Leaching and Transformation of Nitrogen Fertilizers in Soil After Application of N with Irrigation： A Soil Column Method

A soil column method was used to compare the effect of drip fertigation （the application of fertilizer through drip irrigation systems, DFI） on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation （SFI）, and to study the leaching loss and transformation of three kinds of nitrogen fertilizers （nitrate fertilizer, ammonium fertilizer, and urea fertilizer） in two contrasting soils after the fertigation. In comparison to SFI, DFI decreased leaching loss of urea-N from the soil and increased the mineral N （NH4^＋-N ＋ NO3^--N） in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control （without urea addition）, on the first day when soils were fertigated with urea, there were increases in NH4^＋-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH4^＋-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH4^＋-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH4^＋-N fixation or volatilization in the soil during the fertigation process.     

灌溉施用氮肥后氮素在土壤中的转化及淋失状况: 土柱模拟研究

A soil column method was used to compare the effect of drip fertigation (the application of fertilizer through drip irrigation systems, DFI) on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation (SFI), and to study the leaching loss and transformation of three kinds of nitrogen fertilizers (nitrate fertilizer, ammonium fertilizer, and urea fertilizer) in two contrasting soils after the fertigation. In comparison to SFI, DFI decreased leaching loss of urea-N from the soil and increased the mineral N (NH₄⁺-N + NO₃^--N) in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control (without urea addition), on the first day when soils were fertigated with urea, there were increases in NH₄⁺-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH₄⁺-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH₄⁺-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH₄⁺-N fixation or volatilization in the soil during the fertigation process.     

施用控释肥提高直播水稻氮的利用率

Field trials on a silt-loamy paddy soil derived from shallow-sea deposit in direct seeding rice fields were conducted in Zhejing ,China,in 1996 to compare N efficiency of controlled release fertilizers (LP fertilizers) with the conventional urea.Six treatments including CK (no N fertilizer),conventional urea and different types of LP fertilizers at different rates were designed for two succeeding crops of early and late rice.A blend of different types of LP fertilizers as a single preplant “co-situs“ application released n in a rate and amount synchronizing with uptake pattern of direct seeding rice.A single preplant application of the LP fertilizers could meet the N requirement of rice for the whole growth period without need of topdressing,Using LP fertilizer blends ,equivalent grain yields could be maintained even if the N fertilization rates were reduced by 25%-50% compared with the conventional urea .Agronomi efficiency of the LP fertilizers was 13.6%-86.4% higher than that of the conventional urea in early rice and 100%-164.1% in late rice,depending on the amounts of the LP fertilizers applied.N fertilizer recovery rate incereased from 27.4% for the conventional application of urea to 41.7%-54.1%,for the single preplant “co-situs“ application of the LP fertilizers,Use of the LP fertilizers was promising if the increse in production costs due to the hihg LP fertilizer prices could be compensated by increase in yield and N efficiency,reduction in labor costs and improvement in environment.     

