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1.
Abstract

To determine the relationships between microbial biomass nitrogen (N), nitrate–nitrogen leaching (NO3-N leaching) and N uptake by plants, a field experiment and a soil column experiment were conducted. In the field experiment, microbial biomass N, 0.5 mol L?1 K2SO4 extractable N (extractable N), NO3-N leaching and N uptake by corn were monitored in sawdust compost (SDC: 20 Mg ha?1 containing 158 kg N ha?1 of total N [approximately 50% is easily decomposable organic N]), chemical fertilizer (CF) and no fertilizer (NF) treatments from May 2000 to September 2002. In the soil column experiment, microbial biomass N, extractable N and NO3-N leaching were monitored in soil treated with SDC (20 Mg ha?1) + rice straw (RS) at five different application rates (0, 2.5, 5, 7.5 and 10 Mg ha?1 containing 0, 15, 29, 44 and 59 kg N ha?1) and in soil treated with CF in 2001. Nitrogen was applied as (NH4)2SO4 at rates of 220 kg N ha?1 for SDC and SDC + RS treatments and at a rate of 300 kg N ha?1 for the CF treatment in both experiments. In the field experiment, microbial biomass N in the SDC treatment increased to 147 kg N ha?1 at 7 days after treatment (DAT) and was maintained at 60–70 kg N ha?1 after 30 days. Conversely, microbial biomass N in the CF treatment did not increase significantly. Extractable N in the surface soil increased immediately after treatment, but was found at lower levels in the SDC treatment compared to the CF treatment until 7 DAT. A small amount of NO3-N leaching was observed until 21 DAT and increased markedly from 27 to 42 DAT in the SDC and CF treatments. Cumulative NO3-N leaching in the CF treatment was 146 kg N ha?1, which was equal to half of the applied N, but only 53 kg N ha?1 in the SDC treatment. In contrast, there was no significant difference between N uptake by corn in the SDC and CF treatments. In the soil column experiment, microbial biomass N in the SDC + RS treatment at 7 DAT increased with increased RS application. Conversely, extractable N at 7 DAT and cumulative NO3-N leaching until 42 DAT decreased with increased RS application. In both experiments, microbial biomass N was negatively correlated with extractable N at 7 DAT and cumulative NO3-N leaching until 42 DAT, and extractable N was positively correlated with cumulative NO3-N leaching. We concluded that microbial biomass N formation in the surface soil decreased extractable N and, consequently, contributed to decreasing NO3-N leaching without impacting negatively on N uptake by plants.  相似文献   

2.
Diverting the infiltrating water away from the zone of N application can reduce nitrate–nitrogen (NO3–N) leaching losses to groundwater from agricultural fields. This study was conducted from 2001 through 2005 to determine the effects of N-application methods using a localized compaction and doming (LCD) applicator and spoke injector on NO3–N leaching losses to subsurface drainage water and corn (Zea mays L.)–soybean (Glycine max L.) yields. The field experiments were conducted at the Iowa State University’s northeastern research center near Nashua, Iowa, on corn–soybean rotation plots under chisel plow system having subsurface drainage ‘tile’ system installed in 1979. The soils at the site are glacial till derived soils. The N-application rates of 168 kg-N ha?1 were applied to corn only for both the treatments each replicated three times in a randomized complete block design. For combined 5 years, the LCD N-applicator in comparison with spoke injector showed lower flow weighted NO3–N concentrations in tile water (16.8 vs. 20.1 mg L?1) from corn plots, greater tile flow (66 vs. 49 mm), almost equivalent NO3–N leaching loss with tile water (11.5 vs. 11.3 kg-N ha?1) and similar corn grain yields (11.17 vs. 11.37 Mg ha?1), respectively, although treatments effects were found to be non-significant (p?=?0.05) statistically. The analysis, however, revealed that amount and temporal distribution of the growing season precipitation also affected the tile flow, NO3–N leaching loss to subsurface drain water, and corn–soybean yields. Moreover, the spatial variability effects from plot to plot in some cases, resulted in differences of tile flow and NO3–N leaching losses in the range of three to four times despite being treated with the same management practices. These results indicate that the LCD N-applicator in comparison with spoke injector resulted in lower flow weighted NO3–N concentrations in subsurface drain water of corn plots; however, strategies need to be developed to reduce the offsite transport of nitrate leaching losses during early spring period from March through June.  相似文献   

