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1.
A field experiment was conducted to evaluate the combined or individual effects of biochar and nitrapyrin (a nitrification inhibitor) on N2O and NO emissions from a sandy loam soil cropped to maize. The study included nine treatments: addition of urea alone or combined with nitrapyrin to soils that had been amended with biochar at 0, 3, 6, and 12 t ha?1 in the preceding year, and a control without the addition of N fertilizer. Peaks in N2O and NO flux occurred simultaneously following fertilizer application and intense rainfall events, and the peak of NO flux was much higher than that of N2O following application of basal fertilizer. Mean emission ratios of NO/N2O ranged from 1.11 to 1.72, suggesting that N2O was primarily derived from nitrification. Cumulative N2O and NO emissions were 1.00 kg N2O-N ha?1 and 1.39 kg NO-N ha?1 in the N treatment, respectively, decreasing to 0.81–0.85 kg N2O-N ha?1 and 1.31–1.35 kg NO-N ha?1 in the biochar amended soils, respectively, while there was no significant difference among the treatments. NO emissions were significantly lower in the nitrapyrin treatments than in the N fertilization-alone treatments (P?<?0.05), but there was no effect on N2O emissions. Neither biochar nor nitrapyrin amendment affected maize yield or N uptake. Overall, our results showed that biochar amendment in the preceding year had little effect on N2O and NO emissions in the following year, while the nitrapyrin decreased NO, but not N2O emissions, probably due to suppression of denitrification caused by the low soil moisture content. 相似文献
2.
Wheat straw and its biochar have contrasting effects on inorganic N retention and N2O production in a cultivated Black Chernozem 总被引:2,自引:0,他引:2
Yi Cheng Zu-cong Cai Scott X. Chang Jing Wang Jin-bo Zhang 《Biology and Fertility of Soils》2012,48(8):941-946
A laboratory incubation experiment was conducted to investigate the effects of direct incorporation of either wheat straw or its biochar into a cultivated Chernozem on gross N transformations calculated by the 15N pool dilution technique and nitrous oxide (N2O) production rates. Incorporation of wheat straw stimulated gross NH 4 + (ammonium) and NO 3 ? (nitrate) immobilization rates by 302 and 95.2?%, respectively, suppressed gross nitrification rates by 32.2?%, and increased N2O production by 37.7?%. In contrast, the addition of a biochar produced from the wheat straw did not influence any of the above N cycling processes. Therefore, application of biochar could be a possible management strategy for long-term C sequestration (through soil storage of stable C contained in the biochar) in soils without increasing N2O production rates, but could not effectively immobilize NO 3 ? in the soil. 相似文献
3.
Purple soils (Eutric Regosols) are widely distributed in humid subtropical Southwest China. They are characterized by high nitrification activities, with risks of severe NO3? leaching. Incorporation of crop residues is considered an effective method to reduce NO3? loss. In the present study, we compared the effects of alfalfa, rice straw, and sugarcane bagasse on gross N transformation turnover in a purple soil (purple soil, pH 7.62) compared with those in an acid soil (acid soil, pH 5.26), at 12 h, 3 months, and 6 months after residue incorporation. The gross N transformation rates were determined by 15N tracing. All tested crop residues stimulated the gross N mineralization rates, but reduced the net mineralization rates in both soils at 12 h after residue incorporation; however, the extent of the effect varied with the crop residue qualities, with rice straw having the strongest effects. Crop residues reduced net nitrification rates by depressing gross autotrophic nitrification rates and stimulating NO3? immobilization rates in the purple soil, particularly after rice straw incorporation (net nitrification rate decreased from 16.72 mg N kg?1 d?1 in the control to ??29.42 mg N kg?1 d?1 at 12 h of residue incorporation); however, crop residues did not affect the gross autotrophic nitrification rates in the acid soil. Crop residue effects subsided almost completely within 6 months, with sugarcane bagasse showing the longest lasting effects. The results indicated that crop residues affected the N transformation rates in a temporal manner, dependent on soil properties and residue qualities. 相似文献
4.
