典型红壤区稻田树脂包膜控释氮肥氨挥发研究

本文研究了红壤水稻土上,树脂包膜尿素(控释N肥)和普通尿素施用后氨挥发损失的过程及数量。结果表明:①基施后2～4天内和追施后的1～2天内,控释N肥氨挥发通量相对普通尿素处理均有下降,下降幅度分别为28.57%和25.00%;控释N肥氨挥发峰值分别于基肥后第5天和追肥后第4天出现,均滞后于普通尿素处理。②追肥2天后,控释N肥氨挥发通量极显著高于普通尿素处理。因此,只有采取合理的基施方式,控释N肥才能比普通尿素发挥更大的环境效益。     

表施尿素的冬小麦土壤氨挥发损失

Ammonia volatilization was measured with a continuous air flow enclosure method from a winter wheat field in the Experimental Farm of Jurong Agricultural School to investigate its main influencing factors. The experiment with five treatments in triplicate, no N (control), 100, 200 and 300 kg N ha^-1 with rice straw cover at a rate of 1 500 kg ha^-1 and 200 kg N ha^-1 without rice straw, started when the winter wheat was sown in 1994. Sixty percent of the total amount of N applied was basal and 40% was top-dressed. The measurement of ammonia volatilization was immediately conducted after urea was top-dressed on soil surface at wheat elongation stage in spring of 1996 and 1997. The results showed that there was a diurnal variation of ammonia volatilization rate from the winter wheat field, which synchronized with air temperature. N losses through ammonia volatilization increased with increasing N application rate, but the ratio of N lost through ammonia volatilization to applied N was not significantly affected by N application rate. The coverage of rice straw had no significant effect on ammonia volatilization. Soil moisture and rain events after urea was top-dressed affected ammonia volatilization significantly.     

Ammonia volatilization from nitrogen fertilizers surface-applied to corn (Zea mays) and grass pasture (Dactylis glomerata)

Summary The major agronomic concern with NH₃ loss from urea-containing fertilizers is the effect of these losses on crop yields and N fertilizer efficiency. In this 2-year study, NH₃ volatilization from surface-applied N fertilizers was measured in the field, and the effects of the NH₃ losses detected on corn (Zea mays L.) and orchardgrass (Dactylis glomerata L.) yield and N uptake were determined. For corn, NH₄NO₃ (AN), a urea-AN solution (UAN), or urea, were surface-broadcast at rates of 0, 56 and 112 kg N ha^–1 on a Plano silt loam (Typic Argiudoll) and on a Fayette silt loam (Typic Hapludalf). Urea and AN (0 and 67 kg N ha^–1) were surface-applied to grass pasture on the Fayette silt loam. Significant NH₃ losses from urea-containing N sources were detected in one of four corn experiments (12%–16% of applied N) and in both experiments with grass pasture (9%–19% of applied N). When these losses occurred, corn grain yields with UAN and urea were 1.0 and 1.5 Mg ha^–1, respectively, lower than yields with AN, and orchardgrass dry matter yields with urea were 0.27 to 0.74 Mg ha^–1 lower than with AN. Significant differences in crop N uptake between N sources were detected, but apparent NH₃ loss based on N uptake differences was not equal to field measurements of NH₃ loss. Rainfall following N application markedly influenced NH₃ volatilization. In corn experiments, NH₃ loss was low and yields with all N sources were similar when at least 2.5 mm of rainfall occurred within 4 days after N application. Rainfall within 3 days after N application did not prevent significant yield reductions due to NH₃ loss from urea in grass pasture experiments.     

Effect of air flow rate,lime amendments,and chemical soil properties on the volatilization of ammonia from fertilizers applied to sandy soils

NH₃ volatilization from surface-applied urea, diammonium phosphate (DAP), and calcium ammonium nitrate (CAN) was measured with chambers through which air was drawn continuously. Two sandy soils and two sandy loam soils, which had been treated with and without time for the last 25 years, were used for the experiments. The accumulated NH₃ loss from CAN applied to an unlimed sandy soil was linearly related to time. For the other treatments the accumulated loss was exponentially related to time. The NH₃ loss was exponentially related to the maximum soil pH of the fertilizer-amended soil, and was inversely related to the content of exchangeable H⁺. Due to the low cation exchange capacity of these light-textured soils the NH₃ loss was not reduced as the soil CEC increased. The maximum pH after soil amendment was related to soil pH. Therefore, a model is proposed that relates the NH₃ loss solely to fertilizers and soil pH. The NH₃ loss was less than 5% from CAN, about 20% from DAP, and about 30% from urea, with the insignificant loss from urea applied to the unlimed sandy soil excluded. The NH₃ loss from surface-applied DAP was related to the air flow rate and a transfer coefficient (K _a) was estimated. K _a increased exponentially with the flow rate. At a flow rate above 3.9 liters min^–1 (20 volume exchanges min^–1) no further increase was seen.     

