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1.
Summary Dynamics of barley N, mineral N, and organic N were compared at Ellerslie (Black Chernozem, Typic Cryoboroll) and Breton (Gray Luvisol, Typic Cryoboralf) in central Alberta, using 15N-urea. On average, shoot N and shoot 15N recoveries at Ellerslie (14.1 g m–2, 36%) were greater than at Breton (4.5 g m–2, 17%). Root N (g m–2) did not significantly differ between sites (0–30 cm) but root 15N recovery was greater at Breton (3.4%) than Ellerslie (1.8%). Low levels of shoot N and shoot 15N at Breton were partly due to very wet soil conditions in July, which resulted in premature shoot senescence and low plant N uptake. Although the total 15N recoveries from the system (to 30 cm depth) at Ellerslie (63%) and Breton (56%) were similar, soil 15N was greater at Breton (35%) than at Ellerslie (26%). There were no differences in mineral N between sites but the average 15N recovery in the mineral-N pool was significantly greater at Ellerslie (3.3%) than at Breton (1.6%). There was no difference in 15N recovery in the microbial biomass (3%) between sites, although non-microbial organic 15N was greater at Breton (31 %) than at Ellerslie (20%). The two soils showed differences in the relative size of kinetically active N pools and in relative mineralization rates. Microbial N (0–30 cm) was greater at Ellerslie (13.3 g m–2) than at Breton (9.9 g m–2), but total microbial N made up a larger proportion of total soil N at Breton (1.6%) than at Ellerslie (0.9%). In the 0–10 cm interval, microbial N was 1.7-fold greater and non-microbial active N was 3-fold greater at Breton compared to Ellerslie, when expressed as a proportion of total soil N. Net N mineralization in a 10-day laboratory incubation was 1.4-fold greater in the Black Chernozem (0–10 cm interval) from Ellerslie, compared to the Gray Luvisol from Breton, when expressed per gram of soil. Net N mineralization in the soil from Breton was double that of the soil from Ellerslie, when expressed as a proportion of soil N. Although soil N (g m–2) was 2.5-fold greater at Ellerslie compared to Breton, it was cycled more rapidly at Breton. 相似文献
2.
Fertilizer N can be conserved through immobilization by microorganisms (biotic process) and fixation by soil clay minerals (abiotic process), and then subsequently remineralized and released. These processes are significantly affected by inhibitors, and available C application. In this study, a 96-day incubation experiment was conducted to assess the effects of microbial immobilization and ammonium fixation on conservation and supply of urea-N with the nitrification inhibitor (DMPP: 3,4-dimethylpyrazole phosphate), urease inhibitor (NBPT: N-(n-butyl) thiophosphoric triamide), and glucose additions. The results showed that urea-derived soil microbial biomass nitrogen (SMBN) consistently increased with DMPP input, whereas NBPT increased urea-derived SMBN in the absence of glucose but decreased it in the presence of glucose. Both inhibitors enhanced the effects of fixed NH4+ on conservation and supply of urea-N in all cases, and retarded the release of fixed NH4+. Glucose addition intensified the competition for NH4+ between microbial immobilization and mineral fixation, as well as reduced the availability of urea-N and native soil N, resulting in a negative added N interaction at the initial incubation stage. From 12 to 96 days, the release of fixed NH4+ was 2.6-fold greater than the mineralization of organic N (including SMBN and non-microbial organic N) in the non-glucose treatments, whereas the latter was 2.7-fold greater than the former in the glucose treatments. Taken together, our study indicates both microbial immobilization and mineral fixation are important processes by which N is stabilized in soil. Clarification of fertilizer N transformation induced by these biotic and abiotic processes can provide helpful implications for quantifying N cycle and optimizing agricultural nutrient management. 相似文献
3.
