Production of carbon dioxide and nitrous oxide in alkaline saline soil of Texcoco at different water contents amended with urea: A laboratory study

Soil of the former lake Texcoco is alkaline saline with pH often >10 and electrolytic conductivity (EC) >70 dS m^?1 with rapidly changing water contents. Little is known how fertilizing this area with urea to vegetate the soil would affect emissions of carbon dioxide (CO₂) and dynamics of N. Texcoco soil with electrolytic conductivity (EC) 2.3 dS m^?1 and pH 8.5 (TEXCOCO A soil), EC 2.0 dS m^?1 and pH 9.0 (TEXCOCO B soil) and 200 dS m^?1 and pH 11.2 (TEXCOCO C soil) was amended with or without urea and incubated at 40% of water holding capacity (WHC), 60% WHC, 80% WHC and 100% WHC, while emissions of nitrous oxide (N₂O) and CO₂ and dynamics of ammonium (NH₄⁺), nitrite (NO₂^?) and nitrate (NO₃^?) were monitored for 7 days. An agricultural soil served as control (ACOLMAN soil). The emission of CO₂ increased in the urea amended soil 1.5 times compared to the unamended soil, it was inhibited in TEXCOCO C soil and was >1.2 larger in soil incubated at 40%, 60% and 80% WHC compared to soil incubated at 100% WHC. The emission of N₂O increased in soil added with urea compared to the unamended soil, was similar in TEXCOCO A and B soils, but was <0.2 mg N kg^?1 soil day^?1 in TEXCOCO C soil and generally larger in soil incubated at 60% and 80% WHC compared to soil incubated at 40% and 100% WHC. The water content of the soil had no significant effect on the mean concentration of NH₄⁺, but addition of urea increased it in all soils. The concentration of NO₂^? was not affected by the water content and the addition of urea except in TEXCOCO A soil where it increased to values ranging between 20 and 40 mg N kg^?1. The concentration of NO₃^? increased in the ACOLMAN, TEXCOCO A and TEXCOCO B soil amended with urea compared to the unamended soil, but not in the TEXCOCO C soil. It decreased with increased water content, but not in TEXCOCO C soil. It was found that the differences in soil characteristics, i.e. soil organic matter content, pH and EC between the soils had a profound effect on soil processes, but even small changes affected the dynamics of C and N in soil amended with urea.     

Emission of nitrous oxide from hydrocarbon contaminated soil amended with waste water sludge and earthworms

Soils in Mexico are often contaminated with hydrocarbons and addition of waste water sludge and earthworms accelerates their removal. However, little is known how contamination and subsequent bioremediation affects emissions of N₂O and CO₂. A laboratory study was done to investigate the effect of waste water sludge and the earthworm Eisenia fetida on emission of N₂O and CO₂ in a sandy loam soil contaminated with the polycyclic aromatic hydrocarbons (PAHs): phenanthrene, anthracene and benzo(a)pyrene. Emissions of N₂O and CO₂, and concentrations of inorganic N (ammonium (NH₄⁺), nitrite (NO₂^?) nitrate (NO₃^?)) were monitored after 0, 5, 24, 72 and 168 h. Adding E. fetida to the PAHs contaminated soil increased CO₂ production rate significantly 2.0 times independent of the addition of sludge. The N₂O emission rate from unamended soil expressed on a daily base was 5 μg N kg^?1 d^?1 for the first 2 h and increased to a maximum of 325 μg N kg^?1 d^?1 after 48 h and then decreased to 10 μg N kg^?1 d^?1 after 168 h. Addition of PAHs, E. fetida or PAHs + E. fetida had no significant effect on the N₂O emission rate. Adding sludge to the soil sharply increased the N₂O emission rate to >400 μg N kg^?1 d^?1 for the entire incubation with a maximum of 1134 μg N kg^?1 d^?1 after 48 h. Addition of E. fetida, PAHs or PAHs + E. fetida to the sludge-amended soil reduced the N₂O emission rate significantly compared to soil amended with sludge after 24 h. It was found that contaminating soil with PAHs and adding earthworms had no effect on emissions of N₂O. Emission of N₂O, however, increased in sludge-amended soil, but addition of earthworms to this soil and contamination reduced it.     

