Fertilizer In Paddy Fields Research Articles

Nitrogen-fixing cyanobacteria enhance microbial carbon utilization by modulating the microbial community composition in paddy soils of the Mollisols region

Nitrogen-fixing cyanobacteria (NFC) are photosynthetic prokaryotic microorganisms capable of nitrogen fixation. They can be used as biofertilizers in paddy fields, thereby improving the rice tillering capacity and yield. To reveal the microbiological mechanisms by which nitrogen-fixing cyanobacteria alter soil carbon storage, we conducted a field experiment using NFC as a partial substitute for nitrogen fertilizer in paddy fields in the Sanjiang Plain of Northeast China's Mollisols region. Using metagenomic sequencing technology and Biolog Ecoplate™ carbon matrix metabolism measurements, we explored the changes in the soil microbial community structure and carbon utilization in paddy fields. The results indicated that the replacement of nitrogen fertilizer with NFC predisposed the soil microbial community to host a great number of copiotrophic bacterial taxa, and Proteobacteria and Actinobacteria were closely associated with the metabolism of soil carbon sources. Moreover, through co-occurrence network analysis, we found that copiotrophic bacteria clustered in modules that were positively correlated with the metabolic level of carbon sources. The addition of NFC promoted the growth of copiotrophic bacteria, which increased the carbon utilization level of soil microorganisms, improved the diversity of the microbial communities, and had a potential impact on the soil carbon stock. The findings of this study are helpful for assessing the impact of NFC on the ecological function of soil microbial communities in paddy fields in the black soil area of Northeast China, which is highly important for promoting sustainable agricultural development and providing scientific reference for promoting the use of algal-derived nitrogen fertilizers.

Water and Nitrogen Balance under Various Water and Fertilizer Regulation Modes

A experiment was conducted at the Jiangxi Province Center Station of Irrigation Experiment from 2019 to 2021 to study the water and nitrogen balance under water and fertilizer regulation modes. The study aimed to propose a recommended mode for paddy fields that could save water, control pollution, reduce gas emission, and improve fertilizer use efficiency. This study examined the impact of different irrigation methods and nitrogen application levels on water saving and emission reduction in paddy fields. The experiment included six treatments, which involved two irrigation methods (intermittent irrigation and flooding irrigation, referred to as W1 and W0, respectively) and three application rates of nitrogen fertilizer (0 kg/ha, 135 kg/ha, 180 kg/ha, referred to as N0, N1 and N2, respectively). The study found that irrigation methods had a significant effect on the amount of irrigation, drainage, leakage, nitrogen load from drainage, soil nitrification potential, and ammonia volatilization. The results showed that compared to flooding irrigation, intermittent irrigation reduced the amount of irrigation, drainage, leakage and nitrogen load from drainage by an average of 25.98%, 16.03%, 8.43% and 10.86%, respectively. However, the study also found that the nitrification potential and ammonia volatilization increased by an average of 6.45% and 4.32%, respectively. Fertilization levels had a significant effect on drainage nitrogen load, early soil nitrification potential and ammonia volatilization. Compared with the treatment of N2 (180 kg N/ha), the drainage nitrogen load under the treatment of N1 (135 kg N/ha) decreased by 10.86% on average, while nitrification potential and ammonia volatilization increased by 38.74% and 3.33%, respectively. In terms of nitrogen output, the amount of nitrogen absorbed by crops was the largest, followed by the nitrogen load from field drainage, then ammonia volatilization, and then denitrification. Considering the goals of water saving, emission reduction, and the efficient utilization of water and fertilizer in paddy fields, the optimal water and fertilizer regulation mode was the W1N1 mode (intermittent irrigation combined with reduced nitrogen fertilizer application rate, 135 kg N/ha).