Qi Li Na Liao Ni Zhang Guangwei Zhou Wen Zhang Xing Wei 《Soil Science and Plant Nutrition》2016,62(5-6):534-544
Reducing ammonia (NH3) volatilization is a practical way to increase nitrogen (N) fertilizer use efficiency (NUE). In this field study, soil was amended once with either cotton (Gossypium hirsutum L.) straw (6 t ha?1) or its biochar (3.7 t ha?1) unfertilized (0 kg N ha?1) or fertilized (450 kg N ha?1), and then soil inorganic N concentration and distribution, NH3 volatilization, cotton yield and NUE were measured during the next two growing seasons. In unfertilized plots, NH3 volatilization losses in the straw-amended and biochar-amended treatments were 38–40% and 42–46%, respectively, less than that in control (i.e., unamended soil) during the two growing seasons. In the fertilized plots, NH3 volatilization losses in the straw-amended and biochar-amended treatments were 30–39% and 43–54%, respectively, less than that in the control. Straw amendment increased inorganic N concentrations, cotton yield, cotton N uptake and NUE during the first cropping season after application, but not during the second. In contrast, biochar increased cotton N uptake and NUE during both the first and the second cropping seasons after application. Furthermore, the effects of biochar on cotton N uptake and NUE were greater in the second year than in the first year. These results indicate that cotton straw and cotton straw biochar can both reduce NH3 volatilization and also increase cotton yield, N uptake and NUE. In addition, the positive effects of one application of cotton straw biochar were more long-lasting than those of cotton straw. 相似文献
5.
This study evaluated the effect of biochar and phosphorus fertilizer application on selected soil physical and chemical properties in two contrasting soil types: Rhodic Ferralsols (clay) in Thohoyandou and Leptic Cambisols (loamy sand) in Nelspruit, South Africa. Field experiments were conducted in summer and winter. Treatments consisted of a factorial combination of four biochar levels (0, 5, 10 and 20 t ha?1) and two phosphorus fertilizer levels (0 and 90 kg ha?1) arranged in a randomized complete block design with three replicates. Chickpea was the test crop. Soil bulk density, aggregate stability, porosity, total C, total N, C:N ratio, K and Mg were determined. Biochar (10 t ha?1) and phosphorus increased bulk density and decreased porosity at 0–5 and 15–20 cm soil depth on a loamy sand soil in both seasons. The interaction between biochar and phosphorus increased total C and total N on a clay soil in the summer sowing. However, in the loamy sand soil, biochar (10 t ha?1) increased total C, C:N ratio, K and Mg in the summer sowing. The effect of biochar was more evident in the loamy sand soil than the clay soil suggesting that the influence of biochar may be soil-specific. 相似文献
6.
A 5-year study was conducted to monitor patterns of NO3 - accumulation following the addition of plant residues of varying C:N ratios to the soil surface, to determine whether the availability of NO3 - following these applications would be timely and sufficient for typical annual crop uptake. Microbial respiration was measured in the last 3 years of the study to investigate how microbial activity was related to treatment differences in NO3 - accumulation. Treatments included: hairy vetch (Vicia villosa Roth) cut at mid-bloom; wheat (Triticum aestivum L.) straw applied at 4 Mg ha-1; vetch with 4 Mg ha-1 wheat straw; and a bare ground control. Soil NO3 - and respiration rates were correspondingly high for the 3–4 weeks following residue placement. Peak NO3 --N accumulation in vetch treatments occurred between 25 June and 10 July and ranged from 100 to 168 kg ha-1, with an average of 140 kg NO3 ?-N ha-1. Nitrate was sufficient and timely enough to meet most summer annual crop needs in the region. Over 5 years, peak NO3 ?-N was approximately 100 kg ha-1 higher in vetch than non-vetch treatments and roughly twice as high at 0–5 cm than at 5–20 cm. The addition of wheat straw caused a reduction of approximately 20% NO3 --N throughout the season as compared to vetch alone. 相似文献
7.
