Azolla Biomass Research Articles

Hydrothermal carbonization of Azolla biomass for derived carbon as potential sustainable materials for efficient photosynthesis in agricultural plants and as electrochemical electrode materials

Hydrothermal carbonization of Azolla biomass for derived carbon as potential sustainable materials for efficient photosynthesis in agricultural plants and as electrochemical electrode materials

Origin and Evolution of the Azolla Superorganism.

Azolla is the only plant with a co-evolving nitrogen-fixing (diazotrophic) cyanobacterial symbiont (cyanobiont), Nostoc azollae, resulting from whole-genome duplication (WGD) 80 million years ago in Azolla's ancestor. Additional genes from the WGD resulted in genetic, biochemical, and morphological changes in the plant that enabled the transmission of the cyanobiont to successive generations via its megaspores. The resulting permanent symbiosis and co-evolution led to the loss, downregulation, or conversion of non-essential genes to pseudogenes in the cyanobiont, changing it from a free-living organism to an obligate symbiont. The upregulation of other genes in the cyanobiont increased its atmospheric dinitrogen fixation and the provision of nitrogen-based products to the plant. As a result, Azolla can double its biomass in less than two days free-floating on fresh water and sequester large amounts of atmospheric CO2, giving it the potential to mitigate anthropogenic climate change through carbon capture and storage. Azolla's biomass can also provide local, low-cost food, biofertiliser, feed, and biofuel that are urgently needed as our population increases by a billion every twelve years. This paper integrates data from biology, genetics, geology, and palaeontology to identify the location, timing and mechanism for the acquisition of a co-evolving diazotrophic cyanobiont by Azolla's ancestor in the Late Cretaceous (Campanian) of North America.

Reduction of some Heavy Elements of Agricultural Drainage Water using the Azolla Plant (Azolla)

The study was conducted at the Faculty of Science, University of Tikrit and included alaboratory experiments to estimate the proportion of some heavy elements (lead, potassium, cadmium, magnesium, iron) in the biomass ofAzolla pinnata plant to estimate its biocontrol ability to treat agricultural drainage water as samples were taken from the Azolla pinnata cultivated in two different types of agricultural drainage water and Tape water to estimate the percentage of elements before treatment in the water and after it at three periods (21,14,7) days. The results revealed Increasing the concentration of potassium, lead and magnesium elements in the extracted biomass of Azolla pinnata samples after treatmentof agricultural drainage water (1,2) while this increase was slight in tap water, as for cadmium, the results showed a decrease in its concentration in extracted biomass of A. pinnatasamples grown in agricultural drainage water (1,2) and tap water, and that the were non-significant differences (P <0.05) in the concentration ofiron element in extracted plant samples grown in agricultural drainage water1 as it remained at its concentration (2.69 ±0.00) during the three weeks, it also maintained its concentration in the samples of the extracted plant grown in tap water, reaching(2.86 ± 0.00), while the result shows there was a slight decrease in the concentration of Iron inthe extracted plant in treated agricultural drainage water 2, reaching (2.86) in the first week, decreasing to (2.69±0.00) in the second and third week.

Effect of Water Sources on the Growth Performance and Chlorophyll Content of Azolla pinnata R.Br.


 
 
