Verteilung von Stickstoff auf Sproß und Wurzel bei jungen Bohnenpflanzen nach der Aufnahme von NO und NH

Translocation of nitrogen to the shoot of young bean plants after uptake of NO and NH by the root Phaseolus vulgaris plants (var. nana, cv. Saxa) at the primary leaf stage (without nodules) were fed during 6 hours with ¹⁵NO and ¹⁵NH, respectively. 24 hours after the absorption period more ₁₅N from the absorbed NO was translocated from the root to the shoot. The presence of NH in the nutrient solution enhanced the translocation of ¹⁵NON, probably by an inhibition of nitrate reductase. NH_4-⁺¹⁵N is mainly retained in the root by a high incorporation into the root protein. It can be concluded that nitrogen from newly absorbed NO is not retained and used for protein synthesis in the root according to the root's potential to synthesize protein. Nitrate reduction in the root is considered to be the limiting factor. This is supported by the fact that withdrawal of NO in the nutrient solution prior to the ¹⁵N-experiment increased NOtranslocation to the shoot as a consequence of a lowered level of nitrate reductase. In an experiment with ¹⁴NOsupply to the roots and ¹⁵NOapplication to the primary leaves (infiltration method) a considerable amount of ¹⁵N was translocated from the leaves to the roots. This indicates that an insufficient NOreduction in the root can be substituted by a retranslocation of reduced N-compounds from leaves to the roots. The proportion of NO reduced in the root influences also the pattern of primary distribution of nitrogen in the shoot of plants at the 4 leaf stage. At a concentration of 0,2 meq/l NO in the nutrient solution as compared to 20 meq/l NO during 10 hours a relative higher amount of ₁₅N was transported from the root to the younger, growing leaves i.e. via the phloem to metabolic sinks.     

Nitratammonifizierung im Boden mit Abwasserverrieselung

Nitrate Reduction to Ammonium in a Soil with Wastewater Irrigation Flooding with wastewaters including 48 mg/l NH-N, 15 mg/l organic N and 63 mg/l K¹⁵NO-N has led to strong nitrogen losses by denitrification from a sandy Cambisol. Beside this ¹⁵NH was formed also. Possible reasons of the nitrate reduction to ammonium are discussed and conclusions for practical wastewater irrigation are drawn.     

Einfluß von Stroh und Nitrapyrin auf den verfügbaren Stickstoff im Boden,den Ertrag und den Stickstoffentzug von Lolium multiflorum

Effect of straw and nitrapyrin application on the nitrogen availability in the soil and the yield and nitrogen uptake of Lolium multiflorum. In pot experiments the effect of straw and nitrapyrin application on the turn-over of fertilizer NH and on the nitrogen availability in the soil was investigated. The investigation comprised two sections: an incubation experiment in which straw and nitrapyrin together with NH-N were incorporated into a brown podsolic soil and a subsequent pot experiment with ryegrass. Nitrapyrin inhibited the nitrification and reduced the nitrogen loss of the soil. Compared with the treatments without nitrapyrin application, nitrapyrin resulted in a lower dry matter yield and in a lower nitrogen uptake of the ryegrass. Straw application reduced the nitrate content in the soil significantly. This effect was particulary evident in the treatments which did not receive nitrapyrin. Accordingly, nitrogen uptake and yield of ryegrass were significantly lower in the ‘straw treatments’ as compared with the treatments without straw. It is suggested that the impared nitrogen availability in the ‘straw treatments’ was mainly due to nitrogen losses caused by denitrification.     

Soil Acidification and Solute Budgets for Forested Lysimeters in Nordrhein-Westfalen

Solute budgets and nitrogen use were quantified in two 400 m² forested lysimeters in St. Arnold, Nordrhein-Westfalen. The lysimeters are covered by a mixture of oak-beech and Weymouth pine, respectively. The average bulk deposition between May 1985 and May 1987 of NH, SO and NO₃ was 1.1, 1.7, and 0.4 kmol_c ha^?1 yr^?1 in the deciduous stand and 2.1, 2.1, and 0.8 kmol_c ha^?1 yr^?1 in the coniferous stand. The input of N is almost completely retained in the deciduous stand. In the coniferous stand about 30% of this N-input is leached as NO₃. Due to N-transformations, total proton turnover is 4.4 kmol_c ha^?1 yr^?1 in the coniferous stand and only 2.5 kmol_c ha^?1 yr^?1 in the deciduous stand. Ca-mobilization is the major acid buffering process in both lysimeters. Only the deciduous stand was limed in 1980 (90 kmol_c/ha). Mobilization of Al is only relevant down to a soil depth of 30 cm. Below a 30 cm depth, Al is immobilized. The amounts of exchangeable and silicate-bound Ca in the soil underlying the coniferous stand are very small, but no evidence was found for explanation of the observed high Ca-mobilization by artificial Ca-sources.     