In a greenhouse pot study, we examined the availability of N to grain sorghum from organic and inorganic N sources. The treatments were15N-labeled clover residues, wheat residues, and fertilizer placed on a sandy clay loam and loamy sand soil surface for an 8-week period. Soil aggregates formed under each soil texture were measured after 8 weeks for each treatment. Significantly greater 15N was taken up and recovered by grain sorghum in sandy clay loam pots compared with loamy sand pots. Greater 15N recovery was consistently observed with the inorganic source than the organic sources regardless of soil texture or time. Microbial biomass C and N were significantly greater for sandy clay loam soil compared with the loamy sand. Microbial biomass 15N was also significantly greater in the sandy clay loam treatment compared to the loamy sand. The fertilizer treatment initially had the greatest pool of microbial biomass 15N but decreased with time. The crop residue treatments generally had less microbial biomass 15N with time. The crop residues and soil texture had a significant effect on the water-stable aggregates formed after 8 weeks of treatments. Significantly greater water-stable aggregates were formed in the sandy clay loam than the loamy sand. Approximately 20% greater water-stable aggregates were formed under the crop residue treatments compared to the fertilizer only treatment. Soil texture seemed to be one of the most important factors affecting the availability of N from organic or inorganic N sources in these soils.Contribution from the MissouriAgricultural Experiment Station, Journal Series No.12131 相似文献
4.
Summary A pot experiment was conducted to study the N availability to wheat and the loss of 15N-labelled fertilizer N as affected by the rate of rice-straw applied. The availability of soil N was also studied. The straw was incorporated in the soil 2 or 4 weeks before a sowing of wheat and allowed to decompose at a moisture content of 60% or 200% of the water-holding capacity. The wheat plants were harvested at maturity and the roots, straw, and grains were analysed for total N and 15N. The soil was analysed for total N and 15N after the harvest to determine the recovery of fertilizer N in the soil-plant system and assess its loss. The dry matter and N yields of wheat were significantly retarded in the soil amended with rice straw. The availability of soil N to wheat was significantly reduced due to the straw application, particularly at high moisture levels during pre-incubation, and was assumed to cause a reduction in the dry matter and N yields of wheat. A significant correlation (r=0.89) was observed between the uptake of soil N and the dry matter yield of wheat with different treatments. In unamended soil 31.44% of the fertilizer N was taken up by the wheat plants while 41.08% of fertilizer N was lost. The plant recovery of fertilizer N from the amended soil averaged 30.78% and the losses averaged 45.55% 相似文献
5.
Kathrin Grahmann Klaus Dittert Nele Verhulst Bram Govaerts Andreas Buerkert 《Soil Use and Management》2019,35(3):482-491
Tillage and residue retention affect nitrogen (N) dynamics and nutrient losses and therefore nitrogen use efficiency (NUE) and crop fertilizer use, however, there is little information about residual fertilizer effects on the subsequent crop. Micro‐plots with 15N‐labelled urea were established in 2014/2015 on a long‐term experiment on a Vertisol in north‐west Mexico. N fertilizer recovery (NFR) and the effects of residual fertilizer N for summer maize (Zea mays L.) and the subsequent wheat (Triticum durum L.) crop were studied in three tillage–straw management practices (CTB: conventionally tilled beds; PB‐straw: permanent raised beds with residue retention; PB‐burn: permanent raised beds with residue burning). Fertilizer 15N recovery rates for maize grain across all treatments were low with an average of 11%, but after wheat harvest total recovered 15N (15N in maize and wheat straw and grain, residual soil 15N) was over 50% for the PB‐burn treatment. NFR was lowest in CTB after two cropping cycles (32%). Unaccounted N from applied fertilizer for the maize crop averaged 120 kg 15N ha?1 after wheat harvest. However, more than 20% of labelled 15N was found in the 0–90 cm soil profile in both PB treatments after wheat harvest, which highlights the need for long‐term studies and continuous monitoring of the soil nutrient status to avoid over‐application of mineral N fertilizer. 相似文献
6.
