Content Of Available Nitrogen Research Articles

The impact of plant water status on the gas exchange, berry composition and wine quality of Chasselas grapes in Switzerland

Aims: The aim of this research was to study the physiological and agronomical behaviors (leaf gas exchange, plant vigor, mineral supply, and yield components) of the Chasselas grapevine subjected to different water regimes during the growing season. The resulting grape and wine qualities were also determined.Methods and results: Adult vines of Vitis vinifera L. cv. Chasselas (clone 14/33-4, grafted onto 5BB) were subjected to different water regimes (various levels of irrigation) during the growing season. Physiological indicators were used to monitor the plant water status [the predawn leaf (. Leaf photosynthesis (A) and transpiration (E), stomatal conductance (gs), vulnerability to cavitation, yield parameters, berry composition at harvest, and organoleptic quality of wines were analyzed over a period of eight consecutive years between 2009 and 2016, under the relatively dry conditions of the Canton of Wallis, Switzerland.In non-irrigated vines, the progressively increasing water deficit observed over the season reduced the leaf gas exchange (A and E) and gs. The intrinsic water use efficiency (WUEi, A/gs) increased over the season and was greater in vines that had suffered water restriction than in irrigated vines. The rise in WUEi was correlated with an increase in d13C in the must sugars at harvest. Vulnerability to cavitation (embolism phenomenon) increased with increasing water deficit in the non-irrigated vines with covered soils. A decrease in plant vigor was observed in the vines that had been subjected to water restrictions over multiple years. Moderate water stress during fruit ripening was favorable for sugar accumulation in berries and lowered the contents of total and malic acidity in the musts and the content of available nitrogen (YAN). Overall, the organoleptic characteristics and quality of Chasselas wines were little influenced by the vine water regimes, with the exception of the hot, dry season in 2009 (and, to a lesser degree, in 2011). In those years, the quality of the wines from the irrigated vines, which had not suffered any water stress, received a better appreciation. Bitterness was generally greater in samples from the non-irrigated vineyards that had suffered from drought than in samples from the irrigated vines. No significant differences in the aroma and wine structure were measured during the study period, regardless of the vine irrigation status.Conclusions: The physiological behavior (gas exchange, plant vigor, and mineral supplies) and grape ripening in Chasselas vines were largely dependent on the water supply conditions in the vineyard during the growing season.Significance and impact of the study: Vine water status is a key factor in leaf gas exchange, canopy water use efficiency, berry composition and, lastly, wine quality.

Simultaneous sludge degradation, desalination and bioelectricity generation in two-phase microbial desalination cells

The invention of solid phase bioelectrochemical systems (SPBESs) provides a promising method for synchronous dehydrated sludge compost, desalination and bioelectricity generation. However, low power density and anodic salinization are common problems in SPBESs. A two-phase microbial desalination cell (TPMDC) could achieve simultaneous desalination of saline solution and dehydrated sludge by adding concentration chambers. Experimental results indicated that the Dsalt in 3 d for different concentration saline solutions were 6.00 ± 0.05% (35 g L−1), 10.75 ± 0.76% (10 g L−1), and 19.80 ± 0.64% (2 g L−1) respectively during the stable operation period of TPMDC. The Dsalt of anodic sludge reached 31.63 ± 1.26% after 200-day operation, and the removal of organic matter was up to 32.70 ± 1.67%. The Pmax (1.97 ± 0.33 W m−3) was produced on 52 d with open circuit voltage (OCV) of 0.998 ± 0.011 V. After bioelectrochemical stabilization, the feasibility of dehydrated sludge land application was improved. Specifically, the dehydrated sludge humication level significantly enhanced, the contents of available nitrogen, phosphorus and potassium all increased, the heavy metals and metalloids in dehydrated sludge transferred into stable residual form, and phytotoxicity of dehydrated sludge decreased. BES as a pretreatment of dehydrated sludge composting has great potentials.

Soil properties and carbon and nitrogen pools in a young hillside longan orchard after the introduction of leguminous plants and residues.