A large proportion of phosphate fertilizer applied to calcareous soils reacts with calcium. Changes in soil phosphorus (P) availability after single application of biochar and phosphate-solubilizing bacteria have been reported. However, interaction of biochar (increasing soil pH) and phosphate-solubilizing bacteria (decreasing soil pH) on P availability in calcareous soil is not well known. An incubation experiment was conducted to study how the interactive effects of biochars (produced from wheat straw and cow manure at 300°C and 500°C with residence time of 1, 3 and 6 h) at different rates (0, 5 and 10 t ha?1) and phosphate-solubilizing Pseudomonas sp. IS8b2 affected on content of soil available P after 0, 60, 120 and 180 days of incubation (DOI) in a calcareous soil. After 60 DOI, the maximum value of available P (50.31 mg kg?1) was observed in the compound treatment of Pseudomonas sp. IS8b2 and wheat straw biochar (10 t ha?1) produced at 500°C with residence time of 3 h. We conclude that the combination use of wheat straw biochar and phosphate-solubilizing bacterium is promising to potentially improve soil P availability in calcareous soil, but further research at field scale is needed to confirm this. 相似文献
8.
Effects of repeated application of urea (UN) and calcium nitrate (CN) singly and together with crop straw biochars on soil acidity and maize growth were investigated with greenhouse pot experiments for two consecutive seasons. Canola straw biochar (CB), peanut straw biochar (PB) and wheat straw biochar (WB) were applied at 1% of dried soil weight in the first season. N fertilizers were applied at 200 mg N kg?1. In UN treatments, an initial rise in pH was subjected to proton consumption through urea hydrolysis, afterwards nitrification of NH4+ caused drastic reductions in pH as single UN had soil pH of 3.70, even lower than control (4.27) after the 2nd crop season. Post-harvest soil analyses indicated that soil pH, soil exchangeable acidity, NH4+, NO3? and total base cations showed highly significant variation under N and biochar types (P < 0.05). Articulated growth of plants under combined application with biochars was expressed by 22.7%, 22.5%, and 35.7% higher root and 25.6%, 23.8%, and 35.9% higher shoot biomass by CB, PB and WB combined with CN over UN, respectively. Therefore, CN combined with biochars is a better choice to correct soil acidity and improve maize growth than UN combined with biochars. 相似文献
9.
María Xesús Gómez-Rey Serafin Jesús Gonzalez-Prieto 《Biology and Fertility of Soils》2013,49(8):1065-1075
Wildfires often modify soil properties, including the N status and net N mineralization rates, but their impacts on gross N fluxes have been scarcely evaluated. We aimed to ascertain the immediate effects of a medium–high severity wildfire on soil N transformations. Net and gross N rates were analytically and numerically (FLUAZ) quantified in burned (BS) and unburned (US) topsoils from the temperate–humid region (NW Spain). Analytical and numerical solutions were significantly correlated for both gross N mineralization (m) (r 2?=?0.815; p?<?0.001) and gross nitrification (n) (r 2?=?0.950; p?<?0.001). In BS, all NH4 +-N fluxes (net m, gross m and gross NH4 +-N immobilization, ‘ia’) increased, while those of NO3 ?-N decreased (gross n and gross NO3 ?-N immobilization, ‘in’) or did not vary (net n). In US and BS, gross m (0.26–3.60 and 4.70–15.42 mg N kg?1 day?1, respectively) predominated over gross n (0.026–2.45 and 0.001–0.002 mg N kg?1 day?1, respectively), and the same was true for the net fluxes. Compared with the few available data on recently burned soils (m?=?8–55 mg N kg?1 day?1; n?=?0.50–1.83 mg N kg?1 day?1), our gross m and n rates were similar and very low, respectively; gross n showed that nitrifiers were active in US and also in BS, despite the 98 % reduction observed immediately after the fire. For gross fluxes, m increased more than ia suggesting an NH4 +-N accumulation, but there is no risk of NO3 ?-N leaching because n decreased more than in. 相似文献
10.
