Dissolved nitrogen model for paddy field ponded water during irrigation period

Based on an experimental field study in Japan, a model was developed to simulate dissolved nitrogen in water ponded in a paddy field. As input data, the model uses meteorological data, water balance in the field, nitrogen concentration in inlet water, and the nitrogen contribution of applied fertilizer. Five model parameters need calibration. A practical application of the model is the simulation of NH₄-N and NO₂₊₃-N concentrations in water ponded in a paddy field. The model improves our understanding of the interactions between forms of dissolved nitrogen in ponded water and can explain the complex changes in dissolved nitrogen concentrations in water ponded on a paddy field.     

Critical petiole nitrate concentration of two processing potato cultivars in Eastern Canada

Plant-based diagnostic methods of nitrogen (N) nutrition such as petiole nitrate (NO₃-N) concentration can be used to improve the efficiency of N utilization, and hence decrease the risks of N losses to the environment. Our first objective was to determine the effect of N fertilization and supplemental irrigation on the petiole NO₃-N concentration during tuber growth of two potato cultivars, Russet Burbank and Shepody, widely grown for processing in Eastern Canada. Our second objective was to establish the critical petiole NO₃-N concentration using the relationship between petiole NO₃-N concentration and the N nutrition index (NNI), an index based on the N concentration of shoots and tubers. This on-farm study was conducted at two sites in each of three years, 1995 to 1997. The N fertilization rates ranged from 0 to 250 kg N ha^?1 with three rates in 1995, six rates in 1996, and four rates in 1997. The NO₃-N concentration of petioles from the most recently mature leaves was measured on three sampling dates in 1995 and four sampling dates in 1996 and 1997. The petiole NO₃-N concentration generally decreased with time. At all sites and on all sampling dates, the petiole NO₃-N concentration increased with increasing N fertilization and was significantly greater for Shepody than for Russet Burbank. Irrigation had no consistent effect on petiole NO₃-N concentration. Petiole NO₃-N concentration was related to NNI (0.29<R²<0.62). Critical petiole NO₃-N concentrations required to reach a NNI of 1.0, indicating a situation where N is not limiting growth, were greater for Shepody than for Russet Burbank, and they decreased with time. Critical petiole NO₃-N concentrations (Y) expressed as a function of the number of days after planting (X) are Y = 4.80 - 0.055X for Russet Burbank and Y = 5.03 - 0.054X for Shepody.     

Nitrogen fertilization and irrigation affects tuber characteristics of two potato cultivars

Nitrogen fertilization, irrigation, and cultivars affect tuber characteristics such as tuber size, specific gravity, and N concentration. Few studies, however, have investigated the interaction of irrigation and N fertilization on the tuber characteristics of potato cultivars, particularly in Atlantic Canada. The objective of this on-farm study, conducted at four sites in each of three years, 1995 to 1997, was to determine the effects of supplemental irrigation and six rates of N fertilization (0-250 kg N ha^-1) on the number of tubers per plant, the average fresh tuber weight, tuber N concentration, nitrate (NO₃-N) concentration, and specific gravity of the cultivars Shepody and Russet Burbank. Nitrogen fertilization increased the average fresh tuber weight, tuber N and N0₃-N concentrations, and decreased specific gravity. Effects of increasing N fertilization on tuber characteristics were often more pronounced for Shepody than for Russet Burbank, and for irrigated than for non-irrigated conditions. Shepody had greater average fresh tuber weight and tuber N concentration, lower specific gravity, and fewer tubers per plant than Russet Burbank. Supplemental irrigation increased the average fresh tuber weight and the number of tubers per plant, but it had a limited effect on specific gravity and tuber N and NO₃-N concentrations. Tuber NO₃-N con centration and specific gravity were strongly related to tuber N concentration, which in turn depended primarily on N fertilization. Incidents of lowest specific gravity and highest NO₃-N concentration occurred with a relative yield close to or equal to 1.0. We conclude that the risks of low specific gravity and high tuber NO₃-N concentration are greater when fertilization exceeds the N requirements to reach maximum tuber yield.     

Modeling of water and nitrogen balance in the ponded water of rice fields

A water and nitrogen balance model for the surface ponded water compartment of rice fields was developed. The model estimates the daily ponded water depth and the daily losses and the uses of NH₄–N and NO₃–N in their transformation processes. The model was applied with data obtained from two rice fields during 2005 at Thessaloniki plain in northern Greece. Significant amounts of applied irrigation water were lost with the surface runoff and deep percolation to groundwater. The gaseous losses of nitrogen (volatilization and denitrification) and nitrogen uptake by algae were the main processes of nitrogen reduction in the ponded water of rice fields. The study showed that the system of a rice field is a natural system where an important amount of influent nitrogen applied by irrigation water can be reduced. These processes decrease the possibilities of water resources contamination.     

