Soil physical properties and carbon/nitrogen relationships in stable aggregates under legume and grass fallow

Short-season fallow with legumes and/or grasses can restore the soil organic C and nitrogen (N) and improve soil structure. In this study, we accessed the effects of 2-season legume and grass fallow on structural properties and C/N relationships in aggregates of a sandy loam soil. Two legumes (Calopogonium mucunoides and Centrosema pubescens), and two grasses (Guinea grass (Panicum maximum) and goose grass (Eleusine indica) were used. Results showed that Calopogonium and Centrosema increased soil total porosity and reduced soil bulk densities, while goose grass increased bulk density and reduced total porosity of the soils at 0–15 and 15–30?cm depths. Guinea grass significantly increased the saturated hydraulic conductivity (50.4?cm?h^?1) and water holding capacity of the soils. Aggregates, 4.75 to 0.5?mm were greater in Guinea grass and least in goose grass fallowed soils. Calopogonium increased macro-aggregates at 0–15?cm soils by 48%, and mean weight diameter (MWD) by 44%. Organic carbon in 0.5–0.25?mm and <0.25?mm aggregate sizes was higher in Guinea grass soils. Generally, grasses had 4-fold increases of C:N contents in dry aggregates. In conclusion, short-season fallow with Guinea grass, Calopogonium and Centrosema, increased soil C and N and protected them from losses in stable aggregates.     

Nitrogen released from different plant residues of the Loess Plateau and their additions on contents of microbial biomass carbon, nitrogen in soil

An incubation method was used to investigate the nitrogen release characteristics from the residue of ten plant species which commonly grow in the northern part of the Loess Plateau. The effect of the residue on soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) was also determined. There were significant differences in the total N content and the C/N ratios among the different types of plant residue. The total N content of the residues ranged from 6.61 to 32.78 g kg^?1. The C/N ratio of the residue ranged from 14 to 65. There was an immediate increase in soil N after alfalfa, erect milkvetch, and korshinsk peashrub residue was added to the soil. In contrast, soil N decreased after elm, sea buckthorn, and wild peach residue was added to the soil. The soil N content remained relatively low for 14–34 days and then increased. This indicated that N immobilization occurred during the early portion of the incubation period when elm, sea buckthorn and wild peach residue was added to the soil. Soil N levels were low during the entire incubation period when simon poplar, locust, Stipa bungeana, and old world bluestem residue were added to the soil. The addition of plant residue significantly increased SMBC and SMBN in all treatments. The SMBC and SMBN values were greatest in treatments containing plant residue with high total N content and low C/N ratios. The C/N ratios of korshinsk peashrub, sea buckthorn, and wild peach residues were similar, but the amount of N released from these residues and the effects of the residue on SMBC and SMBN in soil were significantly different. This indicates that not only the C/N ratio but also the chemical composition of the plant residue affected decomposition. It is important to consider C and N release characteristics from plant residue in order to adjust the C and N balance of soil when revegetating degraded ecosystems.     

Nitrogen released from different plant residues of the Loess Plateau and their additions on contents of microbial biomass carbon, nitrogen in soil

An incubation method was used to investigate the nitrogen release characteristics from the residue of ten plant species which commonly grow in the northern part of the Loess Plateau. The effect of the residue on soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) was also determined. There were significant differences in the total N content and the C/N ratios among the different types of plant residue. The total N content of the residues ranged from 6.61 to 32.78 g kg^?1. The C/N ratio of the residue ranged from 14 to 65. There was an immediate increase in soil N after alfalfa, erect milkvetch, and korshinsk peashrub residue was added to the soil. In contrast, soil N decreased after elm, sea buckthorn, and wild peach residue was added to the soil. The soil N content remained relatively low for 14–34 days and then increased. This indicated that N immobilization occurred during the early portion of the incubation period when elm, sea buckthorn and wild peach residue was added to the soil. Soil N levels were low during the entire incubation period when simon poplar, locust, Stipa bungeana, and old world bluestem residue were added to the soil. The addition of plant residue significantly increased SMBC and SMBN in all treatments. The SMBC and SMBN values were greatest in treatments containing plant residue with high total N content and low C/N ratios. The C/N ratios of korshinsk peashrub, sea buckthorn, and wild peach residues were similar, but the amount of N released from these residues and the effects of the residue on SMBC and SMBN in soil were significantly different. This indicates that not only the C/N ratio but also the chemical composition of the plant residue affected decomposition. It is important to consider C and N release characteristics from plant residue in order to adjust the C and N balance of soil when revegetating degraded ecosystems.     