改性尿素施用对氨挥发量及无机氮变化的影响

采用室内土壤培养和玉米幼苗盆栽试验的方法,研究了改性尿素施用后的氨挥发量及其对土壤无机氮和pH值的影响。结果表明:(1)表施改性尿素比表施普通尿素的氨挥发量显著减少,从而降低氮素的损失;在一定范围内,土壤含水量越大,氨挥发量越低。(2)硝化抑制剂双氰胺(DCD)能够抑制土壤硝化作用,使NH+4-N能较长时间存在土壤中,从而减少NO-3-N的损失;在一定范围内,DCD施用浓度越大,抑制效果越好。(3)土壤pH值与铵态氮呈极显著指数正相关,与硝态氮呈极显著线性负相关,与无机氮呈多项式相关。因此,改性尿素能够显著减少氨挥发量,抑制土壤硝化作用,从而降低尿素的氮素损失。     

控释掺混肥结合增密对水稻氮肥利用效率和氨挥发的影响

为探究控释掺混肥结合增密对水稻产量、氮素吸收、施肥经济效益和氨挥发损失的影响,该研究以扬籼优418为供试材料,设不施氮对照（CK）、常规施氮（Farmer''s Fertilization Practice,FFP）、优化施氮（Optimized Nitrogen Application,OPT）、控释掺混肥（Controlled Release Blended Fertilizer,CRBF）和控释掺混肥结合增密（Controlled Release Blended Fertilizer Combined with Dense Planting,CRFDP）共5个处理,对比分析了不同处理的水稻产量及构成因子、氮素吸收和氮肥利用效率、经济效益和氨挥发损失的差异。结果发现,CRFDP处理的水稻有效穗数和每穗实粒数显著高于其他处理（P<0.05）,较FFP分别增加26.1%和18.7%。CRFDP处理较FFP处理水稻增产33.3%。与FFP相比,CRFDP的氮肥吸收利用率、氮肥偏生产率、氮肥农学利用率分别提高160%、22.8 kg/kg、16.27 kg/kg。CRFDP较CRBF处理的氮肥吸收利用率显著提高10.0个百分点,氮肥偏生产率、氮肥农学利用率和氮素生理利用率则没有显著差异（P>0.05）;与FFP处理相比,3个优化施氮处理（OPT、CRBF和CRFDP）在氮肥用量降低20%的情况下,水稻每公顷净收益增加3 328～8 968元,其中CRFDP处理的水稻产值和净收益最高。施氮显著提高了水稻生长季的田面水铵态氮浓度和土壤脲酶活性,与FFP处理相比,CRFDP处理的氨挥发强度和累积氨挥发损失分别降低62.5%和46.3%。综上,控释掺混肥与增密结合可兼顾水稻高产、氮肥高效利用和氨减排。研究结果可为水稻高产及环境友好和资源高效的水稻种植新模式数据支持和理论支撑。     

Ammonia volatilization from ammonium sulfate as sulfur source

Surface application of ammonium sulfate (AMS) as S source to soils with pH ≥7.0 is subjected to ammonia (NH₃) volatilization. However, AMS volatilizes less NH₃ than urea does. In soils with pH <7.0, unlike urea, very little NH₃ volatilization from AMS occurs. The associated N with AMS may enhance early biological N fixation by leguminous crops as compared to S sources without N such as polyhalite.     

Ammonia volatilization from poultry manure-amended soil

Summary Poultry manure (PM) is commonly applied to cropland as a fertilizer, usually at rates determined by the nitrogen content of the manure. Limited information is available, however, on the volatilization of ammonia from poultry manure-amended soils, despite the effect these losses may have on the fertilizer value of the manure. This study was initiated to determine the influence of incorporation and residue cover on NH₃ losses from PM-amended soils. In the first experiment, a dynamic flow technique was used to measure NH₃ losses from 18 manures applied to a bare soil surface at a rate of 12 Mg ha^-1. In the second experiment, 3 of the 18 manures were incorporated either immediately, 24 h or 72 h after application. The third experiment compared the same three manures applied to a bare soil surface or to corn or soybean residues. Surface application of the manures resulted in the loss of from 4 to 31% of the total N applied in the manures. Incorporation of the PM with soil significantly reduced NH₃ loss with the greatest decrease following immediate incorporation. Crop residues either had no effect or slightly reduced NH₃ volatilization losses relative to PM application to a bare soil surface. Ammonia volatilization was not well correlated with individual manure properties, but a multiple regression approach using manure pH and total N content offered some promise as a means to segregate manures of the basis of volatilization potential.     

