Mineral Nitrogen Production Research Articles

Organic fertilization strengthens multiple internal pathways for soil mineral nitrogen production: evidence from the meta-analysis of long-term field trials

Organic fertilization strengthens multiple internal pathways for soil mineral nitrogen production: evidence from the meta-analysis of long-term field trials

Influence of Different Land Management Systems on the Dynamics of Carbon Biodegradability and Nitrogen Mineralization in a Sudanian Savanah Grasslands Soil, Western Burkina Faso

This study aimed to assess soil organic carbon (SOC) and total nitrogen (TN) dynamics under fallow lands influenced by the perennial grass Andropogon gayanus and to show how the biological activity is improved during the Sudanian tillage system in the area of Bondoukuy (Western Burkina Faso). Soil samplings were done through cultivated plots (CP), ten (F10) and twenty (F20) years old fallow lands. Measurements were done in thickets and intergrowth areas of the perennial grass in two horizons: the topsoil (0-10 cm) and the subsoil (10-20 cm). Results showed that SOC concentrations are generally higher in the old (0.35%) than in the young fallow lands (0.29%) and in the cultivated plots (0.23%). TN concentrations followed the same pattern (0.022%, 0.017% for the old and young fallows lands and 0.013% for the cultivated plots). The C:N ratio observed (15~20) suggests an important soil organic matter (SOC and TN) maturation state in the fallow lands (F10 and F20) than in the cultivated plots (CP). Soil mineralization is also more important in the two fallow lands than in fields. For the total nitrogen mineralization, we have an important production of mineral nitrogen always in old fallow lands and a positive effect of the thicket on the net mineral nitrogen accumulation (p<0.05). The transition from thicket to intergrowth area permits obtaining positive variations which are relatively significant (p<0.05). A. gayanus fallow lands play an active role in managing SOC and TN dynamics. The most SOC and TN accumulated was found in the topsoil of thickets, where the maximum plant debris is located. Old fallow lands are best conditions for the recovery of SOC and TN from their steady states. Then, when clearing the vegetation for cultivation after the old fallow lands, there is an important input of fresh OM available for plants in the soil for 3 or 4 years. It is recommended to observe the old fallow phase prior to clearing for cropping.

Consequential Life Cycle Assessment of Nitrogen Fertilisers Based on Biomass – a Swedish perspective

The production of mineral nitrogen represents a large fossil energy input in Swedish agriculture. However, mineral nitrogen can be produced in the Haber-Bosch synthesis, with input from renewable energy. This could lower the dependency on fossil energy and the emissions of greenhouse gases in agricultural production. The aim of this study was to investigate the land use, energy use and greenhouse gas emissions from the production of ammonium nitrate based on biomass, using consequential life cycle assessment methodology. Three scenarios are studied. In one scenario the Haber-Bosch synthesis is integrated in an existing forest residue fired combined heat and power plant. In another two scenarios thermochemical gasification of biomass in combination with Haber- Bosch synthesis is studied, using either straw or short rotation coppice (Salix) as raw material. The results showed that the greenhouse gas emissions and use of fossil energy can be significantly lowered. The size of emission reductions compared to using fossil fuels as raw material is dependent on choice of data, but also choice of functional unit and if e.g. indirect land use change is included. The study also showed that using green nitrogen in rapeseed production substantially can lower the carbon footprint. Further, we argue that production of nitrogen based on renewables should be a high-priority activity, as nitrogen is one of the pillars for a secure food and bioenergy supply for a growing world population.

Nitrogen Mineralization in the Soils of the Conifer Forest Communities in the Eastern Mediterranean

The nitrogen mineralization rates in the soils of three coniferous forest communities (Pinus nigra subsp pallasiana, Abies cilicica subsp cilicica, Cedrus libani) in the middle Taurus Mountains (Turkey) were investigated. N mineralization was determined by the standard incubation method under laboratory conditions at 20oC and 60 %WHC. Mineral nitrogen (NH4 + -N ve NO3 - -N) was analyzed in the beginning, 21st and 63rd days of incubation by micro-distillation. Net mineral nitrogen accumulations were calculated for the 63-days (mg N min / 100 g dry-soil / 63-days). Needle-leaf forest communities were crossexamined based on their mineral nitrogen and soil parameters. The relationships between the mineral nitrogen production and soil factors were analyzed by a simple correlation test. Mineral nitrogen production in the soils of these communities is strongly related to the total nitrogen rate. The highest total nitrogen mineralization rates were determined in the soils of the Abies cilicica community. The nitrogen mineralization in the soils of three closely related needle-leaf forest communities in the Eastern Mediterranean phyto-geography region were found to be different.