The importance of soil acidity,moisture, exchangeable cation pools and organic matter solubility to the cationic composition of beech forest (Fagus sylvatica L.) soil solution

Humus horizons of dystric cambisols were sampled six times during 1990–1992 at 66 points along a beech forest transect in Scania, s. Sweden. Cation concentrations of soil solutions obtained by centrifugation of sifted samples at field moisture were related to pH, DOC, exchangeable pools of the cations and soil moisture. Soil solution Al was speciated in free ionic (easily reacting) Al_r and organically complexed Al_org. Two or three variables accounted for a large share (70–90 %) of the cation variability between sampling points. Exchangeable soil pools were the most important variables for K, Mg. Ca, and Mn and contributed more when calculated on C. E. C. than on soil dry weight. Some function of pH was also of importance to most cation concentrations. Al_r correlated well with both Al_org(+) and pH(-). Soil moisture was positively related to DOC and K, negatively to H-ion concentration. pH measured by different methods were closely correlated (r = 0.93–0.97), pH_kcl and pH being ca. 0.5 unit lower, pH ca. 0.3 unit higher than soil solution pH, which varied between 3.5 and 5.6.     

Chemische Bindungen des Lignins mit Ammoniak und Aminen

Chemical bounds of lignin with ammoniak and amines By using absorption spectroscopy in the visible (340–700 nm) and infrared (4000–400 cm^?1) region it was possible to proof reactions between natural lignin and N-compounds like NH₃, Ag(NH₃)₂OH as well as o- and p-anisidin. All reactions can be of practical importance in soil. The nitrogen was bound on lignin ionically as NH3-cation or covalently as primary and secondary amin. The chemical bounds between lignin and ammoniak were influenced by the concentration of hydrogen ions. Increasing pH-values (from 5,15 to 12,5) improved the condition of reaction between carbonyl groups of lignin and ammoniak. Possible reaction mechanisms are discussed.     

Effect of Rate of Urea Application and Soil Moisture on the Behaviour of Urea in Soil

A sandy clay loam soil was used to study the effect of (a) urea application at rates equivalent to 250, 500, 1000 and 2000 ppm-N, at moisture content level of 100 % WHC, and (b) soil moisture levels of 30, 60 and 100 % of the WHC in addition to water-logging conditions, when urea was applied at the rate of 500 ppm-N, on urea-N transformations. In both cases, the incubation took place at 30°C and lasted for 6 weeks. The experiments were carried out in a closed system daily aerated. Complete hydrolysis of the added urea was attained after 1, 2 and 3 weeks for 250, 500 and 1000 ppm urea-N, respectively. Six weeks incubation period was not enough for full hydrolysis of the 2000 ppm urea-N. The rate of urea hydrolysis increased linearly for urea concentration up to 1000 ppm N. This concentration must have been sufficient to saturate the urease present in the soil used. The peak of NON was higher the higher the rate of urea applied. Delay of the nitrate formation was always accompanied by the accumulation of nitrites. At the end of the experiment, the nitrate-N formed represented 93,90,77 and only 20 % of the initially applied nitrogen for 250, 500, 1000 and 2000 ppm-urea-N, respectively. The rate as well as the total ammonia loss increased with increasing the rate of urea application. No appreciable differences were observed in urea hydrolysis due to the variations in moisture levels within the range of WHC. Under water-logging conditions, urea hydrolysis was slower and extended to the 6th week, also the rate of urea hydrolysis was no more than 50 % of the rate produced in moisture treatments within WHC. NON accumulation persisted for one week in the moisture levels within the range of WHC, while it continued in the water-logged treatment till the end of the experiment. Nitrate formation was slightly favoured at 100 % WHC and decreased somewhat with lowering the soil moisture levels. However, it was completely inhibited under water-logging conditions. Ammonia volatilization was not markedly affected by moisture levels within WHC, however, the water-logged treatment showed the highest total loss.     