Carbon dioxide, nitrous oxide and methane dynamics in boreal organic agricultural soils with different soil characteristics

The annual carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄) dynamics were measured with static chambers on two organic agricultural soils with different soil characteristics. Site 1 had a peat layer of 30 cm, with an organic matter (OM) content of 74% in the top 20 cm. Site 2 had a peat layer of 70 cm but an OM content of only 40% in the top 20 cm. On both sites there were plots under barley and grass and also plots where the vegetation was removed. All soils were net sources of CO₂ and N₂O, but they consumed atmospheric CH₄. Soils under barley had higher net CO₂ emissions (830 g CO₂-C m⁻² yr⁻¹) and N₂O emissions (848 mg N₂O-N m⁻² yr⁻¹) than those under grass (395 g CO₂-C m⁻³ yr⁻¹ and 275 mg N₂O-N m⁻² yr⁻¹). Bare soils had the highest N₂O emissions, mean 2350 mg N₂O-N m⁻² yr⁻¹. The mean CH₄ uptake rate from vegetated soils was 100 mg CH₄-C m⁻³ yr⁻¹ and from bare soils 55 mg CH₄-C m⁻² yr⁻¹. The net CO₂ emissions were higher from Site 2, which had a high peat bulk density and a low OM content derived from the addition of mineral soil to the peat during the cultivation history of that site. Despite the differences in soil characteristics, the mean N₂O emissions were similar from vegetated peat soils from both sites. However, bare soils from Site 2 with mineral soil addition had N₂O emissions of 2-9 times greater than those from Site 1. Site 1 consumed atmospheric CH₄ at a higher rate than Site 2 with additional mineral soil. N₂O emissions during winter were an important component of the N₂O budget even though they varied greatly, ranging from 2 to 99% (mean 26%) of the annual emission.     

不同含水量天然硫酸盐盐渍土中二氧化碳和氧化亚氮的排放

Soil salinization may negatively affect microbial processes related to carbon dioxide(CO_2) and nitrous oxide(N_2O) emissions. A short-term laboratory incubation experiment was conducted to investigate the effects of soil electrical conductivity(EC) and moisture content on CO_2 and N_2O emissions from sulfate-based natural saline soils. Three separate 100-m long transects were established along the salinity gradient on a salt-affected agricultural field at Mooreton, North Dakota, USA. Surface soils were collected from four equally spaced sampling positions within each transect, at the depths of 0–15 and 15–30 cm. In the laboratory, artificial soil cores were formed combining soils from both the depths in each transect, and incubated at 60% and 90% water-filled pore space(WFPS) at 25?C. The measured depth-weighted EC of the saturated paste extract(EC_e) across the sampling positions ranged from 0.43 to 4.65 dS m~(-1). Potential nitrogen(N) mineralization rate and CO_2 emissions decreased with increasing soil EC_e, but the relative decline in soil CO_2 emissions with increasing ECe was smaller at 60% WFPS than at 90% WFPS. At 60% WFPS, soil N_2O emissions decreased from 133 μg N_2O-N kg~(-1) soil at EC_e 0.50 dS m~(-1) to 72 μg N_2O-N kg~(-1) soil at EC_e = 4.65 dS m~(-1). In contrast, at 90% WFPS,soil N_2O emissions increased from 262 μg N_2O-N kg~(-1) soil at EC_e = 0.81 dS m~(-1) to 849 μg N_2O-N kg~(-1) soil at EC_e = 4.65 dS m~(-1), suggesting that N_2O emissions were linked to both soil ECe and moisture content. Therefore, spatial variability in soil EC_e and pattern of rainfall over the season need to be considered when up-scaling N_2O and CO_2 emissions from field to landscape scales.     

