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1.
K.MINAMI 《土壤圈》2005,15(2):164-172
To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, livestock wastes,and municipal and agricultural wastes, with national and international concern about its potential adverse effects on environmental quality and public health. To understand these phenomena and problems, first the nitrogen cycle and the environment are described. Then recent trends for nitrogen cycling through the food and feed system, N2O emissions from fertilized upland and paddy soils, and NO3^- pollution in ground water in Japan are reported. Finally, mitigation strategies in Japan for reducing N2O emission and NO3^- pollution are proposed, including nitrification inhibitors, controlled release fertilizers, utilization of plant species that could suppress nitrification, utilizing the toposequence, government policy, and appropriate agricultural practices. Of all the technologies presented, use of nitrification inhibitors and controlled release fertilizers are deemed the most important with further development of these aspects of technologies being expected. These practices, if employed worldwide, could help reduce the load, or environmental deterioration, on the Earth‘s biosphere.  相似文献   

2.
Abstract

Nitrate‐nitrogen (NO3‐N) soil tests have been instituted by several Great Plains States to aid in making nitrogen fertilizer recommendations. The NO3‐N soil test is useful in the Great Plains because climatic conditions are such that NO3‐N leaching is low and soil rooting depths are great.

Essentially four basic approaches to the use and interpretation of the NO3‐N soil test have been developed and are discussed. They are: (1) total amount of NO3‐N extracted from a two foot soil profile is available to the growing crop; (2) only a portion of the extractable NO3‐N is available to the growing crop; (3) other mineral nitrogen, such as NH4‐N, is just as available to the growing crop and (4) some nitrogen becomes available from the soil organic matter. The NO3‐N soil test requires that deep samples (two feet or more) be taken and that they are air‐dried as rapidly as possible. Late fall or early spring soil samples are necessary for interpretation of the NO3‐N soil test.  相似文献   

3.
The present work aims at evaluating the effect of cycloheximide at concentrations of between 0.5 and 5mgg–1 on N2O and NO3 – production in two slightly alkaline soils, sampled from deciduous woodland and arable cultivation. In the first experiment, peptone was used as the “inducing substrate” for heterotrophic activity, and soil was incubated with cycloheximide (at different concentrations) and/or acetylene (1mll–1) to block induced eukaryotic protein synthesis and ammonia monooxygenase activity, respectively. Peptone addition stimulated N2O and NO3 – production significantly in woodland soil, whereas arable soil showed no significant N2O emissions and low NO3 – production. Low cycloheximide concentrations drastically reduced N2O emissions in woodland soil, suggesting a potential role of fungi in N2O emissions. However, acetylene was equally effective in blocking N2O emissions and part of NO3 – production, so that a possible role of ammonia monooxygenase in an organic-inorganic pathway of N nitrification in fungal metabolism can be hypothesized. A second experiment was carried out on the woodland soil to check if low cycloheximide concentrations had non-target biocidal effects on soil microorganisms. Attention was focused on the range of concentrations which had reduced N2O emission in the woodland soil. The results suggested that at concentrations of cycloheximide between 0.5 and 2mgg–1 any biocidal effect on microbial biomass was negligible in the first 48h; therefore only selective inhibition of protein synthesis could be expected. The whole nitrifier population seemed to be particularly sensitive to cycloheximide concentrations higher than 2.5mgg–1. Received: 4 July 1997  相似文献   

4.
A field experiment established in 1997 was conducted to study the effect of long-term N fertilizer application on N mineralization in a paddy soil determined using a laboratory anaerobic incubation followed with a field incubation and to measure the relationship between in situ N mineralization and crop N uptake. To estimate N mineralization in the laboratory, soil samples were collected from plots with N application at different rates for six years and were incubated. Soils treated with fertilizer N mineralized more N than unfertilized soils and mineralization increased with N application rates. Also, the fraction of total N mineralized increased with increasing N fertilizer application. These findings meant that a substantial portion of previously applied N could be recovered slowly over time in subsequent crops. The field incubation of the plot receiving no fertilizer N showed that the NH4^＋-N concentration varied greatly during the rice-growing season and seasonal changes of N mineralization were due more to accumulation of NH4^＋-N than NO3^-N. Hice N uptake increased up to a maximum of 82 kg N ha^-1 during the season. The close agreement found between in situ N mineralization and rice N uptake suggested that the measurement of in situ N mineralization could provide useful recommendations for adequate fertilizer N application.  相似文献   