Changes in soil nitrogen availability due to stand development and management practices on semi‐arid sandy lands,in northern China

Soil nitrogen (N) availability is one of the limiting factors for plant growth on sandy lands. Little is known about impacts of afforestation on soil N availability and its components in southeastern Keerqin sandy lands, China. In this study, we measured N transformation under sandy Mongolian pine (Pinus sylvestris var. mongolica Litv.) plantations of different ages (grassland, young, middle‐aged, close‐to‐mature) and management practices (non‐grazing and free‐grazing) during the growing seasons using the ion exchange resin bag method. Results showed that, for all plots and growing season, soil NH‐N, NO‐N, mineral N, and relative nitrification index, varied from 0·18 to 1·54, 0·96 to 22·05, 1·23 to 23·58 µg d⁻¹ g⁻¹ dry resin, and 0·76 to 0·97, respectively, and NO‐N dominated the available N amount due to intense nitrification in these ecosystems. In general, the four indices significantly increased in the oldest plantation, with corresponding values in non‐grazing sites lower than those in free‐grazing sites (p < 0·05). Our studies indicated that it is a slow, extended process to achieve improvement in soil quality after afforestation of Mongolian pine in the study area. Copyright © 2009 John Wiley & Sons, Ltd.     

Zur Kalkwirkung von Phosphatdüngemitteln

Basic effect of phosphorus fertilizers To test the basic effects of Thomas slag (Basic slag), Rhenaniaphosphate, Superphosphate, Hyperphos (soft rockphosphate) and Novaphos (partly water soluble phosphate), model, pot and longterm field trials were carried out. Changes in soil pH and base saturation served as a measure of the basic effect. The basic effect results from chemical reaction (oxides, hydroxides, carbonates and silicates of alkali- and earth alkali components as well as Ca-phosphates) and physiological reaction (different uptake of P and Ca by plant roots in exchange with HCO and H⁺). In contrast to Thomas slag and Rhenaniaphosphate the basic effect of Hyperphos due to chemical reaction is small; Superphosphate and Novaphos both have a chemically acidic reaction. Plant growth increased the basic effect of all fertilizers, especially of Hyperphos. On acid and weakly acid soils (field and pot trials), Hyperphos achieved about the half effect of Thomas slag expressed on a total phosphate basis whereas the effects of Superphosphate and Novaphos were only poor. The basic effect of P-fertilizers is directly associated with their solubility and P-effectiveness depending on particular soil conditions (pH). In a pot trial using loamy soils with a requirement for lime and small requirement for phosphorus, Thomas slag, Rhenaniaphosphate and Hyperphos showed nearly the same basic effect (50kg CaO per 100kg fertilizer). This value contrasts with the much lower figures for Novaphos (10–20kg) and Superphosphate (0–10kg).     

Response of acid sulphate soils to different liming treatments I. Solubility of sulphate and phosphate

In a preliminary laboratory experiment, samples from three cultivated and three virgin acid sulphate soils (pH 3.9-4.7) were treated with water or equivalent amounts of Ca(OH)₂ or KOH and incubated at about field capacity for three months. Both base treatments (133 meq/kg) similary reduced soil acidity and, thus, the same influence on the pH-dependent biological and chemical reactions was concluded. The liming-induced mineralization of organic S seemed to account for increased extratability of sulphate, being in most soils of the same magnitude in both treatments. Inversely, the solubility of P hardly was affected by the decomposition of organic matter but rather by the reactions of inorganic P. KOH markedly raised water-soluble P, whereas Ca(OH)₂ did not. The results of a rapid extraction test suggested that the poorer extractability of P in the soils amended with Ca(OH)₂ could partly be ascribed to a higher Ca saturation and its impact on the electrochemical properties of charged surfaces. In addition, a higher base-associated ionic strength created by Ca²⁺ was of great importance in reducing the P desorption in the Ca(OH)₂- treated soils.     

Interaction between microbial biomass and activity and the soil chemical conditions and the processes of acid load in coniferous forest soils

The primary aims of the present investigation were to determine the proportion of microbial driven soil processes associated with acidification in coniferous forest soils, and the response of microbial communities with respect to soil acidification and to acidification processes. Lysimeters containing undisturbed soil columns from five forest sites in Europe were installed in a spruce forest in the Soiling (northern Germany) and exposed to the same input and climatic conditions. In the present study root uptake was excluded. Under these conditions, during the 21 months of the experiment, acid load by microbial N-transformations especially mineralization and subsequent nitrification were the most important processes ranging from 50.2% to 79.1%. Except for one soil the balances showed, that increasing levels of soil acidity decreased the potential of mineralization. This agreed with the observation that microbial biomass Cmic decreased. The biomass Cmic (kg ha^?1 a^?1) was significantly correlated to N-output. The caloric quotient qW increased parallel to decreasing pH. During the experiment the PH in all mineral soil horizons decreased significantly. This change in soil chemical conditions did not affect the microbial biomass Cmic but the caloric quotient increased during the experiment, especially in the upper mineral soil.     

