间,添加有机肥处理较CK处理土壤~(15)NH_4~+-N显著提高44.9%～74.2%(P0.05), ~(15)NO_3~--N显著降低8.4%～38.1%(P0.05),净硝化率显著降低10.8%～24.6%(P0.05);GI80处理较GI50处理土壤~(15)NH_4~+-N提高7.9%～11.5%, ~(15)NO_3~--N显著降低18.5%～50.4%(P0.05),净硝化率显著降低15.0%～28.2%(P0.05);GI100处理较GI50处理土壤~(15)NH_4~+-N显著提高11.5%～26.9%(P0.05), ~(15)NO_3~--N显著降低15.8%～22.7%(P0.05),净硝化率显著降低12.5%～23.9%(P0.05)。土壤微生物量氮(MB~(15)N)缓慢上升,添加有机肥处理较CK处理显著提高67.3%～94.1%(P0.05),GI80处理较GI50处理提高6.0%～23.8%,GI100处理较GI50处理显著提高6.9%～25.5%(P0.05)。各处理MB~(15)N占MBN的54.9%～71.6%(P0.05)。相关分析结果表明, MB~(15)N、~(15)NH_4~+-N与~(15)N吸收量、~(15)N利用率呈现极显著正相关关系,且RDA分析结果说明MB~(15)N是影响化肥~(15)N吸收利用的关键驱动因子。因此,有机无机配施体系中适当增加有机肥的腐熟度(GI≥80%)能够明显增强土壤微生物的固氮能力,提高土壤氮素水平,减缓土壤铵态氮向硝态氮的转化速度,降低土壤净硝化速率,从而提高化肥氮的利用效率。     

Scope for more efficient use of fertilizer nitrogen

Abstract. About 1.6 million tonnes of fertilizer N are applied to UK crops each year. In net terms, 10–60% of this is not taken up by the crop to which it was applied. Fertilizer N commonly doubles crop yield, but in the short term at least more than 90% of current production would be possible with only half normal use of N. However, costs of crop production other than fertilizer N are a large proportion of gross returns, so profits are sensitive to adjustments in N use and controls on N use could affect land values. Survey data show that compliance with current recommendations is good; recent improvements have come through restricting the use of N applications in autumn. Further improvements are possible by adjusting N use more fully for the extent to which past N applications have exceeded crop removal, and by better targeting the N used to improve protein concentrations of wheat grain. Research now in progress may provide insights into minimizing the crop N necessary for yield formation and the crop N left in the field at harvest, specifying the growing conditions which result in efficient N uptake from soil.     

基于15N标记的干旱区滴灌肥料氮的去向和效益研究

【目的】采用¹⁵N示踪法,研究滴灌肥料氮与土壤氮素的转化和去向以及在土壤中的残留分布,为新疆滴灌春小麦氮肥优化管理提供科学依据。【方法】试验于2019年在石河子大学农学院试验站进行,供试春小麦材料为强筋型‘新春38’(XC38)和中筋型‘新春49’(XC49)。试验设7个施氮(N)水平：300、285、270、255、240、225和0 kg/hm²,分别记作N300、N285、N270、N255、N240、N225和N0处理。每个试验小区内,安装未封底的PVC管(直径11 cm,高65 cm),管内施用与该处理等量的¹⁵N标记尿素。于小麦成熟期,测定PVC管内植株样品与土壤样品中的¹⁵N丰度,同时在小区内测定产量,计算氮素利用效率。【结果】两品种春小麦吸收的氮素来自肥料的比例为30.49%～36.06%,对土壤氮的依赖程度在60%以上。随着氮肥施用量的降低,对土壤氮的依赖程度逐渐增加。¹⁵N标记氮肥在土壤中的总残留率为24.05%～31.60%,主要集中在0—40cm土层,土...     