5.
Fate of N from Green Manures and Ammonium Sulfate   总被引：4，自引：0，他引：4  
By means of ^15N tracer technique the fate of N in ammonium sulfate,milk vetch,sesbania and azolla,and the availability of their residual N were studied in a microplot experiment.Results showed that a) at the end of the first crop of early rice,both plant recovery and loss of N from ammonium sulfate were the highest whereas those from azolla were the lowest with those from milk vetch and sesbania in between;the sequence was reversed in terms of recovery of N in soil;the net residual N from ammonium sulfate was very low,about 1/7-1/4 of that from green manures,indicating that chemical N fertilizer contributes little to the soil N reserve;b) plant recovery of the residual N was low and it did not always decrease with time;the total plant recovery (from the second to the fifth crops) of the residual N from various test fertilizers was only 8-11% of the total N originally applied;c) the plant recovery of the residual N from ammonium sulfate was the highest,followed by those from milk vetch and sesbania,and that from azolla was the lowest,no matter in which cropping season (from the second to the fifth);N availability ratio showed the same trend,indicating that chemical N fertilizer helps renovate soil organic N,maintain and increase availability of soil N.  相似文献   

6.
Growth and N‐P‐K uptake in pumpkin (Curcubita moschata Poir.) cv ‘Libby‐Select’ were studied in dryland and irrigated culture. In both moisture regimes, maximum rates of dry matter accumulation occurred between the early and mid‐fruiting developmental stages. Higher total dry matter production with irrigated than dryland culture was primarily associated with increased shoot growth. Concentrations of N, P, and K in foliage generally decreased as pumpkin age increased. Irrigated pumpkins in conjunction with higher total vegetative dry matter accumulated more N, P, and K than dryland pumpkins. Up through early fruit development, N, P, and K accumulation was primarily in leaves and vines and by the late growth stages was almost entirely in the fruit. Total N, P, and K uptake at late fruiting was estimated at 219, 32, and 228 kg/ha in irrigated pumpkins and 180, 21, and 177 kg/ha in dryland pumpkins. Approximately 58% of the N, 52% of the K, and 68% of the P accumulated by late‐fruiting was absorbed by the plant after the early‐fruiting stage in both moisture regimes. Potassium redistribution from vegetative tissues during late fruit development decreased foliar K contents 32% in dryland pumpkins and 21% in irrigated pumpkins.  相似文献   

7.
Abstract

Pansy (Viola xwittrockiana Gams.) producers often observe nutrient disorders among plants grown during warm periods (>18°C) of the growing season. These disorders typically are not seen when production temperatures are optimal (≥18°C) even though fertility regimes may remain the same. Our objectives were to assess the effects of temperature and nitrogen (N) fertility on growth and nutrition of pansy. Pansies cultivar ‘Crown White’ were grown until lateral branches had open flowers. Treatments consisted of two temperatures (12 and 22°C) and three NO3 ?:NH4 + molar % ratios (100:0, 62:38, and 25:75) with a total concentration of 100 mg N L?1. A modified Hoagland's solution was used with NO3 ?‐N supplied as Ca(NO3)2 and KNO3 and with NH4 +‐N as (NH4)2SO4. Cumulative nutrient absorption and foliar nutrient content were determined when plant lateral branches flowered. Root and shoot growth were limited when NH4 + was present in solutions at high ambient air temperature (22°C), but not at low temperature (12°C). Individual absorption and accumulation of plant nutrients varied with N regimes and temperatures. Overall, pansies absorbed more total N, NH4 +, NO3 ?, calcium (Ca), potassium (K), magnesium (Mg), phosphorus (P), zinc (Zn), and less iron (Fe) and manganese (Mn) at 12°C than at 22°C. In addition, absorption of NO3 ? by pansy was negligible if any NH4 + was present in solutions at 22°C. Results suggest that pansy growers should adjust fertility programs according to production temperatures to avoid possible nutritional disorders and maximize plant growth. If maximum growth is to be obtained in warm temperatures, the use of NH4 +‐containing fertilizers should be reduced or eliminated. However, the choice of NO3 ?:NH4 + ratio for nutrition may be less important under cool growing conditions.  相似文献   