Calcium carbonate solubilization through H‐proton release from some legumes grown in calcareous saline‐sodic soils

Increasing levels of CO₂ and H⁺ proton in the rhizosphere from some legumes may play an important role in calcite dissolution of calcareous salt affected soils. Soils planted with white and brown varieties of cowpea (Vigna unguiculata L.) and hyacinth bean (Dolichos lablab L.) relying on either fertilizer N (KNO₃) or N‐fixation were compared against soils to which gypsum was applied and a control without plants and gypsum application to study the possibility of Ca²⁺ release from calcite and Na⁺ leaching. As compared to plants relying on inorganic N, leachates from all pore volumes (0·5, 1·0, 1·5, 2·0 pore volume) in lysimeters planted with N‐fixing hyacinth bean contained significantly higher concentrations of HCO with lower concentrations from lysimeters planted with white cowpea relying on N‐fixation. However, the lowest concentrations of HCO were recorded in the gypsum and control treatments. In initial leaching, lysimeters planted with N‐fixing plants maintained similar leachate Ca²⁺ and Na⁺ concentrations compared to gypsum amended soils. However, gypsum amended soils were found to have a prolonged positive effect on Na⁺ removal. It might be concluded that some legumes that are known to fix N in calcareous salt affected soils may be an alternative ameliorant to the extremely expensive gypsum through calcite solubilization and a consequent release of Ca²⁺. Copyright © 2009 John Wiley & Sons, Ltd.     

Impact of urease and nitrification inhibitor on NH4+ and NO3− dynamic in soil after urea spring application under field conditions evaluated by soil extraction and soil solution sampling

The application of mineral nitrogen (N) fertilizers is one of the most important management tools to ensure and increase yield in agricultural systems. However, N fertilization can lead to various ecological problems such as nitrate () leaching or ammonia and nitrous oxide emissions. The application of N stabilizers (i.e., inhibitors) combined with urea fertilization offers an effective option to reduce or even prevent N losses due to their regulatory effect on ammonium () and release into the soil. The present field experiment therefore aimed at soil N speciation dynamics after urea spring fertilization (225 kg N ha^?1) in the presence of a urease inhibitor (UI), a nitrification inhibitor (NI), both inhibitors (UI+NI) or when no inhibitor was applied at all. The study focused on the distribution of N species among soil matrix and soil solution. Plant cultivation was completely omitted in order to avoid masking soil N turnover and speciation by plant N uptake and growth dynamics. Application of UI clearly delayed urea hydrolysis in the top soil, but a complete hydrolysis of urea took place within only 10 days after fertilization (DAF). Nitrification was significantly reduced by NI application, leading to higher and lower concentrations in treatments with NI. Due to sorption of to the soil matrix a significantly larger fraction of was always detected in the soil extracts compared to soil solution. However, while in soil extracts the impact of NI application was less apparent and delayed, in soil solution a quick response to NI application was observed as revealed by significantly increased soil solution concentrations of . Because of the “asymmetric” soil phase distribution soil solution was predominant over only initially after fertilization even in inhibitor treatments (≈ 8 to 10 DAF). Nevertheless, inhibitor application tended towards closer ratios of to concentration in soil solution and hence, might additionally affect concentration dependent processes like plant N uptake and root development. Despite cold spring conditions urea application along with UI and/or NI did not indicate a limited supply of plant available and .     

Depletion of non‐exchangeable NH$ _4^+ $ at the root–soil and hyphae–soil interface of VA mycorrhizal maize (Zea mays) and parsley (Petroselinum sativum)

