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1.
Evaluation of nitrogen (N) dynamic in soil using regression equations is important for proper determination of N fertilization. A 3-year field experiment was conducted to (1) develop the best-fitted regression model relating corn grain and stover yield to soil residual ammonium (NH4)-N and nitrate (NO3)-N for corn yield prediction and (2) evaluate how such a model can be beneficial to the health of ecosystem by predicting the appropriate rates of N fertilization for corn production. Soil NH4-N and NO3-N were determined at corn harvest at the depths of 0–30 and 30–60 cm. Nitrogen fertilizer rates and soil mineral N accounted for a maximum of 93% variation in corn grain yield. Soil mineral N enhanced corn yield more than N fertilizer. Totals of 63.1 and 14.1 kg/ha of soil residual NO3-N and NH4-N were found in the 0- to 60-cm depth, indicating the importance of performing soil N tests.  相似文献   

2.
Optimal fertilizer nitrogen (N) rates result in economic yield levels and reduced pollution. A soil test for determining optimal fertilizer N rates for wheat has not been developed for Quebec, Canada, or many other parts of the world. Therefore, the objectives were to determine: 1) the relationship among soil nitrate (NO? 3)- N, soil ammonium (NH + 4)- N and N fertilizer on wheat yields; and 2) the soil sampling times and depths most highly correlated with yield response to soil NO? 3-N and NH + 4-N. In a three year research work, wet and dried soil samples of 0- to 30- and 30- to 60-cm depths from 20 wheat fields that received four rates of N fertilizer at seeding and postseeding (plants 15 cm tall) were analyzed for NH + 4-N and NO? 3 -N using a quick-test (N-Trak) and a standard laboratory method. Wheat yield response to N fertilizer was limited, but strong to soil NO? 3-N.  相似文献   

3.
2008~2009年通过大田试验,研究了限水灌溉条件下,不同施氮量对冬小麦产量、氮素利用、土壤硝态氮动态变化及氮素平衡的影响。结果表明,施用氮肥显著增加小麦穗数和穗粒数,对千粒重无显著影响。作物产量、吸氮量与施氮量均呈抛物线关系,施氮量超过N240 kg/hm2,产量和吸氮量随施氮量增加略有降低。小麦起身期后,0—100 cm土层都有硝态氮分布,且随土层深度增加而减少;相同土层则随施氮量的增加而增加。土壤硝态氮积累量随生育期推进而降低,N0和N120处理分别在拔节期和开花期后表现出氮素亏缺;成熟期,土壤表观盈余以残留为主,表观损失量占小部分。氮肥表观利用率、农学利用率随施氮量增加呈降低趋势,而氮素残留率随施氮量增加呈增加趋势。在本试验条件下,施氮量在N 180~220 kg/hm2水平可以达到产量、氮素表观利用率、氮素残留率的较好结合,是限水灌溉下兼顾经济效益与环境效益的适宜施氮量。  相似文献   

4.
通过大田试验,研究黄淮平原潮土区不同轮作方式对不同土层土壤速效养分和小麦产量构成因素及产量的影响.采用随机区组设置连续的小麦-玉米(WM-WM-WM)、1周期小麦-玉米+1周期小麦-大豆(WM-WS-WM)、1周期小麦-玉米+1周期小麦-夏花生(WM-WP-WM)、连续的小麦-夏花生(WP-WP-WP)和连续的小麦-大...  相似文献   