The intensification of young hillside Dimocarpus longan orchard cultivation has led to increase soil erosion and decrease soil fertility in South China. Leguminous crops are often used for improving soil properties. An approximately 2-year-long field experiment in lateritic soil in South China was conducted to evaluate the effects of legume introductions on soil properties and carbon (C) and nitrogen (N) pools. Two leguminous and one non-leguminous plant species, including Arachis hypogaea L. (a leguminous oilseed crop species, DA), Stylosanthes guianensis (a perennial herbaceous leguminous species, DS) and Lolium perenne L. (an annual non-leguminous forage species, DL), were introduced into a D. longan orchard as three treatments and compared to the monoculture of D. longan (the control, D0). And the harvested biomass residues of the three cover plants were returned to their corresponding plots as green manure. Soil samples were collected from depths of 0–10 and 10–20 cm approximately 2 years after treatment application. The results showed that, compared with D0, DA significantly improved the contents of soil available phosphorus, dissolved organic carbon (DOC), total nitrogen, ammonium and the N pool. In addition, DS significantly increased the contents of DOC, microbial biomass carbon and ammonium in the soil. However, DL did not affect any soil properties or the C and N pools. In addition, neither DA nor DS altered the soil bulk density or the contents of available nitrogen, total organic carbon and the C pool. The improvement of soil properties by DS and DA was positively correlated with the plant residues amount, plant N content but negatively correlated with the plant C:N ratios. Besides, the plant growth of longan was significantly improved by DA. In conclusion, compared with that of S. guianensis, the introduction of A. hypogaea L. was more helpful for restoring and improving soil properties, N pool and longan growth within the young hillside orchard in South China.

Effectiveness of the Application of Nitrification Inhibitors on the Content of Available Nitrogen Forms in the Soil after Winter Barley Cultivation

Abstract The aim of this study was to examine the effect of split and one-time application of nitrogen-sulphur fertiliser ENSIN (26% N, 13% S) containing nitrification inhibitors (dicyandiamide and 1,2,4-triazole) on the content of nitrate and ammonium nitrogen in soil. The study was conducted in field small-plot experiment with winter barley on Haplic Luvisol with dominance of clay fraction in experimental station of the Central Testing Institute in Agriculture of Veľké Ripňany in the experimental years 2015 to 2017. The dose of nitrogen in all experimental treatments was 140 kg/ha and was applied at once during regenerative fertilisation or split in three partial doses. Soil samples from all examined treatments were taken from two soil depths (0.0‒0.3 m and 0.3‒0.6 m, respectively) by probe rod in three week intervals. Achieved results indicate that in the year 2015/2016, one-time application of fertiliser ENSIN containing nitrification inhibitors considerably reduced portion of N-NO3 - from the content of Nmin by 32 relative % in soil depth of 0.0-0.3 m and by 36 relative % in soil depth of 0.3‒0.6 m. On the other hand, in the year 2016/2017, split application of fertiliser ENSIN substantially reduced portion of N-NO3 - from the content of Nmin by 38‒62 relative % in soil depth of 0.0‒0.3 m, however increased portion of N-NO3 - by 10‒14 relative % in soil depth of 0.3‒0.6 m

Changes in soil physicochemical properties and soil bacterial community in mulberry (Morus alba L.)/alfalfa (Medicago sativa L.) intercropping system.