中国湖南省主要水稻土类型的氨固定

The contents, affecting factors, seasonal changes and availability of fixed ammonium in major types ofpaddy soils derived from different parent materials in Hunan Province, China, were studied using the Silva-Bremner method by laboratory and pot experiments. Results showed that the content of fixed ammoniumin the plough horizons ranged from 88.3 mg kg-1 to 388.1 mg kg-1, with 273.2 ± 77.7 mg kg-1 on average,accounting for 11.2% of total soil N on average. Content of fixed ammonium decreased in the order of newlylacustrine clayey paddy soil ＞ alluvial sandy paddy soil ＞ purple clayey paddy soil ＞ newly alluvial sandypaddy soil ＞ yellow clayey paddy soil ＞ reddish-yellow clayey paddy soil ＞ granitic sandy paddy soil. Therewere four distribution patterns of fixed ammonium in the profiles to 1-m depth, i.e., increase with the depth,decrease with increasing depth, no distinct change with the depth, and abrupt increase or decrease in somehorizon. Percentage of fixed ammonium in total N increased with the depth in most of the soils. Fixationof NH4+ by soil was higher at 30 ℃ than at 20 ℃ and 40 ℃, and continuous submergence benefited thefixation of NH4+ in newly alluvial sandy paddy soil, purple clayey paddy soil and alluvial sandy paddy soil,while alternating wetting and drying contributed to the fixation of NH4+ in yellow clayey paddy soil mostly.Fixed ammonium content in the test paddy soils was significantly correlated with ＜ 0.01 mm clay content(P ＜ 0.05), but not with ＜ 0.001 mm clay content, total N, organic N and organic matter. Fixed ammoniumcontent varied with rice growth stages. Application of N fertilizer promoted fixation of NH4+ by soil, and Nuptake by rice plant promoted release of fixed ammonium from the soil. Recently fixed ammonium in paddysoil after N fertilizer application was nearly 100% available to rice plant, while native fixed ammonium wasonly partly available, varying with the soil type and rice type.     

中国云南省滇池盆地东南区由于土地利用方式的变化（从水田变为旱地或温室土壤）导致土壤理化性质的变化研究

Paddy fields in the southeastern basin of Dianchi Lake have rapidly changed to greenhouses since 1999. A total of 61 surface soil samples, including 43 greenhouse soils, 12 upland soils, and 6 paddy soils, were collected from a flat lowland area mainly used for agricultural production fields in the southeastern basin of Dianchi Lake. Analyses of the soil samples indicated that the greenhouse soils were characterized by a lower organic matter content, lower pH, and higher soluble nutrients than the paddy soils in the area. The lower organic matter content of the greenhouse soils was ascribed to environmental or management factors rather than the clay content of the soil. Accumulation of soluble nutrients, especially inorganic N, was due to over-application of fertilizers, which also caused soil acidification. The average amount of readily available N, P, and K accumulated in the greenhouse soils was estimated to be equal to or higher than the annual input of these nutrients as a fertilizer, indicating that a reduction in fertilizer application was possible and recommended. In contrast, a very low available Si content was observed in the paddy soils, suggesting the need for Si application for rice production.     

Evaluation of Methods for Control of Ammonia Volatilization from Surface-Applied Nitrogen Fertilizers to Sugarcane Trash in North Queensland

Micrometeorological and microplot experiments were conducted in the field of freshly harvested green cane in Queensland,Australia.Results showed that high ammonia loss of fertilizer N could occur under relatively dry conditions when urea or commercial product of mixture of urea and muriate of potash were applied to the surface of sugarcane trash.The moisture content in the trash and the pH of fertilizer were two important factors controlling the processes of urea hydrolysis and ammonia volatilization.Most of the N in the soil was transformed to the nitratel-nitrite from after 70 days of fertilizer application.No significant leaching was found.Urea-free N fertilizers had higher N recoveries compared to urea-containing fertilizers.     

DMPP硝化抑制效果受其浓度、施用方式及土壤基质势的影响

The efficacy of nitrification inhibitors depends on soil properties and environmental conditions. The nitrification inhibitor 3.4-dimethylpyrazole phosphate （DMPP） was investigated in a sandy loam and a loamy soil to study its effectiveness as influenced by inhibitor concentration, application form, and soil matric potential. DMPP was applied with concentrations up to 34.6 mg DMPP kg^-1 soil as solution or as ammonium-sulfate/ammonium-nitrate granules formulated with DMPP. DMPP inhibited the oxidation of ammonium in both soils, but this effect was more pronounced in the sandy loam than in the loamy soil. When applied as solution, increasing DMPP concentrations up to 7 mg DMPP kg^-1 soil had no influence on the inhibition. The effectiveness of DMPP formulated as fertilizer granules was superior to the liquid application of DMPP and NH4^＋, particularly in the loamy soil. Without DMPP, a decline in soil matric potential down to -600 kPa decreased nitrification in both soils, but this effect was more pronounced in the sandy loam than in the loamy soil. DMPP was most effective in the sandy loam particularly under conditions of higher soil moisture, i.e., under conditions favorable for nitrate leaching.     

