Mineralization Rates In Soils Research Articles

Effects of Cow-Dung Vermicomposting on Soil Carbon Mineralization and Temperature Sensitivity in Camellia oleifera Forest

Soil carbon mineralization plays an important role in the carbon cycle of terrestrial ecosystems. When it comes to the soil carbon cycle, however, research on how carbon mineralization characteristics of fertilized Camellia oleifera forest soil respond to temperature changes remains limited. This study used an indoor constant temperature incubation method to examine the effects of the vermicomposting of cow dung by applying it at three different quantities (A: 0.8 kg earthworm + 62.5 kg cow dung/Camellia oleifera; B: 1.6 kg earthworm + 125 kg cow dung/Camellia oleifera; C: 2.4 kg earthworm + 187.5 kg cow dung/Camellia oleifera) and set a control group with Camellia oleifera forest not being fertilized (CK). This research was conducted with incubators set at 5 °C, 15 °C, 25 °C, and 35 °C, and with continuous monitoring of soil carbon mineralization characteristics and temperature sensitivity of organic carbon mineralization. The results showed significant increases in soil MBC, MBN, DOC, DON, NO3−-N, and NH4+-N in groups with applications of cow-dung vermicomposting compared to CK. Except at 35 °C, soil respiration in the Camellia oleifera of Group A was consistently the strongest. The maximum soil carbon emission (C0) was determined through a simulation of potential carbon emissions, with all correlation coefficients exceeding 0.95. The contents of TC and TN were positively correlated with MBC and MBN (p <0.001), while the C: Nmicro was negatively correlated with TN, AN, MBN, and inorganic nitrogen. Based on temperature sensitivity (Q10), the influence of temperature on soil mineralization rate was observed. The vermicomposting of cow dung had a noticeable effect, as Group B showed significantly stronger enzyme activity compared to other groups. These results indicate that changes in MBC can impact the stability of soil carbon mineralization. The roles of soil moisture and microorganisms should be considered when predicting dynamic changes in the soil carbon pool of Camellia oleifera when applying fertilizers and improving its soil carbon sequestration capacity.

Control of inorganic and organic phosphorus molecules on microbial activity, and the stoichiometry of nutrient cycling in soils in an arid, agricultural ecosystem

Background The dynamics of carbon (C), nitrogen (N), and phosphorus (P) in soils determine their fertility and crop growth in agroecosystems. These dynamics depend on microbial metabolism, which in turn depends on nutrient availability. Farmers typically apply either mineral or organic fertilizers to increase the availability of nutrients in soils. Phosphorus, which usually limits plant growth, is one of the most applied nutrients. Our knowledge is limited regarding how different forms of P impact the ability of microbes in soils to produce the enzymes required to release nutrients, such as C, N and P from different substrates. Methods In this study, we used the arable layer of a calcareous soil obtained from an alfalfa cropland in Cuatro Cienegas, México, to perform an incubation experiment, where five different phosphate molecules were added as treatments substrates: three organic molecules (RNA, adenine monophosphate (AMP) and phytate) and two inorganic molecules (calcium phosphate and ammonium phosphate). Controls did not receive added phosphorus. We measured nutrient dynamics and soil microbial activity after 19 days of incubation. Results Different P molecules affected potential microbial C mineralization (CO2-C) and enzyme activities, specifically in the organic treatments. P remained immobilized in the microbial biomass (Pmic) regardless of the source of P, suggesting that soil microorganisms were limited by phosphorus. Higher mineralization rates in soil amended with organic P compounds depleted dissolved organic carbon and increased nitrification. The C:N:P stoichiometry of the microbial biomass implied a change in the microbial community which affected the carbon use efficiency (CUE), threshold elemental ratio (TER), and homeostasis. Conclusion Different organic and inorganic sources of P affect soil microbial community structure and metabolism. This modifies the dynamics of soil C, N and P. These results highlight the importance of considering the composition of organic matter and phosphate compounds used in agriculture since their impact on the microbial activity of the soil can also affect plant productivity.

Stand development reduces soil carbon mineralization in rubber plantations through regulating microbial metabolic strategy and substrate availability