Fuxia Pan Stephen James Chapman Yaying Li Huaiying Yao 《Journal of Soils and Sediments》2017,17(10):2428-2437
Purpose
Organic matter amendment is usually used to improve soil physicochemical properties and to sequester carbon for counteracting climate change. There is no doubt that such amendment will change microbial activity and soil nitrogen transformation processes. However, the effects of straw and biochar amendment on anammox and denitrification activity and on community structure in paddy soil are unclear.Materials and methods
We conducted a 30-day pot experiment using rice straw and rice straw biochar to deepen our understanding about the activity, microbial abundance, and community structure associated with soil nitrogen cycling during rice growth.Results and discussion
Regarding activity, anammox contributed 3.1–8.1% of N2 production and denitrification contributed 91.9–96.9% of N2 production; straw amendment resulted in the highest denitrification rate (38.9 nmol N g?1 h?1), while biochar amendment resulted in the highest anammox rate (1.60 nmol N g?1 h?1). Both straw and biochar amendments significantly increased the hzsB and nosZ gene abundance (p < 0.05). Straw amendment showed the highest nosZ gene abundance, while biochar amendment showed the highest hzsB gene abundance. Phylogenetic analysis of the anammox bacteria 16S rRNA genes indicated that Candidatus Brocadia and Kuenenia were the dominant genera detected in all treatments.Conclusions
Straw and biochar amendments have different influences on anaerobic ammonia oxidation and denitrification within paddy soil. Our results suggested that the changes in denitrification and anammox rates in the biochar and straw treatments were mainly linked to functional gene abundance rather than microbial community structure and that denitrification played the more major role in N2 production in paddy soil.11.
Kannan Pandian Ponmani Subramaniayan Prabukumar Gnasekaran Swaminathan Chitraputhirapillai 《Archives of Agronomy and Soil Science》2016,62(9):1293-1310
The aim of this study was to evaluate the effect of biochar and organic soil amendments on soil physicochemical and microbial load, carbon sequestration potential, nutrient uptake and yield of groundnut in acidic red soil under rainfed condition. Biochar was prepared from red gram, cotton, maize stalk and mesquite wood using pilot scale slow pyrolysis biochar unit. The above sources of biochar at the rate of 2.5 and 5 t ha?1 and enriched farmyard manure 0.75 t ha?1, composted coir pith 10 t ha?1 and arbuscular mycorrhizae 100 kg ha?1 were applied as basal with required nitrogen, phosphorous and potassium fertilizer. Biochar amendment at the rate of 5 t ha?1 reduced the bulk density from 1.41 to 1.36 g cm?3 and increased the soil moisture 2.5%. With respect to soil chemical changes, it raised soil pH from 5.7 to 6.3; increased the cation exchange capacity 1.4 cmol+ kg?1 and enhanced the carbon buildup 4.4 t ha?1. The significant differences in bacteria, fungi and actinomycetes population were observed between biochar and control. The nitrogen, phosphorous and potassium were better utilized under biochar and composted coir pith, which was 21, 5 and 20 kg ha?1 higher than control. The experimental results suggested that application of biochar to acidic red soil favoured good soil physical, chemical and biological environment, and these positive changes influenced growth and yield attributes and enhanced pod yield 29% over control. 相似文献
12.