Accumulation of carbon and nitrogen by old arable land reverting to woodland

The accumulation of carbon (C) and nitrogen (N) was measured on two sites on Rothamsted Farm that had been fenced off some 120 years ago and allowed to revert naturally to woodland. The sites had previously been arable for centuries. One had been chalked and was still calcareous; the other had never been chalked and the pH fell from 7.1 in 1883 to 4.4 in 1999. The acidic site (Geescroft wilderness) is now a deciduous wood, dominated by oak (Quercus robor); the calcareous site (Broadbalk wilderness) is now dominated by ash (Fraxinus excelsior), with sycamore (Acer pseudoplatanus) and hawthorn (Craetagus monogyna) as major contributors. The acidic site gained 2.00 t C ha^?1 yr^?1 over the 118‐year period (0.38 t in litter and soil to a depth of 69 cm, plus an estimated 1.62 t in trees and their roots); the corresponding gains of N were 22.2 kg N ha^?1 year^?1 (15.2 kg in the soil, plus 6.9 kg in trees and their roots). The calcareous site gained 3.39 t C ha^?1 year^?1 over the 120‐year period (0.54 t in the soil, plus an estimated 2.85 t in trees and roots); for N the gains were 49.6 kg ha^?1 yr^?1 (36.8 kg in the soil, plus 12.8 kg in trees and roots). Trees have not been allowed to grow on an adjacent part of the calcareous site. There is now a little more C and N in the soil from this part than in the corresponding soil under woodland. We argue from our results that N was the primary factor limiting plant growth and hence accumulation of C during the early stages of regeneration in these woodlands. As soil organic N accumulates and the sites move towards N saturation, other factors become limiting. Per unit area of woodland, narrow strips; that is, wide hedges with trees, are the most efficient way of sequestering C – provided that they are not short of N.     

内蒙古自治区土壤有机碳、氮蓄积量的空间特征

采用全国策二次土壤普查中内蒙古自治区的典型土种剖面资料,在剖面深度的基础上,用地统计学和地理信息系统(GIS)方法,分别按土壤类型和土地覆被类型计算了土壤有机碳、氮密度,分析了内蒙古自治区土壤有机碳、氮蓄积量的空间分布特征,探讨了土壤有机碳、氮蓄积量与主要气候要素的关系．结果表明,内蒙古自治区土壤有机碳密度处于3．24-43．24kg·m^-3之间,土壤有机氮密度处于269．56-3085．60g·m^-3之间,土壤碳、氮比(C／N)大致在4．46-17．13之间．土壤有机碳、氮密度与温度呈负相关,相关系数分别为0．557和0．460(n＝245);与年均降水量呈正相关,但相关性不是很强,相关系数分别为0．285和0．203．从内蒙古自治区东北地区到西南地区,土壤有机碳、氮蓄积量随着温度递升和降水量递减呈现降低的趋势。     