Forest age, a critical variable for land-use decision makers, is known to change soil microbial communities. However, how such changes affect microbial metabolic strategy and the associated soil C mineralization processes in different forest ages remains unknown, especially in tropical region. To address this issue, three different aged rubber plantations, namely 4-year-old (Young, YRP), 15-year-old (Mature, MRP), and 31-year-old (Old, ORP), were studied to reveal the soil mineralization characteristics. Furthermore, to understand the mechanism from the coupled perspective of decomposers and substrate availability, the microbial metabolic strategy was deciphered by 2D-COS-Biolog assay, and linked with soil microbial composition and labile-/recalcitrant- organic pools. Results showed that YRP was characterized by having more copiotrophic taxa (e.g., actinobacteria) and the largest G(-)/G(+) ratio and invertase activity. Thus, YRP exhibited a preferential utilization for carbohydrate and the largest SOC mineralization rate. In contrast, regardless of abundant labile C and N pools in MRP, the soil microbial communities were shifted to oligotrophic taxa in utilizing resistant polymer, and MRP contained abundant G(+), fungi and arbuscular mycorrhizal fungi related to aggregate formation. As a result, the soil mineralization rate in MRP was reduced by 66 % compared with YRP. However, the SOC mineralization rate was unchanged from MRP to ORP, primarily because the increased proportion of recalcitrant nutrient pool, and soil microorganism had greater priority in utilizing relatively resistant amine. The structural equation modeling revealed that the variations in mineralization were mainly regulated by soil microbial composition and metabolic strategy, and partially affected by soil C and N pools. Furthermore, random forest model indicated that soil pH, NH4-N and C/N were also the crucial factor for mineralization by affecting soil microbial communities during stand development. In summary, these findings improve our understanding in soil C budget and contribute to the C accurate management during plantation development.

Gross nitrogen mineralization and nitrification at an optimal phosphorus input level in southern Chinese red soil with long-term fertilization

In China, phosphorus (P) is recognized as a “key limiting nutrient” for crop production, and its overuse results in underground leaching, ecosystem alterations and risks to humans, such as degraded surface water quality. The coupling of nitrogen (N) and P implies that soil N dynamics are largely affected by P availability. However, how the addition of P affects soil N transformations remains less understood. To determine the optimal P-input level, we performed an incubation experiment on an upland soil from Jinxian in China after long-term mineral fertilizer application and P addition. The two treatments without N addition T1 (no fertilizer) and T2 (inorganic potassium fertilizer) and the two treatments with N addition T3 (inorganic nitrogen fertilizer) and T4 (inorganic nitrogen and potassium fertilizer) were selected from the long-term experiment that involved scientific management at five P-input levels (0, 25, 50, 75, and 100 kg P2O5 ha−1) with three replications. The results showed that soil organic matter (SOM) increased in the T3 and T4 treatments compared with the T1 and T2 treatments. The T4 treatment resulted in the maximum N concentration of 1.28 g kg−1, followed by that in the T3 treatment (1.25 g kg−1), T2 (0.16 g kg−1) and that in the T1 treatment (0.10 g kg−1), in the soil. Among the different treatments, soil microbial biomass carbon (SMBC) and nitrogen (SMBN) were significantly higher (492.69 mg kg−1 and 73.36 mg kg−1, respectively) in the T3 treatment than in the other treatments, while soil microbial biomass phosphorus (SMBP) was higher in the T4 treatment (17.55 mg kg−1). With the addition of P, the gross N mineralization rate was substantially enhanced when N and K were applied. After the 90-day incubation period, with higher concentrations of NO3--N and NH4+-N in the T4 treatment than in the other treatments, the concentrations were significantly increased by P addition, specifically T4P4 by 11.27% and 37.37%, T4P3 by 12.64% and 30.29%, T4P2 by 22.94% and 64.53%, and T4P1 by 3.93% and 11.09%, compared with those of T4P0, respectively; these results indicated a maximum N mineralization potential (No) and mineralization rate constant, k (NMR). As a result of the increased gross nitrogen mineralization rates and associated NH4+ substrate availability, the gross nitrification rate was also increased by P addition. Based on the polynomial regression analysis, the inclusion of P at the rate of 60 kg P2O5 ha−1 can be used effectively to obtain maximum gross N mineralization rates in soil. Additionally, to fully understand why P addition is more effective under specific soil and environmental conditions, more research is necessary to determine the underlying mechanisms.

Performance evaluation of an electronically controlled tractor-operated applicator for liquid urea application

Currently, granular urea (most commonly used fertilizer) is applied through broadcasting by farmers in the field. Granular urea causes significant losses due to slower soil mineralization rates, as well as ammonia volatilization and immobilization. Hence, fertilizing crops is becoming an increasingly difficult task due to low use efficiency and in mulch field conditions, it becomes more severe. The research done on mechatronic systems of applying liquid fertilizer by spot injection in field is limited. In the present study, the performance of the developed tractor operated liquid urea applicator consisting of electronic metering mechanism was evaluated at the Research Farm of Punjab Agricultural University, Ludhiana, Punjab during 2020–22. Research was done at two different types of soil (S1: sandy loam, and S2: loam) for three different forward speeds (3.6, 2.7, 1.8 km/h). Results obtained from experiments indicated that both soil type and forward speed had a significant (P<0.05) effect on the application rate of liquid urea. The best results were obtained without affecting crop yield at a forward speed of the machine 2.7 km/h with the application rate of 1090.85 litre/ha and 1035.18 litre/ha, fuel consumption 4.13 litre/h and 4.02 litre/h and crop yield 39.50 q/ha and 39.63 q/ha, for soil type S1 and S2 respectively. The cost of operation of machine was found 1996.53 `/ha. Developed tractor operated liquid urea applicator would help in improving conventional practices which are not aligned with environmental protection (e.g. gaseous emissions and nutrient losses) and boost the adoption rate of mechanized fertigation in the crops.