Multi-objective decision-making for efficient utilization of water and fertilizer in paddy fields: A case study in Southern China

Effective water and fertilizer management modes (WFMMs) are crucial for mitigating non-point source pollution, enhancing grain quality, and improving resource utilization in paddy fields. Nevertheless, screening WFMMs that can effectively synergize these benefits is challenging, particularly in the wake of climate change. A two-year lysimeter experiment was conducted to investigate the effects of WFMMs on water balance components, nitrogen and phosphorus loss loads, grain yield and quality, and nitrogen utilization efficiency. Four treatments were established, including flooding irrigation (FI) and alternate wetting and drying irrigation (AWD), paired with conventional fertilizers (CF) and sulfur-coated fertilizer (SCF). A multi-criteria evaluation framework was developed to assess the potential values of WFMMs under diverse hydrological conditions using the vertical and horizontal scattering degree method. The results indicated that the AWD regime increased irrigation and drainage by approximately 8% compared to CF during the wet season, while reducing irrigation, percolation, and augmenting capillary rise during the dry season. Irrigation had not a significant effect on rice yield and quality. Compared to CF, AWD significantly increased nitrogen accumulation at maturity and nitrogen recovery efficiency by 20% and 31% on average. The SCF had a significant effect on the nitrogen accumulation at maturity, nitrogen recovery efficiency, N partial factor productivity, yield (increased 8–9% across two years), and protein content (increased ∼8% across two years), but at the cost of higher leachate concentration when compared to CF. Integration of AWD and SCF treatments demonstrates the potential for improved water productivity, yield, and nitrogen utilization efficiency, along with an enhanced ability to purify pollutants. The vertical and horizontal scattering degree method assessment showed that the AWD+SCF treatment exhibits superior performance in water saving, pollution reduction, yield and quality, and nitrogen efficient utilization, which was amplified during the dry season. These findings offer novel perspectives for optimizing WFMMs under varying hydrological conditions in hilly areas of Southern China.

Dynamic Responses of Rhizosphere Microorganisms to Biogas Slurry Combined with Chemical Fertilizer Application during the Whole Life Cycle of Rice Growth.

Biogas slurry combined with chemical fertilizer (BCF) is widely used as a fertilizer in paddy fields and rhizosphere microorganisms are key players in plant growth and reproduction. However, the dynamic responses of rhizosphere microorganisms of field-grown rice to BCF application still remain largely unknown. In this study, a field experiment was conducted in two proximate paddy fields in Chongming Island to study the impacts of BCF on the changes in rhizosphere microorganisms during the whole rice growth, including seedling, tillering, booting, and grain-filling stages, with solely chemical fertilizer (CF) treatment as control. The results showed BCF could increase the N-, P-, and C- levels in paddy water as well as the rhizosphere microbial abundance and diversity compared with control. In particular, the phosphate-solubilizing- and cellulose-decomposing-bacteria (e.g., Bacillus) and fungi (e.g., Mortierella) were more abundant in the rhizosphere of BCF than those of CF. Moreover, these microbes increased markedly at the booting and grain-filling stages in BCF, which could promote rice to obtain available nutrients (P and C). It was noted that denitrifying-like bacteria (e.g., Steroidobacteraceae) decreased and dissimilatory nitrate reduction to ammonia-related bacteria (e.g., Geobacter, Anaeromyxobacter, and Ignavibacterium) increased at the booting and filling stages, which could promote N-availability. TP in paddy water of BCF was most correlated to the bacteria, while COD was the most critical regulator for the fungi. Furthermore, correlation network analysis showed nutrient-cycling-related microorganisms were more closely interconnected in BCF than those in CF. These findings showed the application of biogas slurry plus chemical fertilizer could regulate rhizosphere microorganisms towards a beneficial fertilizer use for rice growth.