5.
为解决区域土壤质地类型针对性氮肥施用问题,在轻壤土和黏壤土上分别设置不施氮肥,氮肥基追比3∶7,4∶6,5∶5,6∶4和7∶3处理,研究小麦产量、水氮利用效率以及土壤含水量、贮水量、NH_4~+-N、NO_3~--N动态变化规律。结果表明:轻壤质土壤氮肥基追比4∶6的处理小麦产量、水分利用效率、氮肥生产效率最高分别为8 265.3 kg/hm~2,27.6 kg/(hm~2·mm),34.4 kg/kg。黏壤质土壤氮肥基追比5∶5的处理小麦产量、水分利用效率、氮肥生产效率最高分别为8 363.2 kg/hm~2,28.3 kg/(hm~2·mm),34.8 kg/kg。小麦不同生育期各土层含水量垂直分布变化较大,轻壤质土壤含水量在9.3%～26.2%,而黏壤质为9.7%～27.6%;小麦全生育期内土壤贮水量呈先升高后降低趋势,黏壤质土壤贮水量高于轻壤质。氮素追施量越多土壤表层NH_4~+-N与NO_3~--N含量越高,且随土层加深土壤NH_4~+-N与NO_3~--N含量降低,受降水影响轻壤质土壤NH_4~+-N与NO_3~--N更易于向土层深处淋溶,成熟期黏壤质各土层的NH_4~+-N和NO_3~--N含量均多于轻壤质。说明黏壤质土壤保水保氮肥能力强于轻壤质,氮肥基追比可以适当增加。  相似文献   

6.
土壤残留氮是不容忽视的土壤氮素资源.通过田间小区试验研究了土壤高残留氮下不同施氮量(0、80、160、240和320 kg/hm2)对夏玉米土壤硝态氮积累、氮素平衡、氮素利用及产量的影响,分析了夏玉米的经济效益.结果表明,土壤剖面硝态氮积累量随施氮量的增加而增加,且施氮处理硝态氮积累量显著高于不施氮处理;各施氮处理土壤硝态氮在0-60 cm土层含量最高,在0--180 cm剖面呈先减少后增加的变化趋势.不施氮处理夏玉米收获后土壤无机氮残留量高达378 kg/hm2,随施氮量的增加,无机氮残留和氮表观损失显著增加.作物吸氮量、氮表观损失量与总氮输入量呈显著正相关,总氮输入量每增加l kg作物吸氮量增加0.156 kg,而表观损失量增加0.369 kg,是作物吸氮量的2.4倍.高残留氮土壤应严格控制氮肥用量,以免造成氮素资源的大量浪费.夏玉米籽粒吸氮量随施氮量的增加呈增加的趋势,氮收获指数呈降低的趋势.氮肥农学效率、氮肥生理利用率、氮肥利用率和氮素利用率在施氮量80 kg/hm2时最高,随施氮量的增加降低;增施氮肥能降低高残留氮土壤中氮肥的增产效果和利用率.综合考虑产量、氮素利用和环境效应,N 80 kg/hm2是氮素高残留土壤上玉米的合理施氮量.  相似文献   

7.
Abstract

Fertilizer N recommendations for small grains are frequently based on soil test N but data is limited for irrigated spring wheat. The relative grain yield response of irrigated spring wheat to N as affected by inorganic soil N (NO3‐N and NH4‐N), yield potential and market class was evaluated in thirteen Southern Idaho field experiments involving N rates. Experiments were conducted on silt loam soils from 1978 to 1986. Preplant soil NO3‐N and NH4‐N to a depth of 60 cm and ranging from 27 to 142 kg/ha accounted for approximately 73% of the relative yield variability. NO3‐N and NH4‐N were significantly correlated (r=.72). NH4‐N with NO3‐N did not account for more of the relative yield variability than using NO3‐N alone.

Inorganic N in the first 30 cm and the second 30 cm were significantly correlated (r=.69) but N in the first depth increment accounted for more of the relative yield variability. The linear regression coefficient relating inorganic N in the first 30 cm to relative yield of unfertilized spring wheat was almost twice as high as the coefficient for the second 30 cm increment (.50 vs .27). Results indicate that inorganic N below 30 cm should be weighted differently than N in the first 30 cm when determining the N requirements of irrigated spring wheat.

Yield potential significantly affected the relative yield response to N. The response to N was not significantly affected by spring wheat market class (hard red vs soft white).

