Soil Organic Nitrogen Content Research Articles

Soil organic nitrogen content and composition in different wetland habitat types along the south-east coast of China

Soil organic nitrogen (SON) turnover regulates soil nitrogen (N) storage and availability. The coastal mudflats (MFs) in China have undergone drastic transformation due to invasive Spartina alterniflora (SAs) and subsequent reclamation of Spartina marshes to create aquaculture ponds (APs), but the impact on the amounts and compositions of soil nitrogen remains unclear. This study measured the topsoil total nitrogen (STN) and organic nitrogen (SON) compositions in 21 coastal wetlands in southeastern China. Results show that conversion of MFs to SAs increased STN by 38.5%, whereas subsequent conversion to APs decreased it by 16.4%, and the effect was consistent across the broad geographic and climate gradients. Most of the change occurred in the non-acid-hydrolysable fraction of SON, which accounted for 32–42% of STN. Within the acid-hydrolysable fraction, amino acid N, ammonia N and amino sugar N together accounted for about 57%, with the remaining 43% unidentified chemically. Our results suggest that invasion by S. alterniflora was the overwhelming driver to increase bioavailability of nitrogen and related biogeochemical processes in coastal soil, and the effects were partly reversed in subsequent reclamation of Spartina marshes to create aquaculture ponds.

Effects of harvest residue management on soil organic nitrogen fractions in young Cunninghamia lanceolata plantation

Different treatments of harvest residues will change the quantity and quality of soil organic matter, with direct or indirect effects on the composition and content of soil nutrient. Nitrogen is one of the most important soil nutrients. However, the response of soil organic nitrogen fractions to different harvest residue treatments is still unclear. In this study, harvest residue treatments, including harvest residue removed, residue retained and residue burnt, were set up after clear-cutting a 50-year-old mature Cunninghamia lanceolata forest in Sanming City, Fujian, China. The H2SO4 hydrolysis method was used to determine soil organic nitrogen fractions and their driving factors in the 0-10 cm and 10-20 cm soil layers after 5 years of harvest residue treatments. The results showed that residue retained treatment significantly enhanced the contents of soil organic nitrogen and its liable fractions. In the 0-10 cm soil layer, soil organic nitrogen content under residue retained treatment (3.36 g·kg-1) was 1.5 and 1.3 times as those of residue removed and residue burnt treatments, respectively. Residue retained treatment had the highest contents of labile nitrogen Ⅰ and Ⅱ fractions. In 10-20 cm soil layer, the contents of soil organic nitrogen and labile nitrogen Ⅱ fraction were also significantly higher in residue retained treatment (2.20, 0.73 g·kg-1) than that in residue removed and residue burnt treatments. The labile nitrogen index Ⅱ in residue retained treatment (33.9%) was significantly higher than in residue burnt treatment (26.1%). The contents of total carbon, dissolved organic carbon, dissolved organic nitrogen, microbial biomass under residue retained treatment were the highest in both soil layers. Compared with residue removed treatment, residue retained treatment significantly enhanced the abundance of soil bacteria (Gram-positive bacteria and Gram-negative bacteria) in 0-10 cm soil layer. In 10-20 cm soil layer, residue retained treatment had the highest content of fungi and the lowest content of actinomycetes. Pearson analysis showed that there were significant positive correlations of labile fractions of soil organic nitrogen with total carbon, dissolved organic carbon, dissolved organic nitrogen, microbial biomass carbon, microbial biomass nitrogen, bacteria (Gram-positive bacteria, Gram-negative bacteria), and fungi, and negative correlations with actinomycetes. It was concluded that the retention of harvest residue was beneficial to increase the content of soil organic nitrogen and labile fractions, improve soil biochemical properties and had a positive effect on soil microbial community composition. Retention of harvest residue was an effective management measure to maintain soil fertility and improve forest productivity.