Effects of Microplastics Addition on Soil Available Nitrogen in Farmland Soil

As microplastics (MPs) are an emerging pollution to farmland ecosystems, the research into the ecological and environmental effects of MPs need to be clarified urgently. Available nitrogen is the determining factor for productivity in most terrestrial ecosystems, especially for the farmland ecosystems with a high productivity. To explore the effects of MPs on soil available nitrogen in farmland soil, an incubation experiment was conducted by adding polyethylene MPs with different concentrations to farmland soil, which was collected from farmland in Fuqing, Fujian Province. The contents of three different nitrogen forms (nitrate, ammonium, and dissolved organic nitrogen) and soil dissolved organic carbon were measured, and the soil mineralization rate was calculated. Bacteria was quantified and bacterial community diversity indexes were measured. The results showed that the MPs addition (T1 and T2) had no significant effect on soil ammonium, nitrate and soil nitrogen mineralization rate compared to the control (p > 0.05). However, a significant increase was observed in soil dissolved organic carbon and dissolved organic nitrogen content (p < 0.05). It can be seen that the influence of PE MPs on the soil dissolved organic nitrogen is greater than that of inorganic nitrogen. The results of this study showed no major detrimental effects of MPs on the abundance of some bacterial families, whereas a significant change in soil bacterial evenness index was observed in T2 treatment compared to the treatment without MPs addition. In the background of current MPs pollution, the research results can provide a scientific basis for reducing nitrogen loss in soil and protecting farmland soil safety.

Potential Nitrogen Mineralization and Its Availability in Response to Long-Term Fertilization in a Chinese Fluvo-Aquic Soil

The determination of organic nitrogen (N) mineralization is crucial for estimating N availability, quantifying exogenous inputs, and estimating associated environmental impacts. The objective of this study was to explore the effect of long-term various fertilization on soil organic N mineralization potential (NMP), which influences plant N accessibility. Treatments from a 26-year long-term field experiment with no fertilization (CK), chemical fertilizer N at 165 kg N ha−1 and P at 82.5 kg P2O5 ha−1 (NP), NP with K fertilizer at 165, 82.5, 82.5 kg ha−1 N, P2O5 and K2O (NPK), NPK at 165, 82.5, 82.5 kg ha−1 N, P2O5 and K2O with manure at 7857.14 kg ha−1 (NPKM), and NPKM at 165, 82.5, 82.5 kg ha−1 N, P2O5 and K2O with manure at 1.5× application rate (11,785.71 kg ha−1) (1.5NPKM) were examined for potentially mineralizable N by aerobic incubation at 35 °C for 30 weeks. Three pools (Pools I, II, and III) of mineralizable N were recognized. Pool I, the mineralization flush on rewetting in the first 2 weeks; Pool II, gross N mineralization between weeks 2 and 30; and Pool III, the potentially mineralizable N, predicted from the fitted curve, that did not mineralize during the incubation period. Soil microbial biomass carbon (SMBC) and N (SMBN) as well as fixed ammonium (NH4+) contents and relationship with N mineralization rate (k) were also studied. Long-term manure application yielded a significantly higher k (0.32 week−1) than other treatments (0.12–0.22 week−1) but not a significantly higher NMP. Nitrogen mineralization during the wheat and maize-growing seasons was predicted to be 8.7–26.3 (mg N kg−1 soil) and 25.9–42.1 (mg N kg−1 soil), respectively. Both labile mineralizable N pools (Pools I and II) followed the same patterns in the treatments: 1.5NPKM > NPKM > NPK > NP > CK, while the reverse was true for stable N (Pool III). The significant positive correlation between k with SMBC and SMBN (R2 = 0.93, p = 0.008 and R2 = 0.94, p = 0.006) suggested that the higher mineralization rate might be contributed by the higher soil microbial biomass in NPKM. The trends of fixed NH4+ and mineralized N were coupled. Long-term manure application significantly improved the N mineralization rate in soil. Manure application is an effective strategy to enhance soil microbial biomass and soil N availability and has the potential to reduce the dependence upon chemical N fertilization.

Long-term fertilization modifies the mineralization of soil organic matter in response to added substrate