3.
In this study, interactions of nickel sulfate and urea sprays on vegetative growth, yield and leaf mineral contents in strawberry were investigated. Rooted Pajaro strawberry plants were potted in 3 liter pots filled with soil, leaf mold and sand (1:1:1, v/v/v). Established plants were foliar sprayed with nickel sulfate at 0, 150, 300 and 450 mg L?1 and urea 0 and 2 g L?1 concentrations. Results indicated that nickel (Ni; 300 mg L?1) plus urea (2 g L?1) significantly increased the yield and runner numbers. Nickel sulfate at the rate of 300 and 150 mg L?1and urea (2 g L?1) significantly increased the crown numbers. The greatest root fresh and dry weights were obtained from untreated plants. Urea at 2 g L?1 without nickel significantly increased shoot fresh and dry weights. Nickel at 450 mg L?1 without urea significantly increased Ni concentration in leaves. Overall, nickel sulfate at 150 and 300 mg L?1 along with urea at 2 g L?1 were the best treatments.  相似文献   

4.
Understanding the temporal distribution of NO3-N leaching losses from subsurface drained ‘tile’ fields as a function of climate and management practices can help develop strategies for its mitigation. A field study was conducted from 1999 through 2003 to investigate effects of the most vulnerable application of pig manure (fall application and chisel plow), safe application of pig manure (spring application and no-tillage) and common application of artificial nitrogen (UAN spring application and chisel plow) on NO3-N leaching losses to subsurface drainage water beneath corn (Zea mays L.)–soybean (Glycine max L.) rotation systems as a randomized complete block design. The N application rates averaged over five years ranged from 166 kg-N ha?1 for spring applied manure to 170 kg-N ha?1 for UAN and 172 kg-N ha?1 for fall applied manure. Tillage and nitrogen source effects on tile flow and NO3-N leaching losses were not significant (P?<?0.05). Fall applied manure with CP resulted in significantly greater corn grain yield (10.8 vs 10.4 Mg ha?1) compared with the spring manure-NT system. Corn plots with the spring applied manure-NT system gave relatively lower flow weighted NO3-N concentration of 13.2 mg l?1 in comparison to corn plots with fall manure-CP (21.6 mg l?1) and UAN-CP systems (15.9 mg l?1). Averaged across five years, about 60% of tile flow and NO3-N leaching losses exited the fields during March through May. Growing season precipitation and cycles of wet and dry years primarily controlled NO3-N leaching losses from tile drained fields. These results suggest that spring applied manure has potential to reduce NO3-N concentrations in subsurface drainage water and also strategies need to be developed to reduce early spring NO3-N leaching losses.  相似文献   

5.
In vermicomposting, the main product is the worm casts, but a leachate is generated that contains large amounts of plant nutrients. This leachate is normally diluted to avoid plant damage. We investigated how dilution of vermicompost leachate combined with different concentrations of nitrogen (N) - phosphorus (P) - potassium (K) triple 17 fertilizer, and polyoxyethylene tridecyl alcohol as dispersant and polyethylene nonylphenol as adherent to increase efficiency of fertilizer uptake, affected sugarcane plant development. The vermicomposting leachate with pH 7.8 and electrolytic conductivity 2.6 dS m?1, contained 834 mg potassium (K) l?1, 247 mg nitrate (NO3?) l?1 and 168 mg phosphate (PO43?) l?1, was free of pathogens and resulted in a 65% germination index. Vermicompost leachate did not inhibit sugarcane growth and mixed with 170 g l?1 NPK triple 17 fertilizer resulted in the best plant development. No dispersant or adherent was required to improve plant height and stem development.  相似文献   