Potato response to split nitrogen timing with varying amounts of excessive irrigation

Irrigation and nitrogen management are two of the most important factors affecting production efficiency and environmental quality in potato cropping systems. Field studies were conducted in 1990 and 1991 to determine the interactive effects of irrigation amount and N timing on potato yield, quality and nitrate leaching potential. Sprinkler irrigation was applied at approximately 1.0, 1.2 or 1.4 times estimated evapotranspiration (ET) to Russet Burbank potatoes grown on a silt loam soil. Following tuber initiation, a total of 132 kg N/ha was applied through the irrigation system to N treatment subplots using either six weekly 22 kg N/ha applications or 3 biweekly 44 kg N/ha applications. Excessive irrigation reduced root zone and petiole NO₃-N concentrations during substantial portions of the tuber bulking period. Biweekly 44 kg N/ha applications in 1991 produced higher and more consistent earlyseason root zone NO₃-N concentrations in the 1.2 and 1.4 ET plots than did the weekly 22 kg N/ha applications. Late-season tuber dry weight, total plant dry weight and plant N uptake were not affected by irrigation rate or N timing. However, excessive irrigation reduced U.S. No. 1 yield and yield of tubers >284 g in both 1990 and 1991 and reduced total yield in 1990. Biweekly N applications produced higher U.S. No. 1 yields than weekly N applications at all irrigation levels. Excessive irrigation also reduced NO₃-N remaining in the top 60 cm of soil at the end of the growing season. These results show that irrigating at optimal rates and applying split N at two week intervals on a silt loam soil can maximize Russet Burbank yield and quality while minimizing NO₃-N losses.     

Effect of N-fertilizer application on return flow water quality from a terraced paddy field in Northern Taiwan

Intensive use of chemical fertilizer for crops may be responsible for nitrogen and phosphate accumulation in both groundwater and surface waters. The return flow polluted by nutrients not only results in the limitation of water reuse goals but also creates many environmental problems, including algal blooms and eutrophication in neighboring water bodies, posing potential hazards to human health. This study is to evaluate the N-fertilizer application of terraced paddy fields impacting return flow water quality. Water quality monitoring continued for two crop-periods around subject to different water bodies, including the irrigation water, drainage water at the outlet of experimental terraced paddy field, and shallow groundwater were conducted in an experimental paddy field located at Hsin-chu County, Northern Taiwan. The analyzed results indicate that obviously increasing of ammonium-N (NH₄ ⁺-N) and nitrate-N (NO₃ ^?-N) concentrations in the surface drainage water and ground water just occurred during the stage of basal fertilizer application, and then reduced to relatively low concentrations (<0.1 mg/l and <3 mg/l, respectively) in the remaining period of cultivation. The experimental results demonstrate the potential pollution load of nitrogen can be reduced by proper drainage water control and fertilizer application practices.     

Effect of chloride in irrigation water and form of nitrogen fertilizer on Virginia (flue-cured) tobacco

One of the main sources of considerable amounts of chloride to soils is irrigation water. The responses of tobacco (Nicotiana tabacum L.) to chloride are varied and inconsistent depending on the tobacco type, variety and methods of fertilization, cultivation and harvesting used. In this work, the impact of the interaction between four chloride levels (10, 20, 40, 80 mg L⁻¹) in irrigation water and three nitrogen fertilizer forms (NO₃–N 100%, NH₄–N 100% and NO₃–N 50%:NH₄–N 50%) on growth, agronomic and chemical characteristics of Virginia tobacco was evaluated over 2 years (1999, 2000) in an outdoor pot experiment. The results showed that the adverse influence of chloride in irrigation water on plant height and number of leaves per plant was already substantial above 40 mg L⁻¹, within 30 days after transplanting. In this period, visual toxicity symptoms of chloride appeared on the lower leaves of plants treated with ammonium nitrogen. In addition, the effect of chloride on flowering time, chlorophyll content of leaves, aboveground fresh weight of plant, total cured product yield and chemical characteristics, depended on the form of nitrogen, with nitrate nitrogen restricting the detrimental effects of chloride in irrigation water up to 40 mg L⁻¹. The reduced yield of cured product at 80 mg L⁻¹ was the result of the adverse effects of chloride on the leaves of the middle and upper stalk position. Leaf chloride concentration was highest in the upper leaves and increased linearly with the increase of chloride level in irrigation water at each leaf position on the stalk and this increase was more rapid as ammonium nitrogen percentage was increased. Chloride increased the concentration of reducing sugars in cured leaves at each leaf position, in all nitrogen forms and nicotine mainly in plants treated with nitrate nitrogen. The changes in total nitrogen and ash content are considered as minimal. We conclude that the optimum chloride level in irrigation water is below 20 mg L⁻¹, whereas the level of 40 mg L⁻¹ in combination with nitrate nitrogen fertilizers can be considered as the upper threshold to avoid adverse effects on Virginia tobacco.     