Effect of carbon rate and type amended with ammonium or nitrate on nitrous oxide emissions in a strong ammonia oxidation soil

Journal of Soils and Sediments - The work aimed to (1) better understand how C rate and type affecting N2O emissions when combined application with different N forms in a strong ammonia oxidation...     

典型菜地土壤剖面N2O、CH4与CO2分布特征研究

为探究菜地土壤剖面N2O、CH4与CO2时空分布特征,利用地下气体原位采集系统与气相色谱法,周年动态监测3种典型菜地,即休闲裸地、轮作地Ⅰ(芹菜?空心菜?小白菜?苋菜)以及轮作地Ⅱ(菜心?芹菜?空心菜?大青菜)7 cm、15 cm、30 cm与50 cm土层N2O、CH4与CO2浓度变化。结果表明,0~50 cm土层范围内,N2O、CH4与CO2 3种气体浓度周年变异性较大,变幅分别为0.63~1 657.0μL(N2O)?L?1、0.8~72.5μL(CH4)?L?1和0.41~36.6 m L(CO2)?L?1。轮作地Ⅰ与轮作地Ⅱ的N2O平均浓度随土壤深度增加而增加,休闲裸地则呈现先增加(0~30 cm)后降低(30~50 cm)的变化趋势。两种轮作菜地4个土层N2O平均浓度均显著高于休闲裸地,二者氮肥施用量不同并未造成相同土层间N2O平均浓度的显著差异。3种菜地CH4与CO2平均浓度均呈现50 cm30 cm15 cm7 cm的梯度特征。轮作地Ⅰ与轮作地Ⅱ0~15 cm土层CH4平均浓度均大于休闲裸地,而在15~50 cm土层则分别大于和小于休闲裸地。CO2浓度呈现明显的季节性变化,除轮作地Ⅰ50 cm土层外,两种轮作菜地其他土层CO2平均浓度均小于休闲裸地对应土层。可见,蔬菜地高氮肥施用、多频次耕作等复杂管理使得N2O、CH4与CO2表现出较大的时空变异特征,其中氮肥施用对N2O的影响大于CH4与CO2,CH4受施肥与耕作的影响均较小,CO2显著受土壤温度与耕作措施的影响,在此基础上需进一步探究N2O、CH4与CO2的其他影响因素。     

Emission of carbon dioxide and dynamics of inorganic N in a gradient of alkaline saline soils of the former lake Texcoco

A plan was developed to apply biosolid to soil of the former lake Texcoco to fertilize the pioneer vegetation. Because, no information exists about how differences in electrolytic conductivity (EC) might affect mineralization of biosolid and dynamics of C and N in soil, 20 soil samples forming a gradient in EC ranging from 22 to 150 dS m⁻¹ were characterized, amended with 500 mg biosolid C kg⁻¹ dry soil and incubated aerobically at 22 ± 2 °C while production of CO₂, concentrations of ammonium (NH₄⁺), nitrite (NO₂⁻), and nitrate (NO₃⁻), and NH₃ volatilization were monitored at 22 ± 2 °C for 70 days. Soil characteristics showed large variations with maximum values often >10-times larger than minimum values. The production of CO₂ in the unamended soil ranged from 25 to 159 mg CO₂-C kg⁻¹ day⁻¹ and NH₃ volatilization from 0 to 189 μg NH₃-N kg⁻¹ day⁻¹_. Application of biosolid increased production of CO₂ significantly 1.4-fold and volatilization of NH₃ 11.5-fold. The EC explained most of the variation in production of CO₂, while particle size distribution explained most of the variation in volatilization of NH₃. The concentration of NH₄⁺ in the biosolid-amended soil decreased sharply in the first 14 days, with the EC explaining most of the variation found, and remained constant thereafter with a small increase at day 70. Significant increases in the concentration of NO₃⁻ were generally found in soil with EC < 64 dS m⁻¹. The EC explained most of the variation in production of CO₂, and dynamics of NH₄⁺ and NO₃⁻ while clay positively and sand content negatively affected NH₃ volatilization. It was found that increases in EC inhibited C and N mineralization in soil of the former lake Texcoco.     