The turnover of SOC in soils is strongly influenced by the availability of substrate and nutrients, especially nitrogen (N) and phosphorus (P). Here, we assessed how long-term fertilization modified SOM mineralization in response to added substrate in a tropical forest. We carried out a 90-day incubation study in which we added two structurally similar compounds which differed in microbial metabolic availability: corn cellulose or corn starch to soils collected from a long-term (11 years) factorial N and P fertilization experiment site in a tropical forest in south China. We measured total soil mineralization rate (CO2 efflux) to characterize SOM mineralization and using 13C isotope signatures to determine the source of the CO2 (original soil C or added substrate) and assessed changes in extracellular enzyme activities: acid phosphomonoesterase (AP), β-1,4-glucosidase (BG), β-1,4- N-acetaminophen glucosidase (NAG), phenol oxidase (PHO) and peroxidase (PER), and microbial biomarkers to determine whether nutrient stoichiometry and decomposer communities explain differences in SOM mineralization rates. Total C mineralization increased substantially with substrate addition, particularly cellulose (5.38, 7.13, 5.58 and 5.37 times for N, P, NP fertilization and CK, respectively) compared to no substrate addition, and original soil C mineralization was further enhanced in long-term N (3.40% and 5.18% for cellulose and starch addition, respectively) or NP (35.11% for cellulose addition) fertilized soils compared to control treatment. Enzyme activities were stimulated by the addition of both substrates but suppressed by P-fertilization. Addition of both substrates increased microbial investment in P-acquisition, but only starch addition promoted C investment in N-acquisition. Finally, fungal abundance increased with substrate addition to a greater extent than bacterial abundance, particularly in cellulose-amended soils, and the effect was amplified by long-term fertilization. Our findings indicate that SOM mineralization might be enhanced in N and P enrichment ecosystems, since the litter input can liberate microbes from C limitation and stimulate SOM mineralization if N and P are sufficient. Our study further demonstrates that structurally similar substrates can have distinct effects on SOM mineralization and the extent of SOM mineralization is strongly dependent on elemental stoichiometry, as well as the resource requirements of microbial decomposers.

Analysis of Nitrogen Transformation Characteristics and Influencing Factors of Forestland Soil in the Qinghai-Tibet Plateau: A Case Study of the Qilian Mountains and Southeast Tibet

Mineralization and nitrification, two important processes of the N cycle in forest ecosystems, play an important role in the maintenance of ecosystem function and soil environmental quality. The net mineralization rate and net nitrification rate are two common indexes for evaluation of the N supply and N loss risk in soil. In order to study the soil N transformation characteristics and their influencing factors in woodlands of the Qinghai-Tibet Plateau, the inorganic N concentrations, net N mineralization rates, and net nitrification rates of 327 soils sampled from the Qilian Mountains and Southeast Tibet were analyzed using indoor incubation experiments. The results showed that the inorganic N concentration, net N mineralization rate, and net nitrification rate of the woodland soil in Southeast Tibet ［109.70 mg·kg-1, 3.08 mg·(kg·d)-1, and 2.19 mg·(kg·d)-1］ were significantly higher than those in the Qilian Mountains ［49.47 mg·kg-1, 0.70 mg·(kg·d)-1, and 0.69 mg·(kg·d)-1］. The net mineralization rate of soil was positively correlated with the mean annual temperature (MAT), mean annual precipitation (MAP), moisture index, and soil organic matter concentrations (P<0.001). There were no significant positive relationships between the net nitrification rate and the MAT and MAP, but the net nitrification rate was positively correlated with the net N mineralization rate (P<0.001). These results indicated that the N supply ability of woodland soil in Southeast Tibet is significantly higher than that in the Qilian Mountains, and the hydrothermal conditions (MAT and MAP) are likely responsible for the difference in the net mineralization rate between the two studied regions. The net mineralization rate is the limiting factor for the net nitrification rate, which has an important influence on the spatial distribution of the forest soil nitrification process in the Qinghai-Tibet Plateau. These results emphasize the important roles of climatic and environmental factors, such as hydrothermal conditions, on the net N mineralization and nitrification rates of woodland soil in the Qinghai-Tibet Plateau, and will further deepen the understanding of the law of soil N transformation in woodlands in the Qinghai-Tibet Plateau.

Assessing the Biological Value of Soluble Organic Fractions from Tomato Pomace Digestates

Anaerobic digestion is proposed for sustainable exploitation of the huge amounts of residues produced yearly by tomato processing. The aim of this study was to analyze the biological effects of water-soluble organic fractions of tomato pomace digestates applied on soil and plant, at a laboratory scale. Digestates are derived from a short-term dark fermentation batch experiment of tomato pomace and buffalo slurry at three decreasing ratios (12:1, 8:1, and 6:1, respectively Set 1, Set 2, and Set 3). Bioassays on soil and plant were carried out after addition of different amounts of dissolved organic carbon (DOC) extracted from the three sets: microbial pool content, respiration activity, root development, and cell division were considered. Digestate from Set 1 showed the highest content of volatile fatty acids (about 80 mg UL−1), suggesting an efficient fermentation process which led to lower water solubility of organic substrates. The highest carbon mineralization rate in soil (4.29%) occurred with DOC additions from Set 1 (p 0.05) was detected in the micronuclei assay. Soluble organic forms of these digestates are a nutrient source for soil microorganism metabolism and at low doses show a hormonal-like action, without toxicological or genotoxicity effects on soil biota and root cell.