基施磷肥对石灰性土壤上番茄产量的影响

A lysimeter experiment with undisturbed soil profiles was carried out to study nitrogen cycling and losses in a paddy soll with applications of coated urea and urea under a rice-wheat rotation system in the Taihu Lake region from 2001 to 2003. Treatments for rice and wheat included urea at conventional, 300 （rice） and 250 （wheat） kg N ha^-1, and reduced levels, 150 （rice） and 125 （wheat） kg N ha^-1, coated urea at two levels, 100 （rice） and 75 （wheat） kg N ha^-1, and 150 （rice） and 125 （wheat） kg N ha^-1, and a control with no nitrogen arranged in a completely randomized design. The results under two rice-wheat rotations showed that N losses through both NH3 volatilization and runoff in the coated urea treatments were much lower than those in the urea treatments. In the urea treatments N runoff losses were significantly （P 〈 0.001） positively correlated （r = 0.851） with applied N. N concentration in surface water increased rapidly to maximum two days after urea application and then decreased quickly. However, if there was no heavy rain within five days of fertilizer application, the likelihood of N loss by runoff was not high. As the treatments showed little difference in N loss via percolation, nitrate N in the groundwater of the paddy fields was not directly related to N leaching. The total yield of the two rice-wheat rotations in the treatment of coated urea at 50% conventional level was higher than that in the treatment of urea at the conventional level. Thus, coated urea was more favorable to rice production and environmental protection than urea.     

共施磷酸二氢钙和硫酸铵对土壤中钾形态转化的影响

Soil potassium (K) deficiency has been increasing over recent decades as a result of higher inputs of N and P fertilizers concomitant with lower inputs of K fertilizers in China; however, the effects of interactions between N, P, and K of fertilizers on K status in soils have not been thoroughly investigated for optimizing N, P, and K fertilizer use effciency. The influence of ammonium sulfate (AS), monocalcium phosphate (MCP), and potassium chloride application on K fractions in three typical soils of China was evaluated during 90-d laboratory soil incubation. The presence of AS significantly altered the distribution of native and added K in soils, while addition of MCP did not significantly affected K equilibrium in most cases. Addition of AS significantly increased water-soluble K (WSK), decreased exchangeable K (EK) in almost all the soils except the paddy soil that contained considerable amounts of 2:1 type clay minerals with K added, retarded the formation of fixed K in the soils with K added, and suppressed the release of fixed K in the three soils without K added. These interactions might be expected to influence the K availability to plants when the soil was fertilized with AS. To improve K fertilizer use effciency, whether combined application of AS and K was to be recommended or avoided should depend on K status of the soil, soil properties, and cropping systems.     

Rice productivity and profitability with slow-release urea containing organic-inorganic matrix materials

Applying slow-release fertilizers is possible means for reducing nitrogen(N) loss in rice production. Matrix-based fertilizers represent novel slow-release fertilizers. To date, there is little consensus about the effect of combined addition of organic and inorganic matrix materials on rice production. We developed a slow-release urea fertilizer with selected organic and inorganic matrix materials. The study aimed to: i) determine the effect of the slow-release urea on rice yield, profit, and agronomic efficiency and ii) elucidate its possible mechanisms. A two-year field experiment was conducted during 2015–2016. Besides,laboratory experiments were conducted to determine the potential N loss risk. Three treatments were set up: control without N application(CK), regular urea treatment(RU, 150 kg N ha~(-1)), and slow-release urea treatment(SU, 150 kg N ha~(-1)). The results showed that rice biomass and grain yield were significantly higher in SU than in RU(P 0.05). The higher panicle density in SU was largely responsible for the greater grain yield. Net profit in SU was US$450 ha~(-1), higher than in RU. Agronomic efficiency was significantly greater in SU than in RU(P 0.05). Rice height, root area, leaf chlorophyll, leaf nitrate reductase activity, and leaf glutamine synthetase activity were larger in SU than in RU. Less N loss and greater soil N availability were partly responsible for the improvements in rice growth traits and physiological parameters in SU. Overall, the slow-release urea is a promising fertilizer for rice production.     