Design and test of a generic cohort model of soil organic matter decomposition: the SOMKO model

Abstract SOMKO is a new simulation model of soil organic matter (SOM) dynamics aimed at predicting long‐term and short‐term SOM dynamics based on a mechanistic approach focusing on microbes as the key agents of decomposition. SOM is partitioned into cohorts and chemical quality pools (classified by age and chemical composition), the microbial community processes are explicitly represented, and the C : N stoichiometric constraints are accounted for through a new mechanism of offer and demand. The analysis of model equations shows that: (1) SOM C : N cannot decrease below microbial C : N; and (2) the nitrogen limitation of decomposition depends on SOM C : N, microbial biomass and soil mineral nitrogen. First tests of the model show good qualitative behaviour for simulating the dynamics of short‐term litter‐bag type decomposition, long‐term SOM increase, pulsed mineral nitrogen production, the priming effect due to easily decomposable carbon addition, and the effects of vegetation clearance and climate change on SOM. Simulations are in good agreement with long‐term experimental data. SOMKO is an integrated component of the coupled soil–vegetation models within the ETEMA (European Terrestrial Ecosystem Modelling Activity) framework. Future extensions of this work include: (1) estimating microbial parameters from specific experiments; (2) spatial distribution of SOMKO in multistrata models; and (3) implementing nitrification/denitrification processes, phosphorus limitation and microfaunal activity.

Effect of salinity on yield and nitrogen uptake of four grain legumes and on biological nitrogen contribution from the soil

Broadbean, chickpea, lentil and soybean were grown in a tank experiment and irrigated with waters of three different levels of salinity. The nitrogen uptake of the crop was determined from the yield of aereal biomass and grain, and the corresponding nitrogen contents. The biological contribution of the soil from nitrogen fixation and transformation of organic nitrogen was calculated as difference between the plant uptake and the amount supplied by fertilizer and irrigation minus the loss by drainage. Soil salinity affected crop yield, crop total nitrogen uptake and the nitrogen contribution of the soil. The latter decreased in % of plant uptake at increasing salinity and also decreased stronger than the plant uptake, pointing to a salinity effect on the mineral nitrogen production by biological activity in the soil through nitrogen fixation and transformation of organic nitrogen. A salinity effect on nitrogen fixation could explain, at least partly, the salt sensitivity of grain legumes.

Modes de fonctionnement d’humus des forêts sempervirentes des Alpes internes françaises

Three humus forms that are widespread in the Inner Alps, a dysmull below Pinus sylvestris, an oligomull below Abies alba and a mor below Pinus cembra, were studied by following mineral nitrogen production and uptake and by a characterization of the pedofauna. Due to the production and uptake of nitrogen, mainly as nitrates and also due to the dominance of Lumbricids versus Arthropods, the oligomull was the sole humus form that functioned as a mull. Nevertheless relatively weak mineral nitrogen production and the dominance of endogeic soil-dwelling earthworms versus anecic earthworms demonstrated the moderate activity of this mull, which is representative of humus forms of old growth forests and cold climates. There was a discrepancy between the very low biological activity of the dysmull and its status of mull, while an observed bifunctioning between the different layers of this humus also differentiated it from the mor.