Gross nitrogen transformations and related N2O emissions in uncultivated and cultivated black soil 总被引:1,自引:0,他引:1
A better understanding of the nitrogen (N) cycle in agricultural soils is crucial for developing sustainable and environmentally friendly N fertilizer management and to propose effective nitrous oxide (N2O) mitigation strategies. This laboratory study quantified gross nitrogen transformation rates in uncultivated and cultivated black soils in Northeast China. It also elucidated the contribution made by nitrification and denitrification to the emissions of N2O. In the laboratory, soil samples adjusted to 60 % water holding capacity (WHC) were spiked with 15NH4NO3 and NH4 15NO3 and incubated at 25 °C for 7 days. The size and 15N enrichment of the mineral N pools and the N2O emission rates were determined between 0 and 7 days. The results showed that the average N2O emission rate was 21.6 ng N2O-N kg?1 h?1 in cultivated soil, significantly higher than in the uncultivated soil (11.6 ng N2O-N kg?1 h?1). Denitrification was found to be responsible for 32.1 % of the N2O emission in uncultivated soil, and the ratio increased significantly to 43.2 % in cultivated soil, due to the decrease in soil pH. Most of the increase in net N2O-N emissions observed in the cultivated soil was resulting from the increased production of N2O through denitrification. Gross nitrification rate was significantly higher in the cultivated soil than in the uncultivated soil, and the ratio of gross nitrification rate/ammonium immobilization rate was 6.87 in cultivated soil, much larger than the uncultivated soil, indicating that nitrification was the dominant NH4 + consuming process in cultivated soil, and this will lead to the increased production of nitrate, whereas the increased contribution of denitrification to N2O emission promoted the larger emission of N2O. This double impact explains why the risk of N loss to the environment is increased by long-term cultivation and fertilization of native prairie sites, and controlling nitrification maybe effective to abate the negative environmental effects. 相似文献
13.
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14.
AbstractThe aim of this study was to assess the mitigating effects of lime nitrogen (calcium cyanamide) and dicyandiamide (DCD) application on nitrous oxide (N2O) emissions from fields of green tea [Camellia sinensis (L.) Kuntze]. The study was conducted in experimental tea fields in which the fertilizer application rate was 544 kg nitrogen (N) ha?1 yr?1 for 2 years. The mean cumulative N2O flux from the soil between the canopies of tea plants for 2 years was 7.1 ± 0.9 kg N ha?1 yr?1 in control plots. The cumulative N2O flux in the plots supplemented with lime nitrogen was 3.5 ± 0.1 kgN ha?1, approximately 51% lower than that in control plots. This reduction was due to the inhibition of nitrification by DCD, which was produced from the lime nitrogen. In addition, the increase in soil pH by lime in the lime nitrogen may also be another reason for the decreased N2O emissions from soil in LN plots. Meanwhile, the cumulative N2O flux in DCD plots was not significantly different from that in control plots. The seasonal variability in N2O emissions in DCD plots differed from that in control plots and application of DCD sometimes increased N2O emissions from tea field soil. The nitrification inhibition effect of lime nitrogen and DCD helped to delay nitrification of ammonium-nitrogen (NH4+-N), leading to high NH4+-N concentrations and a high ratio of NH4+-N /nitrate-nitrogen (NO3–-N) in the soil. The inhibitors delayed the formation of NO3–-N in soil. N uptake by tea plants was almost the same among all three treatments. 相似文献
15.
《Communications in Soil Science and Plant Analysis》2012,43(14):1763-1777
A 56-day aerobic incubation experiment was performed with 15-nitrogen (N) tracer techniques after application of wheat straw to investigate nitrate-N (NO3-N) immobilization in a typical intensively managed calcareous Fluvaquent soil. The dynamics of concentration and isotopic abundance of soil N pools and nitrous oxide (N2O) emission were determined. As the amount of straw increased, the concentration and isotopic abundance of total soil organic N and newly formed labeled particulate organic matter (POM-N) increased while NO3-N decreased. When 15NO3-N was applied combined with a large amount of straw at 5000 mg carbon (C) kg?1 only 1.1 ± 0.4 mg kg?1 NO3-N remained on day 56. The soil microbial biomass N (SMBN) concentration and newly formed labeled SMBN increased significantly (P < 0.05) with increasing amount of straw. Total N2O-N emissions were at levels of only micrograms kg?1 soil. The results indicate that application of straw can promote the immobilization of excessive nitrate with little emission of N2O. 相似文献
16.