Effect of the type of fertilizer and source of irrigation water on N use in a maize crop

An experiment in a maize crop evaluated the influence of several types of commercial nitrogenous fertilizers with different action mechanisms — urea (soluble), Floranid-32 (low water solubility) and Multicote 4 (coated fertilizer) — on maize grain and biomass yields, as well as on plant N use. The fertilizers were applied as a top-dressing of 294 kg N ha⁻¹. All treatments additionally received 64 kg N ha⁻¹ as 8.0 (N):6.5 (P):12.5 (K) compound prior to seedbed preparation. The influence of NO⁻₃ content in the irrigation water was also assessed, using water with either 2.5 or 35 mg l⁻¹ of NO⁻₃. Irrigation plus rainfall totalled 513 mm (1.20 potential ET). Nitrogen lost during the cultivation period was calculated from the N balance of the topsoil.Results obtained under these experimental conditions showed that the type of fertilizer did not alter maize grain and biomass yields. Yields for maize irrigated with the higher NO⁻₃ water were systematically greater than those obtained with irrigation water of low NO⁻₃ content.Nitrogen lost from the topsoil during the cultivation period varied between 240 and 280 kg N ha⁻¹ for all treatments, and was well correlated with NO⁻₃-N leached into the aquifer during the same period.     

Fluctuation of NO3-N in groundwater of the reservoir of the Sunagawa Subsurface Dam, Miyako Island, Japan

The Japanese government started to construct two subsurface dams on Miyako Island in 1988, and the project was completed in 2001. Before the construction of the dams, the NO₃-N concentration of groundwater on the island was about 10 mg/l, the upper limit for drinking water in Japan, owing to the application of fertilizer to sugarcane fields. Predicting the effect of these subsurface dams on the groundwater environment was difficult because they were probably the first mega-subsurface dams in the world. We measured the NO₃-N concentration in the groundwater at observation wells before and after construction of the Sunagawa Dam and after the groundwater began to be used. We also measured the NO₃-N concentration monthly at a typical observation well in the catchment over a period 14 years to evaluate the environmental impact of construction of the dam. The highest NO₃-N concentrations were downstream before completion of the subsurface dam, and a high NO₃-N concentration zone remained around the cut-off wall after its completion, but this high-concentration zone disappeared and the distribution of NO₃-N became uniform after pumping of the groundwater began. Overall, the NO₃-N concentration decreased gradually. These results show that the groundwater quality did not deteriorate as a result of the construction of the Sunagawa Subsurface Dam.     

Effect on water quality in irrigation reservoir due to application reduction of nitrogen fertilizer

Until 1997, tea farmers in the Makinohara district of Shizuoka Prefecture, Japan, applied around 1.2 ton/ha of nitrogen fertilizer per year to their tea fields. In general, uptake amount of nitrogen by tea plants is around 300–350 kg/ha. Then some part of the remainder of nitrogen fertilizer leach into ground water and flow out into the river. The other part of remainder of nitrogen fertilizer is accumulated in the soil layer. Following a recommendation by the local government, this amount was then gradually decreased to 660 kg/ha in 1999 and 540 kg/ha in 2000. Although nitrate nitrogen concentrations in local ground and river water have decreased, they remain high today. The river water runs off from a watershed in the Makinohara area and enters a small irrigation reservoir called Tanno Reservoir, where it has caused deterioration of the water quality, that is, acidification of the reservoir. In Japan, environmental standard for nitrate nitrogen is 10 mg/L in public water body and ground water. Here, the author developed the Water Quality Tank Model, and applied this model to investigate the nitrate nitrogen concentrations in the rivers and an irrigation reservoir called Tanno. The author applies these findings to demonstrate that nitrogen concentrations continue to remain high due to nitrogen accumulation in the soil layer, and that the amount accumulated would be reduced by a reduction in application. The simulation results demonstrate a small decrease in accumulation in the soil layer, and thus that the present high nitrate nitrogen concentrations will continue in ground, river and reservoir water will decrease only gradually.     