加工番茄氮肥用量与氮营养状况诊断研究

通过设置N0(不施氮)、N1(150 kg/hm2)、N2(300 kg/hm2)和N3(450 kg/hm2)4个氮水平的田间小区试验,利用反射仪法对加工番茄新功能叶的叶柄进行硝酸盐测定,并测定地上部分生物量与经济产量,研究叶柄硝酸盐浓度与产量、叶全氮量、植株全氮量、地上部分干物质量等的相关性,建立加工番茄叶柄硝酸盐诊断追肥模型。结果表明,优化施氮处理(N2)经济产量为95 259 kg/hm2,较不施氮处理(N0)增产50 812 kg/hm2,增收14 988元/hm2。各处理加工番茄叶柄硝酸盐浓度随生育期进展呈一致的变化趋势,且叶柄硝酸盐含量在一定范围内随施氮量的增加而增大。加工番茄不同生育时期叶柄硝酸盐浓度与产量均呈显著相关性。经过校检,加工番茄以盛果前期为氮营养诊断时期较为合理,其临界值为4 182 mg/L。同时,初步建立了植株硝酸盐诊断追肥模型。     

淹水培养条件下铵态氮肥对土壤氮素的激发效应

应用淹水培养方法 ,研究了铵态氮肥对土壤氮素的激发效应。结果表明 ,肥料和培养期间矿化出的铵态氮不可避免地会被粘土矿物固定。因此 ,在测定激发效应时 ,只有考虑这一部分氮素 ,才能获得可靠结果。土壤中有机物料不同 ,氮肥的激发效应不同。土壤中有机物料C/N比值低时 ,氮肥会表现出正激发效应 ,反之则为负激发效应。     

控释肥对夏玉米碳、氮代谢的影响

以夏玉米杂交种豫单998为材料,研究3种控释肥对夏玉米碳、氮代谢的影响。结果表明,在等养分量条件下,与常规施肥技术相比,3种控释肥均能有效协调吐丝期至成熟期植株体碳、氮代谢,叶片可溶性蛋白的含量增加2.20%1~0.39%,硝酸还原酶(NR)活性提高3.22%3~2.10%,植株叶片和茎鞘可溶性总糖分别增加6.78%4~6.71%和1.26%3~5.99%,全氮含量分别增加0.50%1~0.69%和1.09%4~1.92%;而可溶性总糖和氮素转运率均小于常规施肥。说明控释肥能较好满足夏玉米在吐丝期至成熟期生长需要,协调其碳、氮代谢,其中以硫加树脂包膜控释肥效果较好。     

辽河三角洲稻区缓释肥施用下氮肥减施潜力研究

为明确辽河三角洲典型单季稻区氮肥减施潜力,采用区域施肥调查和田间试验相结合的方法,以了解区域施肥现状以及不同缓释肥减量替代化肥对产量、氮素供给和流失风险的影响。结果表明,目前辽河三角洲单季稻氮肥施用量主要分布在200～350 kg·hm-2之间,区域平均施氮量为294.5 kg·hm-2,区域平均经济产量为10479.9 kg·hm-2,依据水稻需氮量计算得出适宜的施氮量为182～202 kg·hm-2。经研究表明,根据目前区域内可选择的肥料类型选择适宜的缓释肥料,减氮潜力在19.2%～30.8%之间,在保证作物产量的条件下,可以提高1.39%～15.79%的氮肥利用率,维持土壤养分含量,有效降低田面水中68.4%～79.6%的氮含量,增加541.4～5816.6元·hm-2的经济效益。综上,在减氮潜力较高的地区,适当减氮条件下施用缓释肥可以在保证作物产量的同时降低氮素损失的环境风险,减少人工成本,提高经济效益。     