喀斯特地区不同土地利用方式对土壤有机碳、全氮以及微生物生物量碳和氮的影响

以广西环江大才为代表,选择亚热带典型喀斯特峰林谷地样区,通过对样区土壤进行密集采样和测定分析,研究了土地利用方式对土壤有机碳（O_C）和全氮（TN）含量及土壤微生物生物量碳（B_C）和氮（B_N）含量的影响.结果表明,3种土地利用方式下,土壤有机碳含量在稻田和林地中基本相同,而旱地显著低于稻田和林地.土壤全氮含量为稻田显著高于林地,而林地显著高于旱地.土壤微生物生物量碳含量为稻田显著高于林地,林地显著高于旱地.土壤微生物生物量氮含量在稻田和林地中基本相同,而旱地显著低于稻田和林地.旱地土壤pH值显著低于稻田和林地土壤.3种土地利用方式下,土壤微生物生物量碳与土壤有机碳、土壤微生物生物量氮与全氮含量之间均呈显著的正相关关系.土壤微生物生物量碳和氮含量可以作为评价喀斯特地区土壤质量和肥力的指标之一,对土地利用方式响应较为敏感.     

芦苇湿地土壤有机碳和全氮含量的垂直分布特征

利用元素分析仪,测定了芦苇湿地不同层次土壤有机碳和全N的变化.结果表明,土壤有机碳、全N及C/N随土壤深度的增加呈下降趋势.对不同月份(7、8、9和10月)而言,有机碳、全N及C/N比累积峰位于不同的土层中.土壤温度、水分及芦苇生长状况是引起分异的重要因子.7、8和10月份芦苇湿地不同层次土壤有机碳与全N呈显著相关(R²=0.73、0.73、0.71),而9月份芦苇湿地不同层次土壤有机碳与全N之间的相关性相对较差(R²=0.41).土壤C/N与土壤有机碳、全N均呈负相关,但C/N与全N的相关性强于土壤有机碳,说明C/N的大小主要决定于全N含量.     

冬小麦生境中土壤养分对凋落物碳氮释放的影响

土壤养分影响植物生长, 进而影响凋落物质量和产量; 凋落物质量和产量影响凋落物分解过程。基于一个生长实验和一个相同环境分解实验, 研究了冬小麦(Triticum aestivum)生境中养分可利用性对凋落物碳(C)和氮(N)释放的影响。结果显示: (1)冬小麦凋落物产量、叶/根C:N比、C释放量和N释放量随土壤养分梯度呈单调变化; (2)土壤养分影响叶凋落物丢失率而不影响根凋落物丢失率; (3)初始叶/根C:N比与其C、N释放量之间存在负相关关系; (4)分解过程降低叶C:N比和根C:N比。结果表明: 生境中土壤养分的提高可加速凋落物C、N归还, 这反过来可能促进冬小麦生长, 因此这种效应是正反馈; 初始C:N比可预测凋落物C、N释放量。     

Changes of EUF-N and EUF-K fractions in three deep grey-brown luvisols during 18 months under fallow

Summary The EUF-N and EUF-K contents of deep grey-brown luvisols under fallow were investigated over a period of 18 months.EUF-NO₃-N increased continuously during the spring and summer of 1983, reaching their peak in September/October. They declined in the winter of 1984, and increased again during the spring and summer of the same year.During the spring and winter EUF-N_org was higher than EUF-NO₃-N. A decline in EUF-N_org due to mineralization was associated with an increase of EUF-NO₃-N. EUF-N_org increased due to mobilization of soil N in April/May. EUF-N_org also increased in autumn 1983 as a consequence the incorporation of mineral nitrogen into this fraction. When mineral N was incorporated EUF-NO₃-N declined.EUF-N_org in the subsoil was lower than in the topsoil. EUF-NO₃-N in the subsoil decreased as EUF-N_org increased. It may therefore be assumed that the higher the content of EUF-N_org in the subsoil the more mineral nitrogen will be immobilized.     