6.
Abstract

This trial was carried out to establish an appropriate nutrient solution for Aglaonema commutatum and to investigate the nutritional effects generated by modifications in the solution. Six treatments were tested: control (T0; pH 6.5, E.C. 1.5 dS m?1, 6 mmol L?1 NO3 ?‐N, and 6 mmol L?1 K+); high nitrogen (N) level (T1; 9 mmol L?1 6:3 NO3 ?–NH4 +); N form (T2; 6 mmol L?1 N‐NH4 +); high K+ level (T3; 12 mmol L?1 K+); high electrical conductivity (T4; E.C. 4 dS m?1, 25 mmol L?1 NaCl), and basic pH (T5; pH 8). At the end of the cultivation, leaf, shoot, and root dry weights and elemental concentrations were determined. Nutrient contents and total plant uptake were calculated from the dry weights and nutrient concentrations. Plant K+ uptake increased with application of K+ or basic nutrient solution. The uptake and transport of calcium (Ca) were enhanced by the use of NO3 ?‐N and inhibited by the presence of other cations in the medium (NH4 +, K+, Na+) and by basic pH. Magnesium (Mg) uptake increased with NO3 ?‐N application and with pH. Sodium (Na) uptake was the highest in the saline treatment (T4), followed by the basic pH treatment. Sodium accumulation was detected in the roots (natrophobic plant), where the plant generated a physiological barrier to avoid damage. Dry weight did not differ significantly (p<0.05) among treatments except in the NaCl treatment. These results may help in the formulation of nutrient solutions that take into account the ionic composition of irrigation water and the physiological requirements of plants.  相似文献   

7.

Purpose

Few studies have examined the effects of biochar on nitrification of ammonium-based fertilizer in acidic arable soils, which contributes to NO3 ? leaching and soil acidification.

Materials and methods

We conducted a 42-day aerobic incubation and a 119-day weekly leaching experiment to investigate nitrification, N leaching, and soil acidification in two subtropical soils to which 300 mg N kg?1 ammonium sulfate or urea and 1 or 5 wt% rice straw biochar were applied.

Results and discussion

During aerobic incubation, NO3 ? accumulation was enhanced by applying biochar in increasing amounts from 1 to 5 wt%. As a result, pH decreased in the two soils from the original levels. Under leaching conditions, biochar did not increase NO3 ?, but 5 wt% biochar addition did reduce N leaching compared to that in soils treated with only N. Consistently, lower amounts of added N were recovered from the incubation (KCl-extractable N) and leaching (leaching plus KCl-extractable N) experiments following 5 wt% biochar application compared to soils treated with only N.

Conclusions

Incorporating biochar into acidic arable soils accelerates nitrification and thus weakens the liming effects of biochar. The enhanced nitrification does not necessarily increase NO3 ? leaching. Rather, biochar reduces overall N leaching due to both improved N adsorption and increased unaccounted-for N (immobilization and possible gaseous losses). Further studies are necessary to assess the effects of biochar (when used as an addition to soil) on N.  相似文献   