Small-scale heterogeneity in carbon dioxide, nitrous oxide and methane production from aggregates of a cultivated sandy-loam soil

Spatial variability in carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄) emissions from soil is related to the distribution of microsites where these gases are produced. Porous soil aggregates may possess aerobic and anaerobic microsites, depending on the water content of pores. The purpose of this study was to determine how production of CO₂, N₂O and CH₄ was affected by aggregate size and soil water content. An air-dry sandy loam soil was sieved to generate three aggregate fractions (<0.25 mm, 0.25–2 mm and 2–6 mm) and bulk soil (<2 mm). Aggregate fractions and bulk soil were moistened (60% water-filled pore space, WFPS) and pre-incubated to restore microbial activity, then gradually dried or moistened to 20%, 40%, 60% or 80% WFPS and incubated at 25 °C for 48 h. Soil respiration peaked at 40% WFPS, presumably because this was the optimum level for heterotrophic microorganisms, and at 80% WFPS, which corresponded to the peak N₂O production. More CO₂ was produced by microaggregates (<0.25 mm) than macroaggregate (>0.25 mm) fractions. Incubation of aggregate fractions and soil at 80% WFPS with acetylene (10 Pa and 10 kPa) and without acetylene showed that denitrification was responsible for 95% of N₂O production from microaggregates, while nitrification accounted for 97–99% of the N₂O produced by macroaggregates and bulk soil. This suggests that oxygen (O₂) diffusion into and around microaggregates was constrained, whereas macroaggregates remained aerobic at 80% WFPS. Methane consumption and production were measured in aggregates, reaching 1.1–6.4 ng CH₄–C kg⁻¹ soil h⁻¹ as aggregate fractions and soil became wetter. For the sandy-loam soil studied, we conclude that nitrification in aerobic microsites contributed importantly to total N₂O production, even when the soil water content permitted denitrification and CH₄ production in anaerobic microsites. The relevance of these findings to microbial processes controlling N₂O production at the field scale remains to be confirmed.     

Methane and nitrous oxide fluxes, and carbon dioxide production in boreal forest soil fertilized with wood ash and nitrogen

Wood ash has been used to alleviate nutrient deficiencies and acidification in boreal forest soils. However, ash and nitrogen (N) fertilization may affect microbial processes producing or consuming greenhouse gases: methane (CH₄), nitrous oxide (N₂O) and carbon dioxide (CO₂). Ash and N fertilization can stimulate nitrification and denitrification and, therefore, increase N₂O emission and suppress CH₄ uptake rate. Ash may also stimulate microbial respiration thereby enhancing CO₂ emission. The fluxes of CH₄, N₂O and CO₂ were measured in a boreal spruce forest soil treated with wood ash and/or N (ammonium nitrate) during three growing seasons. In addition to in situ measurements, CH₄ oxidation potential, CO₂ production, net nitrification and N₂O production were studied in laboratory incubations. The mean in situ N₂O emissions and in situ CO₂ production from the untreated, N, ash and ash + N treatments were not significantly different, ranging from 11 to 17 μg N₂O m^?2 h^?1 and from 533 to 611 mg CO₂ m^?2 h^?1. However, ash increased the CH₄ oxidation in a forest soil profile which could be seen both in the laboratory experiments and in the CH₄ uptake rates in situ. The mean in situ CH₄ uptake rate in the untreated, N, ash and ash + N plots were 153 ± 5, 123 ± 8, 188 ± 10 and 178 ± 18 μg m^?2 h^?1, respectively.     