Effect of plastic-film mulching on leaching of nitrate nitrogen in an upland field converted from paddy

A lysimeter experiment was conducted to examine the effects of plastic film mulching on the leaching rate of nitrate nitrogen (NO₃-N) from chemical fertilizer that was applied to an upland field that had been converted from paddy rice production. Leaching was monitored in two lysimeters filled with sandy loam soil, which contained low soil organic matter content, under different surface mulch conditions. One was mulched only on the ridge (ridge-mulch treatment) and another one was mulched fully, including the furrow, with black plastic film (full-mulch treatment). Chemical fertilizer was mixed into the top 0.2 m of soil in the two lysimeters before installing the mulch. After transplanting broccoli, the amount of subsurface discharge water and the NO₃-N concentrations in the discharge water were measured every day. Larger NO₃-N discharges occurred in the ridge-mulch treatment for three days after heavy rainfalls in which cumulative precipitation exceeded 10 mm, and the daily NO₃-N load was twice as large as the full-mulch treatment. The differences in the amount of subsurface discharge water and NO₃-N discharged between treatments were not significant when there was no rainfall. Cumulative NO₃-N loads for the ridge- and full-mulch treatment during the last month of the experimental period were 0.246 and 0.195 g m^–2, respectively. The effect of mulching on the reduction of NO₃-N discharge rate was higher for the full-mulch treatment. This result showed that a plastic-film mulching system would be effective as an appropriate fertilizer management to reduce nitrate-leaching losses.     

增铵营养对玉米品质影响初探

试验利用盆栽,选用远征808(收敛型)和四单19(平展型)作试验材料,研究了增铵营养对玉米子粒中蛋白质、淀粉和可溶性糖含量的影响.在氮素水平一致的条件下,设6个处理,NO3--N和NH4+-N比例分别是3:0、2:1、1:1、1:2、0:3及对照(不施氮).试验表明,增铵营养可以提高玉米子粒中蛋白质含量,但不同类型品种表现有差异,远征808在NO₃^--N和NNH₄⁺-N比例为2:1时蛋白质含量最高,而四单19在1:2时     

Nitrogen transport and transformation in packed soil columns from paddy fields

Our understanding of nitrogen transformation in paddy fields or wetlands is limited due to the complex interactions between soil, water, and biomass. Therefore, we studied transformation patterns resulting from the oxic level in the soil, and studied saturated (anoxic) and unsaturated (oxic) flow conditions. We present a model designed to predict concentrations of nitrate and ammonium at several soil depths resulting from the processes of nitrification, denitrification, and ammonification. Model equations were obtained that describe NO₃-N and NH₄-N concentrations in terms of position, rate constant, and average flow velocity. Although many parameters were included in the model equations, some were determined from the literature and others were derived from experiments. A sensitivity analysis of the rate coefficients for NO₃-N and NH₄-N revealed that they are extremely sensitive to denitrification and ammonification respectively. Experimental results show that there were large differences in the transformations of NO₃-N and NH₄-N, the water pressure distributions, and the oxygen reduction potentials (ORP) between saturated and unsaturated pore water flow conditions. The performance of the model for sequential transformations during the transport of NO₃-N is well documented under both saturated and unsaturated flow conditions.     

Long-term changes in nitrogen loads of a stream in the vicinity of an earthen waste storage pond

It is not sufficiently known for how long earthen waste storage ponds that are no more in use continue to affect surface water quality. In 2006, we carried out an investigation on the water quality and hydrology at the outlet of a small agricultural catchment area (area A) by estimating the in-stream nitrogen loads and nitrogen inputs. In this area, swine waste had been retained in an earthen waste storage pond, which was not in use since 1990. Similar investigations were conducted at the same location in 1992 and 2002, and the results of all these three studies were compared. The average nitrate nitrogen (NO₃-N) concentrations were 26, 4.9, and 4.0 mg L⁻¹ in 1992, 2002, and 2006, respectively. Despite 76% of the land use of area A being forest, the average NO₃-N concentration was relatively high, indicating that effluents from the earthen waste storage pond continued to affect surface water quality in 2006. The ranges of in-stream nitrogen loads derived from the earthen waste storage pond were estimated to be 154 to 207, −14 to 39, and 14 to 74 kg ha⁻¹ for 1992, 2002, and 2006, respectively. The results suggested that although the effects of effluents from the earthen waste storage pond on water quality decreased over 14 years, they still continued in 2006.     