Mobilization of non‐exchangeable ammonium (NH ) by hyphae of the vesicular‐arbuscular mycorrhizal (VAM) fungus Glumus mosseae was studied under controlled experimental conditions. Maize (Zea mays) and parsley (Petroselinum sativum) were grown either alone or in symbiosis with Glomus mosseae in containers with separated compartments for roots and hyphal growth. In one experiment, ¹⁵NH was added to the soil to differentiate between the native non‐exchangeable NH and the non‐exchangeable NH derived from N fertilization. Non‐exchangeable NH was mobilized by plant growth. Plant dry weight and N uptake, however, were not significantly influenced by mycorrhizal colonization of the roots. The influence of root infection with mycorrhizal fungus on the mobilization of non‐exchangeable NH was negligible. In the hyphal compartment, hyphal uptake of N resulted in a decrease of NH in the soil solution and of exchangeable NH . However, the NH concentration was still too high to permit the release of non‐exchangeable NH . The results demonstrate that, in contrast to roots, hyphae of VAM fungi are not able to form a non‐exchangeable‐NH depletion zone in the adjacent soil. However, under conditions of a more substantial depletion of the exchangeable NH in the mycorrhizal sphere (e.g., with longer growth), an effect of mycorrhiza on the non‐exchangeable NH might be found.     

Thermal Expansion of Flour-Water Dough Measured with a Dynamic Mechanical Analyzer

Thermal expansion of a wheat flour-water dough was measured with a dynamic mechanical analyzer (DMA) at a temperature scan range of 25 to 160°C, in 5°C/min increments. Dough water-absorption levels were increased from 50 to 70% (14% mb) in 4% increments. A standard breadbaking method was used, and loaf volume was measured for regression analysis. The thermal expansion pattern of flour-water dough during heating included four stages with changes in the thermal expansion coefficient: gas thermal expansion (GTE) (25–60°C), starch gelatinization-gluten matrix formation (GMF) (60–100°C), vapor pressure expansion (VPE) (100–120°C), and structure fixation-crust formation (SCF) (>120°C). The onset temperature (T_o) between each stage and the thermal expansion coefficient (C_e) of each stage were affected significantly by dough water content. The onset temperature () from GTE to GMF (the starting temperature of gelatinization of starch in dough) decreased from 68 to 55°C as water absorption increased from 50 to 70%. The thermal expansion coefficient () of flour-water dough during GMF was highly correlated (r² = 0.886) to bread loaf volume. The ratio () of thermal expansion coefficient during the GMF stage to the coefficient during the GTE stage also was significantly correlated (r² = 0.882) to baking volume. Thus, DMA measurement of dough thermal expansion has the potential to be a powerful method of predicting baking quality in cultivar screenings, baking simulations, and scale-up studies.     

Einfluß einer hohen Nitratdüngung auf Kinetik und Gaszusammensetzung der Denitrifikation in unterschiedlichen Böden

Effect of high nitrate application on the kinetic and gaseous composition of denitrification in different soils Kinetic and gaseous composition of denitrification were studied with 16 different soil horizons after application of a relatively high amount of nitrate (400 μg NO N/g dry soil) at defined conditions (He atmosphere; 80 % WHC; 30°C; 3 weeks). At the conditions given, denitrification followed zero-order kinetics depending on the amount of decomposable organic matter rather on than the nitrate concentration. Denitrification intensity was most significantly correlated with the amount of extractable or mineralizable organic carbon (C_H2O and C_min, respectively). N₂ and N₂O (but not NO) were liberated by all samples, the amount and ratio depending on the soil and time of sampling. At the end of the three week's incubation period, the N₂/N-N₂O ratio varied between 8.1 and 1.4/1 (with an average of 3.1/1), except for the acid Ah-sample of the Pararendzina (N₂/N-N₂O = 1.0/1.2). The incorporation of an excess of easily decomposable leaf-powder resulted in an increased nitrate turn-over (from 64.7 % to 95,7 % of the nitrate loss) with N₂ as the single denitrification product. N₂O could be detected only with the acid “B”-material of the Pararendzina. The denitrifying capacity Y (in μg N₂+N-N₂O/g soil) of a soil at the conditions given may be predicted by the amount of water-extractable organic carbon X (in μg C_H2O/g soil) according to the equation Y = 0.808 X + 120,1.     

Response of acid sulphate soils to different liming treatments II. Exchangeability of soil cations