Bionic Design of Furrow Opener Based on Muskrat Claw-Toe Structure to Improve the Operating Performance of Deep Application of Liquid Fertilizer in Paddy Fields in Cold Region of China

The deep application of liquid fertilizer in paddy fields is a fertilization technique that applies liquid fertilizer deep near the root system of paddy field crops, which can effectively improve the absorption rate of the crops and reduce the amount of fertilizer applied. In the cold regions of China, the soil return rate of the furrowing operation of the deep application of liquid fertilizer in paddy fields is low, which can easily cause the excessive liquid leakage of fertilizer and affect crop growth. Therefore, it is difficult to popularize in large areas. According to the characteristics of paddy soil in the cold regions of China and the operating requirements of a high backfill rate and low disturbance rate of the soil of the deep application of liquid fertilizer, this paper designed a bionic liquid fertilizer deep application furrow opener based on the claw-toe structure of the muskrat. In this study, an indoor soil bin test was conducted by constructing a deep application environment for the liquid fertilizer in paddy fields. The results of the soil bin test showed the effects of the key operating parameters of the bionic design of the liquid fertilizer deep application furrow opener, spraying pressure of the liquid fertilizer and operating speed on the furrowing resistance, soil disturbance rate and the leakage amount of liquid fertilizer. The bionic design of the liquid fertilizer deep application furrow opener has a low soil disturbance rate and leakage amount of fertilizer when the operating speed is 0.8 m s−1, and the spraying pressure is 0.2 MPa. This furrow opener significantly improves the operating performance of the deep application of liquid fertilizer in the cold regions of China and is suitable for the deep application of liquid fertilizer in the paddy fields of this region.

Manure applications combined with chemical fertilizer improves soil functionality, microbial biomass and rice production in a paddy field

AbstractThe current farming system is highly reliant on synthetic fertilizers, which adversely affect soil quality, the environment, and crop production. Improving crop productivity on a sustainable basis is a challenging issue in the current agricultural system. To address this issue, we assumed that the combined use of manure and chemical fertilizers (CF) could improve rice (Oryza sativa L.) grain yield and soil properties without the expense of the environment. Therefore, a 2‐yr field experiment was conducted to explore optimal fertilizer management strategies using a combination of CF and organic fertilizer in the form of cattle manure (CM) or poultry manure (PM). Manure was added at two levels and soil microbial biomass production, enzyme activities, nutrient content, as well as grain yield of rice were measured. The study consisted of six treatments: no N fertilizer control, 100% chemical fertilizer (Pos‐Con), 60% cattle manure + 40% chemical fertilizer (High‐CM), 30% cattle manure + 70% chemical fertilizer, 60% poultry manure + 40% chemical fertilizer, and 30% poultry manure + 70% chemical fertilizer. Results showed that the addition of manure significantly increased soil enzymatic activities such as soil invertase, acid phosphatase (POH), urease, catalase (CAT), β‐glucosidase, and cellulase as compared to sole CF application. Similarly, the combined fertilizers application led to significant increases in soil microbial biomass C (MBC), microbial biomass N (MBN), soil pH, soil organic C (SOC), total N, available N (AN), available P (AP), and rice yield. Average increases in soil MBC, MBN, SOC AN, and AP in the 0‐to‐20‐cm soil depth were 62.2, 54.5, 29.2, 17.4, and 19.8%, respectively, across the years in the High‐CM treatment compared with the Pos‐Con. In addition, the linear regression analysis showed that soil enzymatic activities were highly positively correlated with soil MBC and MBN. The principal component analysis and linear regression analyses showed that the increased soil enzyme activities and microbial biomass production played a key role in the higher grain yield of rice. Overall, the results of this study demonstrate that the combined use of synthetic fertilizer and organic fertilizer in paddy fields could be beneficial for the farmers in southern China by improving soil functionality and yield of rice on a sustainable basis.

Effects of Biogas Slurry Combined With Chemical Fertilizer on Soil Bacterial and Fungal Community Composition in a Paddy Field.