Growth, carbon dioxide exchange and mineral accumulation in potatoes grown at different magnesium concentrations

Plants of Norland potatoes (Solanum tuberosum L.) were maintained for 42 days at Mg concentrations of 0.05, 0.125, 0.25, 1, 2, and 4 mM in a nonrecirculating nutrient film system under controlled environment. With the increased Mg supply from 0.05 to 4 mM, Mg concentrations in the leaves of the 42-day old plants increased significantly from 1.1 to 11.2 mg g-1 dry weight. Plant leaf area and plant and tuber dry weights increased with increased Mg concentrations up to 1 mM in solution or 6.7 mg g-1 in leaves, and then decreased with further increases in Mg concentrations. Rates of CO2 assimilation measured on leaflets in situ at ambient and various intercellular CO2 concentrations were consistently lower at 0.05 and 4 mM Mg than at other Mg treatments, which may indicate decreased photosynthetic activity in mesophyll tissues at the lowest and highest Mg concentrations. Dark respiration rates in leaves were highest at 0.05 and 4 mM Mg, lowest at 0.25 and 1 mM Mg, and intermediate at 0.125 and 2 mM Mg. The different Mg treatments also influenced accumulation of other minerals in leaves. Leaf concentrations of Ca and Mn decreased with increased Mg supply except that Ca and Mn were lower at 0.05 mM than at 0.125 mM Mg. Leaf K concentrations were lower at 1, 2 and 4 mM Mg than at other Mg treatments. Foliar concentrations of P, Fe, Zn, and Cu had small but inconsistent variation with different Mg concentrations. Leaf concentrations of N, S, and B were similar at different Mg concentrations. This study demonstrates that various Mg nutrition, along with altered accumulation of other nutrients, could regulate dry matter production in potatoes by affecting not only leaf area but also leaf carbon dioxide assimilation and respiration.     

优化施氮对宁夏引黄灌区稻田CO2、H4和H2O 通量的影响

针对宁夏引黄灌区稻田施氮严重过量现象,在宁夏引黄灌区的青铜峡稻田,采用静态箱-气相色谱法,通过田间试验研究常规施氮（N300）、优化施氮（N240）和不施氮（N0）对水稻不同生育期CO2、CH4和N2O通量以及稻田增温潜势（GWP）的影响。结果表明：CO2排放主要在水稻灌浆和成熟期,CH4排放主要发生在水稻孕穗期,而N2O排放关键期在水稻的分蘖和拔节期。与N0处理相比,施氮能显著增加稻田CO2、CH4和N2O排放通量以及稻田GWP;常规施氮处理中CO2、CH4和N2O的累积排放量分别为18446.87、146.57 kg C·hm-2和2.93 kg N·hm-2;为期一年的优化施氮没有显著增加水稻生育期内稻田CO2排放,但使灌区稻田CH4和N2O排放分别显著降低了24.42%和36.28%。总的来看,为期一年的优化施氮使宁夏引黄灌区稻田GWP显著降低了26.70%。未来应结合土壤有机碳氮形态和含量变化以及土壤微生物技术,分析长期优化施氮对土壤温室气体通量的影响机制。     

Potential contribution of Lumbricus terrestris L. to carbon dioxide, methane and nitrous oxide fluxes from a forest soil

 Potential effects of earthworms (Lumbricus terrestris L.) inoculated into soil on fluxes of CO₂, CH₄ and N₂O were investigated for an untreated and a limed soil under beech in open topsoil columns under field conditions for 120 days. Gas fluxes from L. terrestris, beech litter and mineral soil from soil columns were measured separately in jars at 17  °C. The inoculation with L. terrestris and the application of lime had no effect on cumulative CO₂ emissions from soil. During the first 3–4 weeks earthworms significantly (P<0.05) increased CO₂ emissions by 16% to 28%. In contrast, significantly lower (P<0.05) CO₂ emission rates were measured after 11 weeks. The data suggest that earthworm activity was high during the first weeks due to the creation of burrows and incorporation of beech litter into the mineral soil. Low cumulative CH₄ oxidation rates were found in all soil columns as a result of CH₄ production and oxidation processes. L. terrestris with fresh feces and the beech litter produced CH₄ during the laboratory incubation, whereas the mineral soil oxidised atmospheric CH₄. Inoculation with L. terrestris led to a significant reduction (P<0.02) in the CH₄ oxidation rate of soil, i.e. 53% reduction. Liming had no effect on cumulative CH₄ oxidation rates of soil columns and on CH₄ fluxes during the laboratory incubation. L. terrestris significantly increased (P<0.001) cumulative N₂O emissions of unlimed soil columns by 57%. The separate incubation of L. terrestris with fresh feces resulted in rather high N₂O emissions, but the rate strongly decreased from 54 to 2 μg N kg^–1 (dry weight) h^–1 during the 100 h of incubation. Liming had a marked effect on N₂O formation and significantly (P<0.001) reduced cumulative N₂O emissions by 34%. Although the interaction of liming and L. terrestris was not significant, N₂O emissions of limed soil columns with L. terrestris were 8% lower than those of the control. Received: 2 September 1999     