Laboratory Evaluation on Ammonia Volatilization from Coated Urea Fertilizers

Coated urea fertilizers are assumed to enhance crop yield and reducing the environmental pollution. Nevertheless, many of the coated urea fertilizers are expensive, thus not readily available for most farmers. In addition, many of these fertilizers release N not in tandem with the plant’s need, thus retard growth. Therefore, a laboratory study was conducted to evaluate effects of coated urea fertilizers on N losses via volatilization. Measurement of ammonia volatilization was carried out using the closed-dynamic air flow system. The study for ammonia volatilization was conducted using different rates of fertilizer (50, 100, and 200 kg N ha^?1) with different types of fertilizer (Urea, Sulfur-coated urea; SCU and Gypsum sulfur coated urea using rotating drum; GSCUD) in 37 days of incubation. The results indicate that SCU represents the best fertilizer which decreases the amount of ammonia volatilization at each rate of fertilizer. Besides, the rate of 50 kg N ha^?1 has the lowest percentage of ammonia volatilization. Moreover, the result proved the effectiveness of coating urea fertilizer may reduce the ammonia loss to the environment and new product which GSCUD can be comparable to the commercial product.     

Effect of blending urea with pyrite or coating urea with polymer on ammonia volatilization loss from surface-applied prilled urea

Laboratory studies on a sandy clay loam (Typic Ustochrept) alkaline soil showed that NH₃ volatilization loss from surface-applied prilled urea during an 8-dya incubation under aerobic conditions was 27.5% of applied N (400 kg N ha^-1) and was reduced to 8.9% when the urea was blended physically with pyrite in a 1:2 ratio; under anaerobic conditions the values for urea and pyrite-urea were 19.3 and 16.9%, respectively. Other treatments tested were urea-gypsum, neemcake-coated urea and polymer-coated urea. A 6% polymer coating showed the least NH₃ volatilization under anaerobic conditions and was next best to pyrite-urea under aerobic conditions. A 3% polymer coating was slightly inferior to the 6% coating. Urea-gypsum and neemcake-coated urea did not differ very much from urea alone under anaerobic conditions, but under aerobic conditions neemcake-urea showed a significantly lower total NH₃ loss compared to prilled urea alone and urea-gypsum.     

不同氮肥缓释化处理对夏玉米田间氨挥发和氮素利用的影响

【目的】氨挥发是农田氮素损失的重要途径之一,氮肥类型或尿素氮肥缓释处理方式直接或间接影响作物吸收及土壤理化性质,进而影响氨挥发和氮素利用效率。通过不同缓释处理技术减低氨挥发和氮素降解释放速率来提高作物氮素吸收,对于提高作物氮素利用率具有重要意义。【方法】通过两年田间原位监测试验,以不施氮肥为对照（CK）,设硝酸钙（CN）、常规尿素（CU）、树脂包膜尿素（CRF）、控失尿素（LCU）、凝胶尿素（CLP）、脲甲醛（UF）7个处理,研究不同氮肥缓释化处理对夏玉米土壤氨挥发损失量、玉米产量和氮素利用的影响。【结果】1）氨挥发主要集中于施肥后一周以内,常规尿素氨挥发累积量占整个生育期氨挥发累计总量平均为81.6%,凝胶尿素、控失尿素、树脂包膜尿素、脲甲醛氨挥发累积量占整个生育期氨挥发累计总量的比例介于62.2%~82.2%之间。2）2014年夏玉米田间氨挥发监测期内,常规尿素的氨挥发累计总量为N 14.9 kg/hm2,凝胶尿素、控失尿素、树脂包膜尿素、脲甲醛处理与常规尿素相比下降幅度介于21.7%~64.6%。2015年,常规尿素的氨挥发累计总量为N 17.3 kg/hm2,凝胶尿素、控失尿素、树脂包膜尿素、脲甲醛处理与常规尿素相比下降幅度介于17.3%~57.2%。3）化肥氮在常规尿素、树脂包膜尿素以及控失尿素处理中的贡献率较高,两年均达60%以上,其中常规尿素中化肥氮的贡献率平均高达76.0%。而化肥氮在脲甲醛中的贡献率较低,平均仅为37.6%。4）与常规尿素相比,脲甲醛、凝胶尿素、控失尿素以及树脂包膜尿素的产量也有显著增加,两年平均产量增幅为6.3%~18.8%。5）不同氮肥的夏玉米氮肥利用率也有显著差异,其中脲甲醛为最高,平均高达57.9%,其次为凝胶尿素、控失尿素、树脂包膜尿素、硝酸钙和常规尿素,分别为42.4%、38.3%、38.3%、23.5%和20.8%。【结论】氮肥中的氨挥发主要集中于施肥后一周以内。与常规尿素相比,脲甲醛、控失尿素、树脂包膜尿素、凝胶尿素均能明显减少氨挥发损失、提高产量和氮肥利用率,以脲甲醛和凝胶尿素效果更显著,是高产、高效、低损失的肥料类型。     