Soil nitrogen‐hydrolyzing enzyme activity and stoichiometry following a subtropical land use change

AbstractSoil extracellular enzyme activities reflect the microbial nutrient demand by microorganisms and can be strongly affected by land use change. However, how soil N‐hydrolyzing enzymes and soil extracellular enzyme stoichiometry (EES) respond to land use change remains unclear. Here, we explored seasonal variations in β‐1,4‐N‐acetyl glucosaminidase and leucine aminopeptidase activities and EES under afforested land (woodland and shrubland), cropland, and uncultivated land for better understanding microbial metabolism around the Danjiangkou Reservoir area. Both afforested and cropland soils averaged higher N‐hydrolyzing enzyme and specific enzyme activities [i.e., enzyme activities per unit of soil organic nitrogen (SON)] compared to the uncultivated soils, indicating fast N turnover rates after afforestation and cultivation. Higher N‐hydrolyzing enzyme activities under afforestation and cultivation could be attributed to increasing soil organic carbon and soil organic nitrogen contents. All land use types were generally restricted by nutrients limitation than C demand as mean soil ecoenzymatic C:N:P ratios deviated from 1:1:1. However, afforestation and cultivation r|esulted in greater C demand and alleviate nutrient limitation for soil microorganisms with higher ecoenzymatic C:N ratios, C:P ratios, and vector lengths. In addition, all land use types were restricted by P than N limitation with ecoenzymatic N:P ratios less than 1 and vector angle >45°, among which afforestation increased P limitation and cultivation alleviated P limitation for microbes compared with uncultivated land. Overall, our results provide insight into mechanisms of soil microbial metabolic limitation regulated by soil N‐hydrolyzing enzyme activity and EES under global land use change.

Environmental conditions to support blue carbon storage in mangrove forest: A case study in the mangrove forest, Nusa Lembongan, Bali, Indonesia

Abstract. Pricillia CC, Patria MP, Herdiansyah H. 2021. Environmental conditions to support blue carbon storage in mangrove forest: A case study in the mangrove forest, Nusa Lembongan, Bali, Indonesia. Biodiversitas 22: 3304-3314. Mangrove ecosystems can provide ecosystem services to mitigate climate change by absorbing and storing carbon in their systems. The question arises of how to manage a mangrove forest to store more carbon. The Nusa Lembongan mangrove forest was examined to assess the optimal environmental settings for blue carbon storage in the mangrove ecosystem. Five stations were selected purposively. The parameters observed in each station were aboveground living biomass, mangrove stand density, clay percentage in soil, bulk density, water content, soil organic carbon (%C), and soil organic nitrogen (%N). Based on this study, the total carbon stock in mangrove forest Nusa Lembongan was 68.10 ± 20.92 Mg C ha-1 and equals to 249.95 ± 76.77 MgCO2 ha-1 with a significant contribution of soil carbon stock. This study indicates that the essential parameters that can promote carbon sequestration in mangrove forest Nusa Lembongan were aboveground living biomass, soil organic carbon content and soil organic nitrogen content. In addition, as soil organic carbon content also negatively correlates with bulk density, it also can be considered. These findings can contribute to blue carbon planning and management to improve the effectiveness of the blue carbon project.

How will future climate depending agronomic management impact the yield risk of wheat cropping systems? A regional case study of Eastern Denmark

AbstractOne of the major challenges in agriculture is how climate change influences crop production, for different environmental (soil type, topography, groundwater depth, etc.) and agronomic management conditions. Through systems modelling, this study aims to quantify the impact of future climate on yield risk of winter wheat for two common soil types of Eastern Denmark. The agro-ecosystem model DAISY was used to simulate arable, conventional cropping systems (CSs) and the study focused on the three main management factors: cropping sequence, usage of catch crops and cereal straw management. For the case region of Eastern Denmark, the future yield risk of wheat does not necessarily increase under climate change mainly due to lower water stress in the projections; rather, it depends on appropriate management and each CS design. Major management factors affecting the yield risk of wheat were N supply and the amount of organic material added during rotations. If a CS is characterized by straw removal and no catch crop within the rotation, an increased wheat yield risk must be expected in the future. In contrast, more favourable CSs, including catch crops and straw incorporation, maintain their capacity and result in a decreasing yield risk over time. Higher soil organic matter content, higher net nitrogen mineralization rate and higher soil organic nitrogen content were the main underlying causes for these positive effects. Furthermore, the simulation results showed better N recycling and reduced nitrate leaching for the more favourable CSs, which provide benefits for environment-friendly and sustainable crop production.