For estimating fertilizer N requirements, the results provide little justification for the current widespread practices of (1) using the combined NH4‐N and NO3‐N inorganic soil test N values when NO3‐N alone has as much predictive value and (2) assigning equal weight to inorganic soil N at all sampling depths.  相似文献   

8.
Field trials were conducted over two years to investigate the effect of increasing N supply on apparent fertilizer N recovery by winter cereal crops (4 × wheat and 2 × barley) and on non‐recovered N. Apparent fertilizer N recovery was calculated by comparing N in fertilized and unfertilized crops. Non‐recovered N is defined as N which was neither found in crops nor soil mineral N (Nmin = NH4‐N + NO3‐N). At N supply levels according to common farming practice (Ncfp = 190 to 220 kg N/ha), 60— 93% of the fertilizer N was recovered in crops at harvest, while at high N supply levels of 265 to 273 kg N/ha 58—76% of fertilizer N was recovered. There were small differences in soil Nmin in 0—200 cm between Ncfp and unfertilized plots, but substantial increases in Nmin occurred at the highest N supply. Amounts of non‐recovered N differed substantially between sites (maximum value of 84 kg N/ha). Non‐recovered N increased with increasing N rate on only 3 out of the 6 sites, indicating that N immobilization was not necessarily dependent on N rate. The fate of non‐recovered N was studied for a further year by growing catch crops on the sites after cereal harvest. N re‐mineralization deduced from changes in catch crop N and in Nmin indicated that non‐recovered N had been immobilized in the soil. At three sites, crop N uptake was found between milk‐ripe stage and harvest (19 to 60 kg N/ha) suggesting substantial uptake of N mineralized from soil. However, grain yields were lower with N rates below Ncfp, indicating that late net soil N mineralization could not compensate for reductions in N fertilizer rate in these trials.  相似文献   

9.
To-date, assessments of nitrogen use efficiency (NUE) of sugarcane have not included the contribution of its components, nitrogen uptake efficiency (NUpE) and nitrogen utilization efficiency (NUtE). This study determined these values, based on biomass and plant nitrogen (N) content, in two four-month-old pot-grown genotypes. The treatments included six N regimes, with nitrate (NO3—N) or ammonium (NH4+-N) supplied alone, or as NO3?-N for the first 6 weeks and then NH4+-N until harvest, each as 4 or 20 mM. Regardless of the N form, NUE was higher at four than at 20 mM due to significantly higher NUpE at low N supply. The results indicated that there was luxury N uptake and preference for NH4+-N nutrition, which resulted in the highest determined NUE. There were significant differences between genotypes in biomass, morphological growth parameters, N uptake, total plant N and NUE, the latter matching previously established sucrose yield-based NUE field rankings.  相似文献   

10.
对不同施肥条件下23年小麦连作地和苜蓿连作地土壤矿质氮分布和累积进行研究,探讨种植浅根系和深根系植物对硝态氮淋溶的影响。结果表明,不施肥(CK)和单施磷(P)肥,小麦和苜蓿连作地土壤硝态氮主要集中在0—60 cm土层,0—60 cm土层以下硝态氮含量变化稳定并小于2 mg/kg。氮肥、磷肥和有机肥配施(NPM)时,小麦连作地土壤硝态氮累积在20—100 cm和140—320 cm土层,年累积速率可达42.12 kg/(hm2.a);苜蓿连作土壤硝态氮主要集中在0—60 cm土层,仅在200—300 cm土层出现轻微累积,年累积速率仅为1.01 kg/(hm2.a)。在不施肥和单施磷肥下,种植小麦或苜蓿对土壤硝态氮残留量影响不显著,而氮、磷和有机肥配施时,小麦连作地土壤硝态氮残留量迅速增加,并与不施肥、单施磷肥处理有显著差异;苜蓿连作地土壤硝态氮残留量虽有少量增加,但与不施肥、单施磷肥处理无显著差异。不施肥、单施磷肥和氮、磷和有机肥配施,小麦连作、苜蓿连作地土壤剖面铵态氮含量主要在10—20 mg/kg之间波动,在土壤剖面无明显的累积现象,铵态氮残留量受施肥和作物种类的影响不显著。  相似文献   