Potential urea-derived nitrogen losses caused by ammonia volatilization and nitrogen leaching in a rainfed semiarid region,China

Abstract

In the rainfed semiarid region of the China Loess Plateau, rainfall is concentrated in the growing season and usually occurs in large storms. This makes for a high risk for fertilizer-derived nitrogen losses. However, relatively little attention has been given to fertilizer efficiency in this region. In this study, ammonia volatilization at natural field conditions as affected by urea-application rate was measured to evaluate the potential ammonia volatilization losses. Nitrogen-leaching potential in the 0–100 cm soil profile as affected by urea-application rate and -application depth for different rainfall-simulated irrigation regimes (two irrigation volumes: 70 and 105 mm; two irrigation methods: single irrigation and three-split irrigation) was also investigated. Results showed that the low initial soil moisture content at the crop-planting stage and a strong following rainfall made ammonia volatilization of low importance from an agricultural management perspective. The stock percentage of urea-derived nitrogen in the soil profile was significantly affected by irrigation method and irrigation volume but not by urea-application rate. Generally, the 105 mm irrigation volume and the single-irrigation method had a lower percentage of applied nitrogen remaining in the soil profile. The results of this rainfall-simulated irrigation investigation indicated that heavy rainfall, especially occurring in large storms, in this area increased the risk of nitrogen leaching. We recommend that split applications of urea should be adopted instead of a conventional lumped (single) application to reduce nitrogen losses in this rainfed semiarid region.     

Applied Model for Estimating Potential Ammonia Loss from Surface-Applied Urea

Ammonia loss from urea fertilizer is a major concern to farmers all over the world. Various environmental factors such as temperature, soil water content, wind speed, pH, rainfall, relative humidity, cation exchange capacity (CEC), soil organic matter, and others influence ammonia volatilization loss. The objective of this work was to establish a model for estimating ammonia loss utilizing published data. Also, using current day inputs (temperature, wind speed, and known soil pH) estimates could relate risk to producers considering surface applications of urea fertilizer without incorporation. Linear models for soil pH and ammonia loss, ambient temperature and ammonia loss, and wind speed and ammonia loss were determined based on more than 40 published articles. Final estimates of ammonia loss from surface applications of urea employed an additive effects model using inputs for pH, temperature, and wind speed. Web access to this model can be located at www.nue.okstate.edu/ammonia_loss.htm.     

常规灌溉条件下施氮对温室土壤氨挥发的影响

为明确温室土壤的氨挥发特征,探讨适宜的减量施氮措施对氨挥发损失量及黄瓜产量的影响,在常规灌溉条件下设置了3个施氮（尿素）处理,采用通气法测定了冬春季黄瓜地中的氨挥发速率。结果表明：温室土壤在氮肥基施后7 d出现氨挥发速率峰值,但在氮肥追施后,施肥带与非施肥带的氨挥发速率峰值分别在第1 d与第5 d出现,氨挥发速率的峰值比氮肥基施时下降了8.6%～46.3%,施肥带的累积氨挥发量是非施肥带的0.91～1.54倍。冬春季黄瓜地的氨挥发损失量为16.7～26.6 kg/hm2,其中减施氮25%处理N900（900 kg/hm2）与减施氮50%处理N600（600 kg/hm2）与习惯施氮处理N1200（1 200 kg/hm2）相比,氨挥发损失量分别降低了22.1%和37.2%。而2 a黄瓜产量的平均值以处理N600（600 kg/hm2）最高,比处理N1200（1 200 kg/hm2）增加了6.52%。综合考虑氨挥发损失量、黄瓜产量及施氮量,在河北省的温室冬春季黄瓜生产中,比农民习惯氮用量（1 200 kg/hm2）减少25%～50%的措施是可行的。     