Development of the nitrogen cycle in the soils of a coastal dune succession

SUMMARY The development of the soil nitrogen cycle in a coastal dune succession (xerosere) on the East Frisian Island Spiekeroog was investigated. In 13 sites of different successional age the nitrogen pools in the topsoil (0–30 cm) and the organic soil layers were determined. The nitrogen mineralization was studied at the sites during the vegetation period in 1987 (38 weeks) and winter 1990-91 (14 weeks). Turnover rates and nitrification rates were calculated. The nitrogen pool of the soil was very low in the first stage of the succession (<100 kg N ha−1 30cm−1) and increased rapidly to more than 1500 kg N ha−1 within approx. 200 years. This accumulation rate was strongly exposition-dependent. Mineralization of nitrogen was low in the young sites (15 kg Nmin ha−1 year−130 cm−1) and increased to more than 100 kg Nmin ha−1 year−1 in sites covered by buckthorn (Hippophae rhamnoides) and in dune forest. Mineralization was also exposition-dependent. The annual nitrogen turnover rate was very high in the young dune sands (up to 18%) and was only 2% in the brown dune sand podsols under Empetrum heathland. Nitrification dropped as well in the course of the dune development from 80–90% to 20% nitrate of total mineral nitrogen production over a year. Some hypotheses on nitrogen accumulation and retention during ecosystem and plant cover development are discussed.

Influence of drought on the production of mineral nitrogen in a typical argiudol of the pampas

A typical Argiudol of Pergamino (Buenos Aires province) was sampled in August 1988 and April 1989. The samples were air-dried at room temperature. Samples were analyzed at different times with regard to: (a) real and potential ammonification, i.e. NH 4 +-N at sampling time and after 60 days at 28°C at 75% equivalent humidity (e.h.). Ammonifier counts were obtained by the most-probable-number method (MPN). (b) real and potential nitrification: determination of (NO 2 − + NO 3 −)N at sampling time and after 60 days at 28°C and 75% e.h. MPN of ammonium and nitrite oxidizers were also determined, (c) Denitrification: N 2O was determined by gas chromatography and denitrifying bacteria by MPN. (d) Determination of water-stable aggregates at the beginning and end of the assay. Potential nitrification and denitrification increased as a function of the drying period, at variance with potential ammonification. Nitrifying and denitrifying bacteria appear to be able to grow under hygroscopic humidity. In both runs performed, numbers of nitrite-oxidizing bacteria were higher than that of ammonium-oxidizing bacteria. Correlation of the curves corresponding to MPN variations between denitrifiers and nitrite-oxidizers during drying was observed. This result supports the theory of cyclic reduction of NO 3 − to NO 2 − in anaerobic microsites; the latter then diffuses to aerobic sites, where it is reoxidized to NO 3 − No relationship was observed between bacterial numbers and ammonifying or nitrifying activity. It is proposed that enzymes from bacteria that die during drying could remain protected by clays or organic matter in the soil. These enzymes could act together with those present in living bacteria, thus leading to an increase of potential nitrification and denitrification.

The nitrogen content of particle size fractions separated from peat and its rate of mineralization during incubation

SummaryParticle size fractions, varying from 5 to 0.005 mm, were separated from samples of several peat types using a wet sieving technique. In all types, nitrogen content of fractions increased as particle size decreased, the fine fractions (0.15–0.005 mm) accounting for around 43–64% of the total nitrogen. During incubation, fractions from two blanket peats showed a net release of mineral nitrogen, whereas those from raised bog peats were characterized, for the most part, by net immobilization. Amounts of mineral nitrogen released in fractions from any one peat after 28 days incubation at 30°C did not always correlate with either total nitrogen content or C:N ratio. However, better correlations between mineral nitrogen production and total N were obtained for fractions of similar particle size. The proportion of the total nitrogen that was mineralized tended to be higher in coarse fractions &gt; 0.15 mm, blanket peats giving much higher values than samples from raised bogs. Carbon dioxide release also varied with particle size, being highest in large particles and fibres and least in the size range 0.15–0.5 mm. Smaller particles &lt; 0.15 mm, gave intermediate values that were higher in blanket than in raised bog peat.

Effects of trace elements on nitrogen mineralisation in soils

Studies to evaluate the effects on nitrogen mineralisation of 19 trace elements showed that all 19 inhibit mineral nitrogen production in soils. Results showed that the relative effectiveness of the trace elements in inhibition of nitrogen mineralisation depends on the soil. When the trace elements were compared by using 5 μmole/g of soil, Ag(I) and Hg(II) were the most effective [with Ag(I) ≥ Hg(II)] and Co(II), As(III), Se(IV), As(V), and W(VI) the least effective in inhibition of nitrogen mineralisation. Other trace elements that inhibited nitrogen mineralisation in soils were: Cu(II), Cd(II), Pb(II), Mn(II), Fe(II), Zn(II), Ni(II), Sn(II), Cr(III), Fe(III), Al(III) B(III), V(IV) and Mo(VI); their degrees of effectiveness varied in the four soils studied. Ag(I), Hg(II), Cd(II), Ni(II), Cr(III), Fe(III), Al(III), B(III), and Se(IV) inhibited nitrification, causing accumulation of ammonium-N in some of the soils used.