The application of biogas slurry and chemical fertilizer in paddy fields can be a practical method to reduce the environmental risk and utilize the nutrients of biogas slurry. The responses of bacterial and fungal communities to the application of biogas slurry and chemical fertilizer are important reflections of the quality of the ecological environment. In this study, based on a 3-year field experiment with different ratios of biogas slurry and chemical fertilizer (applying the same pure nitrogen amount), the Illumina MiSeq platform was used to investigate the bacterial and fungal community diversity and composition in paddy soil. Our results revealed that compared with the observations under regular chemical fertilization, on the basis of stable paddy yield, the application of biogas slurry combined with chemical fertilizer significantly enhanced the soil nutrient availability and bacterial community diversity and reduced the fungal community diversity. Dissolved organic carbon (DOC), DOC/SOC (soil organic carbon), available nitrogen (AN) and available phosphorus (AP) were positively correlated with the bacterial community diversity, but no soil property was significantly associated with the fungal community. The bacterial community was primarily driven by the application of biogas slurry combined with chemical fertilizer (40.78%), while the fungal community was almost equally affected by the addition of pure biogas slurry, chemical fertilizer and biogas slurry combined with chemical fertilizer (25.65–28.72%). Biogas slurry combined with chemical fertilizer significantly enriched Proteobacteria, Acidobacteria, Planctomycetes, Rokubacteria, and Ascomycota and depleted Chloroflexi, Bacteroidetes, Crenarchaeota, Basidiomycota, and Glomeromycota. The observation of the alteration of some bacteria- and fungus-specific taxa provides insights for the proper application of biogas slurry combined with chemical fertilizer, which has the potential to promote crop growth and inhibit pathogens.

The input–output balance of microplastics derived from coated fertilizer in paddy fields and the timing of their discharge during the irrigation season

Polymer-based microcapsules derived from coated fertilizers are not recovered after use. Therefore, they are a source of microplastics to the agricultural lands and coastal areas of Japan. In this study, we investigated the input–output balance of microcapsules in three paddy fields and the timing of microcapsule discharge from the fields with the aim of developing effective techniques to reduce microcapsule discharge. Microcapsules were discharged from the paddy fields primarily during puddling, when the weir plate was overflowed, and when surface drainage was implemented. About 50% of the total discharge during the irrigation period occurred during puddling, which is a process for leveling paddy fields. Therefore, contamination of the surrounding environment by microcapsules from paddy fields can be effectively reduced by preventing the release of microplastics from paddy fields during puddling. We also showed that the total microcapsule discharge cannot be controlled solely by irrigation water management, such as by adjusting the height of the weir plate. We found that about 0.067–0.076% of the total number of microcapsules accumulated in the soil of the paddy fields was discharged during the irrigation season in 2020. Furthermore, 70% of the microcapsules discharged from one field in 2020 had resided in the soil for at least two years. The use as fertilizer coatings of biodegradable polymers that would degrade completely in the soil within a few years could therefore substantially reduce the amount of microplastics released into the ocean from agricultural fields, and their development is thus urgently needed.

Accumulation of microcapsules derived from coated fertilizer in paddy fields

Japanese agriculture uses large amounts of plastics. Fertilizer-containing plastic microcapsules with a diameter of 2–5 mm (“coated fertilizer”) are not recovered after use, and after diffusion of the fertilizer components these microcapsules are found in large quantities, not only on agricultural land but also along the coast of Japan. Here, we investigated the accumulation of microcapsules derived from coated fertilizer in 19 paddy fields. Microcapsules were detected in all of the paddy fields surveyed, at concentrations in the range of 6–369 mg/kg (mean 144 mg/kg)—much higher than the concentrations of microplastics in farmlands in other countries. There was no difference in mean microcapsule concentration between sampling sites with continuous rice cultivation and those with crop rotation, but that of a paddy field that had never received coated fertilizer was significantly lower. Examination of the spatial distribution of microcapsules in one paddy field showed that there was a hot spot with a high concentration near the drainage outlet. This was likely due to the strong influence of irrigation water flowing from the water inlet to the drainage outlet. The amount of microcapsules accumulated in Japanese paddy fields, as estimated from our results, and the amount applied to the fields, as estimated from the statistics, were almost equivalent. Therefore, most of the microcapsules that have already been applied to paddy fields may continue to accumulate. The impact of these high concentrations of microcapsules on the soil environment needs to be assessed.