太湖水稻土麦季尿素氨挥发损失

Ammonia volatilization losses from urea applied as a basal fertilizer and a top dressing at tillering stage in a wheat field of Taihu Region, China, were measured with a micrometeorological technique. Urea as fertilizer was surface broadcast at 81 (low N) and 135 (high N) kg N ha-1 as basal at the 3-leaf stage of the wheat seedling on December 2002, and 54 (low N) and 90 (high N) kg N ha-1 as top dressing on February 2003. Ammonia volatilization losses occurred mainly in the first week after applying N fertilizer and mainly during the period after basal fertilizer application, which accounted for more than 80% of the total ammonia volatilization over the entire wheat growth period. Regression analysis showed that ammonia volatilization was affected mainly by pH and NH4^ -N concentration of the surface soil and air temperature.Ammonia volatilization flux was significantly correlated with pH and NH4^ -N concentration of the surface soil and with daily air average temperature and highest temperature. Thus, application of urea N fertilizer to wheat should consider the characteristics of ammonia volatilization in different periods of N application so as to reduce ammonia losses.     

典型双季稻田基施碳酸氢铵和尿素的氨挥发损失研究

采用密闭室连续抽气法研究了湖南典型双季稻田,尿素和碳酸氢铵基施后的氨挥发特征。结果表明,基施碳酸氢铵(NC)稻田初始氨挥发强度和氨挥发总量大于基施尿素(UR)稻田。早稻季NC处理稻田氨挥发排放量为45.19 kg·hm-2,损失率达30.12%,UR处理氨挥发排放量为32.93 kg·hm-2,损失率达21.95%;晚稻季NC处理稻田氨挥发排放量为70.91 kg·hm-2,损失率达31.93%,UR处理氨挥发排放量为61.78 kg·hm-2,损失率达27.04%。基施尿素能够显著降低稻田氨挥发排放,减少氮素损失。     

Ammonia loss following surface application of urea fertilizers to a calcareous soil

Abstract

N loss by volatilization was measured for surface‐applied granular urea and ammonium nitrate, liquid urea‐ammonium nitrate and liquid acid urea in closed containers. Urea‐containing fertilizers lost between 10 and 451 of the N added within 10 days. The presence of a straw mulch accentuated the losses. N volatilization losses from acid urea solutions were significantly less than from granular urea. Addition of water following surface application of granular urea significantly reduced the loss of N as ammonia from the soil. The results of this laboratory study indicate that use of acid urea for surface application of N fertilizers may reduce N volatilization losses relative to granular urea, but losses still exceed those from ammonium nitrate.     

太湖地区水稻追肥的氨挥发损失和氮素平衡

采用密闭室通气法和¹⁵N 微区试验, 对太湖地区水稻不同生育期追施氮肥的氨挥发损失、水稻对氮肥的吸收利用和土壤氮素残留情况进行了研究。结果表明, 氨挥发损失主要发生在施肥后1 周内, 峰值出现在施肥后1~2 d, 氨挥发速率变化与田面水NH₄⁺-N 浓度变化规律一致, 分蘖肥和穗肥氨挥发损失率分别为16.7%和6.3%; 水稻分蘖肥的作物氮素利用率低于穗肥, 分别为36.7%和49.6%, 主要原因是穗肥的氨挥发损失较少,并且更易于向籽粒转移; 2 次追施氮肥的表观损失率分别为52.8%和40.7%; 在土壤中残留肥料氮为10.6%, 大都集中在0~20 cm 土壤中, 耕层以下较少。本结果表明, 在水稻孕穗时期施氮肥有利于提高氮肥利用效率、减少氮肥损失, 主要体现在穗肥拥有较低的氨挥发损失率和较高的籽粒利用率。     

尿素二次加工产品的氨挥发损失特征研究

应用密闭法对尿素及其二次加工产品—复合肥料、包膜尿素和包膜复合肥料在施入土壤后的氨挥发特征进行了研究。结果表明,尿素二次加工产品的氨挥发损失特征各不相同:尿素、复合肥料、包膜尿素、包膜复合肥的氨挥发分别占总施氮量的9.2%、10.4%、7.6%、9.3%;复合肥料氨挥发损失比尿素高12.9%,而包膜尿素的氨挥发损失较尿素低17.9%。包膜复合肥与尿素相比,二者氨挥发总体上接近,但在施肥后前25 d包膜复合肥降低氨挥发15.6%,降雨后25 d却增加氨挥发20.7%。尿素二次加工产品的氨挥发损失特征需结合其生产工艺进行进一步研究。