Fate of residual 15N-labeled fertilizer in dryland farming systems on soils of contrasting fertility
AbstractUp to 50% of nitrogen (N) fertilizer can remain in soil after crop harvest in dryland farming. Understanding the fate of this residual fertilizer N in soil is important for evaluating its overall use efficiency and environmental effect. Nitrogen-15 (15N)-labeled urea (165 kg N ha?1) was applied to winter wheat (Triticum aestivum L.) growing in three different fertilized soils (no fertilizer, No-F; inorganic nitrogen, phosphorus and potassium fertilization, NPK; and manure plus inorganic NPK fertilization, MNPK) from a long-term trial (19 years) on the south of the Loess Plateau, China. The fate of residual fertilizer N in soils over summer fallow and the second winter wheat growing season was examined. The amount of the residual fertilizer N was highest in the No-F soil (116 kg ha?1), and next was NPK soil (60 kg ha?1), then the MNPK soil (43 kg ha?1) after the first winter wheat harvest. The residual fertilizer N in the No-F soil was mainly in mineral form (43% of the residual 15N), and for the NPK and MNPK soils, it was mainly in organic form. The loss rate of residual 15N in No-F soil over summer fallow was as high as 48%, and significantly (P < 0.05) higher than that in the NPK soil (22%) and MNPK soil (19%). The residual 15N use efficiency (RNUE) by the second winter wheat was 13% in the No-F soil, 6% in the NPK soil and 8% in the MNPK soil. These were equivalent to 9.0, 2.0 and 2.2% of applied 15N. The total 15N recovery (15N uptake by crops and residual in 0–100 cm soil layer) in the MNPK and NPK soils (84.5% and 86.6%, respectively) were both significantly higher than that in the No-F soil (59%) after two growing seasons. The 15N uptake by wheat in two growing seasons was higher in the MNPK soil than in NPK soil. Therefore, we conclude that a high proportion of the residual 15N was lost during the summer fallow under different land management in dryland farming, and that long-term combined application of manure with inorganic fertilizer could increase the fertilizer N uptake and decrease N loss. 相似文献
7.
采用盆栽试验和短期矿化培养相结合的方法,研究了施入15N标记氮肥(+N)及其与秸秆配施(+1/2N+1/2S)在3种长期(19年)不同培肥土壤(即:No-F,长期不施肥土壤;NPK,长期施用NPK化肥土壤;MNPK,长期有机无机肥配施土壤)中的残留及其矿化和作物吸收特性。结果表明,第一季小麦收获后,+1/2N+1/2S处理下三供试土壤和+N处理下的NPK和MNPK土壤残留肥料氮(残留15N)中有82.6%~95.1%以有机态存,而+N处理下No-F土壤残留15N有47.7%以矿质态存在。经过28 d矿化培养后,与NPK土壤相比,MNPK土壤氮素净矿化量显著增加,增幅为39%~49%;NPK和MNPK土壤残留肥料氮(残留15N)矿化量为1.23~1.90 mg kg-1,占总残留15N的2.78%~5.53%,均显著高于No-F土壤。与+N处理相比,+1/2N+1/2S处理显著提高了3供试土壤氮素净矿化量,但两施肥处理对NPK和MNPK土壤残留15N矿化量无显著影响。+N处理下No-F土壤残留15N的利用率为20%,显著高于NPK(9%)和MNPK(12%)土壤。两种施肥处理下,MNPK土壤残留15N的利用率均显著高于NPK土壤。短期培养期间土壤氮素矿化量和第二季小麦生育期作物吸氮量呈显著性正相关,而残留15N矿化量和第二季小麦吸收残留15N量间无显著性相关关系。长期有机无机配施可以提高土壤残留肥料氮的矿化量及有效性。 相似文献
8.
《Communications in Soil Science and Plant Analysis》2012,43(3-4):574-586
Abstract Nitrogen (N) management may be improved by a thorough understanding of the nutrient dynamics during previous‐crop residue decomposition and its impact on fertilizer N fate in the soil–plant system. An experiment was conducted in the Argentine Pampas to evaluate the effect of maize and soybean as previouscrops and plow‐till and no‐till methods on N dynamics and 15N‐labeled fertilizer uptake during a wheat growing season. Maize and soybean residues released N under both tillage treatments, but N release was faster from soybean residues and when residues were buried by tillage. Net immobilization of N on decomposing residues was not detected. A regression model that accounted for 92% of remaining N variability included time, previous crop, and tillage treatment as independent variables. The rapid residue decomposition with N release was attributed to the high temperatures of the agroecosystem. The recovery of 15N‐labeled fertilizer in the wheat crop, soil organic matter, and decomposing residues was not statistically different between previous crop treatments or tillage systems. Crop uptake of fertilizer N averaged 52% across treatments. Forty percent of fertilizer N was removed in grains. Immobilization of labeled N on soil organic matter was substantial, averaging 34% of the 15N‐labeled fertilizer retained, but was very small on decomposing residues, averaging 0.2–3.0%. Fertilizer N not accounted for at harvest in the soil–plant system was 12% and was ascribed to losses. Previous crop or tillage system had no impact on wheat yield, but when soybean was the previous crop, N content of grain and straw+roots increased. Discussion is presented on the potential availability of N retained in wheat straw, roots, and soil organic matter for future crops. 相似文献
9.