 Azolla pinnata R.Br. is an aquatic fern that grows on the surface of water bodies. The unique quality of A. pinnata is its symbiotic relationship with a prokaryotic cyanobacterium (Anabaena azollae), which confers a high rate of nitrogen fixation. It is important to find the growing conditions of Azolla in different water sources for its optimum biomass production for different usages such as biofertilizers, animal feeds, water purification and biofuel production. This preliminary study was conducted to investigate the effect of water sources on the growth performance (shoot biomass, root biomass, root length), and the chlorophyll content of Azolla. Presence of Anabaena in Azolla fronds was monitored by light microscope and number of filaments were counted per leaflet. The experiment utilized three types of water sources (tap water as control (T1), lake water (T2) and cattle manure mixed tap water (T3), in plastic buckets with 40 cm in diameter and 25 cm in height. Each treatment was triplicated in a completely randomized design and total biomass was collected weekly. Data were statistically analyzed using Minitab 17. The highest biomass of Azolla was obtained in T3 from the first week until 8th week and it was higher from T1 and T2. The highest chlorophyll content was obtained in T3 (6.4 SPAD value) showed a significant difference from T1 and T2 (p<0.05). The dry weight of roots and root length in T1 showed a significant difference from T2 and T3 (p<0.05). The highest root length was observed as 5 cm in T1 indicating that roots may be in search of nutrients and the lowest root length was observed as 0.8 cm in T3 with high nutrient concentrations in water. The highest number of Anabaena was observed in the leaflet of Azolla fronds in T3 which in turn increase N content in Azolla plants. It reveals that application of cattle manure in tap water significantly affects the plant biomass and the chlorophyll content of Azolla. Further studies are needed to conduct in large scale growing facilities with different nutrient concentrations of water sources to find sustainable and optimum growing conditions for Azolla and the nutrient concentrations of the plants.
 Keywords: Azolla, Chlorophyll, Growth performance, Water sources
 
 

Azolla of poultry farms, reproduction, production of its biomass'use as additional feed

In this article, poultry enterprises in wastewater Azolla (Azolla carolinianaWILL) the results of scientific and practical research carried out for the purpose of plant propagation and water purification, as well as the use of the resulting azolla biomass as additional feed for feeding broilers, are described. During the research poultry farm enterprise After planting Azolla in wastewater, its physico-chemical composition was studied (day 8), it was found that the water temperature in the experiment increased from 27.5 0C to 33.8 0C, the water (pH) environment changed from acidity to alkalinity (6.8-7, 6) increased, the color changed from reddish-yellow to transparent, the smell disappeared, the amount of suspended matter decreased (107.5-72.5 mg/l), the amount of oxygen (1.4-12.3 mg/l l) increased, the amount of KBS5 (123.5-28.7 mg/l) decreased, the amount of O2 in the oxidation process increased from 118.4 mg/l to 28.9 mg/l, and the amount of ammonia decreased from 9.0-1.8 mg/l l, as well as the loss of nitrites, nitrates, sulfates by 121.0-67.0 mg/l, chlorides by 113.0-54.8 mg/l, phosphates by 8.3-1.4 mg/l it was noted that it decreased to. At the same time, the biomass of Azolla in 8 days when Azolla is planted in poultry waste water is 100 g/m2from 750g/m2has been found to have increased to Broiler by giving 10-25-30% additional feed from Azolla biomass to the main feedohall are fed. Broiler johThe animals were fed for 35 days, with 30% azolla biomass as the main feedohOut of the total 340 kg of feed used during feeding, the main feed was 238 and the additional feed was 102 kg. In this case, broiler j compared to the controlohIt is scientifically proven that the weight of the cattle increased by 0.2 kg and 102 kg of basic feed was saved.

A comprehensive study on the assessment of chemically modified Azolla pinnata as a potential cadmium sequestering agent

The major environmental issue raised throughout the world is the egression of toxic pollutants in water bodies. Hence, employment of novel technological interventions such as bioremediation and phytoremediation for mitigating the toxic effects caused by the pollutants has gained attention. The aquatic macrophyte, Azolla pinnata is utilized as a biofiltering agent in the present study for the chelation of metal toxicants from the artificial wastewater system. The nutritive value of A. pinnata was determined to be 268.99Kcal/100g energy and the mineral profiling showed the highest amount of calcium (54.7ppm), iron (14.04ppm) and manganese (7.96 ppm). The quantitative screening of total phenolic and total flavonoid contents showed a maximum of 402.33±4.29 mg/g GAE and 105.25±3.81 mg/g QE respectively and the sample exhibited strong antioxidant activity in quenching the DPPH radicals with an IC50 value of 88.27μg/ml. Similarly, the highest bioactivity was observed in methanolic and chloroform extract of A. pinnata biomass showing the zone of growth inhibition against E. coli (17mm) and S. aureus (18mm). The results recorded from the SEM-EDX, GCMS, FTIR and XRD confirmed the adsorptive properties of biomass. The chemically modified and unmodified Azolla exposed to cadmium metal solution showed the maximum adsorption of about 0.47±0.001 and 0.48±0.003 ppm in 60mins using the unmodified biomass with dosage of 0.75 and 1.0g respectively. Moreover, the results recorded from the instrumental characterization for the adsorptive properties of Azolla biomass proved that cadmium chelation is due to the modifications caused in porosity, surface structure and the addition of functional groups in the treated biomass surface.