马尾松林采伐迹地火烧黑炭对土壤活性碳氮库的影响

黑炭是火烧过程中不完全燃烧的产物,在火烧迹地的分布具有异质性。为了解黑炭输入量对土壤活性碳氮库的影响,选取中亚热带33年生马尾松人工林采伐迹地为研究对象,对比炼山1年后移除(B0)、单倍(B1)和双倍黑炭输入(B2)处理和未火烧对照土壤可溶性有机碳氮含量(DOC和DON)、矿质氮、土壤微生物量碳氮含量(MBC和MBN)之间的差异。结果表明:炼山对土壤DOC和DON含量的影响因土层而异,在0—10 cm土层,火烧土壤DOC和DON含量与对照土壤没有显著差异,而在10—20 cm土壤要显著低于对照土壤(P0.05)。火烧土壤矿质氮、土壤MBC和MBN含量均低于对照土壤,但差异未达到显著性水平(P0.05)。火烧土壤含水率、pH、全碳和全氮、铵态氮、土壤MBN含量均与黑炭输入量成正比,特别是在10—20 cm土层,B2处理土壤铵态氮含量显著高于B0和B1处理(P0.05)。对于土壤MBN,黑炭输入处理(B1和B2)火烧土壤MBN含量与对照土壤没有显著差异,而去除黑炭处理(B0)火烧土壤MBN含量则显著低于对照土壤(P0.05)。结果说明黑炭输入对火烧土壤的微生物群落恢复和N素保持具有积极意义,因此亚热带人工林管理过程中应重视黑炭的利用。     

牧草覆盖对坡面土壤矿质氮素流失的影响

利用室内模拟降雨试验,探讨了降雨、地表径流以及土壤矿质氮素有效作用深度（effective depth of interaction,EDI）的确定方法,研究了牧草覆盖对土壤矿质氮素EDI和地表流失的影响．结果表明,牧草覆盖增加了地表径流与表层土壤的相互作用,导致水土混合体深度增加,较深土层的土壤矿质氮通过溶解和解吸作用、对流-扩散作用等方式进入到地表径流中,矿质氮EDI增加．覆盖度越大,EDI值越大．与裸地相比,60％、80％和100％覆盖度处理中径流矿质氮平均浓度分别增加了34．52％、32．67％和6．00％,地表径流量分别减少了4．72％、9．84％和12．89％,侵蚀泥沙量分别减少了83．55％、87．11％和89．01％．60％和100％覆盖度处理的矿质氮地表流失总量分别为裸地处理的95．73％和84．05％,而80％覆盖度处理则为裸地处理的109．04％．草地植被对矿质氮素地表流失有“双重效应”：加剧了矿质氮向地表径流中的释放,使径流养分浓度高于裸地浓度;不同程度地减少了地表径流量和泥沙量及其养分含量．两种效应共同决定了土壤矿质氮素的地表流失量．     

Comparison of carbon and nitrogen accumulation rate between bog and fen phases in a pristine peatland with the fen-bog transition

Long-term carbon and nitrogen dynamics in peatlands are affected by both vegetation production and decomposition processes. Here, we examined the carbon accumulation rate (CAR), nitrogen accumulation rate (NAR) and δ¹³C, δ¹⁵N of plant residuals in a peat core dated back to ~8500 cal year BP in a temperate peatland in Northeast China. Impacted by the tephra during 1160 and 789 cal year BP and climate change, the peatland changed from a fen dominated by vascular plants to a bog dominated by Sphagnum mosses. We used the Clymo model to quantify peat addition rate and decay constant for acrotelm and catotelm layers during both bog and fen phases. Our studied peatland was dominated by Sphagnum fuscum during the bog phase (789 to −59 cal year BP) and lower accumulation rates in the acrotelm layer was found during this phase, suggesting the dominant role of volcanic eruption in the CAR of the peat core. Both mean CAR and NAR were higher during the bog phase than during the fen phase in our study, consistent with the results of the only one similar study in the literature. Because the input rate of organic matter was considered to be lower during the bog phase, the decomposition process must have been much lower during the bog phase than during the fen phase and potentially controlled CAR and NAR. During the fen phase, CAR was also lower under higher temperature and summer insolation, conditions beneficial for decomposition. δ¹⁵N of Sphagnum hinted that nitrogen fixation had a positive effect on nitrogen accumulation, particular in recent decades. Our study suggested that decomposition is more important for carbon and nitrogen sequestration than production in peatlands in most conditions and if future climate changes or human disturbance increase decomposition rate, carbon sequestration in peatlands will be jeopardized.     