A better understanding of tree‐based intercropping effects on soil physicochemical properties and bacterial community has a potential contribution to improvement of agroforestry productivity and sustainability. In this study, we investigated the effects of mulberry/alfalfa intercropping on soil physicochemical properties and soil bacterial community by MiSeq sequencing of bacterial 16S rRNA gene. The results showed a significant increase in the contents of available nitrogen, available phosphate, available potassium, and total carbon in the rhizosphere soil of the intercropped alfalfa. Sequencing results showed that intercropping improved bacterial richness and diversity of mulberry and alfalfa based on richness estimates and diversity indices. The relative abundances of Proteobacteria, Actinobacteria, and Firmicutes were significantly higher in intercropping mulberry than in monoculture mulberry; and the abundances of Proteobacteria, Bacteroidetes, and Gemmatimonadetes in the intercropping alfalfa were markedly higher than that in monoculture alfalfa. Bacterial taxa with soil nutrients cycling were enriched in the intercropping system. There were higher relative abundances of Bacillus (0.32%), Pseudomonas (0.14%), and Microbacterium (0.07%) in intercropping mulberry soil, and Bradyrhizobium (1.0%), Sphingomonas (0.56%), Pseudomonas (0.18%), Microbacterium (0.15%), Rhizobium (0.09%), Neorhizobium (0.08%), Rhodococcus (0.06%), and Burkholderia (0.04%) in intercropping alfalfa soil. Variance partition analysis showed that planting pattern contributed 26.7% of the total variation of bacterial community, and soil environmental factors explained approximately 56.5% of the total variation. This result indicated that the soil environmental factors were more important than the planting pattern in shaping the bacterial community in the field soil. Overall, mulberry/alfalfa intercropping changed soil bacterial community, which was related to changes in soil total carbon, available phosphate, and available potassium.

Using digital image analysis to improve a simple colorimetric kit for COD and to estimate the content of available nitrogen in paddy soils from the measurement of COD in the water extracts of oven-dried soil samples

Using digital image analysis to improve a simple colorimetric kit for COD and to estimate the content of available nitrogen in paddy soils from the measurement of COD in the water extracts of oven-dried soil samples

Evaluation of root-knot nematode disease control and plant growth promotion potential of biofertilizer Ning shield on Trichosanthes kirilowii in the field.

Biofertilizer Ning shield was composed of different strains of plant growth promotion bacteria. In this study, the plant growth promotion and root-knot nematode disease control potential on Trichosanthes kirilowii in the field were evaluated. The application of Ning shield significantly reduced the diseases severity caused by Meloidogyne incognita, the biocontrol efficacy could reached up to 51.08%. Ning shield could also promote the growth of T. kirilowii in the field by increasing seedling emergence, height and the root weight. The results showed that the Ning shield could enhance the production yield up to 36.26%. Ning shield could also promote the plant growth by increasing the contents of available nitrogen, phosphorus, potassium and organic matter, and increasing the contents of leaf chlorophyll and carotenoid pigment. Moreover, Ning shield could efficiently enhance the medicinal compositions of Trichosanthes, referring to the polysaccharides and trichosanthin. Therefore, Ning shield is a promising biofertilizer, which can offer beneficial effects to T. kirilowii growers, including the plant growth promotion, the biological control of root-knot disease and enhancement of the yield and the medicinal quality.

Effects of root pruning on the physicochemical properties and microbial activities of poplar rhizosphere soil.

This study aimed to determine the effects of root pruning on the physicochemical characteristics and microbial activities of poplar rhizosphere soil. The root systems of 5-year-old poplar (Populus×euramericana cv. ‘Neva’) trees were manually pruned at 6, 8, or 10 times diameter at breast height (DBH) from the trunk (severe, moderate, and light, respectively) along both inter-row sides. Moderate root pruning significantly increased the concentrations of amino acids, organic acids, and total sugars in the root exudates and decreased the pH of rhizosphere soil. This treatment also increased the contents of available nitrogen, phosphorus, potassium, and total organic carbon as well as high-, medium-, and low-activity organic carbon in rhizosphere soil. Moreover, moderate pruning increased the contents of microbial biomass carbon and nitrogen, and enhanced basal respiration, in addition to decreasing the metabolic quotients in rhizosphere soil by 8.9%, 5.0%, and 11.4% compared with control, light, and severe root pruning treatments, respectively. Moderate pruning increased the growth rates of DBH, tree height, and volume to the highest levels. Furthermore, these indices were not significantly different between the light root pruning and control groups, but varied significantly between severe and moderate root-pruning treatments. Thus, root pruning, depending on the distance from the trunk, significantly influences the physicochemical properties and microbial activities in poplar rhizosphere soil.