Effects of activated charcoal and tannin added to compost and to soil on carbon dioxide,nitrous oxide and ammonia volatilization

Given high mineralization rates of soil organic matter addition of organic fertilizers such as compost and manure is a particularly important component of soil fertility management under irrigated subtropical conditions as in Oman. However, such applications are often accompanied by high leaching and volatilization losses of N. Two experiments were therefore conducted to quantify the effects of additions of activated charcoal and tannin either to compost in the field or directly to the soil. In the compost experiment, activated charcoal and tannins were added to compost made from goat manure and plant material at a rate of either 0.5 t activated charcoal ha^?1, 0.8 t tannin extract ha^?1, or 0.6 t activated charcoal and tannin ha^?1 in a mixed application. Subsequently, emissions of CO₂, N₂O, and NH₃ volatilization were determined for 69 d of composting. The results were verified in a 20‐d soil incubation experiment in which C and N emissions from a soil amended with goat manure (equivalent to 135 kg N ha^?1) and additional amendments of either 3 t activated charcoal ha^?1, or 2 t tannin extract ha^?1, or the sum of both additives were determined. While activated charcoal failed to affect the measured parameters, both experiments showed that peaks of gaseous CO₂ and N emission were reduced and/or occurred at different times when tannin was applied to compost and soil. Application of tannins to compost reduced cumulative gaseous C emissions by 40% and of N by 36% compared with the non‐amended compost. Tannins applied directly to the soil reduced emission of N₂O by 17% and volatilization of NH₃ by 51% compared to the control. However, emissions of all gases increased in compost amended with activated charcoal, and the organic C concentration of the activated charcoal amended soil increased significantly compared to the control. Based on these results, tannins appear to be a promising amendment to reduce gaseous emissions from composts, particularly under subtropical conditions.     

秸秆还田施氮调节碳氮比对土壤无机氮、 酶活性及作物产量的影响

秸秆的质量,特别是C/N是影响秸秆分解速率和养分释放的重要因素。在秸秆还田条件下,如何科学合理地施用氮肥是秸秆利用和优化施肥研究的关键问题。本研究以秸秆还田施入碳氮的C/N为切入点,于2012—2013年通过田间试验(设秸秆不还田不施肥、秸秆还田不施氮、秸秆还田施用无机氮肥调节C/N为10∶1、16∶1和25∶1以及秸秆还田施用有机氮肥调节C/N为25∶1处理),研究秸秆还田不同氮输入对小麦-玉米轮作田土壤无机氮、土壤微生物量氮、酶活性以及作物产量的影响。结果表明:1)在C/N为25∶1下,施用有机氮肥和无机氮肥对土壤无机氮含量无显著影响;在施用无机氮肥的情况下,C/N越低土壤无机氮含量越高。2)秸秆还田施氮提高了土壤微生物量氮含量,但是各秸秆还田施氮处理之间差异不显著;秸秆还田不同施氮处理对脲酶活性无显著影响;秸秆还田施氮提高了FDA水解酶活性,并随C/N降低呈升高趋势,施用无机氮肥的效果强于施用有机氮肥的。3)秸秆还田施用无机氮肥显著提高了小麦和玉米地上部生物量,施用无机氮肥调节C/N为10∶1和16∶1相比于C/N为25∶1提高了小麦和玉米的苗期和成熟期地上部生物量;施用有机氮肥调节C/N为25∶1相比秸秆还田不施氮对地上部生物量无显著影响。秸秆还田施用无机氮肥提高了作物产量,施用无机氮肥调节C/N为16∶1产量最高,而施用有机氮肥调节C/N为25∶1有降低作物产量的趋势。综合以上结果来看,施用无机氮肥调节C/N为16∶1较为合理。     