施用控释氮肥对减少稻田氮素径流损失和提高水稻氮素利用率的影响

采用渗漏池模拟研究了洞庭湖区双季稻种植条件下施用控释肥料对氮素径流损失、水稻产量和稻株氮素含量的影响。结果表明,施用等N量控释氮肥 (CRNF) 和70%N量控释氮肥 (70% CRNF) 的处理总氮 (TN) 径流损失量比施用尿素处理 (CF) 分别降低了24.5%和27.2% (P0.05)。主要是施用控释氮肥显著降低了水稻前期 (施肥后10 d内)的径流水中氮素浓度。与施用尿素相比,两种土壤上施用控释肥的早、晚稻产量均明显提高,特别是在河沙泥上,稻谷总产量以70% CRNF处理最高,比尿素处理增产4.95% (P0.05)。控释氮肥能明显提高水稻生长后期的植株和子粒中的N含量;在水稻增产显著的河沙泥上,70% CRNF处理的早、晚稻子粒N含量较CF处理提高了9.4% (P0.05)和23.3%(P0.01);其氮素利用率高于施用全量尿素的CF处理。     

有机无机肥配施对双季稻田土壤养分利用与渗漏淋失的影响

采用田间小区试验,研究稻草、猪粪、猪粪堆肥或沼渣沼液与化肥配施对双季稻田土壤养分利用与渗漏淋失的影响。结果表明,有机肥与化肥配施有利于提高稻田土壤中N、P、K养分和有机质含量,降低稻田渗漏液中TN、TP、NH4+-N、NO3--N浓度,促进水稻养分吸收与利用。其中,以20%的猪粪堆肥氮与化肥配施效果较好,与施纯化肥相比,1年后土壤中全氮、全磷、全钾和有机质含量分别提高了2.59%,0.87%,0.15%和21.45%,碱解氮、速效磷、速效钾含量分别提高3.31%,3.22%和12.24%;氮、磷、钾肥料利用率分别提高5.22%,0.55%,3.50%;水稻地上部氮、磷、钾养分累积量分别提高7.83,0.33,3.14g/kg;水稻生长期稻田渗漏液中TN、TP、NH4+-N、NO3--N浓度明显降低;早稻增产19.65%,晚稻无明显减产。     

Effects of Temperature and Soil Type on Ammonia Volatilization from Slow-Release Nitrogen Fertilizers

Ammonia (NH₃) volatilization is the major pathway for mineral nitrogen (N) loss from N sources applied to soils. The information on NH₃ volatilization from slow-release N fertilizers is limited. Ammonia volatilization, over a 78-d period, from four slow-release N fertilizers with different proportions of urea and urea polymer [Nitamin 30L (liquid) (L30), Nitamin RUAG 521G30 (liquid) (G30), Nitamin 42G (granular) (N42), and Nitroform (granular) (NF)] applied to a sandy loamy soil was evaluated. An increase in temperature from 20 to 30 °C increased cumulative NH₃ volatilization loss in the sandy soil by 1.4-, 1.7-, and 1.8-fold for N42, L30, and G30, respectively. Increasing the proportion of urea in the slow-release fertilizer increased NH₃ volatilization loss. At 30 °C, the cumulative NH₃ volatilization over 78 d from a sandy soil accounted for 45.6%, 43.9%, 22.4%, and <1% of total N applied as N42, L30, G30, and NF, respectively. The corresponding losses in a loamy soil were 9.2%, 3.1%, and 1.7%. There was a significantly positive correlation between NH₃ volatilization rate and concentration of NH₄-N released from all fertilizers, except for NF (n = 132; r = 0.359, P = 0.017 for N42; r = 0.410, P = 0.006 for L30; and r = 0.377, P < 0.012 for G30). Lower cumulative NH₃ volatilization from a loamy soil as compared to that from a sandy soil appeared to be related to rapid nitrification of NH₄-N in the former soil than that in the latter soil. These results indicate the composition of slow-release fertilizer, soil temperature, and soil type are main factors to dominate NH₃ volatilization from slow- release fertilizers.     