8.
Abstract

A laboratory study was conducted to assess the effectiveness of phenylphosphorodiamidate (PPD) and N‐(n‐butyl) thiophosphoric triamide (NBT) in retarding urea hydrolysis in four flooded rice soils under simulated oxidized and reduced conditions. Urea (400 μg N g‐1soil) with PPD or NBT (2.0% w/w) was added to preincubated soils and analyzed for urea content 1, 3, 5, 7 and 15 days after N application. N‐(n‐butyl) thiophosphoric triamide was more effective in delaying urea hydrolysis under oxidizing conditions and at 5 days 57% of the added urea remained in the oxidized soils compared to only 4% under reduced soil conditions. In three soils, PPD was observed to be effective under reducing soil constraints. At 5 days 56 and 31% of the added urea was unhydrolyzed under reducing and oxidizing soil conditions, respectively, with the addition of PPD. For two soils 48% of the added urea remained at the 15 day sampling for the urea + NBT treatment  相似文献   

9.
INTRODUCTION Nitrogen is a key component of soil organic matter. Only when we have succeeded in characterizing the major part of organic N-containing compounds will we be able to understand fully the transformation reactions in the soil and to use soil-N more efficiently. However, only about 1/4-1/2 of the total N in humic acid (HA), one of the major constituents of soil organic matter, can be accounted for as amino acids and amino sugars, and most of the remainder has still to be accounted for.  相似文献   

10.
Abstract

Pot experiments were conducted to determine effects of applied N on NO3‐N and total N concentrations in Swiss chard (Beta vulgaris var. cicla) and of applied N, P, and K on Bloomsdale spinach (Spinacia oleracea L.) and on curly mustard (Brassica pervirdis L.). Ammonium nitrate produced greater increases in NO3‐N and total N concentrations in chard than did sulfur‐coated urea at the same rates of applied N. Both N and K increased yields and NO3‐N accumulation in spinach and mustard; response to applied P resulted only in decreased NO3‐N. Both total and NO3‐N concentrations decreased with dilution and/or assimilation associated with time of growth and higher yields.

An examination of published results with several spinach cultivars indicates that differences in NO3‐N accumulation attributed to leaf type can also be explained by the higher yields of the low NO3‐N accumulators. The same is true for differences in NO3‐N accumulations attributed to light and temperature effects.  相似文献   

11.
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12.
Non-point source pollution from the Agri-sector (especially nitrogen (N)) due to the application of conventional urea with heavy rates not only depleted the water quality of Erhai Lake but also declined the nitrogen use efficiency (NUE) of different crops grown in the Erhai Lake Basin, Dali, Yunnan, China. It is imperative to mitigate the total nitrogen and its forms (nitrate (NO3?)-N and ammonium (NH4+)-N) loading to the surface and subsurface water flow through optimum fertilizer management for crop production in the region. To achieve this goal, a balanced crop nutrition system was practiced with different fertilizer types for rice-broad bean crop rotation system. The crop nutrition system consisted of No Fertilizers (CK), Conventional Fertilizer Practice (CF), Conventional urea as environmental Fertilizer (T1), Refined Organic Fertilizer applied solely (T2), Refined Organic Fertilizer applied with conventional urea (T3), Refined Organic Fertilizer applied in T2 was increased 4 times (T4), Refined Organic Fertilizer applied in T3 was increased 4 times but the same amount of conventional urea (T5), and Controlled Release Fertilizer (CRF) application (T6). The same rate of nitrogen (20% lower than CF) was applied in T1, T2, T3, and T6. All the former mentioned treatments were compared to CF with respect to different variables. In case of crop production, T6 gave maximum rice grain yield (9.9 t ha?1) and broad bean yield (5.1 t ha?1). Treatments T1 and T5 were at par for rice grain yield (7.8 t ha?1) and this quantity was not significantly lower than CF. Treatments T6, T5, and T1 were observed 29%, 47%, and 46%, respectively lower in TN loading to the surface and percolating water than the CF. Conventional urea and refined organic fertilizer combined with conventional urea at reduced nitrogen rates can be a reliable option for crop production in the Erhai Lake Basin with optimum yield under the rice-broad bean crop rotation system. CRF at reduced nitrogen rate can be a better option for higher yield and lower NO3–N, NH4+-N and total nitrogen losses to the surface runoff and leached water.  相似文献   