11.
A 5-year study was conducted to monitor patterns of NO3 - accumulation following the addition of plant residues of varying C:N ratios to the soil surface, to determine whether the availability of NO3 - following these applications would be timely and sufficient for typical annual crop uptake. Microbial respiration was measured in the last 3 years of the study to investigate how microbial activity was related to treatment differences in NO3 - accumulation. Treatments included: hairy vetch (Vicia villosa Roth) cut at mid-bloom; wheat (Triticum aestivum L.) straw applied at 4 Mg ha-1; vetch with 4 Mg ha-1 wheat straw; and a bare ground control. Soil NO3 - and respiration rates were correspondingly high for the 3–4 weeks following residue placement. Peak NO3 --N accumulation in vetch treatments occurred between 25 June and 10 July and ranged from 100 to 168 kg ha-1, with an average of 140 kg NO3 ?-N ha-1. Nitrate was sufficient and timely enough to meet most summer annual crop needs in the region. Over 5 years, peak NO3 ?-N was approximately 100 kg ha-1 higher in vetch than non-vetch treatments and roughly twice as high at 0–5 cm than at 5–20 cm. The addition of wheat straw caused a reduction of approximately 20% NO3 --N throughout the season as compared to vetch alone.  相似文献   

12.
ABSTRACT

The components that define cereal-grain yield potential have not been well defined. The objective of this study was to collect many differing biological measurements from a long-term winter wheat (Triticum aestivum L.) study in an attempt to better define yield potential. Four treatments were sampled that annually received 0, 45, 90, and 135 kg N ha?1 at fixed rates of phosphorus (P) (30 kg ha?1) and potassium (K) (37 kg ha?1). Mid-season measurements of leaf color, chlorophyll, normalized difference vegetative index (NDVI), plant height, canopy temperature, tiller density, plant density, soil moisture, soil NH4-N, NO3-N, organic carbon (C), total nitrogen (N), pH, and N mineralization potential were collected. In addition, soil texture and bulk density were determined to characterize each plot. Correlations and multiple linear-regression analyses were used to determine those variables that can predict final winter wheat grain yield. Both the correlation and regression analyses suggested mid-season NDVI, chlorophyll content, plant height, and total N uptake to be good predictors of final winter wheat grain yield.  相似文献   

13.
Determination of appropriate nitrogen (N) fertilization for wheat (Triticum aestivum L.) production with respect to the available resources can result in the enhanced efficiency of agricultural systems and ecosystem health. Hence, a 3-year field experiment was conducted to determine (1) the effects of soil total N and soil mineral N (including nitrate, NO3-N, and ammonium, NH4-N) measured at seeding and postseeding for wet and dry soil samples at 0- to-30 cm and 0- to 60-cm depths on wheat grain N uptake and (2) the regression equations that can best explain the variation in wheat grain N uptake by N fertilizer and soil total and mineral N. Determination of wheat grain N uptake as affected by soil NO3-N in areas with reasonable amounts of organic matter can also be used as a very useful tool for determination of appropriate N fertilization, which is of great agricultural and environmental implications.  相似文献   

14.
Inhibition of nitrification as a mitigation tool to abate nitrogen (N) losses and improve N use efficiency (NUE) is a promising technology. Nitrification inhibitor (dicyandiamide, DCD) was evaluated in two consecutive wheat-maize rotations (2015–2017), with two different N fertilizer levels applied in wheat (160, 220 kg N ha?1) and maize (180, 280 kg N ha?1). More NH4+-N contents (101% and 102% in wheat and 74% and 73% in maize) and less NO3–-N contents (37% and 43% in wheat and 46% and 57% in maize) were observed at both N levels treated with DCD compared to without DCD. Higher pH, lower EC and reduced NO3–-N accumulation were the other benefits of DCD. The NO3–-N accumulation within the 0–200 cm soil profile was significantly less at both N levels with DCD (66 mg kg?1 and 121 mg kg?1) compared to without DCD (96 mg kg?1 and 169 mg kg?1). Application of DCD also improved the growth and yield in both crops. Increase in NUE from 38% to 49% in wheat and 27% to 33% in maize with DCD at higher N level was also observed. Overall, the effectiveness of DCD in retarding the nitrification process was higher in wheat than maize.  相似文献   