8.
Bypass flow, the vertical flow of free water along the walls of macropores or preferential flow paths in the soil, can lead to movement of fertilizer nutrients beyond the reach of plants. Fertilizer type and the rate of application, as well as the amount, frequency, and intensity of rainfall, can influence the amount of fertilizer nitrogen (N) loss in leaching or bypass flow. The effect of fertilizer N form and rate of application on N recovery in bypass flow in a Kenyan Vertisol was determined. Calcium nitrate and ammonium sulfate, used to supply nitrate (NO3 ?)‐N and ammonium (NH4 +)‐N, respectively, were surface‐broadcast to 40‐cm‐long undisturbed soil columns at equivalent rates of 50, 100, and 200 kg N ha?1. Using a rainfall simulator, two rainfall events (30 mm of water applied in 1 h) were applied to the soil columns, one before and the other after fertilizer application. Total N, NO3 ?‐N, and NH4 +‐N concentrations in the bypass flow were determined after the second rainfall event. The application of NH4 +‐N, regardless of the rate, had no effect on N recovery in the bypass flow. When nitrate N was applied, the amount of fertilizer N recovered in the bypass flow significantly increased with the rate of NO3 ?‐N application. Of the total N in the bypass flow, 24 to 48% was derived from the soil, the bulk of which was organic N. It is concluded that following the application of NO3 ?‐N, bypass flow is an important avenue of loss of both fertilizer and soil N from Vertisols.  相似文献   

9.
Abstract

To study the response of inorganic and organic nitrogen (N) sources both alone and in conjunction and their influence on soil quality, a field experiment was conducted during kharif and rabi seasons using sunflower (MSFH‐8) as test crop. The experimental site soil was Typic Haplustalf situated at Hayatnagar Research Farm of Central Research Institute of Dryland Agriculture, Hyderabad, India, at 17° 18′ N latitude, 78° 36′ E longitude. The experiment design was a simple randomized block design with 11 treatments replicated four times. Among all the treatments, vermicompost (VC)+Fert at 25+25 kg N ha?1 recorded the highest grain yields of 1878 and 2160 kg ha?1 during both kharif and rabi seasons, respectively, which were 43.9 and 85.1% higher than their respective control plots. Apparent N recovery varied from as little as 38.30% (FYM at 50 kg N ha?1) to 62.16 (25 kg N ha?1) during kharif and 49.65 (75 kg ha?1) to 83.28% (VC+Fert at 25+25 kg N ha?1) during rabi season. Conjunctive nutrient treatments proved quite superior to other set of treatments in improving the uptake of N, phosphorus (P), potassium (K), sulfur (S), and micronutrients in sunflower and their buildup in the soil. Highest relative soil quality indexes (RSQI) were observed under VC+Fert at 25+25 kg N ha?1 (1.00) followed by VC+Gly at 25+25 kg N ha?1 (0.87). Considering the yield and relative soil quality indices (RSQI), conjunctive applications of VC with either inorganic fertilizer, FYM, or Gly at 25+25 kg N ha?1 could be a successful and sustainable soil nutrient management practice in semi‐arid tropical Alfisols. Besides this, the fertilizer N demand could be reduced up to 50%.  相似文献   

10.
Nitrate-N (NO3 ?-N) is a ubiquitous pollutant in both surface and groundwater in many agro-ecosystems. This has elicited a concerted effort to identify management strategies that mitigate NO3 ?–N pollution, without compromising crop yield. This study was conducted on a field site located at the Bio-Environmental Engineering Centre (BEEC) in Truro, NS, Canada during 1999 and 2000. The site has been used since 1997 to investigate the relative effect of inorganic versus organic fertilizer (liquid hog manure; LHM) applied at rates (70 kg N ha?1) on NO3 ?-N leaching from a carrot rotation system. NO3 ?-N concentrations were monitored in both the soil profile and in tile drainage effluents from eight treatment plots. The LHM treatment elicited significantly (P < 0.01) higher soil NO3 ?-N concentrations than inorganic fertilizer (IF) in June and October during 1999, but not 2000. The sampling date and soil depth were significant in most cases. Annual flow weighted averages (FWA) of NO3 ?-N in drainage water were generally greater for plots receiving LHM (15.4 and 10.5 mg L?1 for 1999 and 2000, respectively), when compared to IF (8.9 and 6.0 mg L?1 for 1999 and 2000, respectively), but the difference was significant (P < 0.05) only in 1999. Maximum NO3 ?-N concentrations in drainage water were similar for both treatments, while the LHM treatment had a significantly higher percentage of samples that were > 10 mg L?1. The total NO3 ?-N load was greater for the LHM treatment when compared to the IF treatment in 1999. Barley and carrot yields were unaffected by treatment applications.  相似文献   