13.
Abstract

Two greenhouse studies were conducted to evaluate the effect of B, Mn and Zn on nodulation and N2‐fixation of southernpea (Vigna unguiculata (L.) Halp.) cultivars ‘Freezegreen’, ‘Mississippi Silver’ and ‘Pinkeye Purple Hull’. The cultivars were grown in plastic pots with a Norfolk sandy loam (fine, loamy siliceous thermic, Typic Paleudult) soil treated with B, Mn and Zn at rates of 0, 5, 10 and 20 kg/ha each at pH levels 5.5, 6.0 and 6.5. At pH 6.5 all micronutrient treatments significantly increased nodulation and N2‐fixation over the control (no micronutrient applied). The effects of B, Mn and Zn on nodulation and N2‐fixation depended on the cultivar and soil pH. For plants given the 5 kg/ha B and Mn treatments, ‘Mississippi Silver’ produced the highest number of nodules and ‘Pinkeye Purple Hull’ the least. At 20 kg/ha Zn, nodulation of ‘Freezegreen’ was highest and ‘Pinkeye Purple Hull’ the lowest. As a whole, maximum nodulation was at 5 kg/ha B and Mn and 20 kg/ha for Zn. Nitrogen fixation rates responded similarly except that the optimum rate for Zn was 10 kg/ha. Seed yield of plants peaked at 5 kg/ha for B and 10 kg/ha for Zn, indicating a possible relation of N2‐fixation to seed yield.  相似文献   

14.
Abstract

Nitrogen‐form effect on nutrient uptake and the subsequent concentration of nutrients in turfgrass plant tissue has not been thoroughly investigated. This study evaluated the effects of clipping regime and N‐form on the tissue concentration of macronutrients and micronutrients and macronutrient uptake in ‘Penncross’ creeping bentgrass (Agrostis palustris Huds.). Turfgrass plugs were grown under greenhouse conditions in a modified Hoagland's solution with a combination of three nutrient solutions (100% NO3 ?, 100% NH4 +, and 50:50 ratio of NH4 +:NO3 ?) and two cutting regimes (cut and uncut). Concentrations of macronutrients and micronutrients were determined for shoot, root and verdure. Nutrient uptake was determined weekly. Uncut NO3 ?‐treated plants accumulated higher concentrations of K, Ca, Mg, B and Cu in the shoot tissue; P, K, Ca, Mg, B, Cu, Mn and Zn in the root tissue; and P, Ca, Mg, B, Fe and Mn in the verdure compared to uncut NN4 +‐treated plants. Nitrate uptake was greater with uncut NO3 ?‐treated plants than was NH4 + absorption with uncut NH4 +‐treated plants. Plants grown with the uncut 50:50 treatment adsorbed more NH4 + than NO3 ?. Plants grown with the uncut NO3 ? and 50:50 treatments adsorbed higher amounts of P, K, and Ca compared to the NH4 + treatment. The cut NO3 ?‐treated plants accumulated higher concentrations of K in the shoot tissue; P, Ca, Mg, B, Cu, Fe and Mn in the root tissue; and B in the verdure than did the cut NH4 +‐treated plants. Cut NO3 ?‐treated plants adsorbed less NO3 ? than did cut NH4 +‐treated plants adsorbed NH4 +. The cut 50:50 treatment adsorbed more NH4 + than NO3 ?. Plants grown with NO3 ? and 50:50 treatments, under both cutting regimes, resulted in higher concentrations of most macro‐ and micronutrients and greater nutrient uptake compared to the NH4 +‐treated plants.  相似文献   

15.
Nitrogen (total and 15N) uptake by barley (Hordeum vulgare L., cv. ‘Walfajr') and wheat (Triticum aestivum L., cv. ‘Karaj I') plants subjected to water stress were studied at the College of Agriculture, University of Tehran Experimental Farm located in the city of Karaj, Iran. The treatments consisted of two irrigation intervals, 7 days (control) and 14 days (stress). The plants were at the reproductive stage of growth at the start of the 15N treatment. Nitrogen (15N) was applied to 1m x 1m plots selected at the center of the 2.5m x 2.5m main plots. The 15N was provided to plants by adding 250 mg 13N as (NH4)2SO4 (5.1 Atom % 15N) dissolved in water to each plot. The 15N treatment period continued for 48 hours. The plants were harvested at 6‐hour intervals during the 15N treatment period. After each harvest, the straw and the grains were separated, oven dried at 65°C and dry weights were recorded. Plant materials were ground in a Wiley Mill to pass through a 2mm sieve for chemical analysis. Total N was measured by an Auto‐Analyzer after Kjeldahl digestion, and 15N was measured using a mass spectrometer.