15.
Abstract

A sandy soil was amended with various rates (20 – 320 g air-dry weight basis of the amendments per kg of air-dry soil) of chicken manure (CM), sewage sludge (SS), and incinerated sewage sludge (ISS) and incubated for 100 days in a greenhouse at 15% (wt/wt) soil water content. At the beginning of incubation, NH4-N concentrations varied from 50 – 280 mg kg?1 in the CM amended soil with negligible amounts of NO3-N. Subsequently, the concentration of NH4-N decreased while that of NO3-N increased rapidly. In soil amended with SS at 20 – 80 g kg?1 rates, the NO3-N concentration increased sharply during the first 20 days, followed by a slow rate of increase over the rest of the incubation period. However, at a 160 g kg?1 SS rate, there were three distinct phases of NO3-N release which lasted for160 days. In the ISS amended soil, the nitrification process was completed during the initial 30 days, and the concentrations of NH4-N and NO3-N were lower than those for the other treatments. The mineralized N across different rates accounted for 20 – 36%, 16 – 40%, and 26 – 50% of the total N applied as CM, SS, and ISS, respectively.  相似文献   

16.
选取闽江福州下游段水体及河口短叶茳芏湿地土壤水作为研究对象,采用SAN++连续流动分析仪测试样品中NO-3—N,NO-2—N和NH+4—N含量,以揭示河流水体N含量的季节差异和对土壤水N含量的影响。研究结果表明:(1)闽江福州下游段秋季河流水NH+4—N和NO-3—N含量高于春季,NO-2—N含量低于春季;秋季短叶茳芏湿地土壤水NH+4—N和NO-2—N含量也明显高于春季,土壤水NO-3—N含量低于春季;春、秋季土壤水NH+4—N含量皆高于河流水,而NO-3—N和NO-2—N含量皆明显低于河流水。(2)河流水的浸淹对土壤N含量影响较大,说明河流水是湿地土壤的主要N源。(3)闽江福州下游段河流水3种形态的N含量表现为秋季大于春季,存在较明显的季节差异。(4)与2007—2008年的观测值相比较,闽江河口河流水体N含量呈大幅上升趋势,水体富营养化加剧。  相似文献   

17.
In the framework of the European nitrate directive (91/676/EEG), losses of nitrate (NO3)– nitrogen (N) to both surface and groundwater are limited to 50 mg/l. Because the residual NO3-N in the soil profile after harvest is considered the main determinant of nitrate leaching during wintertime, the Flemish government imposed a limit value of 90 kg NO3-N ha?1 up to a soil depth of 90 cm between 1 October and 15 November. This study compared two different soil sample preparation methodologies. When samples were analyzed immediately upon arrival, no differences in NO3-N concentration were observed. However, although field-moist samples are maintained at 4 °C, nitrification is not completely stopped, as indicated by the increased NO3-N concentration in field-moist samples 10 days after storage at 4 °C . In contrast, nitrification in air-dried samples is stopped during the oven drying when 40 °C is reached. Moreover, the reproducibility was significantly greater in air-dried samples as compared to field-moist samples.  相似文献   