Liming-induced changes in cation exchangeability were studied in six samples from acid sulphate soils (pH 3.9-4.7) incubated with water or with equivalent quantities of Ca(OH)₂ or KOH. The extractability of acid cation species susceptible to hydrolysis was shown to be affected not only by increased pH but also by the kind of the cation and related electrochemical properties of the base used. Both liming treatments practically eliminated the exchangeable Al. In the virgin soils, however, the polynuclear Al-complexes formed by Ca(OH)₂ treatment seemed to have been hydrolyzed further. The superiority of Ca(OH)₂ was assumed to be due to the higher valency of its cation and its act of provoking a higher increase in ionic strength. The liming agents affected to varying extents also the extractability of base cations. Exchangeable soil K seemed to decrease by the KOH treatment and the soil Ca by the Ca(OH)₂ treatment, whereas K and Ca were only slightly, if any, affected by the Ca(OH)₂ and KOH treatments, respectively. Thus, the reductions were assumed to be attributable to other factors than increased pH. A fixation of K and a possible precipitation of Ca as CaSO₄ were discussed. Ca(OH)₂ decreased in all soil samples the exchangeability of Mg more than did KOH. The depression was not related to the Al polymerization and, thus, cannot entirely be ascribed to specific sorption on Al gel. The results imply that liming may affect base cation exchange reactions by neutralizing exchangeable Al of high bonding strength and by replacing it by cations of the liming agent.     

Accompanying ions of ammonium sources and nitrate : ammonium ratios in tomato plants

The tomato (Solanum lycopersicum L.) cultivar Micro‐Tom (MT) is widely used in physiological studies, but the effects of nitrate ( ) and ammonium ( ) ratios ( : ratios) and, in particular, the effects of the accompanying ions in sources are unknown. To determine whether the accompanying ions in sources influence toxicity, the effects of : ratios on the physiology, electrolyte leakage index, nutrition, and dry weight were studied using hydroponics. The sources were ammonium chloride (NH₄Cl) or ammonium sulfate [(NH₄)₂SO₄], and five : ratios were used: 100 : 0, 75 : 25, 50 : 50, 25 : 75, and 0 : 100. The source was calcium nitrate [Ca(NO₃)₂], and the nitrogen (N) concentration was 15 mmol L^?1. The results indicate that NH₄Cl or (NH₄)₂SO₄ can be used in studies on toxicity because the accompanying ions did not influence the tomato plants. In addition, : ratios of 100 : 0 and 75 : 25 resulted in the highest dry weight of tomato plants, whereas ratios of 25 : 75 or 0 : 100 were toxic.     

The effect of cation–anion interactions on soil pH and solubility of organic carbon

Alkaline soil is widely distributed and cultivated throughout the agricultural regions of the world. Organic carbon (OC) concentrations in alkaline soil are often small, partly because of the limitations of a high pH on the productivity of crops and pastures together with the effects of high pH on the chemistry of soil OC. Soil pH is often hypothesized to be a major factor in regulating OC turnover in agricultural soil, but there are few detailed studies on the effects of high pH on carbon cycling in alkaline soil. Sodium, K⁺, Mg²⁺ and Ca²⁺ are the major cations in alkaline soil, whereas Cl^?, , and are the major anions. The effect of different combinations of these cations and anions on soil pH and OC is not well described in the literature. The objectives of this study were to evaluate the effect of cations and anions on soil pH and to quantify the dissolution of OC in relation to these changes in pH. The results showed that (Na⁺, K⁺ and Mg²⁺) salts and CaCO₃ dominate in the pH range 7.0–8.5, and salts of Na⁺ and K⁺ dominate above pH 8.5. The amount of dissolved OC (DOC) increased significantly as pH increased. Therefore, the presence of large concentrations of and not only increased pH but also promoted the dissolution of soil OC. The concentration of Ca²⁺ modified this effect; large concentrations of Ca²⁺ increased the adsorption and reduced the concentration of DOC.     

Morphological and physiological responses of Picea asperata to different nitrogen availability and pH

Soil nitrogen (N) availability and pH are two determinants affecting plant growth, both of which are influenced by long‐term N deposition. However, the physiological mechanism of plants response to the changes in soil N availability and pH are not fully understood. To investigate the response of Picea asperata to both factors, seedlings of P. asperata were exposed to 50 or 1000 µM NH₄NO₃ with pH 5 or pH 7. In the current study, P. asperata, regardless of N availability and pH in growth medium, exhibited invariably a preference. Lower root biomass, root : shoot mass ratio, total root length and area, and root vitality were detected in high N condition compared to those in low N supply, corresponding well to lower net influxes of and at the root surface in both pH treatments. These results indicate that P. asperata may employ an active‐forge strategy to exploit nutrient resources for growth under low N availability, probably by increased below‐ground carbon allocation and net influxes of and . Although low pH, to some extent may generate more malondialdehyde, P. asperata would enhance pH tolerance by increased detoxification, i.e., antioxidant enzymes (peroxidase), free proline and soluble protein as well as improved carbohydrate status (i.e., soluble sugar and starch).