Nitrogen (total‐N and 15N) content of both plant species decreased under stress, with wheat appearing more severely affected than barley. However, nitrogen concentration was slightly higher for the stressed plants as compared with the controls. This pattern was essentially similar for both plants.  相似文献   

16.
Abstract

Soil compaction is a significant production problem for agriculture because of its negative impact on plant growth, which in many cases has been attributed to changes in soil N transformations. A laboratory experiment was conducted to study the effect of soil compaction and water‐filled pore space on soil microbial activity and N losses. A hydraulic soil compaction device was used to evenly compress a Norfolk loamy sand (fine‐loamy, siliceous, thermic Typic Kandiudults) soil into 50 mm diameter by 127 mm long cores. A factorial arrangement of three bulk density levels (1.4, 1.6, and 1.8 Mg/m3) and four water‐filled pore space levels (60, 65, 70, 75%) was used. Fertilizer application of 168 kg N/ha was made as 1.0 atom % 15N as NH4NO3. Soil cores were incubated at 25°C for 21 d. Microbial activity decreased with both increasing water‐filled pore space and soil bulk density as measured by CO2‐C entrapment. Nitrogen loss increased with increasing bulk density from 92.8 to 334.4 g N/m3 soil at 60% water‐filled pore space, for 1.4 and 1.8 Mg/m3, respectively. These data indicate that N loss and soil microbial activity depends not only on the pore space occupied by water, but also on structure and size of soil pores which are altered by compaction.  相似文献   

17.
Disruption in the nitrogen (N) cycle balance has a negative impact on the overall trend of sustainable development, and using soil amendments is necessary to reduce these hazards. This study was carried out as a factorial experiment in a completely randomized design. The treatments consisted of three levels of amendments (0, 7.5 g/kg of pistachio residues, and 7.5 g/kg of biochar) and four levels of irrigation water salinity including 0.5 (urban water), 5.5, 8, and 10.5 dS/m and in three replications. Two pistachio seedlings were transferred to all columns and then in three steps, and in each step, 25 mg N/kg of potassium nitrate was added. The results indicated that pistachio residuals and its biochar increased nitrate outflow from effluent by 9% and 52%, respectively. The effects of amendment treatment and irrigation water salinity on all three characteristics of output nitrate, soil nitrate, and absorbed plant nitrate were significant at 1% level.  相似文献   

18.
Crop Yield, N Uptake and Nitrates in a Fluvo-Aquic Soil Profile   总被引：3，自引：0，他引：3  
《土壤圈》2004,14(1):131-136
  相似文献   

19.
蔬菜瓜果鲜样中NO^—3—N及NO^—2—N测定方法的改进   总被引：11，自引：1，他引：10  
本方法采用硫酸铝，乙酸锌和碳酸镁，氢氧化钙制备植物浸提液，不但操作简单，而且更有效地除去了有机物质的干扰。进而用铜锌粒还原ＮＯ＾－３，以紫外差减法测定ＮＯ＾－３－Ｎ，检测限为１ｍｇ／ｋｇ，回收率达９６．０％－１０２．１％。用此浸提液以盐酸萘乙二胺显色测定ＮＯ＾－２－Ｎ，检测限为０．０１ｍｇ／ｋｇ，回收率达９５．０％－９９．２％。  相似文献   

20.
Indirect evidence of the nitrogen (N) status of tropical forests strongly suggests that in heavily weathered soils under old-growth lowland tropical forests nitrogen is in relative excess. However, within the lowland forests of the Amazon basin, there is substantial evidence that soil texture influences soil NH4+ and NO3? concentrations and hence possibly N availability and retention in the soil. Here, we evaluate the soil N status of two heavily weathered soils which contrast in texture (sandy versus clay Oxisol). Using 15N pool dilution, we quantified gross rates of soil N cycling and retention. We also measured the δ15N signatures from the litter layer down to 50-cm depth mineral soil and calculated the overall 15N enrichment factor (ε) for each soil type. The clay soil showed high gross N mineralization and nitrification rates and a high overall 15N enrichment factor, signifying high N losses. The sandy soil had low gross rates of N cycling and 15N enrichment factor, manifesting a conservative soil N cycling. Faster turnover rates of NH4+ compared to NO3? indicated that NH4+ cycles faster through microorganisms than NO3?, possibly contributing to better retention of NH4+ than NO3?. However this was opposite to abiotic retention processes, which showed higher conversion of NO3? to the organic N pool than NH4+. Our combined results suggest that clay Oxisol in Amazonian forest have higher N availability than sandy Oxisol, which will have important consequences for changes in soil N cycling and losses when projected increase in anthropogenic N deposition will occur.  相似文献   

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