间歇淋洗干湿交替条件下氮肥的氮行为研究

采用土柱淋洗试验方法 ,对包膜尿素、尿素和硝酸铵在石碴土和粘壤质石灰性土壤中氮的行为进行了评价。结果表明 ,包膜尿素、尿素和硝酸铵的回收总氮量 (包括淋洗溶液中各种形态氮 ,土壤吸附的肥料氮和残余的肥料氮 )分别为施入总氮量的 90.5%、74.2 %、93.5%和91.5%、58.5%、91.1%。在 1750mL淋洗溶液中NO3--N分别占淋洗溶液中总氮量的 90%以上。在 7次淋洗干湿交替之后 ,土壤吸附的肥料氮 (NH4+-N和NO3--N)均不超过施氮总量的2.1% ;包膜尿素有62.7%和70.8%的氮以颗粒肥料存在于土壤中。 3种氮肥中包膜尿素较尿素和硝酸铵在土壤中释放持续的时间显著延长 ,尿素的氨挥发损失较高 ,硝酸铵淋失较快     

Nitrogen slow-release behavior of oxamide granules in two different types of paddy soils

Oxamide is a potential slow-release nitrogen (N) fertilizer, especially under waterlogged conditions, due to its low solubility in water and the slow-release of ammonium by soil amidases. To investigate the effects of oxamide granules (2.00–2.38 mm in diameter) as a single basal fertilizer (180 or 144 kg N ha^-1)on rice growth, soil properties, and N use efficiency in terms of N recovery efficiency (NRE), we conducted field experiments on two different types of paddy soils over two ric...     

Leaching of nitrogen forms from controlled‐release nitrogen fertilizers

Abstract

Application of soluble forms of nitrogen (N) fertilizers to sandy soils may cause leaching of nitrate N (NO₃‐N) resulting in contamination of groundwater. The leaching loss of N may be reduced to a certain extent by the use of controlled‐release N formulations. A leaching column study was conducted to evaluate the leaching of urea, ammonium N (NH₄‐N), and NO₃‐N forms from selected urea‐based controlled‐release formulations (Meister, Osmocote, and Poly‐S) and uncoated urea under eight cycles of intermittent leaching and dry conditions. Following leaching of 1,760 mL of water (equivalent to 40 cm rainfall) through the soil columns, the recovery of total N (sum of all forms) in the leachate accounted for 28, 12, 6, or 5% of the total N applied as urea, Poly‐S, Meister, and Osmocote, respectively. Loss of urea‐N from all fertilizer sources was pronounced during the initial leaching events (with the exception of Meister). Cumulative leaching of urea‐N was 10% for uncoated urea while <1.7% for the controlled‐release formulations. Cumulative leaching of NH₄‐N was 6.2% for uncoated urea while <0.5% for the controlled‐release formulations. Cumulative leaching loss of NO₃‐N was 3.78% for Osmocote, 4.6% for Meister, 10.4% for urea, and 10.5% for Poly‐S. This study demonstrates a significant reduction in leaching of N forms from controlled‐release formulations as compared to that from the soluble form.     