Yujiao DONG Jiang YUAN Guangbin ZHANG Jing MA Padilla HILARIO Xuejun LIU Shihua LU 《土壤圈》2020,30(6):759-768
China has the world''s highest nitrogen (N) application rate, and the lowest N use efficiency (NUE). With the crop yield increasing, serious N pollution is also caused. An in-situ field experiment (2011-2015) was conducted to examine the effects of three N levels, 0 (i.e., no fertilizer N addition to soil), 120, and 180 kg N ha-1, using integrated rice management (IRM). We investigated rice yield, aboveground N uptake, and soil surface N budget in a hilly region of Southwest China. Compared to traditional rice management (TRM), IRM integrated raised beds, plastic mulch, furrow irrigation, and triangular transplanting, which significantly improved rice grain yield, straw biomass, aboveground N uptake, and NUE. Integrated rice management significantly improved 15N recovery efficiency (by 10%) and significantly reduced the ratio of potential 15N loss (by 8%-12%). Among all treatments, the 120 kg N ha-1 level under IRM achieved the highest 15N recovery efficiency (32%) and 15N residual efficiency (29%), with the lowest 15N loss ratio (39%). After rice harvest, the residual N fertilizer did not achieve a full replenishment of soil N consumption, as the replenishing effect was insufficient (ranging from -31 to -49 kg N ha-1). Furthermore, soil surface N budget showed a surplus (69-146 kg N ha-1) under all treatments, and the N surplus was lower under IRM than TRM. These results indicate IRM as a reliable and stable method for high rice yield and high NUE, while exerting a minor risk of N loss. In the hilly area of Southwest China, the optimized N fertilizer application rate under IRM was found to be 100-150 kg N ha-1. 相似文献
10.
Dong Wang Zhenzhu Xu Junye Zhao Yuefu Wang 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(8):681-692
Abstract Excessive use of nitrogen (N) fertilizers in wheat fields has led to elevated NO3-N concentrations in groundwater and reduced N use efficiency. Three-year field and 15N tracing experiments were conducted to investigate the effects of N application rates on N uptake from basal and topdressing 15N, N use efficiency, and grain yield in winter wheat plants; and determine the dynamics of N derived from both basal and topdressing 15N in soil in high-yielding fields. The results showed that 69.5–84.5% of N accumulated in wheat plants derived from soil, while 6.0–12.5%and 9.2–18.1% derived from basal 15N and top 15N fertilizer, respectively. The basal N fertilizer recovery averaged 33.9% in plants, residual averaged 59.2% in 0–200 cm depth soil; the topdressing N fertilizer recovery averaged 50.5% in plants, residual averaged 48.2% in 0–200 cm soil. More top 15N was accumulated in plants and more remained in 0–100 cm soil rather than in 100–200 cm soil at maturity, compared with the basal 15N. However, during the period from pre-sowing to pre-wintering, the soil nitrate moved down to deeper layers, and most accumulated in the layers below 140 cm. With an increase of N fertilizer rate, the proportion of the N derived from soil in plants decreased, but that derived from basal and topdressing fertilizer increased; the proportion of basal and top 15N recovery in plants decreased, and that of residual in soil increased. A moderate application rate of 96–168 kg N ha?1 led to increases in nitrate content in 0–60 cm soil layer, N uptake amount, grain yield and apparent recovery fraction of applied fertilizer N in wheat. Applying above 240 kg N ha?1 promoted the downward movement of basal and top 15N and soil nitrate, but had no significant effect on N uptake amount; the excessive N application also obviously decreased the grain yield, N uptake efficiency, apparent recovery fraction of applied fertilizer N, physiological efficiency and internal N use efficiency. It is suggested that the appropriate application rate of nitrogen on a high-yielding wheat field was 96–168 kg N ha?1. 相似文献
11.