Plant nutrient uptake and potato yield response to banded and broadcast nitrogen

The response of potato plants to banding and broadcasting of N was evaluated under sprinkler irrigation utilizing well water containing 20 to 24 ppm NO₃-N. A potato crop was grown for three consecutive years on a Wasco sandy loam soil at rates of 67, 134, 202, and 269 kg N/ha, as (NH₄)₂SO₄. At each rate of N, 58 kg P/ha as superphosphate, and 112 kg K/ha as K₂SO₄, were included. Differences in PO₄-P or K concentrations in petiole tissue were minimal with no consistant differences in NO₃-N concentration whether N was banded or broadcast. With each increment of N the NO₃-N concentration increased. Total or U.S. No. 1 yields of potatoes were not consistently different whether N was banded or broadcast. Total yields increased when N was increased from 67 to 202 kg/ha. Neither yield of U.S. No. 1 grade or dry matter content of potatoes was improved when N was increased above 134 kg/ha.     

Effects of alternate wetting and drying irrigation on percolation and nitrogen leaching in paddy fields

The widely adopted alternate wetting and drying (AWD) irrigation for rice production is increasingly needed to quantify the different water outflows and nitrogen leaching losses. We investigated the effects of AWD on percolation, water productivity, nitrogen leaching losses, and nitrogen productivity through in situ experiments. Results show that AWD reduced irrigation water without a significant impact on grain yields and increased the mean water productivity by 16.9 % compared with continuously flood irrigation (CFI). The mean nitrogen productivity of 135 kg ha^?1 N level was 22.2 % higher than that of 180 kg ha^?1 N level, although grain yields substantially increased because of nitrogen fertilization application. The percolation was also reduced by 15.3 % in 2007 and 8.3 % in 2008 compared to CFI. However, the cumulative percolation of the first 5 days after irrigation in AWD plots is significantly larger than that in CFI plots. The NH₄ ⁺–N and TN leaching losses of AWD and CFI had no significant variations while the NO₃ ^?–N leaching losses were increased caused by AWD. The total NH₄ ⁺–N, NO₃ ^?–N, and TN leaching losses of AWD in the first 3 days after irrigation were higher than that of contemporaneous CFI. The results indicate that the bypass or preferential flow and strengthened nitrification–denitrification nitrogen transformation processes because of alternate wetting and drying potentially decrease the water saving effectiveness and increase the NO₃ ^?–N loading to the groundwater.     

Effects of moisture stress and nitrogen fertilization on tuber nitrate-nitrogen content

Moisture stress in potato plants results in a significant increase in tuber NO_3?N levels. Research plots with three irrigation treatments and four nitrogen fertilizer rates (0, 100, 200, and 500 lb N/A) (0, 112, 224, and 560 kg N/ha) were established to test the influence of soil moisture and nitrogen rate on tuber NO_3?N content. Data from these plots showed that regardless of nitrogen rate, potato tubers from plants subjected to moisture stress had NO_3?N levels approximately twice as high as tubers from plants under optimum or excessive irrigation. With low nitrogen fertilizer rates, tuber NO_3?N levels were 78 to 80 ppm under optimum and excessive irrigation treatments as compared to 144 ppm under the deficient irrigation treatment. With excessive nitrogen fertilizer rates, tuber NO_3?N levels were 151 to 154 ppm under optimum and excessive irrigation treatments compared to 370 ppm under deficient irrigation. Correlation between tuber NO_3?N and petiole NO_3?N levels suggest that moisture stressed plants have a different relationship between tuber and petiole than plants under proper to high soil moisture conditions.     

Influence of liming and form of nitrogen fertilizer on nutrient uptake,growth, yield,and quality of Virginia (flue-cured) tobacco