The effect of active forms of silicon on the biomass of agricultural crops during their growth period on technogenically altered soils of the Nikopol Manganese Ore Basin

The problem of recovery of technogenically affected soils remains unsolved. Silicon which moves in the “soil – plant” system has been insufficiently studied, though this element takes part in many processes. For assessing the role of silicon compounds, we selected samples of technogenically affected soils of different types in the territory of the research station for land reclamation of Dnіpro State Agrarian-Economic University in the Nikopol Manganese Ore Basin. We conducted a vegetative experiment and a series of laboratory tests with adding SiO 2 . We chose the following crops: buckwheat ( Fagopyrum esculentum Moench, 1794), vetch ( Vicia sativa Linnaeus, 1753) and sunflower ( Helianthus annuus Linnaeus, 1753). The рН of the studied soils fluctuated between 7.1 to 7.8. The content of available nitrogen and phosphorus in the soils was low, except the content of phosphorus in pedozems. We analyzed 240 samples of plants and measured their biomass. Vetch grew best on sod-lithogenous soils on forest-like lomy soils, buckwheat and sunflower – on sod-lithogenous soils on grey-green clays. The variant of experiment with 0.2% solution of SiO 2 was most the efficient during growing all chosen crops on all types of studied soils. After adding amphoteric silicon, the best biomass indicators of vetch and buckwheat were observed on sod-lithogenous soils on forest-like loam, and indicators for sunflower – on sod-lithogenous soils on grey-green clays. After using 0.3% and 0.4% solution of SiO 2 , a gel film forms, which the seeds have no energy to penetrate and run out. Thus it slows the plant’s growth. An exception was an experiment with pedozems with adding 0.4% solution of SiO 2 , when the biomass of vetch was 1.5 times greater than in the experiment with 0.2% solution. We observed no similar positive effect in other variants of the experiment. All chosen crops on technogenically affected soils reacted to addition of silicon compounds by increasing biomass under the influence of SiO 2 solutions with concentration higher than 0.2%. Possibly, the increase in biomass during the first 14 days is connected with adsorbing activity of silicon, which retains water and accelerates the development of plants. Even with low content of available nitrogen and phosphorum, addition of silicon compounds increased the biomass of plants by two-four times, therefore silicon in this case is a limiting factor.

Performance of mango (Mangifera indica) based agri-horticultural systems under rainfed plateau conditions of eastern India

An attempt was made at ICAR RCER, Research Centre, Ranchi to analyse the plant growth behavior, productivity of different component crops, profitability, soil fertility status and carbon sequestration potential of 20 different agri horticultural systems during young bearing stage (6th to 10th year) of mango plants. The field trial was established during the year 1999-2000 to standardize suitable filler crop and intercrop combinations for mango based agri-horticultural systems under rainfed uplands of eastern plateau and hill region. The study indicated enhanced growth of mango and filler plants with paddy as intercrop. With respect to soil fertility, reduction in the content of available nitrogen and potassium was recorded after 10 years of planting particularly under Mango + Guava + Paddy agri-horticultural system. Among all the systems, the maximum cumulative Rice equivalent yield was recorded under Mango + Guava + French Bean. During all the five years, the significantly higher REY was recorded in case of Agri-horti systems with either guava as filler crop or French bean as intercrop.