Numerical analysis and performance optimization of a spiral fertilizer distributor in side deep fertilization of a paddy field

To improve the quality of side deep fertilization in paddy fields and study the dynamic change in fertilizer particles in fertilizer boxes, a model connecting the mechanical components and fertilizer based on the discrete element method was established, and a numerical simulation analysis of the spiral fertilizer distributor was conducted with EDEM software. The primary factors affecting the uniformity and stability of the fertilizer were studied. Using an orthogonal experimental design and numerical simulation technology, the speed, lead and diameter of a steel wire were selected as experimental factors, the mean fertilization value and the fertilization coefficient of the variation were selected as evaluating indicators, a mathematical model between the factors and indicators was established by virtual orthogonal testing, and the numerical processing was optimized with Design-Expert 6.0.10 software. The results showed that the primary and secondary factors affecting the comprehensive performance occurred in the following sequence: steel wire speed > steel wire diameter > steel wire lead. When the speed, lead, and diameter of the steel wire were 15 r/min, 65 mm and 7 mm, respectively, the operation performance was superior. High-speed video camera analysis and bench tests showed that the results were consistent with the simulation optimization. The mean value and the coefficient of variation of fertilization were 9.39 g and 3.71%, respectively, which satisfy the agronomic requirements for paddy field side deep fertilization.

Dinamika Amonium dan Nitrat Pada Lahan Sawah Semi Organik untuk Tanaman Padi Lokal dan Hibrida di Subak Jatiluwih Kabupaten Tabanan

Dynamics Of Ammonium And Nitrate In Semi Organic Rice Fields For Local And Hybrid Rice Plants In Subak Jatiluwih, Tabanan Regency. The study was conducted to determine the dynamics of ammonium and nitrate and time subsequent fertilization in paddy fields with local and hybrid rice. Soil and water samples in two replications were taken each the two paddy fields periodically, namely during the tillage (DTT), 0, 7, 14, 21, 28, 42, 56, 70, 84, 98, and 112 days after planting (DAP). Ammonium and nitrate levels were analyzed by Macro Kjeldahl method. The results showed that the dynamics of ammonium and soil nitrate were different in two rice varieties. The highest ammonium content of local rice at the age of 7 DAP rice and the highest nitrate content at age 14 DAP. Ammonium and nitrate levels are highest in hybrid rice fields at 28 DAP rice age. The lowest ammonium and nitrate levels in two different varieties of rice land, namely the lowest local rice varieties at the age 28 DAP, whereas in hybrid rice land at age of 98 DAP. The results of this study indicate that supplementation of urea can be carried out at the age of 21 and 98 DAP for local rice varieties, and at the age of 14 DAP and 42 DAP for hybrid rice varieties.

Development of a liquid-jet nozzle for fertilizer injection in paddy fields using CFD

The current broadcasting method for chemical fertilizer applications for rice production causes significant nitrogen losses through volatilization. To minimize this problem, a liquid-jet nozzle was developed for injection of liquid fertilizer in paddy fields. With computational fluid dynamics (CFD), the liquid-jet nozzle was modelled to examine the mass flow rates and velocities as affected by the critical design parameters of the nozzle: fertilizer inlet diameter (df) and nozzle orifice diameter (do). The model was validated with tests, and the performance of the liquid-jet nozzle was evaluated through injecting Urea Ammonium Nitrate solution into a clay loam soil. Simulation results showed that flow velocities decreased and mass flow rates increased at larger do values in a non-linear fashion. Effects of df were less pronounced and depended on the values of do. The model results agreed well with the test results with relative errors between 0.4 and 13.3%. Considering the requirements of nitrogen application rates for rice (60–180 kg ha−1) and soil cutting depths (20–50 mm), the optimal design parameters for the liquid-jet nozzle were the combinations of (df, do): (1.0, 1.0 mm) for producing the highest nitrogen application rate, and (0.6, 0.8 mm) for having the highest ability in cutting soil. The liquid-jet nozzle, a non-traditional injection method, has high potential to become a cost-effective and low soil-disturbance practice for rice production.