Tillage, crop residue and N fertilizer effects on crop yield, nutrient uptake, soil quality and nitrous oxide gas emissions in a second 4-yr rotation cycle

An 8-yr (1998–2005) field experiment was conducted on a Gray Luvisol (Boralf) soil near Star City, Saskatchewan, Canada, to determine the effects of tillage (no-tillage – NT and conventional tillage – CT), straw management (straw retained – R and straw not retained – NR) and N fertilizer (0, 40, 80 and 120 kg N ha⁻¹, except no N to pea (Pisum sativum L.) phase of the rotation) on seed and straw yield, mass of N and C in crop, organic C and N, inorganic N and aggregation in soil, and nitrous oxide (N₂O) emissions for a second 4-yr rotation cycle (2002–2005). The plots were seeded to barley (Hordeum vulgare L.) in 2002, pea in 2003, wheat (Triticum aestivum L.) in 2004 and canola (Brassica napus L.) in 2005. Seed, straw and chaff yield, root mass, and mass of N and C in crop increased with increasing N rate for barley in 2002, wheat in 2004 and canola in 2005. No-till produced greater seed (by 51%), straw (23%) and chaff (13%) yield of barley than CT in 2002, but seed yield for wheat in 2004, and seed and straw yield for canola in 2005 were greater under CT than NT. Straw retention increased seed (by 62%), straw (by 43%) and chaff (by 12%) yield, and root mass (by 11%) compared to straw removal for barley in 2002, wheat in 2004, and seed and straw yield for pea in 2003. No-till resulted in greater mass of N in seed, and mass of C in seed, straw, chaff and root than CT for barley in 2002, but mass of N and C were greater under CT than NT for wheat in 2004 and for canola in 2005 in many cases. Straw retention had greater mass of N and C in seed, straw, chaff and root in most cases compared to straw removal for barley in 2002, pea in 2003 and wheat in 2004. Soil moisture content in spring was higher under NT than CT and with R than NR in the 0–15 cm depth, with the highest moisture content in the NT + R treatment in many cases. After eight crop seasons, tillage and straw management had no effect on total organic C (TOC) and N (TON) in the 0–15 cm soil, but light fraction organic C (LFOC) and N (LFON), respectively, were greater by 1.275 Mg C ha⁻¹ and 0.031 Mg N ha⁻¹ with R than NR, and also greater by 0.563 Mg C ha⁻¹ and 0.044 Mg N ha⁻¹ under NT than CT. There was no effect of tillage, straw and N fertilization on the NH₄-N in soil in most cases, but R treatment had higher NO₃-N concentration in the 0–15 cm soil than NR. The NO₃-N concentration in the 0–15, 15–30 and 30–60 cm soil layers increased (though small) with increasing N rate. The R treatment had 6.7% lower proportion of fine (<0.83 mm diameter) and 8.6% greater proportion of large (>38.0 mm) dry aggregates, and 4.5 mm larger mean weight diameter (MWD) compared to NR treatment. This suggests a lower potential for soil erosion when crop residues are retained. There was no beneficial effect of elimination of tillage on soil aggregation. The amount of N lost as N₂O was higher from N-fertilized (580 g N ha⁻¹) than from zero-N (155 g N ha⁻¹) plots, and also higher in CT (398 g N ha⁻¹) than NT (340 g N ha⁻¹) in some cases. In conclusion, retaining crop residues along with no-tillage improved some soil properties and may also be better for the environment and the sustainability of high crop production. Nitrogen fertilization improved crop production and some soil quality attributes, but also increased the potential for NO₃-N leaching and N₂O-N emissions, especially when applied in excess of crop requirements.