Characteristics of soil nutrients and their relationship with soil microbial properties in Artemisia sacrorum communities in the loess hilly region

Artemisia sacrorum communities with different growth years were selected to analyse soil nutrient characteristics, the variation in soil microbial properties, and their relationships in the loess hilly region. The results showed that with an increase in the number of growth years, soil microbial biomass carbon and nitrogen contents as well as soil phosphatase and urease activities initially decreased and then increased in the A. sacrorum communities. The soil organic carbon, organic nitrogen, and total nitrogen contents as well as soil respiration rate showed an increasing trend and reached a maximum at age (a) 37. The soil available phosphorus content first decreased and then increased, with the lowest level observed at 18 a. By contrast, soil available potassium initially increased and then decreased. Soil microbial biomass carbon had a significant positive correlation with soil organic carbon, total nitrogen and organic nitrogen, while soil respiration had a significant positive correlation with organic nitrogen, soil phosphatase and organic carbon. Soil respiration had a highly significant positive correlation with organic carbon and total nitrogen, while soil phosphatase had a highly significant positive correlation with total nitrogen and organic nitrogen. In the A. sacrorum communities, the soil organic carbon and total nitrogen contents were mainly affected by soil respiration, soil available potassium content was mainly affected by soil urease activity, and soil organic nitrogen content was mainly affected by soil phosphatase activity. These findings indicate that soil basal respiration, urease activity and phosphatase activity were the major microbial factors affecting the characteristics of the soil nutrients in the A. sacrorum communities. In conclusion, the natural restoration process of A. sacrorum communities can enhance soil microbial activity and improve soil quality. Keywords: loess hilly, soil nutrients, soil microbial biomass, soil enzyme activities, soil basal respiration rate DOI: 10.25165/j.ijabe.20181104.3942 Citation: Song L J, Liu W Y, Wu H F, Gao T, Hao W F. Characteristics of soil nutrients and their relationship with soil microbial properties in Artemisia sacrorum communities in the loess hilly region. Int J Agric & Biol Eng, 2018; 11(4): 127-134.

Characteristics of soil nutrients and their relationship with soil microbial properties in Artemisia sacrorum communities in the loess hilly region

Artemisia sacrorum communities with different growth years were selected to analyse soil nutrient characteristics, the variation in soil microbial properties, and their relationships in the loess hilly region. The results showed that with an increase in the number of growth years, soil microbial biomass carbon and nitrogen contents as well as soil phosphatase and urease activities initially decreased and then increased in the A. sacrorum communities. The soil organic carbon, organic nitrogen, and total nitrogen contents as well as soil respiration rate showed an increasing trend and reached a maximum at age (a) 37. The soil available phosphorus content first decreased and then increased, with the lowest level observed at 18 a. By contrast, soil available potassium initially increased and then decreased. Soil microbial biomass carbon had a significant positive correlation with soil organic carbon, total nitrogen and organic nitrogen, while soil respiration had a significant positive correlation with organic nitrogen, soil phosphatase and organic carbon. Soil respiration had a highly significant positive correlation with organic carbon and total nitrogen, while soil phosphatase had a highly significant positive correlation with total nitrogen and organic nitrogen. In the A. sacrorum communities, the soil organic carbon and total nitrogen contents were mainly affected by soil respiration, soil available potassium content was mainly affected by soil urease activity, and soil organic nitrogen content was mainly affected by soil phosphatase activity. These findings indicate that soil basal respiration, urease activity and phosphatase activity were the major microbial factors affecting the characteristics of the soil nutrients in the A. sacrorum communities. In conclusion, the natural restoration process of A. sacrorum communities can enhance soil microbial activity and improve soil quality. Keywords: loess hilly, soil nutrients, soil microbial biomass, soil enzyme activities, soil basal respiration rate DOI: 10.25165/j.ijabe.20181104.3942 Citation: Song L J, Liu W Y, Wu H F, Gao T, Hao W F. Characteristics of soil nutrients and their relationship with soil microbial properties in Artemisia sacrorum communities in the loess hilly region. Int J Agric & Biol Eng, 2018; 11(4): 127-134.