腾格里沙漠东南缘不同类型生物土壤结皮对土壤有机碳矿化的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 腾格里沙漠东南缘不同类型生物土壤结皮对土壤有机碳矿化的影响 DOI: 10.5846/stxb201902220317 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41671111，41530746） Carbon mineralization of soil covered by different types of biological crusts in the southeastern fringe of the Tengger Desert Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:生物土壤结皮（BSCs）是荒漠生态系统的重要组成部分，是该区土壤碳循环及碳平衡的关键影响因素。研究了腾格里沙漠东南缘不同类型生物土壤结皮覆盖下土壤碳矿化过程及其对温度（10℃、25℃和35℃）和水分（土壤含水量10%和25%）变化响应特征，分析了土壤碳矿化过程与土壤理化性质的关系。结果表明：（1）结皮的形成和发育显著影响土壤有机碳矿化过程，藻类、地衣和藓类结皮覆盖的土壤碳矿化速率和CO2-C累积释放量均显著高于去除结皮的土壤，不同类型BSCs覆盖土壤和去除结皮土壤之间均表现为藓类结皮土壤 > 地衣结皮土壤 > 藻类结皮。（2）含结皮层土壤的平均和最大矿化速率均随温度升高和水分增加而逐渐增大，有结皮覆盖的土壤和去除结皮的土壤对温度和水分变化的响应规律相同。（3）有结皮土壤和去除结皮土壤碳矿化速率的温度敏感性（Q10）与结皮类型密切相关，均表现为藓类结皮 > 地衣结皮 > 藻类结皮。结果表明生物土壤结皮由以藻类为主向以藓类为主的演变进一步促进了土壤碳矿化过程，结皮对土壤碳循环的调控作用受水热等环境因子的共同影响。 Abstract:Biological soil crusts (BSCs) are the association of soil organisms including algea, cyanobacteria, bacteria, fungi, lichen and moss and soil particles, which cover as much as 70% of the interspaces between vegetation and are the key component of arid and semiarid ecosystems. They play a significant role in the process of soil formation and biogeochemical cycling of carbon and nitrogen. Although the functions of BSCs in soil carbon cycling in drylands have been extensively described in the literature, previous research has primarily focused on the effects of BSCs on soil carbon sequestration and respiration. Knowledge is rather poor regarding their effects on soil organic carbon mineralization which is the major part of global carbon cycling and an important process of carbon loss from soils in terrestrial ecosystem. Consequently, understanding the effects of BSCs on soil organic mineralization and their regulating factors is crucial to thoroughly addressing their contribution to the soil carbon budget and balance in drylands.In this study, both intact soil (IS) and BSC-being-removed soil (BRS) samples were collected from algae-, lichen-, and moss-covered soil plots in the southeastern fringe of the Tengger Desert. Carbon mineralization rates of different types of soils and their responses to soil moisture and temperature were investigated by dark incubation. The relationships between soil mineralization rates and soil physicochemical factors were also analyzed. The results showed that (1) SOC mineralization rates and cumulative CO2-C release from IS were significantly higher than those from BRS. These two parameters for both IS and BRS were in the order moss crust > lichen crust > algae crust. (2) The average and maximum soil carbon mineralization rates increased with increasing magnitude of incubation temperature and soil water content, and the dynamic patterns of their response both were similar. (3) Temperature sensitivity (Q10) of the three intact soils and their respective subsoils were closely linked to BSC types, with the highest value for moss-covered soil and the lowest for algae-covered soil. Our understanding of the effects of on soil carbon mineralization suggests that the evolution of BSCs from algae-dominated to moss-dominated soil promoted carbon mineralization, and their regulation of soil carbon cycling was strongly controlled by environmental factors, such as temperature and soil moisture. 参考文献 相似文献 引证文献

Litter Inhibitory Effects on Soil Microbial Biomass, Activity, and Catabolic Diversity in Two Paired Stands of Robinia pseudoacacia L. and Pinus nigra Arn.

Research Highlights: Plant cover drives the activity of the microbial decomposer community and affects carbon (C) sequestration in the soil. Despite the relationship between microbial activity and C sequestration in the soil, potential inhibition of soil microbial activity by plant cover has received little attention to date. Background and Objectives: Differences in soil microbial activity between two paired stands on soil at a very early stage of formation and a common story until afforestation, can be traced back to the plant cover. We hypothesized that in a black locust (Robinia pseudoacacia L.) stand the high-quality leaf litter of the tree, and that of the blackberry (Rubus fruticosus L.) understory had an inhibitory effect on soil microbial community resulting in lower mineralization of soil organic matter compared to the paired black pine (Pinus nigra Arn.) stand. Materials and Methods: We estimated potential mineralization rates (MR), microbial (MB), and active fungal biomass (AFB) of newly-shed litter, forest floor, and mineral soil. We tested the effects of litters’ water extracts on soil MR, MB, AFB and its catabolic response profile (CRP). Results: Newly-shed litter of black locust had higher MR than that of blackberry and black pine; MR, MB, and AFB were higher in forest floor and in mineral soil under black pine than under black locust. Water extracts of black locust and blackberry litter had a negative effect on the amount, activity of microorganisms, and CRP. Conclusions: The results demonstrate the potential for black locust and blackberry litter to have a marked inhibitory effect on decomposer microorganisms that, in turn, reduce organic matter mineralization with possible consequences at the ecosystem level, by increasing C sequestration in mineral soil.