青藏高原灌丛土壤碳氮含量及其相关功能基因分布特征

在微生物的代谢活动下,土壤中有机态碳氮化合物矿化分解释放矿质养分和二氧化碳,深刻影响着自然生态系统土壤碳、氮等元素的循环转化、土壤的养分供应和有机质的更新,并对地上植被的演替和分布有极为重要的意义。青藏高原灌丛面积分布广泛,地形和气候条件复杂,但目前对灌丛分布地区土壤碳氮含量、矿化作用强度及其影响因素等的认识较少。研究结合土壤理化分析和高通量定量PCR(quantitative microbial element cycling, QMEC)技术研究了青藏高原喜马拉雅山-冈底斯山地区不同类型灌丛土壤碳氮含量、碳氮矿化速率和相关功能基因的分布特征及其与植被、气候和土壤因子间的耦联关系。结果表明,不同类型灌丛土壤的有机碳、全氮含量、CO₂释放速率、净氮矿化速率、碳氮矿化基因的丰度有显著差异。其中,位于青藏高原东南部的雪层杜鹃和香柏灌丛分布区土壤有机碳和全氮含量、CO₂释放速率、净氮矿化速率显著高于位于中西部的变色锦鸡儿、金露梅和砂生槐灌丛地区,并与年平均降雨量显著正相关。然而,碳、氮矿化基因丰度分布趋势与之相反,在雪层杜鹃和香柏灌丛分布区丰度显著...     

Impact of long-term nitrogen addition on carbon stocks in trees and soils in northern Europe

The aim of this study was to quantify the effects of fertiliser N on C stocks in trees (stems, stumps, branches, needles, and coarse roots) and soils (organic layer +0–10 cm mineral soil) by analysing data from 15 long-term (14–30 years) experiments in Picea abies and Pinus sylvestris stands in Sweden and Finland. Low application rates (30–50 kg N ha⁻¹ year⁻¹) were always more efficient per unit of N than high application rates (50–200 kg N ha⁻¹ year⁻¹). Addition of a cumulative amount of N of 600–1800 kg N ha⁻¹ resulted in a mean increase in tree and soil C stock of 25 and 11 kg (C sequestered) kg⁻¹ (N added) (“N-use efficiency”), respectively. The corresponding estimates for NPK addition were 38 and 11 kg (C) kg⁻¹ (N). N-use efficiency for C sequestration in trees strongly depended on soil N status and increased from close to zero at C/N 25 in the humus layer up to 40 kg (C) kg⁻¹ (N) at C/N 35 and decreased again to about 20 kg (C) kg⁻¹ (N) at C/N 50 when N only was added. In contrast, addition of NPK resulted in high (40–50 kg (C) kg⁻¹ (N)) N-use efficiency also at N-rich (C/N 25) sites. The great difference in N-use efficiency between addition of NPK and N at N-rich sites reflects a limitation of P and K for tree growth at these sites. N-use efficiency for soil organic carbon (SOC) sequestration was, on average, 3–4 times lower than for tree C sequestration. However, SOC sequestration was about twice as high at P. abies as at P. sylvestris sites and averaged 13 and 7 kg (C) kg⁻¹ (N), respectively. The strong relation between N-use efficiency and humus C/N ratio was used to evaluate the impact of N deposition on C sequestration. The data imply that the 10 kg N ha⁻¹ year⁻¹ higher deposition in southern Sweden than in northern Sweden for a whole century should have resulted in 2.0 ± 1.0 (95% confidence interval) kg m⁻² more tree C and 1.3 ± 0.5 kg m⁻² more SOC at P. abies sites in the south than in the north for a 100-year period. These estimates are consistent with differences between south and north in tree C and SOC found by other studies, and 70–80% of the difference in SOC can be explained by different N deposition.     