18.
太行山前平原农田生态系统氮素循环与平衡研究   总被引：17，自引：0，他引：17  
在中国科学院栾城生态农业试验站1公顷小麦玉米轮作农田,运用乙炔抑制原状土柱培育法、微气象学法和陶土头多孔杯水量平衡法分别定量测定了氮素硝化反硝化损失、氨挥发、NO3--N淋溶损失等氮素循环转化途径。研究结果表明,每年因氨挥发而造成的肥料氮损失量为N.60.kg/hm2,占施入肥料氮的15%;NO3--N淋溶损失量为N.68～4.kg/hm2,占肥料施用量的1.4%2～0.3%;每年因硝化反硝化过程造成的肥料损失量为N.2.021～0.49.kg/hm2,占肥料施入量的0.51%1～.37%。氨挥发、NO3--N淋溶和硝化反硝化损失主要发生在施肥灌溉/降雨之后,玉米季肥料损失明显高于小麦生长季节。氨挥发和NO3--N淋溶损失是本区域农田氮素损失的主要途径,是氮肥利用率低的重要原因。在当地农民所采用的常规农业管理措施下,小麦玉米轮作农田氮素平衡处于盈余状态,小麦季盈余N+115.5～+124.5.kg/hm2,明显高于玉米季;由于玉米季氮素损失严重,氮素盈余较少,甚至出现亏缺,玉米季氮素平衡状况为-54.6～+14.3.kg/hm2。  相似文献   

19.
Studies were conducted to evaluate response of dryland corn (Zea mays L.) along the upper Texas Gulf Coast to residual soil nitrate-nitrogen (NO3-N) measured to depths of 15, 30, and 61 cm. Residual soil NO3-N levels ranged from 3.4 to 31.6, 7.8 to 49.3, and 9.0 to 71.7 kg ha?1, respectively, in 0 to 15, 15 to 30, and 30 to 61 cm depth increments, with cumulative NO3-N ranging from 23.5 to 114.5 kg ha?1 across sites-years. Where N fertilizer was reduced due to N crediting, yields and bushel weights at all 13 site-years showed no difference from those receiving full recommended N rates. A yield response to any level of added fertilizer N above the control was observed for only 6 of 13 site-years. These results indicate a high potential for success in crediting carryover soil NO3-N to 61 cm as a means of reducing applied nitrogen fertilizer rates.  相似文献   

20.
华北山前平原农田土壤硝态氮淋失与调控研究   总被引：11，自引：5，他引：6  
本文依托中国科学院栾城农业生态系统试验站小麦-玉米一年两熟长期定位试验, 应用土钻取土和土壤溶液取样器取水的方法, 研究了不同农田管理措施下土壤硝态氮的累积变化, 计算了不同氮肥处理通过根系吸收层的硝态氮淋失通量。结果表明, 小麦-玉米生长季土壤硝态氮累积量和淋失量随着施氮量的增加显著增加, 相同氮肥水平下增施磷、钾肥增加了作物的收获氮量, 施磷肥增加的作物收获氮量最高可达123kg·hm-2·a-1, 施钾肥增加的作物收获氮量最高为31 kg·hm-2·a-1。不同灌溉水平下0~400 cm 土体累积硝态氮随着灌溉量的增加而降低, 控制灌溉(小麦季不灌水, 玉米季灌溉1 水)、非充分灌溉(小麦季灌溉2~3 水, 玉米季按需灌溉)、充分灌溉(小麦季灌溉4~5 水, 玉米季按需灌溉)各处理剖面累积硝态氮量分别为1 698 kg·hm-2、1148 kg·hm-2 和961 kg·hm-2。与非充分灌溉和充分灌溉处理相比, 控制灌溉在100~200 cm 土层硝态氮累积量显著高于其他层次, 2003~2005 年间控制灌溉剖面增加的硝态氮量占施肥总量的23%; 非充分灌溉处理剖面增加的硝态氮量占施肥总量的22%; 充分灌溉处理剖面增加的硝态氮量占施肥总量的47%。免耕措施降低了作物产量, 影响土壤水的运移, 增加了硝态氮的淋失风险。根据作物所需降低氮素投入(N 200 kg·hm-2·a-1), 增施磷、钾肥, 控制灌溉量是减少华北山前平原地区硝态氮淋失, 保护地下水的有效措施。  相似文献   

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