Soil acidity is a limiting factor affecting the growth and yield of many crops all over the world. It is recognized that liming is the most common management practice of profitable crop production on acid soils. On the other hand, it is well-known that the form of nitrogen may affect tobacco yield and quality. In this work, the impact of the interaction between three hydrated lime (HL, Ca(OH)₂) rates (0, 1.5 and 3 t HL ha⁻¹) and three nitrogen fertilizer forms (NO₃-N 100%, NH₄-N 100% and NO₃-N 50% plus NH₄-N 50%) on growth, yield and quality characteristics of Virginia (flue-cured) tobacco was investigated in a 4-year (1995–1998) field experiment established in an acid soil (pH_{water 1:1} 5.3) located in Northern Greece. Lime was applied only once in December 1994, while nitrogen fertilizer was applied annually before transplanting. The results showed that the effect of liming on tobacco growth was not dependent on time, weather conditions and form of nitrogen fertilizer. Liming increased soil pH, enhanced the early growth of tobacco (within 30 days after transplanting (DAT)) and finally increased the total gross and trade yield of tobacco proportionally to the amount of HL added. However, the quality index (organoleptic characteristics) of the cured product was improved only at the HL application rate of 3 t HL ha⁻¹. Furthermore, liming significantly increased Ca and P concentrations but decreased K concentration in cured tobacco leaves. Tobacco yield increase was attributed to the increase of P uptake. Liming also increased the ash content of cured leaves, whereas it did not significantly affect nicotine, total nitrogen and reducing sugars. The use of ammonium N in fertilizer delayed the early growth of tobacco, reduced the nicotine concentration and increased the reducing sugars concentration of the cured product. Total-N, P, K and Mg concentrations of cured leaves were not significantly affected by the form of nitrogen fertilizer used. The results suggested that an initial application of hydrated lime at a rate of 3 t HL ha⁻¹ may ameliorate soil acidity and increase the yield and quality characteristics of Virginia tobacco at least over a 4-year period after application, independent of the form of N fertilizer used.     

Effects of nitrogen rate on nitrate–nitrogen accumulation in forage kale and rape crops

Nitrogen fertilizer is applied to supplement soil nitrogen supply to maximize forage brassica crop dry-matter production. However, nitrogen fertilizer applications in excess of that required to maximize growth result in potentially toxic nitrate–nitrogen (NO₃–N) concentrations in grazeable plant tissues. Three experiments, two for forage kale at Lincoln (Canterbury) and one for forage rape at Hastings (Hawke's Bay) in New Zealand were grown under different rates of nitrogen (0–500 kg N ha⁻¹) to determine the effect of different rates of nitrogen on NO₃–N content of different plant parts of the crops. One of the kale experiments was grown with either full irrigation or no rain and no irrigation over summer, hereafter referred to as summer drought. The NO₃–N concentration on a whole plant (weighted average) basis increased from 0·1 mg g⁻¹ dry matter for the control plots to 2·30 mg g⁻¹ for the 500 kg N ha⁻¹ plots for forage kale. It increased from 0·99 for the control plots to 3·37 mg g⁻¹ for the 200 kg N ha⁻¹ plots for forage rape crops. However, NO₃–N concentration increased with N supply under the summer-drought plots from an average of 0·33 mg g⁻¹ when ≤120 kg N ha⁻¹ was applied to 2·30 mg g⁻¹ for the 240 kg N ha⁻¹ treatments but was unaffected by N supply under irrigation. The NO₃–N concentrations were higher in the stems and the petiole (which included the midrib of the leaf) than leaves in all three experiments. The NO₃–N concentration was highest at the bottom of the kale stem and decreased towards the top. We recommend N application rates based on soil tests results, and for conditions similar to the current studies up to 300 kg N ha⁻¹ under irrigation and adjusted lower N rates for regions prone to dry summers.     

氮素形态配比对玉米氮素积累及转运的影响

通过田间试验,研究6种(N_1~N_6)硝态氮与铵态氮配比处理对旱地全膜双垄沟播玉米植株氮素积累、转运、氮素利用及子粒产量的影响。结果表明,单施硝态氮时玉米的养分吸收、氮素利用及产量均最低。N6(硝态氮与铵态氮3∶1配比)处理下玉米全生育期氮素积累量最高,氮素吸收强度较单施硝态氮处理高55.19%~73.28%(P0.05),该处理下叶片和茎中氮素转移量较单施硝态氮处理高78.99%和93.52%(P0.05);叶片和茎中分别有66.50%~71.89%和43.44%~55.59%的氮素转移到子粒中;叶片和茎对子粒的氮素贡献率分别较单施硝态氮处理高43.80%和56.00%(P0.05);玉米子粒产量、氮素吸收效率及氮肥偏生产力较其他处理显著增加3.31%~9.94%、4.62%~33.89%和3.31%~9.93%。硝态氮和铵态氮配施对玉米的养分吸收有明显的促进作用,提高硝态氮的施用比例有利于提高玉米叶片和茎对子粒氮素的贡献率,硝态氮与铵态氮按3∶1比例配施有利于提高当地玉米子粒产量。