基于有机肥 /生物有机肥和菌剂的化学氮肥减施技术在大蒜上的应用

在中国出口大蒜主产区山东省济宁市金乡县王丕镇玛丽亚大蒜种植基地连续种植 25年的大蒜田,分别研究化学氮肥减施 30%、化学氮肥减施 30%结合有机肥和菌剂组合技术、化学氮肥减施 30%结合生物有机肥和菌剂组合技术对大蒜生长、产量和品质的影响。结果显示:与常规施肥对照相比,化学氮肥减施 30%可导致大蒜长势、蒜头产量和部分品质降低;化学氮肥减施 30%结合有机肥和菌剂组合技术可以维持大蒜长势和蒜头产量,并提高大蒜品质;化学氮肥减施 30%结合生物有机肥和菌剂组合技术可以显著提高大蒜长势、蒜头产量和大蒜品质。可见,基于生物有机肥和菌剂的化学氮肥减施技术是适合中国出口大蒜主产区连作大蒜的减肥增效技术。     

控释氮肥替代水溶肥对草莓产量和品质的影响

为解决基质栽培条件下草莓肥料投入量大、追肥次数多、劳动力成本投入高等问题,研究以控释氮肥代替水溶肥实现草莓的一次性施肥。以“红颜”草莓为试验材料,以常规优化施肥处理为对照,测定基质栽培条件下优化施肥处理和不同氮用量的控释氮肥处理对草莓产量、品质、经济效益的影响,分析计算最优施氮量。结果表明:与常规优化施肥处理相比,控释氮肥处理的草莓产量提高了7.4%～26.5%,单果重提高了9.1%～33.3%,经济效益增加了7.5%～26.7%,糖度提升了7.7%～31.4%,Vc含量提升了8.8%～14.0%;除控释氮肥氮用量97.50 kg/hm²处理外,氮肥偏生产力和农学效率较常规优化施肥处理也分别提高了26.5%～144.3%和73.7%～222.7%。这说明,控释氮肥替代水溶肥既减少了肥料用量,保证草莓的产量,而且可以实现高产,提高了草莓的经济效益。通过二次曲线拟合控释氮肥施氮量与草莓产量、单果重的关系,得出控释氮肥的最佳推荐用量约为N 60 kg/hm²,为实际生产提供参考。综上所述,控释氮肥替代水溶肥提高了草莓的产量,保证了草莓的品质,降低了肥料投入成本,提高了经济效益。综合考虑草莓的产量、单果重、品质、肥料生产力和经济效益,推荐适宜草莓生产的控释氮肥用量约为N 60 kg/hm²。     

烤烟基肥施用时间与氮肥利用的相关性研究

烤烟是一种氮素敏感型的品质作物, 对氮素的需求非常严格。氮肥的合理施用不仅有利于提高烤烟对氮素养分的吸收利用, 也有利于提高烤烟烟叶品质。本研究采用大田试验的方法, 在湖北省烤烟主产区研究了基肥在3个不同施用时间(烤烟烟苗移栽前0 d、15 d和30 d)对烤烟氮肥利用参数的影响及其相关性。结果表明, 烤烟地上部烟叶和茎秆中干物质累积量和氮素含量均随着基肥施用时间的提前而表现出增加趋势。与移栽当天(0 d)施用基肥相比, 提前15 d、30 d施用基肥, 烤烟烟叶中干物质累积量和氮素含量分别平均增加16.4%、22.6%和1.5%、8.7%; 茎秆中则分别平均增加2.5%、12.7%和13.4%、33.9%。提前施用基肥有提高烤烟氮肥表观利用率的趋势, 但是各处理间差异不显著(P>0.05), 而在烤烟烟苗移栽前15 d、30 d施用基肥显著降低烤烟地上部氮肥农学利用率(35.2%、37.4%)和生理利用率(35.4%、41.6%)(P<0.05)。另外, 基肥施用时间与氮肥农学利用率、生理利用率和偏生产力均表现出显著或者极显著负相关关系, 而氮肥农学利用率与生理利用率和氮肥偏生产力以及氮肥生理利用率与偏生产力之间均表现出显著或极显著正相关关系。因此, 在烤烟烟苗移栽时适当提前基肥的施用时间(15~30 d)有利于提高烤烟对氮素的吸收利用, 促进烟叶中干物质的累积。