Long‐term mineral fertilization in paddy soil alters the chemical structures and decreases the fungistatic activities of humic acids

Fungistatic activity is a newly identified ecological function for soil humic acids. However, the relation between fungistatic activities of soil humic acids and their chemical structures is still unclear. In addition, how fertilizer application affects fungistatic activity is still unknown. We sampled paddy soils with different long‐term fertilizer schemes, namely: unfertilized control (CK), mineral fertilizer applied (NPK) and mineral fertilizer applied plus straw return (NPKRS). Soil humic acids were extracted and their fungistatic activities against 14 phytopathogenic fungi were investigated to evaluate their ecological functions. The humic acids from NPK and NPKRS treatments showed much smaller fungistatic effects than those from CK treatments. The chemical structures of humic acids were investigated by 13C nuclear magnetic resonance (13C NMR) spectroscopy. Long‐term fertilization significantly changed the chemical structure of soil humic acid, and the variation in chemical structure affected the fungistatic activities. The relative content of alkoyl C and alkyl C, the alkoyl C/alkyl C ratio and aliphaticity all had positive correlations with the fungistatic effects of humic acids. That indicated humic acids with more aliphatic and decomposable structures showed more fungistatic activity. From the results, we believe that long‐term application of mineral fertilizer in paddy fields makes the soil humic acids less aliphatic and more recalcitrant, and concomitantly weakens their ability to inhibit phytopathogenic fungi.Highlights We studied the inhibitory effects of paddy soil humic acids on 14 phytopathogenic fungi. Fertilization‐induced changes in humic acids affect inhibition of phytopathogenic fungi. Long‐term mineral fertilization significantly changed chemical structures of humic acids. Humic acid with more aliphatic and decomposable structures had more fungistatic activity.

Reducing ammonia volatilization from paddy field with rice straw derived biochar

Ammonia (NH3) volatilization is a major loss of nitrogen fertilizer in paddy fields. The incorporation of straw or biochar has been considered to be the alternative options for soil improvement and agriculture sustainability. A field experiment was conducted to evaluate the potential role of rice straw and rice straw derived biochar in controlling NH3 volatilization according to the conventional nitrogen fertilizer level (urea, 270 kg N ha−1) during one rice (Oryza sativa L., cv. Xiushui134) growing season. Four treatments comprised rice straw at the rate of 8 t ha−1 (RS); rice straw derived biochar at the rate of 2.8 t ha−1 (RSBL); rice straw derived biochar at the rate of 22.5 t ha−1 (RSBH) and a control (CK). Compared to straw application, biochar incorporation reduced the cumulative NH3 volatilization (about 20%) from paddy fields significantly (p < 0.05), promoted rice yields and plant N aboveground as well as increased the abundance of ammonia oxidation amoA genes. In contrast with the control, the ratios of NH3-N to total N input for RS, RSBL and RSBH declined significantly 4.15%, 4.40% and 11.12%, respectively (p < 0.05). Reduced NH3 volatilization in RSB treatments were mainly attributed to the decrease of NH4+-N concentration in the surface water, which could resulted from the enhancement of rice growth and the promotion of ammonia oxidation in soil. The increase of soil pH and soil CEC with biochar amendment played important roles in nitrogen retention and nitrogen cycle in soil. These results indicated that the incorporation of rice straw derived biochar instead of rice straw could be a promising approach to controlling NH3 volatilization and improving rice yield.

Occurrence characteristics of Echinochloa and its response to long-term fertilization in paddy fields of yellow soil.