Alfred Mapiki G. Bhaskar Reddy Bal Ram Singh 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(4):231-237
Abstract A field study with maize (Zea mays L.) was conducted in the 1988/89 cropping season to investigate the fate of 15NO3-N-labelled NH4 15NO3 applied at 40, 80 and 120 kg N ha?1 (unlabelled N applied at 0, 80, 160 and 240 N ha?1) with and without lime. The investigations were conducted in northern Zambia at Misamfu Regional Research Centre, Kasama on a Misamfu red sandy loam soil. The experimental design was a split plot arrangement with four replications with main plots receiving 0 and 2 Mg ha?1 dolomitic limestone, while subplots received fertilizer N at various rates. Significant (p < 0.001) grain and DM yield responses to applied N up to 160 kg ha?1 were observed. At higher rates little or no crop responses were observed and fertilizer use efficiency declined. Partitioning of amounts of total N and 15N in plants was in the order of seed = tassel > leaf> cob = earleaf> stem. Fertilizer N rates showed a highly significant (p < 0.001) effect on plant uptake of labelled N. Lime and its interaction with N rates had no effect on all measured parameters. Leaching of NO3-N fertilizer to lower soil depths was in proportion to the rate of N applied, with highly significant (p < 0.001) differences among soil depths. Although higher concentrations of fertilizer-15N were recovered in the 0–20 cm depth the recovered portion at lower soil depths was still significant. Total recovery of labelled N by plant and by soil after crop harvest averaged 75, 55 and 54% of originally applied fertilizer-15N at 40, 80 and 120 kg N ha?1, respectively. Corresponding unaccounted for 15N was 25, 45 and 46%. The most probable loss mechanism could have been by leaching to depths greater than 60 cm, gaseous losses to the atmosphere and root assimilation. 相似文献
12.
Erich Inselsbacher Nina Hinko-Najera Umana Markus Gorfer Katrin Ripka Rebecca Hood-Novotny Wolfgang Wanek 《Soil biology & biochemistry》2010,42(2):360-372
Agricultural systems that receive high amounts of inorganic nitrogen (N) fertilizer in the form of either ammonium (NH4+), nitrate (NO3−) or a combination thereof are expected to differ in soil N transformation rates and fates of NH4+ and NO3−. Using 15N tracer techniques this study examines how crop plants and soil microbes vary in their ability to take up and compete for fertilizer N on a short time scale (hours to days). Single plants of barley (Hordeum vulgare L. cv. Morex) were grown on two agricultural soils in microcosms which received either NH4+, NO3− or NH4NO3. Within each fertilizer treatment traces of 15NH4+ and 15NO3− were added separately. During 8 days of fertilization the fate of fertilizer 15N into plants, microbial biomass and inorganic soil N pools as well as changes in gross N transformation rates were investigated. One week after fertilization 45-80% of initially applied 15N was recovered in crop plants compared to only 1-10% in soil microbes, proving that plants were the strongest competitors for fertilizer N. In terms of N uptake soil microbes out-competed plants only during the first 4 h of N application independent of soil and fertilizer N form. Within one day microbial N uptake declined substantially, probably due to carbon limitation. In both soils, plants and soil microbes took up more NO3− than NH4+ independent of initially applied N form. Surprisingly, no inhibitory effect of NH4+ on the uptake and assimilation of nitrate in both, plants and microbes, was observed, probably because fast nitrification rates led to a swift depletion of the ammonium pool. Compared to plant and microbial NH4+ uptake rates, gross nitrification rates were 3-75-fold higher, indicating that nitrifiers were the strongest competitors for NH4+ in both soils. The rapid conversion of NH4+ to NO3− and preferential use of NO3− by soil microbes suggest that in agricultural systems with high inorganic N fertilizer inputs the soil microbial community could adapt to high concentrations of NO3− and shift towards enhanced reliance on NO3− for their N supply. 相似文献
13.
The fate of fertilizer N applied with different irrigation amounts in tobacco fields was quantitatively studied by applying 15N double-labelled NH4NO3 in lysimeters. The 15N (fertilizer N originating from the fertilizer applied in 2011) in tobacco plants, 15N in soils and 15N loss were observed continuously from 2011 to 2014. The results showed that 21.6% of 15N was utilized by tobacco plants, 72.1% remained in the 0–60 cm soil layer and 6.3% was lost from the soil–plant system after the first season’s harvest (2011) of flue-cured tobacco. During the four seasons from 2011 to 2014, cumulative utilization of 15N by tobacco plants was 34.3%, while 54.2% remained in the 0–60 cm soil layer, and 11.5% was lost via mechanisms such as leaching and volatilization. The fate of 15N in terms of accumulation in plants and soils or losses from the soil–plant system from 2012 to 2014 was greatly affected by the fertilizer and irrigation management strategies in 2011. The results of this investigation suggest that the major amount of fertilizer N applied during the first season remains available in the soil for utilization by tobacco plants after 4 years. 相似文献
14.