Using near-infrared reflectance spectroscopy to predict carbon, nitrogen and phosphorus content in heterogeneous plant material

The aim of this study was to produce calibration equations between near-infrared reflectance (NIR) spectra and the concentrations of carbon, nitrogen, and phosphorus in heterogeneous material: from living needles to litter in Pinus halepensis stands subjected to prescribed burnings. The aim was to determine whether calibrations should be conducted within each stage in the transformation of needles (local calibrations), giving relationships that were accurate but valid only for each particular stage, or whether it was possible to integrate the various forms of variation in needles (global calibrations) while retaining an acceptable accuracy. A principal component analysis calculated from the sample spectral data was used to distinguish three different sets, each sharing spectral characteristics and corresponding to three categories of needle: needles collected on the pines (N), falling needles (F), and litter (L), and each containing samples collected from the burnt sites and a control site. Samples representative of all the forms of variation in spectral properties were selected from within each category and their carbon, nitrogen, and phosphorus concentrations were measured using standard wet chemistry methods; these constituted the calibration sets n, f, and l. Calibrations were produced between the nutrient concentrations and the NIR spectra of the calibration sets n, f, and l and the grouped sets (n+f, f+l, n+f+l). The results of local calibrations made from each individual category showed that the carbon, nitrogen, and phosphorus concentrations were accurately predictable by NIR spectra. The global calibrations made by lumping together several categories were valid for a wider range of concentrations and for spectrally heterogeneous materials and in most cases were just as accurate as the local calibrations produced from each individual category. Received: 2 March 1998 / Accepted: 19 November 1998     

云雾山典型草原火烧不同恢复年限土壤化学性质变化

云雾山典型草原处于黄土高原半干旱地区,也是草原火灾多发区,试验比较了未烧地与新烧地、火烧后3 a和火烧后11 a土壤有机碳(SOC)、全N、全P和速效K含量的变化过程。测量的土壤深度为50 cm,每10 cm一层,比较了4个样地0—10 cm、10—20 cm、20—30 cm、30—40 cm、40—50 cm土壤养分的变化。结果表明:(1)新烧地土壤剖面各层SOC、全N、全P和速效K含量都显著高于未烧地。(2)火烧后3 a样地土壤剖面各层SOC、全N、全P和速效K含量与未烧地差异不显著。(3)火烧后11 a样地土壤剖面各层全N含量都显著高于未烧地,SOC、全P和速效K含量除了0—10 cm层与未烧地差异不显著外,其它土层均显著增加。(4)4个样地的土壤剖面各层从上到下SOC、土壤全N、全P和速效K含量呈递减趋势。(5)3个火烧样地土壤表层(0—10 cm)的pH值和未烧地差异不显著。     

Recent carbon and nitrogen accumulation and acidification in soils of two Scots pine ecosystems in Southern Germany