We studied the characteristics of Echinochloa and its response to variation of rice yield and soil properties under long-term fertilization in paddy field of yellow soil, based on a 23-year long-term fertilization experiment in Scientific Oberving and Experimental Station of Arable Land Conservation and Agricultural Environment (Guizhou), Ministry of Agriculture. The occurrence characteristics of Echinochloa (density, panicle number per plant, totle panicles, seed number per panicle, 1000-seed mass and seed mass per panicle) of ten treatments including CK, N, PK, NK, NP, NPK, 1/4MNP, 1/2MNP, M (manure), MNPK were examined. The results showed that the characteristics of Echinochloa significantly varied with long-term different fertilization. The highest density, panicle number per plant and total panicles of Echinochloa were attained in the MNPK treatment, followed by the 1/4MNP treatment. Compared with the NPK treatment, the density of Echinochloa was significantly decreased in no fertilizer treatment (CK) and unbalanced chemical fertilizer treatments (N, PK, NK, NP). The panicle number per plant significantly increased in organic fertilizer treatments (1/4MNP, 1/2MNP, M, MNPK). Both the density and total panicles of Echinochloa were positively correlated with rice yield. The occurrence characteristics of Echinochloa were positively correlated with soil organic matter, total N, total P, available N, available P and available K. Results from path analysis showed that soil total N had a direct positive effect on panicle number per plant and soil total P content was the main factor affecting the density and total panicles of Echinochloa. Soil available K content was the factor with strongest influence on seed number per panicle and seed mass per panicle. We concluded that the occurrence characteristics of Echinochloa varied with long-term different fertilization. The density, panicle number per plant and total panicles of Echinochloa could be increased with appling cow manure. Soil total P was the direct influencing factor for the variation of density and total panicle of Echinochloa in paddy field of yellow soil.

Ammonia volatilization from Vietnamese acid sulfate paddy soil following application of digested slurry from biogas digester

In some areas of Vietnam, digested slurry from biogas digesters is discharged into canals without wastewater treatment. In order to reduce environmental pollution, utilization of digested slurry as a fertilizer in paddy fields is one promising measure. NH3 in the digested slurry is easily volatilized after application. Therefore, NH3 volatilization is a key factor for fertilizer design. In this study, we conducted laboratory experiments to examine the characteristics and mechanism of NH3 volatilization from Vietnamese paddy soil (acid sulfate soil) following application of digested slurry with the overall goal of evaluating digested slurry as a fertilizer. Incubation experiments under flooded conditions were conducted with Vietnamese acid sulfate soil and Japanese soil. Six fertilizer treatments were carried out, namely Vietnamese soil with no fertilizer, Vietnamese soil with urea, Vietnamese soil with digested slurry, Vietnamese soil with half the amount of digested slurry, Japanese soil with no fertilizer, and Japanese soil with digested slurry. pH, NHx–N, and SO4 2− in the floodwater and NH3 volatilization fluxes were measured for 1 week after application of digested slurry or urea. The results indicated that the amount of NH3 volatilization in Vietnamese soil is small compared to Japanese soil because the pH of floodwater from Vietnamese soil remains low (3.7–7.6) due to oxidation of pyrite, and this low pH inhibits NH3 volatilization. Therefore, we conclude that NHX–N in digested slurry can be efficiently utilized as a fertilizer in Vietnamese paddy fields with acid sulfate soils. Moreover, the results also indicate that relatively more NH3 is volatilized even in Vietnamese soil by the slowdown in pyrite oxidation and the buffering capacity of digested slurry when much digested slurry is applied. Therefore, NH3 volatilization can be reduced using methods such as a split application to maintain low floodwater pH.

PENINGKATAN PERTUMBUHAN PADI VAR CIHERANG SETELAH DIINOKULASI DENGAN Azospirillum MUTAN MULTIFUNGSI PENAMBAT N2, PELARUT P DAN PENGHASIL FITOHORMON INDOLE ACETIC ACID (IAA).