Effects of phenolic acids on soil nitrogen mineralization over successive rotations in Chinese fir plantations

Phenolic acids are secondary metabolites of plants that significantly affect nutrient cycling processes. To investigate such effects, the soil available nitrogen (N) content, phenolic acid content, and net N mineralization rate in three successive rotations of Chinese fir plantations in subtropical China were investigated. Net N mineralization and nitrification rates in soils treated with phenolic acids were measured in an ex situ experiment. Compared with first-rotation plantations (FCP), the contents of total soil nitrogen and nitrate in second (SCP)- and third-rotation plantations (TCP) decreased, and that of soil ammonium increased. Soil net N mineralization rates in the second- and third-rotation plantations also increased by 17.8% and 39.9%, respectively. In contrast, soil net nitrification rates decreased by 18.0% and 25.0%, respectively. The concentrations of total phenolic acids in the FCP soils (123.22 ± 6.02 nmol g−1) were 3.0% and 17.9% higher than in the SCP (119.68 ± 11.69 nmol g−1) and TCP (104.51 ± 8.57 nmol g−1, respectively). The total content of phenolic acids was significantly correlated with the rates of net soil N mineralization and net nitrification. The ex situ experiment showed that the net N mineralization rates in soils treated with high (HCPA, 0.07 mg N kg−1 day−1) and low (LCPA, 0.18 mg N kg−1 day−1) concentrations of phenolic acids significantly decreased by 78.6% and 42.6%, respectively, comparing with that in control (0.32 mg N kg−1 day−1). Soil net nitrification rates under HCPA and LCPA were significantly higher than that of the control. The results suggested that low contents of phenolic acids in soil over successive rotations increased soil net N mineralization rates and decreased net nitrification rates, leading to consequent reductions in the nitrate content and enhancement of the ammonium content, then resulting in enhancing the conservation of soil N of successive rotations in Chinese fir plantation.

Effects of shrub species on soil nitrogen mineralization in the desert-loess transition zone

Shrubs play a vital role in ecosystem restoration in the desert transition zone, which suffers intensive desertification, land degradation, and nitrogen (N) limitation. To evaluate the effects of different shrub species on soil N availability, transformation, and their seasonal dynamics, we determined mineral N contents and mineralization rates in soils under three common shrub species (Artemisia ordosica Krasch., Caragana korshinskii Kom., and Salix psammophila C.) and in bare land during the growing season in the desert-loess transition zone in northwestern China. The average contents of soil nitrate N and mineral N were 153% and 55% greater, respectively, and cumulative net N nitrification and mineralization were 101.2 and 121.0 mg N m−2 higher, respectively, in soils beneath C. korshinskii than in bare land (P < 0.05) at the 0–10 cm depth over the growing season. The net N mineralization rate in 0–10 cm depth was significantly higher in soils under C. korshinskii than that in bare land during 21 Jun-23 Jul and 23 Aug-15 Oct of the growing season. However, C. korshinskii did not influence soil N metrics at the 10–20 cm depth. The incorporation of A. ordosica and S. psammophila into bare land did not influence soil N availability or transformation rates. Our results demonstrated that C. korshinskii was more preferable than A. ordosica and S. psammophila in ameliorating soil N cycling in the desert-loess transition zone.