11.
This study shows the effect of organic fertilizers at different stocking rates, on nitrogen (N) leaching, measured using zero-tension lysimeters under undisturbed grassland soil. The experiment included two organic fertilizer types – cow dung with dung water (D) and slurry (S), both at a range of stocking rates: 0.9 LU (livestock unit) ha?1, 1.4 LU ha?1, 2.0 LU ha?1 (corresponding to 54, 84 and 120 kg N ha?1, respectively) and a control (C) treatment. In percolated water, the contents of ammonia nitrogen (NH4+–N) and nitrate nitrogen (NO3?–N) were studied. The average concentration of NH4+–N ranged from 0.91 to 1.44 mg l?1 on fertilized plots compared to 0.55 mg l?1 on the control plot. The average concentration of NO3?–N ranged from 5.2 to 9.5 mg l?1 on fertilized plots compared to 3.2 mg l?1 on the control plot. The results of this study showed that the use of organic fertilizers at chosen stocking rates influenced N leaching, but the concentration of N did not exceed the limits for drinking water permitted by Czech legislation. Stocking rates at 2.0 LU ha?1 and below do not result in elevated N concentrations in percolated water that pose environmental threat.  相似文献   

12.
The long-term control of fertilizer pollution in the Danjiangkou Reservoir is an important task, and promoting good fertilizer pollution control methods is necessary to conserve water quality. A 3-year experiment was conducted to evaluate the fertilizer losses, economic benefits, and feasibility of different nutrient and water management methods in the area. The experiment included the following treatments: (1) local recommended fertilizer dose (450, 144, and 189 kg ha?1 y?1 of N, P2O5, and K2O) under rain-fed conditions (CK); (2) chicken manure at 7500 kg ha–1 without drip irrigation (OF); (3) same dosage of treatment OF but with drip irrigation (OFD); and (4) drip fertigation with 30% of the fertilization dose of CK (DF). The results showed that organic fertilizer and drip fertigation treatments reduced total N (TN) and total P (TP) losses compared to CK due to considerably less amounts of N and P nutrient inputs. Total N runoff losses, and TN and TP concentrations in leaching water did not differ significantly among treatments OF, OFD, and DF. Net income among the CK, OF, and OFD treatments did not differ significantly. Treatment DF resulted in 19.5% and 13.8% more net income than CK and OFD, respectively. Such results provided guidance for promotion to maximize benefits and minimize environmental impacts.  相似文献   

13.
This study is the first to report nitrite occurrence and variability in surface water across an agricultural watershed in the province of Quebec, Canada. Nitrite (NO2 ?) concentrations were monitored across a 2.4 km2 watershed during 2 years. Water samples were collected at the outlet from April to November and in three contrasted stream branches (six stations) during three hydrological regimes (summer low water levels, fall recharge, and snowmelt). Our study clearly demonstrates that NO2 ? levels observed at the outlet are not representative of NO2 ? variability across the micro-watershed. Surface water collected in cropped areas presents high NO2 ? concentrations during summer low water levels, often exceeding guidelines for aquatic life, with NO2 ? means ranging from 0.022 to 0.107 mg N L?1 and maximum value reaching 0.156 mg N L?1. Furthermore, the two stream branches in cropped area have demonstrated significant differences in NO2 ? concentrations and other water quality parameters. The importance of groundwater discharge to streams in the micro-watershed Bras d’Henri may potentially generate different in-stream sources of NO2 ? and water quality parameters. However, further studies are essential to determine sources and processes related to in-stream NO2 ? peaks.  相似文献   