Decomposition of organic materials from hill soils and pastures: II. Comparative studies on the mineralization of carbon, nitrogen and phosphorus from plant materials and sheep faeces

Four plant materials obtained from Nardus and Agrostis-Festuca hill pastures, and the sheep faeces derived from these materials were incubated at 30°C for periods up to 12 weeks. The evolution of CO 2 and the production of mineral nitrogen and phosphorus were measured: 10–20 per cent and 30–55 per cent of the original carbon was evolved as CO 2 from faeces and plant materials respectively. Of the total original nitrogen, up to 8 per cent was mineralized from faeces, and up to 25 per cent was mineralized from plant materials. Grass from monthly cut treatments decomposed more rapidly than annually accumulated grass, and mineralization was greater from Agrostis-Festuca than from Nardus. More than half of the nitrogen which was mineralized was evolved as NH 3. Throughout most of the incubation period plant materials immobilized phosphorus while between 3 and 34 per cent of the total phosphorus in faeces was mineralized. The results are discussed in relation to the role of sheep in the soilplant-animal nutrient cycle.

Effect of several herbicides on bacterial populations and activity and the persistence of these herbicides in soil

Samples of a sandy loam soil were supplied with normal, 10-fold and 100-fold rates of ioxynil, dalapon, mecoprop, dichlorprop, MCPA + dichlorprop, picloram, and amitrole-T and incubated at 29°C at 65 per cent of the waterholding capacity. Treated soil samples were compared with untreated samples. Samples supplied with (NH4)2SO4 and herbicides were used to investigate the effect of the herbicides on the rate of nitrification and the production of nitrite. In several cases higher numbers of bacteria were found for a longer or shorter period in soil treated with herbicides. There was some evidence that certain groups of bacteria had adapted to ioxynil in a soil sample supplied with the 100-fold rate of this chemical. After 2 or 4 weeks lower numbers ofAzotobacter chroococcum were found at the normal rate of ioxynil, dalapon, mecoprop, and dichlorprop. At the 100-fold rate of application the numbers of Azotobacter were unfavourably affected by all herbicides. The production of mineral nitrogen was hardly affected by the normal and 10-fold rates of application. In the first week the rate of nitrification was slightly depressed in soil samples treated with the normal rates of dichlorprop and amitrole-T and with the 10-fold rates of dalapon, mecoprop, and MCPA + dichlorprop. Strong inhibition of the nitrification for at least 7 weeks was shown by the 10-fold rate of amitrole-T. At the 100-fold rate all herbicides, with the exception of picloram, depressed the rate of nitrification for a longer or shorter period. During the second week a very small increase of nitrite was found in the samples treated with the normal and 10-fold rates of dalapon, mecoprop, dichlorprop, and amitrole-T. A small increase of nitrite was noted for 26 weeks in samples treated with the 100-fold rates of amitrole-T. A highly significant depression of CO2 evolution was found in the first week in samples treated with the normal rates of ioxynil, dalapon, mecroprop, dichlorprop, and amitrole-T, also in samples treated with the 10-fold rates of dalapon, mecoprop, dichlorprop, MCPA + dichlorprop, picloram, and amitrole-T. A highly significant depression of CO2 production was found after 8 weeks in all the samples treated with herbicides at the 100-fold rate with the exception of the sample treated with picloram. The decomposition of the herbicides was studied in soil samples treated with the 100-fold rates of herbicides. Only traces of dalapon and mecoprop were found after 9 months, but 7.2% ioxynil, 29.8% dichlorprop, 39% (MCPA + dichlorprop), 52.1% picloram and 52.2% amitrole-T were still present in active form.

The production of mineral nitrogen by soil samples, contained in polyethylene bags, under field conditions and in the laboratory

The production of mineral nitrogen by soil samples, contained in polyethylene bags, under field conditions and in the laboratory