洞庭湖区不同稻田土壤及施肥对养分淋溶损失的影响

在渗漏池模拟洞庭湖区三种主要水耕人为土的基础上,进行了为期2 a的施用化肥(CF)、控释氮肥(CRNF)和配施猪粪(OM)对N、P、K养分淋失影响的试验,以探明双季稻田养分淋溶损失现状和规律。结果表明,普通简育水耕人为土(THS)、底潜简育水耕人为土(EHS)、普通铁聚水耕人为土(TFS)双季稻田CF处理的氮素淋溶损失总量分别占施氮量的2.28%、0.66%和1.50%。其中,THS的渗漏水总氮(TN)浓度与TFS相近,但由于渗漏水量高而导致TN淋失显著增加,EHS的渗漏水量及其TN浓度均显著低于其他两种土壤;稻田淋溶损失的氮素形态中,铵态氮占39.7%,有机态氮占56.8%,硝态氮仅占3.5%。三种土壤的总钾(TK)淋溶损失分别占施钾量的14.0%、4.68%和11.5%,但渗漏水TK浓度高低顺序为:TFS>THS>EHS;各土壤的总磷(TP)淋失均很小且施磷与不施磷(CK)无差异。比较不同施肥处理的养分渗漏损失情况显示,CRNF处理的渗漏水TN浓度最高,三种土壤中均显著高于CK,CF和OM处理仅THS和TFS的TN淋失量显著高于CK;配施猪粪和单施氯化钾时,三种土壤的渗漏水TK浓度均显著高于CK。由于养分淋溶损失是一个长期累积的过程,而本试验仅连续2 a,施用不同氮、钾肥源的N、K素淋溶损失差异不显著。     

不同土壤肥力条件下水稻控释氮肥效应及其氮素利用的研究

田间试验在湖南的衡山县和长沙县进行,探讨了不同肥力水平水稻土上水稻控释氮肥对早、晚稻的增产效果和肥料氮利用率。结果表明,在肥力水平较低的水稻土上施用水稻控释氮肥对水稻的增产效果极为显著,应当增加施用量;在肥力水平较高的水稻土上,水稻吸收土壤氮较多,肥料氮的吸收量与增产作用自然减少,应适当减少施用量。不同肥力水平的土壤上水稻控释氮肥较等氮量尿素增产4.4%～16.4%。较无氮区增产13.8%～74.5%。水稻控释氮肥在不同肥力水平土壤中早、晚稻的利用率为69.7%～86.9%,平均比等N量尿素高37.6%,且水稻控释氮素利用率的高低与土壤肥力水平有关。水稻控释氮肥作一次性全量基肥施用,氮素生产效率明显高于尿素,是增产的主要原因。     

Fate of 15N-Labeled Potassium Nitrate in Different Citrus-Cultivated Soils: Influence of Spring and Summer Application

The fate of ¹⁵N-labeled potassium nitrate (8.5% ¹⁵N excess) was determined in 3-year-old Valencia orange trees grown in 1-m³ containers filled with different textured soils (sandy and loamy). The trees were fertilized either in spring (24 March) or summer (24 July). Spring fertilized trees gave higher fruit yields in sandy than in loamy soils, which exceeded summer fertilized trees in both cases. Summer fertilized trees had greater leaf biomass than spring fertilized trees. Fibrous root weight was 1.9-fold higher in sandy than in loamy soil. At the end of the cycle, tree N recovery from spring application was 45.7% for sandy and 37.7% for loamy soil; from summer fertilization, N recovery was 58.9% and 51.5% for sandy and loamy soils, respectively. The ¹⁵N recovered in the inorganic soil fraction (0?C90?cm) was higher for loamy (1.3%) than for sandy soil (0.4%). Fertilizer N immobilized in the organic matter was lower in sandy (2.5%) than in loamy soil (6.0%). Potential nitrate leaching from fertilizer (¹⁵NO ₃ ^? ?CN in the 90?C110-cm soil layer plus ¹⁵NO ₃ ^? ?CN in drainage water) was 34.8% higher in sandy than in loamy soil. The low N levels in sandy soil resulted from both higher NO ₃ ^? ?CN leaching losses and higher N uptake of plants grown in the former. The great root mass and higher soil temperatures could account for raised plant N uptake in sandy soil and in summer, respectively.