Influence of soil phosphorus status and nitrogen addition on carbon mineralization from 14C-labelled glucose in pasture soils 总被引:2,自引:0,他引:2
This study examines the effect of soil P status and N addition on the decomposition of 14C-labelled glucose to assess the consequences of reduced fertilizer inputs on the functioning of pastoral systems. A contrast
in soil P fertility was obtained by selecting two hill pasture soils with different fertilizer history. At the two selected
sites, representing low (LF) and high (HF) fertility status, total P concentrations were 640 and 820 mg kg–1 and annual pasture production was 4,868 and 14,120 kg DM ha–1 respectively. Soils were amended with 14C-labelled glucose (2,076 mg C kg–1 soil), with and without the addition of N (207 mg kg–1 soil), and incubated for 168 days. During incubation, the amounts of 14CO2 respired, microbial biomass C and 14C, microbial biomass P, extractable inorganic P (Pi) and net N mineralization were determined periodically. Carbon turnover was greatly influenced by nutrient P availability.
The amount of glucose-derived 14CO2 production was high (72%) in the HF and low (67%) in the LF soil, as were microbial biomass C and P concentrations. The 14C that remained in the microbial biomass at the end of the 6-month incubation was higher in the LF soil (15%) than in the
HF soil (11%). Fluctuations in Pi in the LF soil during incubation were small compared with those in HF soil, suggesting that P was cycling through microbial
biomass. The concentrations of Pi were significantly greater in the HF samples throughout the incubation than in the LF samples. Net N mineralization and nitrification
rates were also low in the LF soils, indicating a slow turnover of microorganisms under limited nutrient supply. Addition
of N had little effect on biomass 14C and glucose utilization. This suggests that, at limiting P fertility, C turnover is retarded because microbial biomass becomes
less efficient in the utilization of substrates.
Received: 18 October 1999 相似文献
15.
北京郊区冬小麦/夏玉米轮作体系中氮肥去向研究 总被引:38,自引:14,他引:38
采用田间微区15N示踪试验研究了肥料氮在冬小麦、夏玉米当季和后茬的去向。结果表明 ,在供试土壤的肥力水平和生产条件下 ,N 120kg/hm2 的施肥水平已经达到了较高产量 ,再增加氮肥施用量作物产量不再增加 ;其氮肥利用率和残留率均显著高于施氮量为N 360kg/hm2,损失率则远低于后者 ;在一季作物生长后仍有 20.9%~48.4%肥料氮残留于 0~100cm土层 ,这些残留的肥料氮在后茬的利用率不足 8% ,至施肥后第 2或第 3茬作物 ,仍有部分肥料氮残留于土壤。在低施氮量时 ,肥料氮以NO3--N残留的量很低 ,在高施氮量时 ,残留氮除以有机态、微生物态氮形式存在外 ,以NO3--N形式存在的比例也很高 ;在氮素损失途径中 ,淋洗损失可能占有相当重要的地位。 相似文献
16.
《Communications in Soil Science and Plant Analysis》2012,43(3):322-331
The Fengqiu long-term field experiment was established to examine effects of organic manure and mineral fertilizers on soil total nitrogen (N) and natural 15N abundance. Fertilizer regimes include organic manure (OM), one-half N from organic manure plus one-half N from mineral N fertilizer (1/2OMN), mineral fertilizers [N–phosphorus (P)–potassium (K), NP, NK, PK], and a control. Organic manure (OM and 1/2OMN) significantly increased soil total N and δ15N, which was expected as a great amount of the N applied remained in soils. Mineral NPK fertilizer and mineral NP fertilizer significantly increased total N and slightly increaed δ15N. Phosphorus-deficient fertilization (NK) and N-deficient fertilization (PK) had no effect on soil total N. Significantly greater δ15N was observed in the NK treatment as compared to the control, suggesting that considerable N was lost by ammonia (NH3) voltalization and denitrification in this P-deficiency fertilization regime. 相似文献
17.