14.
ABSTRACT

Controlled-release fertilizers (CRF) are used to reduce leaching of nutrients, especially nitrate-nitrogen (NO3 ?-N) to groundwater, caused mainly by application of soluble N fertilizers to sandy soils in Florida. A leaching column study was conducted to evaluate N release and transformation from a CRF (CitriBlen) over a 16-week period when it was applied on the soil surface or incorporated into the soil. When one pore volume of water was applied to column weekly or biweekly, the CRF released urea-N slowly over time with three peaks of release on 3–4, 8, and 12 week after application. Both ammonium-nitrogen (NH4 +-N) and NO3 ?-N were leached in large amounts on week 2, likely from soluble forms of N. Cumulatively, the most leached N at the end of study was in the NH4 + form, followed by the NO3 ? form. The sum of all N forms leached and volatilized accounted for 53–69% of total N applied. Total N recovery was 70% and 93% of total N applied for surface and sub-surface application of the fertilizer, respectively. It was indicated that the better recovery rate found with sub-surface application may have been due to minimized N loss by volatilization. Sub-surface application of fertilizer resulted in more than three times NH4 +-N remained in soil, compared with surface application. On average for both application treatments throughout 16-week period, 5.8 h was required for ammonification and 4.7 d for nitrification to occur after N release from the fertilizer. Characterization of CRFs for specific soil type, leaching volume and cycle, and application manner as well as knowledge of N requirement of the crop will allow for the Best Management Practices of these fertilizers, thus obtaining optimum yields and minimizing nutrient losses from CRFs.  相似文献   

15.
A column lysimeter study was conducted under greenhouse conditions to determine the impact of moderately saline irrigation water on NO3 leaching from turfgrass. Bermudagrass (Cynodon dactylon L. ‘NuMex Sahara’) was fertilized at three N levels (25, 50 and 75 kg NH4NO3-N ha?1 month?1) and irrigated with saline water (0, 3.0 and 6.0 dS m?1) in a factorial arrangement. Leachate was analyzed for salinity and NO3, and clippings were collected and analyzed for total N. Nitrate leaching was not affected by either N level or salinity. Nitrate concentrations in the leachate were low, averaging approximately 0.3 mg N L?1; less than 1% of the applied N leached. Longer-term N allocation to leaf growth accounted for up to 98% of applied N, whereas short-term allocation, determined using 15N, ranged from 46–67%. Salinity had no affect on clipping yield, the biomass of root and verdure, or root distribution. These data indicate the potential for moderately saline irrigation water to be used on bermudagrass turf without increasing NO3 contamination of groundwater, as long as leaching is adequate to prevent rootzone salinity reaching damaging levels.  相似文献   

16.
ABSTRACT

Field experiments were conducted for 2 years in sandy loam soil, to study the direct effect of organic manures i.e. sewage sludge (SS), vermicompost (VC) and sesbania (SB) and chemical fertilizers on rice (Oryza sativa) and their residual effect on wheat (Triticum aestivum) grown in sequence in winter (Rabi) and summer (Kharif) season during 2015–2016 to 2016–2017 at Varanasi, Uttar Pradesh. Residual effect of organic sources of nutrients as SS, VC and SB were monitored up to fourth crop (II wheat) in sequence applied in conjunction with 75% recommended dose of fertilize (RDF). Among the nutrient sources, the maximum grain yield in I rice (4.89 t ha?1), II rice (4.95 t ha?1), was recorded in treatment T3 (100% RDF with S, Zn, B) whereas in I wheat (4.68 t ha?1) and II wheat (4.59 t ha?1), it was recorded in T4 (customized fertilizer). The maximum straw yield during all four crops was recorded in T3 (100% RDF with S, Zn, B) in rice and T4 (customized fertilizer) in wheat crop, which showed 25, 32, 23 and 28% increase over 100% RDF (T2). Application of 100% RDF along with S, Zn, B and customized fertilizer increased the total uptake of N, P, K, S and B and also in net returns and B:C ratio followed by organic treatments.  相似文献   