氮磷添加对杉木林土壤碳氮矿化速率及酶动力学特征的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 氮磷添加对杉木林土壤碳氮矿化速率及酶动力学特征的影响 DOI: 10.5846/stxb201608231718 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41571251，41571130043）；中科院技术创新项目（201604） Effects of nitrogen and phosphorus additions on soil organic carbon and nitrogen mineralization and hydrolase kinetics in Chinese fir plantations Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以江西杉木林红壤为研究对象，开展野外长期氮（N）、磷（P）添加控制试验，设置对照（CK）、N （50kg N hm-2 a-1）、P （50kg P hm-2 a-1）、NP （50kg N hm-2 a-1+50kg P hm-2 a-1）处理，分析N、P添加对土壤碳矿化速率（Cmin）、氮矿化速率（Nmin）和相关的β-1，4-葡萄糖苷酶（βG）和β-1，4-N-乙酰葡糖氨糖苷酶（NAG）动力学参数的影响。结果表明：（1） N添加明显降低了Cmin和Nmin，比CK分别减少了25%和18%；N添加减小了NAG的潜在最大酶活性（Vmax）、半饱和常数（Km）、催化效率（Vmax/Km），但差异不显著（P>0.05）；N添加显著增加了βG的Vmax、Km，但对Vmax/Km有抑制作用。（2） P输入（P、NP）较CK使NAG的Vmax、Km减小26%-60%；NP同时添加明显提高βG和NAG的Vmax/Km（P<0.05），但P输入（P、NP）对Cmin和Nmin影响不显著（P>0.05）。（3）Cmin与土壤溶解性有机碳正相关，Nmin与pH显著正相关，与土壤NH4+-N、NO3--N显著负相关；βG和NAG的Vmax/Km均与NH4+-N、NO3--N负相关（P<0.05），Km均与NH4+-N、NO3--N正相关（P<0.05）。βG的Vmax与NH4+-N、NO3--N正相关（P<0.05），NAG的Vmax与有机碳、全氮、全磷、有效磷负相关（P<0.05）。研究结果表明，在亚热带杉木人工林中，N添加降低土壤pH，增加土壤有效氮含量，抑制βG和NAG的Vmax/Km，对土壤Cmin和Nmin产生抑制作用；而NP添加增加土壤有效磷含量，增加土壤βG和NAG的Vmax/Km。 Abstract:A long-term field experiment of nitrogen (N) and phosphorus (P) additions was established in Chinese fir plantations in subtropical China. Four treatments, i.e. control (CK), N (50kg N hm-2 a-1), P (50kg P hm-2 a-1), and NP (50kg N hm-2 a-1+ 50kg P hm-2 a-1),were selected in this study. We studied the effects of N and P additions on the soil mineralization rate of carbon (Cmin) and nitrogen (Nmin) and the kinetics of β-glucosidase(βG)and N-acetyl-glucosaminidase(NAG). The results showed that (1) N additions had negative effects on Cmin and Nmin, which were lower by 25% and 18%, respectively, compared to CK. (2) P (P, NP) additions decreased the Vmax and Km of NAG by 26%-60% compared to CK, whereas NP combined additions greatly enhanced the catalytic efficiency (Vmax/Km) of βG and NAG (P<0.05). (3) Cmin was positively correlated with dissolved organic carbon (DOC) contents, whereasNmin was positively correlated with pH and negatively correlated with NH4+-N and NO3--N contents. The catalytic efficiencies of βG and NAG were negatively correlated with NH4+-N and NO3--N contents (P<0.05). The Km of βG and NAG was positively correlated with NH4+-N and NO3--N (P<0.05), The Vmax of βG was positively correlated with NH4+-N and NO3--N (P<0.05), and the Vmax of NAG was negatively correlated with soil organic carbon, total nitrogen, total phosphorus, and available contents (P<0.05). Our results suggest that N additions had negative effects on Cmin and Nmin by decreasing soil pH, increasing soil available N contents, and inhibiting the Vmax/Km of βG and NAG, whereas NP additions increased soil available P and the Vmax/Km of βG and NAG in southern subtropical Chinese fir plantations. 参考文献 相似文献 引证文献

Do Soil Tests Help Forecast Nitrogen Response in First‐Year Corn Following Alfalfa on Fine‐Textured Soils?

Core Ideas ISNT and PSNT concentrations did not differ among alfalfa stand ages in five long‐term trials. Only PSNT concentration increased during first‐year corn in three of five long‐term trials. The PSNT was less related to soil N mineralization and more related to available N than the ISNT. The PSNT more accurately predicted corn response or nonresponse to fertilizer N than the ISNT. The product of alfalfa stand age and PSNT separated N response in 87% of 15 independent site‐years. Improved methods are needed to predict grain yield response to fertilizer N for first‐year corn (Zea mays L.) following alfalfa (Medicago sativa L.) on fine‐textured soils. Data from 21 site‐years in the North Central Region of the United States were used to determine how Illinois soil nitrogen test (ISNT) and pre‐sidedress soil nitrate test (PSNT) concentrations change during alfalfa–corn rotations and how they relate to mineralized N, available N, and grain yield response to fertilizer N in first‐year corn. In five long‐term crop rotation trials, ISNT and PSNT taken in the alfalfa phase did not change with alfalfa stand age, but PSNT concentration in first‐year corn increased with alfalfa stand age in three of five trials. Across 21 site‐years, the PSNT more accurately predicted corn response or nonresponse to fertilizer N than the ISNT (67 vs. 52% of site‐years). The interaction of PSNT with alfalfa stand age resulted in 87% accuracy when validated with 15 independent site‐years; no N response was likely in first‐year corn when the product of PSNT × stand age exceeded 42. Incubation of soil from first‐year corn showed that the ISNT explained over twice as much variation in soil nitrate‐N accumulation after 17 wk than the PSNT (30 vs. 13%). Overall, the PSNT was less related to soil N mineralization and more related to aboveground corn N uptake, total available N, and grain yield response to fertilizer N in first‐year corn than the ISNT. This research provided a simple method for predicting when N response is likely in first‐year corn after alfalfa, but further research is needed to predict the size and mineralization rate of soil N pools after alfalfa termination to estimate the economically optimum nitrogen rate when fertilizer N response is likely.

Degradation of flubendiamide as affected by elevated CO2, temperature, and carbon mineralization rate in soil.