《Communications in Soil Science and Plant Analysis》2012,43(12):1525-1539
Swine lagoon sludge is commonly applied to soil as a source of nitrogen (N) for crop production but the fate of applied N not recovered from the soil by the receiver crop has received little attention. The objectives of this study were to (1) assess the yield and N accumulation responses of corn (Zea mays L.) and wheat (Triticum aestivum) to different levels of N applied as swine lagoon sludge, (2) quantify recovery of residual N accumulation by the second and third crops after sludge application, and (3) evaluate the effect of different sludge N rates on nitrate (NO3-N) concentrations in the soil. Sludge N trials were conducted with wheat on two swine farms and with corn on one swine farm in the coastal plain of North Carolina. Agronomic optimum N rates for wheat grown at two locations was 360 kg total sludge N ha?1 and the optimum N rate for corn at one location was 327 kg total sludge N ha?1. Residual N recovered by subsequent wheat and corn crops following the corn crop that received lagoon sludge was 3 and 12 kg N ha?1, respectively, on a whole-plant basis and 2 and 10 kg N ha?1, respectively, on a grain basis at the agronomic optimum N rate for corn (327 kg sludge N ha?1). From the 327 kg ha?1 of sludge N applied to corn, 249 kg N ha?1 were not recovered after harvest of three crops for grain. Accumulation in recalcitrant soil organic N pools, ammonia (NH3) volatilization during sludge application, return of N in stover/straw to the soil, and leaching of NO3 from the root zone probably account for much of the nonutilized N. At the agronomic sludge N rate for corn (327 kg N ha?1), downward movement of NO3-N through the soil was similar to that for the 168 kg N ha?1 urea ammonium nitrate (UAN) treatment. Thus, potential N pollution of groundwater by land application of lagoon sludge would not exceed that caused by UAN application. 相似文献
17.
《Communications in Soil Science and Plant Analysis》2012,43(20):2679-2690
Soil, crop, and fertilizer management practices may affect quality of organic carbon (C) and nitrogen (N) in soil. A long-term field experiment (growing barley, wheat, or canola)was conducted on a Black Chernozem (Albic Argicryoll) loam at Ellerslie, Alberta, Canada, to determine the influence of 19 years (1980 to 1998) of tillage [zero tillage (ZT) and conventional tillage (CT)], straw management [straw removed (SRem) and straw retained (SRet)], and N fertilizer rate (0, 50, and 100 kg N ha?1 in SRet and 0 kg N ha?1 in SRem plots) on macro-organic matter C (MOM-C) and N (MOM-N), microbial biomass C (MB-C), and mineralizable C (Cmin) and N (Nmin) in the 0- to 7.5-cm and 7.5- to 15-cm soil layers. Treatments with N fertilizer and SRet generally had a greater mass of MOM-C (by 201 kg C ha?1 with 100 kg N ha?1 rate and by 254 kg C ha?1 with SRet), MOM-N (by 12.4 kg N ha?1 with 100 kg N ha?1 rate and by 8.0 kg N ha?1 with SRet), Cmin(by 146 kg C ha?1 with 100 kg N ha?1 rate and by 44 kg C ha?1 with SRet), and Nmin(by 7.9 kg N ha?1 with 100 kg N ha?1 rate and by 9.0 kg N ha?1 with SRet)in soil than the corresponding zero-N and SRem treatments. Tillage, straw, and N fertilizer had no consistent effect on MB-C in soil. Correlations between these dynamic soil organic C or N fractions were strong and significant in most cases, except for MB-C, which had no significant correlation with MOM-C and MOM-N. Linear regressions between crop residue C input and mass of MOM-C, MOM-N, Cmin, and Nmin in soil were significant, but it was not significant for MB-C. The effects of management practices on dynamic soil organic C and N fractions were more pronounced in the 0- to 7.5-cm surface soil layer than in the 7.5- to 15-cm subsoil layer. In conclusion, the findings suggest that application of N fertilizer and retention of straw would improve soil quality by increasing macro-organic matter and N-supplying power of soil. 相似文献
18.