Effect of Micro-Remediation on Enzymes Activity and Available Nutrients in Chlorpyrifos-Polluted Soils

In order to find out the effect of micro-remediation on enzyme activity and available nutrient in chlorpyrifos-polluted soils and the correlation of enzyme activity, available nutrients and chlorpyri fos residue during soil remediation process, the soils planting <i>Brassica juncea</i> throughout the year, sprayed with chlorpyrifos and treated with bacteria were selected as restoration land, while the soils only sprayed with chlorpyrifos were regarded as reference land. The results showed that the activities of urease, catalase, amylase and phosphatase in the restoration land were higher than those in the reference land, especially in the subsequent phase of sample time (<i>P</i> < 0.05). Correlation analysis demonstrated that there was significantly negative correlation between amylase activity and chlorpyrifos residue in the soils only sprayed chlorpyrifos, while amylase and catalase activity had a significantly negative correlation with chlorpyrifos residue respectively in the restoration soils (<i>P</i> < 0.01). Meanwhile, just as the soil enzyme activities, the available nutrients content in the restoration soils were higher than those in the soils only sprayed chlorpyrifos, and significant difference for available phosphorus between the two soils (<i>P</i> < 0.05) can be observed. Correlation analysis demonstrated that there was no significant correlation between available nutrients and chlorpyrifos residue in the reference soils, while available phosphorus content was significantly negatively correlated with chlorpyrifos residue in the restoration soils (<i>P</i> < 0.01). In general, the microbial remediation can contribute to effectively enhancing the contents of available nitrogen, available potassium and available phosphorus in soils polluted by chlorpyrifos and improve soil fertility well.

微量元素锰对耕作层氮元素的迁移规律研究

研究微量元素锰的含量对耕作层氮元素的迁移规律，以便优化化肥养分在土壤中的传递过程。基于实验室土柱模拟，采用不同含量的微量元素锰与微生物菌剂配施处理，通过测定5 cm与15 cm处速效氮的含量来研究氮元素的迁移规律。结果表明：微生物菌剂和肥料混施，固氮菌能够将大气和土壤空气中的N2还原为NH3，最终转化为NH+4 -N，增加了土壤中速效氮的含量。所以微生物菌剂和肥料混施不但有利于土壤中氮素的增加，而且有利于氮素的向下迁移。锰元素与氮素的循环有着密切的关系。在本实验中，15 cm处加入锰元素的各组的速效氮含量均高于空白组，p<0.001具有显著性差异。最佳锰离子浓度为C/Mn = 40。氮元素在好氧环境下，适量浓度的还原性锰离子会参与氨氮的氧化过程，即把NH+4-N氧化成NO-3-N或NO-2-N，则氮素更容易向下迁移。 Based on the laboratory soil column simulation, we studied the effects of different manganese contents on migration rules of nitrogen element in the cultivated layer to optimize the transfer process of fertilizer nutrient in soil by using the different content of trace elements manganese and microbial agents, and the 5 cm and 15 cm available nitrogen content were measured to study the migration regularity of nitrogen element. The results showed that with mixed microbial agents and fertilizer, nitrogen-fixing bacteria reduced N2 to NH3, eventually NH+4-N, which increased the content of available nitrogen in the soil. So mixed microbial agents and fertilizer were beneficial for the increase of nitrogen in the soil as well as the downstream migration of nitrogen. Manganese was closely related to the cycle of nitrogen. In this experiment, the various groups of the manganese elements were higher than the non-manganese elements group at the 15 cm section, p < 0.001 which had statistical significance. And the optimum manganese ion concentration was C/Mn = 40. When nitrogen was in aerobic environment, moderate concentration of reducible manganese ion would participate in the process of ammonia nitrogen oxide, which oxidized NH+4-N toNO-3-N or NO-2-N, and nitrogen migrating down more easily.

Spatiotemporal Heterogeneity of Soil Available Nitrogen During Crop Growth Stages on Mollisol Slopes of Northeast China