An experiment was conducted under three levels of atmospheric CO2 [ambient (398 ± 10μmolmol(-1)), elevated (570 ± 10μmolmol(-1)) and open condition], three levels of temperature (4, 25, and 40°C) to study the degradation pattern of flubendiamide in soil and also carbon mineralization in soil. Results of this study revealed that flubendiamide was found to persist longer under outdoor condition (T1/2, 177.0 and 181.1days) than ambient (T1/2, 168.4 and 172.3days) and elevated condition (T1/2, 159.3 and 155.3days) at 1 and 10μgg(-1) fortification level, respectively. Results also revealed that flubendiamide dissipated faster at 40°C (T1/2, 189.4days) than 25°C (T1/2, 225.3days). Slower dissipation was recorded at 4°C (T1/2, 326.3days). Thus, increased CO2 levels and temperature following global warming might adversely affect flubendiamide degradation in soil. Laboratory study on microbial biomass carbon (MBC) and carbon mineralization (Cmin) in soil revealed that in des-iodo flubendiamide-treated soils, MBC significantly increased up to 45days and then decreased. Flubendiamide-treated soil showed a non-significantly decreasing trend of soil MBC with time up to the 15th day of incubation and after 15days significantly decreased up to 90days of incubation. In des-iodo flubendiamide-treated soil, the evolution of CO2 decreased up to 45days, which was increased after 45days up to 90days. In flubendiamide-treated soil, CO2 evolution decreased up to 30days and after 45days, it increased up to 90days.

Mineralização e efeitos de biocarvão de cama de frangosobre a capacidade de troca catiônica do solo

O objetivo deste trabalho foi caracterizar o processo de mineralização do C em amostras de cama de frango e de seu respectivo biocarvão, além de determinar a capacidade de troca catiônica (CTC) e as taxas de mineralização do C nos solos tratados com cama de frango e biocarvão. A mineralização do C foi avaliada em experimento com quantificação do C-CO2 liberado a partir de incubação (64 dias) de misturas de solo com cama de frango e de solo com biocarvão, em doses equivalentes a 0, 1.000, 2.000, 4.000 e 8.000 mg kg-1 de C. Ao final da incubação, determinaram-se, nas amostras de solo, o teor de C, o pH e a CTC. A mineralização do C dos materiais obedeceu à cinética química de primeira ordem. Os fluxos de C-CO2 foram mais intensos dos 20 aos 40 dias de incubação, seguidos da redução desses fluxos até a estabilização no tempo. As taxas de mineralização do C da cama de frango e de seu biocarvão foram respectivamente de 49,7 e 5,1%. Incrementos da CTC foram observados nos tratamentos com biocarvão, em consequência da elevação do pH, e, em ambos os materiais, em consequência de alterações do teor de C no solo.

Nitrogen mineralization rates in soils amended with different poultry manures

The Nitrogen (N) availability from field-applied poultry manure for crop production is influenced by a number of complex processes. Keeping these in view, an experiment was conducted to evaluate the decomposition of poultry manure by analysing the nitrogen mineralization. Thus the rate and timing of PM applications need to consider the N requirements of the given crop to ensure the efficient use of these products.

Biodegradability of crude glycerol-based polyurethane foams during composting, anaerobic digestion and soil incubation

Abstract In this study, the biodegradability of polyurethane (PU) foams made from crude glycerol- and petroleum-based polyols was compared during composting, anaerobic digestion (AD), and soil incubation. Chemical changes in the PU foams before and after composting were further analyzed using Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Evolved Gas Analysis–Mass Spectrometry (EGA–MS), and Fourier Transform Infrared Spectroscopy (FT-IR). The results showed that during composting, AD, and soil incubation conditions, none of the PU foams were mineralized more than 10%. PU foams made from 100% crude glycerol-based polyols were mineralized during 320 days of soil incubation at rates faster than those observed for the petroleum-based analogs. However, no significant differences in soil mineralization rates were observed between PU foams made from blend polyols, which contained 50% crude glycerol-based polyols and 100% petroleum-based polyols. SEM analysis showed that some surface deterioration occurred in the PU samples made from bio-based and blend polyols during composting. Minor differences were observed in the TGA curves of the PU foams made from petroleum-based polyols before and after composting and pronounced differences occurred in PU foams made from both crude glycerol-based and blend polyols in the thermal regions of urethane and ester segments. In terms of EGA–MS analyses, the major degradation of PU foams made from crude glycerol-based and blend polyols was attributed to the decomposition of FAMEs and fatty acid chains in the polyol side of the polymer. FT-IR analysis showed that little degradation of urethane and ester segments of the polymer occurred during composting of petroleum-based PU foam. FT-IR analysis of PU foams made from 100% crude glycerol-based polyols revealed that the ester segments (–COO–) of the material were the preferred sites of microbial attack. The PU foams made from blend polyols showed some structural changes in urethane linkages (–NHCOO–) but degradation was more noticeable in the ester segments (–COO–) of the polymer, similar to that observed for 100% bio-based polyols.