Application of microwave-pretreated cephalosporin mycelial dreg (CMD) as soil amendment: Temporal changes in chemical and fluorescent parameters of soil organic matter

Land application of treated cephalosporin mycelial dreg (CMD) as a soil amendment is an alternative to its disposal in landfills and incineration because it has environmental and agronomic benefits. This study validated the efficacy of using the dewatered, microwave-pretreated CMD as a soil amendment. Pot experiments were conducted to assess the temporal changes in soil organic matter (SOM) profiles via chemical and fluorescent parameters. During the ageing period, the CMD-treated soil experienced a sudden rise in soil pH and soil electrical conductivity, along with a rapid decline in soil organic carbon and soil organic nitrogen content. The specific Ex/Em peak related to protein-like substances gradually disappeared, while those related to humic acid-like substances continued to increase thereafter. Fluorescence regional integration (FRI) results showed an ascended PV,n/PIII,n index (1.94) and significant correlations with chemical data (M2=0.2875, r=0.8441, P<0.001, 999 permutations for Procrustes analysis). Taken together, despite the temporal changes in chemical and fluorescent data after soil conditioning, the increased content of SOM containing humic acid-like substances was observed at the end of the incubation period compared with control soil samples, indicating that the microwave-pretreated CMD might be applied as a soil amendment.

Contrast of nitrogen contents around roots of mangrove plants

Nitrogen is one of the most limiting elements for plant growth. Although nitrogen dynamics in mangrove forests are well understood at the ecosystem level, the nitrogen conditions in the root-zones of plants are less clear. The aim of this study was to analyze in detail the nitrogen conditions in the root zone of mangroves. We conducted a field survey in an area inhabited by three species of mangroves (Avicennia marina (Forsk.) Vierh., Rhizophora stylosa Griff. and Bruguiera gymnorrhiza (L.) Lam.). We collected soil and soil pore-water from the mangrove root zone, in which there were abundant fine roots, and from an area 10-cm away from the root zone (no-root zone). We determined soil organic nitrogen contents and concentrations of ammonium-N, nitrite-N and nitrate-N in soil pore-water along with soil temperature, NaCl and pH. We observed several common characteristics among the three mangrove species; in the root zone, pH was lower, soil organic matter content was higher, soil C:N was lower, and soil pore-water nitrite-N and nitrate-N were higher than their respective values in the no-root zone. These trends were observed in both summer and winter while soil temperature was about 10°C higher in summer than in winter. The fact that C:N was lower in the root zone than in the no-root zone suggests that bacterial nitrogen assimilation occurred near plant roots. The contrast in nitrogen content within a small scale (10 cm) between the root zone and no-root zone suggests that mangroves retain nitrogen source in their root zone. This property clearly works efficiently in intertidal habitats where tidal nitrogen export occurs naturally.

Long-term effects of organic amendments on soil fertility. A review

Common agricultural practices such as excessive use of agro-chemicals, deep tillage and luxury irrigation have degraded soils, polluted water resources and contaminated the atmosphere. There is increasing concern about interrelated environmental problems such as soil degradation, desertification, erosion, and accelerated greenhouse effects and climate change. The decline in organic matter content of many soils is becoming a major process of soil degradation, particularly in European semi-arid Mediterranean regions. Degraded soils are not fertile and thus cannot maintain sustainable production. At the same time, the production of urban and industrial organic waste materials is widespread. Therefore, strategies for recycling such organic waste in agriculture must be developed. Here, we review long-term experiments (3-60 years) on the effects of organic amendments used both for organic matter replenishment and to avoid the application of high levels of chemical fertilizers. The major points of our analysis are: (1) many effects, e.g. carbon sequestration in the soil and possible build-up of toxic elements, evolve slowly, so it is necessary to refer to long-term trials. (2) Repeated application of exogenous organic matter to cropland led to an improvement in soil biological functions. For instance, microbial biomass carbon increased by up to 100% using high-rate compost treatments, and enzymatic activity increased by 30% with sludge addition. (3) Long-lasting application of organic amendments increased organic carbon by up to 90% versus unfertilized soil, and up to 100% versus chemical fertilizer treatments. (4) Regular addition of organic residues, particularly the composted ones, increased soil physical fertility, mainly by improving aggregate stability and decreasing soil bulk density. (5) The best agronomic performance of compost is often obtained with the highest rates and frequency of applications. Furthermore, applying these strategies, there were additional beneficial effects such as the slow release of nitrogen fertilizer. (6) Crop yield increased by up to 250% by long-term applications of high rates of municipal solid waste compost. Stabilized organic amendments do not reduce the crop yield quality, but improve it. (7) Organic amendments play a positive role in climate change mitigation by soil carbon sequestration, the size of which is dependent on their type, the rates and the frequency of application. (8) There is no tangible evidence demonstrating negative impacts of heavy metals applied to soil, particularly when high-quality compost was used for long periods. (9) Repeated application of composted materials enhances soil organic nitrogen content by up to 90%, storing it for mineralization in future cropping seasons, often without inducing nitrate leaching to groundwater.