Modern agriculture rellies on the application of fertilizer to enhanched plant growth. Excessive application of chemical fertilizers in the long term will decrease soil fertility, therefore the use of biological fertilizers is expected to reduce the negative impact. The aim of this study was to determine the effect of multi-functional Azospirillum for N2-fixation, phosphate solubilizer and producing phytohormone Indole Acetic Acid (IAA) on the growth of rice plants Ciherang in the pot experiment conducted in the BB Biogen’s greenhouse. Two treatments were tested: types of inoculation (not inoculated, were inoculated with the wildtype AjB 6.4.1.2 and inoculated with mutant isolates AJM 3.7.1.14), and 4 levels of fertilizer application (not fertilized, a quarter dose of paddy fertilizer recommendations, a half dose of fertilizer rice in the rice fields, and the appropriate dose of fertilizer in paddy fields). Azospirillum used is wildtype isolate AjB 6.4.1.2 and mutant isolate AJM 3.7.1.14 isolated and and mutated in BB Biogen. Ciherang rice seed inoculated with Azospirillum on the cell density of 106 cells / ml at the different seedlings tub. After the age of 14 days after planting, the seedlings were transferred into pots with three plants per pot. Parameters measured were: plant height, number of tillers, number of panicles per clump, fresh weight and dry panicles per clump, weight of 100 grains, and the content of N and P stover. Results show that inoculantion, affect significantly on the number of panicles per hill, grain weight per panicle and the dry weight of grains per panicle.

Development of a Fertilizer Application Device Capable of Producing and Pouring Liquid Fertilizer in Paddy Fields

Development of a Fertilizer Application Device Capable of Producing and Pouring Liquid Fertilizer in Paddy Fields

Elevated methane emissions from a paddy field in southeast China occur after applying anaerobic digestion slurry

AbstractOne hundred million tons of farm stalk waste and livestock and poultry excrement are used every year in China for the production of clean energy (biogas) by anaerobic digestion. Consequently, a large amount of fermented liquid is produced, and if disposed of improperly, it will result in secondary pollution. Agricultural application of this anaerobic slurry as a liquid fertilizer would reduce possible eutrophication of water sources from random slurry discharge and supply a superior organic fertilizer for farming. This study investigated the effect of applying anaerobic digestion slurry as a liquid fertilizer on the methane emitted from a paddy field. A two‐year (2008–2009) field experiment replacing chemical fertilizer with liquid fertilizer from anaerobically digested pig manure slurry was conducted in a paddy field in Yixing, Jiangsu, China. A static closed chamber method was used to measure methane fluxes over the period from June 2008 to October 2009. All fertilizer treatments increased methane emissions relative to untreated controls, with increases in methane ranging from 40–70% in 2008 to 48–84% in 2009. Paddy fields treated with anaerobically digested pig manure slurry had greater methane emissions (8–84% in 2008 and 3–26% in 2009) than those treated with chemical fertilizer. This suggests that the anaerobic digestion slurry would increase methane emission and so is unsuitable as a liquid fertilizer in paddy fields without development of cultivation practices to limit these emissions.

Ammonia volatilization and nitrogen balance after topdressing fertilization in paddy fields of Taihu Lake region

采用密闭室通气法和¹⁵N 微区试验, 对太湖地区水稻不同生育期追施氮肥的氨挥发损失、水稻对氮肥的吸收利用和土壤氮素残留情况进行了研究。结果表明, 氨挥发损失主要发生在施肥后1 周内, 峰值出现在施肥后1~2 d, 氨挥发速率变化与田面水NH₄⁺-N 浓度变化规律一致, 分蘖肥和穗肥氨挥发损失率分别为16.7%和6.3%; 水稻分蘖肥的作物氮素利用率低于穗肥, 分别为36.7%和49.6%, 主要原因是穗肥的氨挥发损失较少,并且更易于向籽粒转移; 2 次追施氮肥的表观损失率分别为52.8%和40.7%; 在土壤中残留肥料氮为10.6%, 大都集中在0~20 cm 土壤中, 耕层以下较少。本结果表明, 在水稻孕穗时期施氮肥有利于提高氮肥利用效率、减少氮肥损失, 主要体现在穗肥拥有较低的氨挥发损失率和较高的籽粒利用率。