17.
Nitrogen (N) balance method is a valuable tool for estimating N losses. However, this technique could lead to incorrect estimates of the amount of nitrate (NO3?N) leaching if processes relevant to N losses are not considered properly. The aim of this study was to compare NO3?-N leaching losses estimated using an N balance (nonrecovered N, Nne) with data of NO3?-N leaching losses (Nl). The experiment was made on a Typic Argiudoll soil planted with corn (five growing seasons) under 0, 100, and 200 kg N ha?1. The ceramic soil-water suction samplers were installed (1 m deep). Drainage was estimated by the LEACH-W model. The greatest overestimation with the N balance method occurred for years with annual rainfall below the historical average and at times of high NO3?-N availability. Future research should focus on investigating mechanisms of N losses relevant under limited water availability.  相似文献   

18.
This study assessed the effectiveness of vermicompost as a germination media and nitrogen source for kidney bean Phaseolus vulgaris L. Five treatments were tested, based on the addition of increasing quantities of barren soil to vermicompost, and irrigated with four treatments of increasing urea-water solution. Chemical analysis of the different mixtures of vermicompost and barren soil were made. Percentage germination, plant growth, and foliar nitrogen assimilation were measured. Bean seeds in vermicompost germinated earlier than those planted in barren soil, but germination was less than 60% in trays with 85% and 100% vermicompost. Plants in vermicompost were taller and appeared to be healthier-looking. Plants with 0%, 50% and 85% vermicompost concentrations assimilated about 4 mg·L?1 more nitrogen than other treatments (25% and 100%). Plants in the 85% vermicompost mixture had the best response to nitrogen assimilation.  相似文献   

19.
Abstract

The recovery of 15N‐labelled nitrogen (N) by perennial ryegrass can be significantly increased by mixing gypsum (CaSO4 · 2H2O) into soil rooting medium at rates equivalent to 0.7 t ha?1. Similar improvements in fertilizer N efficiency might be achieved, at less cost and more conveniently, by applying smaller amounts of CaSO4 anhydrite more strategically to fertilizer microsites as a fertilizer filler or diluting agent, in calcium ammonium nitrate (CAN), in place of CaCO3. With this in mind, two complementary pot experiments were conducted under simulated spring conditions in a controlled environment chamber. Use of CaSO4 as diluting agent, in place of CaCO3, appreciably enhanced (>30%) the uptake of labeled N by perennial ryegrass plants within the second week of regrowth, but thereafter, because losses of 15N‐labeled NO3 ?‐N from pots by denitrification or leaching had been minimal, plants in both treatments eventually recovered equal amounts of this N form from the soil.  相似文献   

20.
Two vermicompost treatments providing 45 (V1) and 90 (V2) kg P ha?1 and mycorrhizae (M) inoculation were evaluated alone and in combinations for wheat (Triticum aestivum L.) growth and soil fertility status. The treatments included; the Control, nitrogen (N): dipotassium oxide (K2O) as basal dose (BD; 120:60 kg ha?1), N: phosphorus pentoxide (P2O5): K2O as recommended dose (RD; 120:90:60 kg ha?1), BD+Myccorhiza (BDM), BD+V1 (BDV1), BDM+V1 (BDMV1), BD+V2 (BDV2), and BDM+V2 (BDMV2). Combination of mycorrhizae and vermicompost (BDMV1 and BDMV2) significantly and maximally improved the growth, plant N, phosphorus (P), and micronutrient concentrations over the control, reduced the soil pH by 5 and 6%, increased OM by 25 and 112%, total N by 41%, and extractable P up to 200% while the extent of improvement was directly related to the content of added vermicompost. Results indicated that vermicompost at either level synergistically affected the mycorrhizae in plant nutrition as well as improved soil fertility status and soil chemical properties.  相似文献   

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