《Soil & Tillage Research》1987,9(1):33-43
Differences in soil tillage can influence the utilization of fertilizer N. This study determined the effect of zero tillage (ZT) and conventional shallow tillage (CT), of three years duration, on the deposition and dynamics of residual 15N urea. The study was conducted on a Chernozemic soil in a semiarid region of the Canadian prairie. In the absence of tillage, microbial biomass N levels increased by 48% and mineral N levels decreased by 62%, at the 0–5-cm soil depth, compared to the CT soil. The ZT soil had 96% more residual N distributed in the non-biomass organic N, but 52% less in the mineral and microbial biomass forms of soil N, compared to the CT soil. These tillage induced changes affected the short-term availability of residual 15N as determined by N mineralization and plant utilization studies. Potentially mineralizable N (N0) was higher, but release of 15N residual fertilizer was slower in the ZT soil, compared to CT soil. Initial plant uptake of soil N was similar between tillage systems, although three times as much residual fertilizer was derived from the CT as compared to the ZT soil. Mineralization or plant uptake reduced the differences in 15N residual fertilizer deposition between tillage soil samples. Tillage differences may influence the short-term N balance of soils receiving N fertilizer. Such changes are related to the greater level of microbial biomass in the surface of ZT soils. 相似文献
18.
19.
Isabeli Pereira Bruno Klaus Reichardt Rafael Pivotto Bortolotto Victor Meriguetti Pinto Osny Oliveira Santos Bacchi Durval Dourado-Neto 《Journal of plant nutrition》2015,38(13):2055-2076
Brazil is a major world coffee producer, using increasing quantities of nitrogen (N) fertilizer as the monoculture expands across the savannas. The fate and efficiency of this fertilizer N were evaluated for one complete cropping cycle using 15N tracer, permitting an N balance at harvest. Annual rates of 200, 400, 600, and 800 kg N ha?1 year?1 of 15N-labeled urea and an unfertilized control were applied every 14 days via fertigation. The N concentration, percentage of N derived from fertilizer, quantity of N derived from fertilizer, and percentage of nitrogen derived from fertilizer per N rate was assessed for 8-year-old coffee trees. The most efficient N use was with 200 kg ha?1 year?1 because it presented the lowest losses and highest N recoveries in the crop. Conversely, the least sustainable rate was 800 kg ha?1 year?1, which presented the greatest losses and the lowest N recovery in the whole plant. 相似文献
20.
太湖地区不同轮作模式下的稻田氮素平衡研究 总被引:3,自引:0,他引:3
采用田间微区15N示踪,研究了太湖地区稻田不同轮作模式(紫云英-水稻轮作、休闲-水稻轮作、小麦-水稻轮作)和施氮水平(0、120 kg·hm?2、240 kg·hm?2、300 kg·hm?2)下水稻对氮肥的吸收利用效率及土壤氮素残留特征。结果表明,水稻吸收的氮素来自肥料的比例为20.9%~49.6%,休闲-水稻轮作模式下水稻产量的获得更加依赖无机氮肥的大量投入。当季水稻对肥料氮的利用率为25.0%~41.5%,肥料氮的土壤残留率为13.4%~24.6%,其中90%以上的土壤残留肥料氮集中在0~20 cm土层,在土壤剖面中的残留率随土层深度增加而迅速降低,30~40 cm土层的肥料残留量仅占氮肥施用量的0.2%~0.7%。紫云英?水稻轮作和休闲?水稻轮作模式下氮肥利用率和土壤残留率均在施氮240 kg·hm?2时达到最大值,其氮肥利用率显著高于小麦?水稻轮作55.6%和66.0%。稻季施氮240 kg·hm?2时,小麦-水稻轮作模式下的氮肥利用率、土壤残留率以及总回收率显著最低,损失率显著最大;紫云英?水稻轮作模式下的氮肥损失率最小,分别小于休闲?水稻轮作和小麦-水稻轮作13.9%、39.2%。不同轮作模式下,水稻籽粒产量随施氮量的增加而增加,稻季施氮240 kg·hm?2时,紫云英?水稻轮作下水稻籽粒产量显著高于休闲?水稻轮作和小麦?水稻轮作,小麦?水稻轮作籽粒产量虽略高于休闲?水稻轮作,但没有达到显著水平。本研究认为,选择紫云英还田配施氮肥240 kg·hm?2,既可以保证水稻氮肥利用率而获得高产,又能减少氮肥损失而带来的环境风险,是一种值得在当地大力推广的耕作制度。 相似文献