AbstractSpatiotemporal heterogeneity of soil available nitrogen (AN) (sum of NO3−–N and NH4+–N) is the essential basis for soil management and highly correlates to crop yield. Both geostatistical and traditional analyses were used to describe the spatiotemporal distribution of AN in the 0–20‐cm soil depth on typical Mollisol slopes (S1 and S2) in Northeast China. The concentration of NO3−–N dynamics at slope positions was typically opposite to NH4+–N. The peak values of AN typically moved from the summit of the slope to the bottom from spring to autumn and were mainly influenced by the content of NO3−–N (S1, 7·9–18·9 mg kg−1; S2, 1·2–103·6 mg kg−1), both of NO3−–N (S1, 3·9–8·3 mg kg−1; S2, 2·2–28·0 mg kg−1) and NH4+–N (S1, 21·4–30·5 mg kg−1; S2, 2·1–23·3 mg kg−1), and NH4+–N (S1, 10·5–28·9 mg kg−1; S2, 5·0–39·0 mg kg−1) in the seedling stage, vegetative growth stage, and reproductive growth stage, respectively. The spatial autocorrelation of AN was strong and was mainly influenced by structural factors during crop growth stages. This was mainly determined by soil erosion–deposition (SED) and soil temperature–moisture (STM) in the seedling stage; this was also mainly influenced by SED, STM, crop type, and crop growth in the vegetative growth stage and by early STM and early SED in the reproductive growth stage. Generally, the content of AN, NO3−–N, and NH4+–N on the whole slope was mainly determined by the early SED and local fertilizer application, while their spatiotemporal heterogeneity, especially the evenness, was mainly changed by SED, STM, crop growth, and crop types on the slope scale. In order to increase more crop yields, additional N fertilizer application on both the summit and the bottom during the vegetative growth stage and conservation tillage systems or additional soil amendments on the back slopes was necessary. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Soil Carbon Sequestration and Crop Yields in Rice–Wheat and Sugarcane–Ratoon–Wheat Cropping Systems Through Crop Residue Management and Inoculation of Trichoderma viride in Subtropical India

A field experiment was conducted at ICAR-IISR, Lucknow, in a split-plot design with two cropping systems and eight different crop residue management practices. In main plots, cropping systems, viz. CS1—rice–wheat (R–W) and CS2—sugarcane (plant crop)–ratoon–wheat (S–R–W) and subplots residue management practices, viz. residue removal (T1-RR); residue burning (T2-RB); residue incorporation (T3-RI); residue incorporation + Trichoderma (T4-RI + T), residue incorporation +25 % extra nitrogen application (T5-RI + N), partial residue incorporation (T6-PRI), partial residue incorporation + Trichoderma (T7-PRI + T) and partial residue incorporation +25 % extra nitrogen application (T8-PRI + N), were allocated. The observations on soil physical parameters indicated the lower mean bulk density (1.10 Mg m−3) in sugarcane–ratoon–wheat system than the rice–wheat system (1.145 Mg m−3). Increased porosity (58.68 %) was obtained in sugarcane–ratoon–wheat (S–R–W) system as compared to rice–wheat system (56.83 %). In S–R–W system, higher (19.51 %) SOC was recorded than the R–W system (16.31 Mg ha−1) at 0–15 cm depth. After harvesting of wheat in both the cropping systems, higher total carbon sequestered (@1.42 Mg ha−1) in S–R–W system than the R–W cropping system (0–15 cm soil depth). Higher contents of available nitrogen, phosphorous and potassium were recorded in S–R–W system than the R–W system after completion of crop cycle. The agronomic efficiency of rice, wheat and sugarcane crops indicated the higher level with residue incorporation along with Trichoderma application. Thus, it could be concluded that sugarcane–ratoon–wheat system acted as soil fertility restorer and crop reside management along with application of Trichoderma sustained the soil carbon level, crop productivity and agronomic/production efficiency of N for longer period.