Lu Yu Xing Lu Yan He Philip C. Brookes Hong Liao Jianming Xu 《Journal of Soils and Sediments》2017,17(3):599-610
Purpose
Soil acidification is universal in soybean-growing fields. The aim of our research was to evaluate the effects of soil additives (N fertilizers and biochar) on crop performance and soil quality with specific emphasis on ameliorating soil acidity.Materials and methods
Four nitrogen treatments were applied as follows: no nitrogen (N0), urea (N1), potassium nitrate (N2), and ammonium sulfate (N3), each providing 30 kg N ha?1. Half plot area of the N1, N2, and N3 treatments was also treated with biochar (19.5 t ha?1) to form N-biochar treatments (N1C, N2C, N3C). Both bulk and rhizosphere soils were sampled separately for the following analyses: pH, exchangeable base cations (EBC), exchangeable acidity (EA), total inorganic N (IN), total N (TN), and microbial phospholipid fatty acids (PLFAs). Soybean biomass and nutrient contents were also determined. Correlation analysis was applied to analyze the relationships between soil chemical properties and soybean plant parameters.Results and discussion
With N-biochar additions (N1C, N2C, N3C), soil chemical properties changed as follows: pH increased by 0.6–1.2 units, EBC, IN, and TN increased by 175–419, 38.5–54.7, and 136–452 mg kg?1, respectively, and PLFAs increased by 23.6–40.9 nmol g?1 compared to the N0 in the rhizosphere. Microbial PLFAs had positive correlations with soil pH; EBC; exchangeable K, Ca, Na, and Mg; TN; IN; NH4 +; and NO3 ? (r?=?0.66–0.84, p?<?0.01). There were negative correlations between PLFAs and EA or exchangeable Al (r?=??0.64, ?0.66, p?<?0.01), which indicated that the additives increased microbial biomass by providing a suitable environment with less acid stress and more nutrients. The additives increased soil NH4 + and NO3 ? by promoting soil organic N mineralization and reducing NH4 + and NO3 ? leaching. Moreover, the soybean seed biomass and the nutrient contents in seeds increased with N-biochar additions, especially in the N3C treatment.Conclusions
N-biochar additions were effective in ameliorating soil acidity, which improved the microenvironment for more microbial survival. N-biochars influenced N transformations at the plant–soil interface by increasing organic N mineralization, reducing N leaching, and promoting N uptake by soybeans. The soil additive ammonium and biochar (N3C) were best in promoting soybean growth.19.
Sajjad Raza Zhujun Chen Muneer Ahmed Muhammad Rahil Afzal Tariq Aziz 《Archives of Agronomy and Soil Science》2019,65(4):450-464
Inhibition of nitrification as a mitigation tool to abate nitrogen (N) losses and improve N use efficiency (NUE) is a promising technology. Nitrification inhibitor (dicyandiamide, DCD) was evaluated in two consecutive wheat-maize rotations (2015–2017), with two different N fertilizer levels applied in wheat (160, 220 kg N ha?1) and maize (180, 280 kg N ha?1). More NH4+-N contents (101% and 102% in wheat and 74% and 73% in maize) and less NO3–-N contents (37% and 43% in wheat and 46% and 57% in maize) were observed at both N levels treated with DCD compared to without DCD. Higher pH, lower EC and reduced NO3–-N accumulation were the other benefits of DCD. The NO3–-N accumulation within the 0–200 cm soil profile was significantly less at both N levels with DCD (66 mg kg?1 and 121 mg kg?1) compared to without DCD (96 mg kg?1 and 169 mg kg?1). Application of DCD also improved the growth and yield in both crops. Increase in NUE from 38% to 49% in wheat and 27% to 33% in maize with DCD at higher N level was also observed. Overall, the effectiveness of DCD in retarding the nitrification process was higher in wheat than maize. 相似文献
20.