Aliphatic compounds, organic C and N and microbial biomass and its activity in long-term field experiment

The content of aliphatic compounds, hydrophobicity index, organic C and N content and the microbial biomass and respiration activity were analysed in soil samples originating from different plots of a long-term field experiment (variants: nil, NPK &amp;ndash; mineral fertilization: 64.6&amp;ndash;100 kg/ha/year, FYM &amp;ndash; farmyard manure and FYM + NPK) from three blocks (III, IV and B) with different crop rotation. Samples were taken from 0&amp;ndash;200 mm layer in 2002 and 2003 (spring and autumn). The plots without any fertilization had the significantly lowest aliphatic compound content compared to variants fertilized by FYM or FYM + NPK in all the evaluated blocks in both years. The variants fertilized only by mineral NPK without any organic fertilization had the slightly increased aliphatic compound content but they did not exceed significantly the control variants in most cases. The aliphatic compound contents correlated significantly with the organic C contents in 2002 and 2003, as well. The values of the hydrophobicity index showed a similar trend like the data mentioned above. Organic manure increased the soil organic nitrogen content, similarly to the carbon content. In variants fertilized by FYM and FYM + NPK the higher microbial biomass content was found comparing to unfertilized variants. Correlations between aliphatic compound content and biomass differed in spring (2002: r = 0.065, 2003: r = 0.068) and autumn (2002: r = 0.407, 2003: r = 0.529). Organically fertilized variants had increased basal respiration, in autumn 2002 the basal respiration was higher in variants fertilized by mineral NPK, too. The highest specific respiration was recorded in the unfertilised plot in block B (autumn 2002 and 2003), where low microbial biomass exhibited high activity. Increased specific respiration was found also in plots fertilized by FYM and FYM&amp;nbsp;+ NPK (block III and IV, autumn samplings). Positive significant correlations between microbial biomass content and basal respiration were found in 2002 (spring: r = 0.716) and 2003 (spring: r = 0.765, autumn: r = 0.671).

Regional application of a cropping systems simulation model: crop residue retention in maize production systems of Jalisco, Mexico

To ensure the productivity of smallholder maize production systems in Central America, increased attention must be paid to conserving soil and water resources. Various stakeholders from national agricultural research services (NARS), networks, non-governmental organizations (NGO’s) and research institutes seek to develop and target productivity enhancing resource conserving management practices such as crop residue retention systems. To support this process, a methodology with explicit spatial and temporal dimensions using the DSSAT crop simulation models was developed and applied to the case study of residue retention in maize production systems of Jalisco, Mexico. Systems where crop residues were partially or totally retained were compared with systems with no residue retention. Variables considered included crop production, soil surface runoff water, soil organic carbon and soil organic nitrogen content. Gridded climate surfaces and a range of soil profile scenarios formed the basis of the regional input. Three levels of nitrogen application (0, 150 and 235 kg ha −1) were selected to represent current agronomic practices. Simulation models for maize and fallow were run in sequence for 12 consecutive years. Results demonstrated that soil water holding capacity and topography affected benefits of residue retention much more than nitrogen management. Benefits to maize production from residue retention were found mainly in areas in the northeast of Jalisco and surrounding regions, where low precipitation limits maize production. Reductions in soil surface runoff due to residue retention were most evident in high rainfall areas in the central-east of Jalisco and surrounding regions. Although the effect of soil loss is not accounted for in DSSAT, areas of pronounced soil surface runoff reduction are hypothesized to be areas of productivity gain in the longer term. The assessment provided insight in the regional potential for and the soil and climate conditions under which successful introduction of residue retention in maize cropping systems in Jalisco may be achieved. In combination with socio-economic assessment studies and experimental work, the approach and its results contribute to targeted introduction of new production technologies.