Effects of different fertilization practices on the incidence of rice pests and diseases: A three-year case study in Shanghai, in subtropical southeastern China

To implement organic rice farming around a drinking water source in the western suburbs of Shanghai, pioneering field experiments on the relationships between fertilizer applications and occurrences of rice pests and diseases were performed without the use of pesticides and fungicides from 2012 to 2014. The rice plants treated with chemical fertilizers (CF) accumulated higher content of available nitrogen (NH4++NO3−) and grew higher and more luxuriantly, but they were more susceptible to pests and diseases. Comparatively, the plants treated with organic manure demonstrated higher resistance to rice pests and diseases and grew more healthily. However, excessive application of organic manure also increased the risks of pests and diseases. The unfertilized plants were highly deficient in nutrients, but they maintained the lowest rates of pests and diseases. This suggests that rice pests and diseases were easily triggered by a high content of N-related nutrients in plant tissues and inhibited by nutrient deficiency. Annual climatic conditions also deeply affected the occurrences of rice pests and diseases. Long-term warm and humid weather in the growing areas favored the development of herbivorous pests and fungal diseases. The incidence of migratory pests in Shanghai is also linked to violent summer storms. Frequent rain storms in southern or southwestern China increased the chance of infestations of migratory pests in Shanghai. Rice yield was primarily determined by the infestations of pests and diseases. In the pest-infested year of 2012, the grain yield for the different fertilizers was only 40%–44% of that under conventional farming practices, and the yield in CF was even significantly lower than that in the unfertilized CK. In 2013, with lower infestation rates, the grain yield of the different fertilizers was more than 80% of the conventional yield. The application of a lower amount of organic manure, 2100kgha−1 of cake manure, was recommended for the implementation of organic rice farming in the water source areas in Shanghai.

Spatiotemporal variations and factors affecting soil nitrogen in the purple hilly area of Southwest China during the 1980s and the 2010s

Determination of soil nitrogen distributions and the factors affecting them is critical for nitrogen fertilizer management and prevention of nitrogen pollution. In this paper, the spatiotemporal variations of soil nitrogen and the relative importance of their affecting factors were analysed at a county scale in the purple hilly area of the mid-Sichuan Basin in Southwest China based on soil data collected in 1981 and 2012. Statistical results showed that soil total nitrogen (TN) increased from 0.88gkg−1 in 1981 to 1.12gkg−1 in 2012, whereas available nitrogen (AN) decreased from 84.22mgkg−1 to 74.35mgkg−1. In particular, AN showed a significant decrease in agricultural ecosystems but remained stable in woodland and grassland. Correspondingly, most of the study area exhibited increased TN content and decreased AN content in space. The nugget/sill ratios of TN and AN increased from 0.419 to 0.608 and from 0.733 to 0.790, whereas spatial correlation distances decreased from 12.00km to 9.50km and from 9.50km to 9.00km, respectively, suggesting that the spatial dependence of soil nitrogen became weaker and that the extrinsic factors played increasingly important roles in affecting the soil nitrogen distribution. Soil group and land use type were the two dominant factors in 1981, followed by topographic factors, vegetation coverage and parent material, whereas land use type became the most important factor in 2012, and the relative contribution of topographic factors declined markedly. The results suggested that land use related to cultivation management and fertilizer application was the decisive factor for soil nitrogen change. The increase in TN content and the decrease in AN content over the study period also suggested improper use of nitrogen fertilizer, which can result in nitrogen loss through increasing nitrification rates. Thus, effective measures should be taken to increase the uptake rate of nitrogen and prevent nitrogen pollution.

Citric acid and ethylene diamine tetra-acetic acid as effective washing agents to treat sewage sludge for agricultural reuse

This paper presents the effects of different concentrations of citric acid (CA) and ethylene diamine tetra-acetic acid (EDTA) when used as additive reagents for the treatment of sewage sludge for agricultural use. Herein, both the retention of nutrients and removal of metals from the sewage sludge are examined. The average removal rate for the metals after treatment by CA decreased in the order Cu>Pb>Cd>Cr>Zn, while the rates after treatment by EDTA decreased in the order of Pb>Cu>Cr>Cd>Zn. After treatment with CA and EDTA, total nitrogen and total phosphorus concentrations in the sludge decreased, while the content of available nitrogen and Olsen-P increased. In addition, a multi-criteria analysis model-fuzzy analytic network process method (with 3 main factors and 12 assessment sub-factors) was adopted to evaluate the effectiveness of different treatment methods. The results showed that the optimal CA and EDTA concentrations for sewage sludge treatment were 0.60 and 0.125mol/L, respectively.