Changes of the soil chemical status during the recent 22–30 years at two historically degraded forest sites in southern Germany (Pfaffenwinkel, Pustert) stocked with mature Scots pine (Pinus sylvestris L.) stands were studied by repeated soil inventories conducted in 1974, 1982–1984, 1994, and 2004 on replicated control plots of fertilization experiments, allowing a statistical analysis. Additionally, the nutritional status of the stands at all plots was monitored from 1964 until 2004 by annual or bi-annual analysis of current-year foliage, and stand growth was assessed by repeated stand inventories carried out in 3- to 9-year intervals. For both sites, a statistically significant systematic decrease of the forest floor C/N ratio between 1974 and 2004 from 35.4 to 29.2 (Pfaffenwinkel) and from 36.5 to 23.0 (Pustert) was observed. The soils at both sites also showed a considerable accumulation of organic carbon (210 and 400 kg C ha⁻¹ year⁻¹ for Pfaffenwinkel and Pustert, respectively) and nitrogen (13 and 18 kg N ha⁻¹ year⁻¹). In addition, the mineral topsoil at both sites has acidified considerably, indicated by significantly decreased pH values (Pustert only; mean decrease 0.1 units per decade), base saturation, and base cation stocks. The trend of N enrichment and base cation loss in the soils is mirrored by the trends of stand nutrition at both sites, which are characterized by improved N nutrition and reduced supply with K, Mg (Pustert only), and Ca. The results confirm findings of other studies indicating a recent N eutrophication and acidification of forest soils in Central Europe and southern Scandinavia. Since soils with historic degradation due to earlier non-sustainable forest utilization are widespread in Central Europe, the results obtained on our study sites probably apply for large forested areas, suggesting a significant potential of Central European forests to sequester atmospheric carbon and nitrogen not only in stand biomass, but also in the soil.     

植被恢复十年喀斯特坡地细根对土壤碳氮存留与可利用性的影响

土壤碳氮存留与可利用性对恢复生态系统的稳定性和可持续性产生重要影响,研究其细根控制过程对深入理解植被恢复的作用及其针对性应用具有重要意义。依托中国科学院环江喀斯特生态系统观测研究站10年植被恢复平台,通过分析8种植被恢复模式植物（细根生物量、δ¹³C、δ¹⁵N）、土壤（有机碳、总氮、δ¹³C、δ¹⁵N、团聚体、砂粒、交换性钙、可溶性有机碳和氮、铵态氮、无机氮、微生物生物量碳和氮）理化性质的变化和关系,阐明细根对土壤碳氮存留与可利用性的影响。研究结果表明：细根对土壤碳氮存留的影响可能主要基于对土壤团聚体结构的改善,加强了对土壤原有机碳、氮的保护和存留,而细根有机质输入的影响是较弱的;细根可能通过影响微生物调控土壤可利用性碳和氮;因高的细根生物量和固氮植物,封育林和刈割草地模式具有较高的土壤碳氮存留效应。综上所述,喀斯特植被恢复过程中细根对土壤碳氮存留与可利用性产生积极的影响。因此,石漠化生态工程治理可以考虑根系发达与固氮植物共同引种。     

Evaluation of laboratory-based measures of soil mineral nitrogen and potentially mineralizable nitrogen as predictors of field-based indices of soil nitrogen supply in potato production

Accurate estimation of soil nitrogen (N) supply in the field is required to optimize fertilizer N management and to minimize environmental N losses in humid environments. Laboratory-based measures of N availability were evaluated as predictors of field-based indices of soil N supply within potato production systems. Pre-plant soil samples (0–15 cm) were collected from a series of forty treatments in established potato trials located in Atlantic Canada and Maine, USA. Total plant N uptake at topkill with no fertilizer N applied (PNU_0N), PNU_0N plus soil mineral N to 30 cm depth at harvest and relative yield were considered as field-based indices of soil N supply. The potentially mineralizable N (N₀) was determined by aerobic incubation at 25°C and periodic leaching for 24 weeks. A series of laboratory-based measures of soil N supply were measured in soil samples. Pre-plant soil nitrate or total mineral N at 0–30 cm depth was the best single predictor of PNU_0N (r = 0.67 and 0.71, respectively) and relative yield (r = 0.58 and 0.61). The ultraviolet absorbance of 0.01 M NaHCO₃ extract at 205 nm (NaHCO₃-205) was suitable as a predictor of PNU_0N and relative yield in each growing season, however, the relationship between this parameter and PNU_0N or relative yield varied somewhat among years. A combination of pre-plant mineral N plus N mineralized in the first 2 weeks period of incubation after re-wetting is proposed as a more robust measure of N availability compared with use of mineral N alone.