Effect of fertilizer levels on soil nutrient status at different growth stages and yield of Bt and non-Bt cotton

The Bt cotton is one of the outcome of gene revolution undertaken for production of cotton. Growing Bt cotton is proved as profitable as compare to non-Bt cotton which resulted in increase the area under cultivation of Bt cotton in Maharashtra as well as in India. The field experiment on effect of fertilizer levels on soil nutrient status at different growth stages and yield of Bt and non-Bt cotton was conducted at Cotton Improvement Project, Mahatma Phule Krishi Vidyapeeth, Rahuri during May to September, 2008. The experiment was laid out in Factorial Randomized Block Design with three replications and two main treatments i.e ., hybrid Bt RCH-2 and Non-Bt RCH-2 and nine sub treatments with different fertilizer doses i.e. , F 1 -No recommended doses of fertilizer (RDF), F 2 -50 % RDF, F 3 - 75 % RDF, F 4 -100 % RDF, F 5 -125 % RDF, F 6 -150 %RDF, F 7 -100 % RDF+ 2 %DAP spray, F 8 -100 % RDF + 1 % MgSO 4 and F 9 -100 % RDF + 1 % KNO 3 . The common RDF for Bt as well as non-Bt was 100 N, 50 P 2 O 5 and 50 K 2 O kg ha ?1 . The results revealed that the Non-Bt hybrid at 100 % NPK recorded maximum content of available nitrogen, potassium, magnesium and iron in soil as compared to Bt hybrid but except phosphorus which was more in Bt than non-Bt Non-Bt hybrid recorded maximum soil available nitrogen and potassium content in F 9 (100 % RDF + 1 % KNO 3 ) treatment at boll development stage as compared to Bt hybrid. However, magnesium and iron were maximum in F 8 (100 % RDF + 1 % MgSO 4 ) treatment in non-Bt as compared to Bt hybrid and phosphorus content was maximum in F 7 (100 % RDF + 2 % DAP) treatment in Bt as compared to non-Bt hybrid at boll development stage. The application of 100 % RDF + 1 % MgSO 4 spray recorded highest yield of Bt and non-Bt cotton hybrids.

Effect of potassium chloride on the emission of carbon dioxide from chernozem

The dynamics of carbon dioxide emission from the soil is traced over nine months by the method of microbial succession initiation for characterizing the microbial activity of soil. A twofold decrease of carbon dioxide emission from the fertile chernozem is observed when potassium chloride is used as a fertilizer. The contents of available nitrogen and especially phosphorus decrease in a pot experiment with barley at standard rates of fertilizer application. The reduction in the content of soluble salts (primarily chlorides and nitrates) in the nonsaline soil after leaching increases the microbial activity.

Inversion of available nitrogen content in hilly paddy soil of southern China based on hyperspectral characteristics

To analysis the relationship between the hyperspectral reflectance in the visible / near infrared bands and available nitrogen( AN) in paddy soil in southern China hilly areas,the authors collected the hyperspectral reflectance of paddy soil and made analysis with spectral analysis methods with the purpose of discovering the spectral characteristics of field reflectance and its influencing factors. The spectral indices were derived,and then paddy soil AN predicting model based on the correlation between AN content and spectral indices was built. The results were as follows: The different AN content paddy soil reflectance curves showed the tendency that,with the increase of AN content,the spectral reflectance decreased and the absorption depth became greater; by analyzing the correlation coefficient of paddy soil AN content and 16 kinds of mathematical transformations of spectral reflectance,the sensitive wavelengths were extracted,which were 694 nm,2 058 nm and 2 189 nm; the predicting model for paddy soil AN content was built with spectral resample reflectance at 694 nm,2 058 nm and 2 189 nm as independent variables and AN as dependent variable,and the coefficients of determination R2 of the model was0. 56,suggesting that the model is quite good in stability and predictability.