The Role of Bacteria and Factors Affecting the Biodegradation of Pollutants in the Biofilter Reactor: A Review

The findings showed that several types of bacteria can help biodegrade organic pollutants, such as Comamonadacea, which can biodegrade volatile fatty acids and aromatic compounds. Proteobacteria, Bacteroidetes, and Actinobacteria can biodegrade ammonium. Burkholderiales can biodegrade ferric ions and hydrogen. Comamonas testosteroni is able to biodegrade nitrates. Pseudomonas taiwanensis, Acinetobacter guillouiae, and Klebsiella pneumoniae can reduce copper, chromium and zinc levels. Azolla biomass reduces strontium. Rhodospirillum sp. can biodegrade cadmium, mercury, lead, and nickel. Gallionella ferruginea and Leptothrix sp. can biodegrade arsenic and manganese. Gracilaria sp. can biodegrade aluminum, chromium, and zinc. Desulfovibrio sp. can biodegrade copper, zinc, nickel, iron, and arsenic. Thiomonas sp. can biodegrade arsenic and iron. Thauera selenatis can biodegrade copper, zinc, cadmium, nickel, lead, cobalt, chromium, and mercury. Thiobacillus thiooxidans can degrade both zinc and copper. Sargassum filipendula biodegrades copper and nickel. Meanwhile, in the findings of the factors that affected biofiltration, it was identified that there were four that played a significant role such as temperature, dissolved oxygen, hydraulic retention time, organic loading rate, biological organisms, and supply nutrients. In conclusion, several types of bacteria grow and help biodegrade in biofilter reactors. This is inseparable from the supporting factors that increase the efficiency of pollutant reduction in biofilter reactors.

Effect of Azolla Culture Medium on Biomass, Nutrient and Protein Concentrations of Azolla and Its Application as a Nutrient Supply for Bell Pepper

Effect of Azolla Culture Medium on Biomass, Nutrient and Protein Concentrations of Azolla and Its Application as a Nutrient Supply for Bell Pepper

Identification of combustion regularities of fuel mixtures from Azolla biomass, goat manure biochar and goat manure bio-oil for FCC furnace

Fluid catalytic cracking (FCC) is a method of cracking vegetable oils into simpler fractions and green fuel oils. One component of the FCC system is the FCC furnace. The FCC furnace is where the combustion process occurs and provides high heat transfer throughout the FCC system, especially for heating the reactor. The reactor temperature is the catalyst cracking temperature. The cracking temperature of the catalyst depends on the feed oil used in the cracking process, such as crude palm oil at 450‒550 °C or crude bio-oil at 300 °C. The fuel for heating an FCC furnace is usually coal. To reduce coal, we use a mixture of Azolla microphylla biomass with biochar and bio-oil from goat manure. The aim of this study was to analyze the mixture of Azolla microphylla biomass with biochar and bio-oil from goat manure to obtain sufficient furnace temperature to heat the FCC reactor, perform analytical calculations to obtain the volume of flue gas formed from the combustion reaction. We conducted two experiments; the first experiment used a mixture of 1 kg of Goat Manure Biochar (GMBC) with 0.5 kg of Azolla microphylla and the second experiment used a mixture of one kg of GMBC with 0.5 kg of Azolla microphylla plus 300 ml of Goat Manure Bio-oil (GMBO). A fuel mixture of one kilogram GMBC with 0.5 kg Azolla is not effective in combustion because the maximum temperature in the furnace is 177 °C but the fuel mixture of one kg GMBC, 0.5 kg Azolla and 300 ml GMBO has a furnace temperature of 472.75 °C, which can heat the stripper up to 313.25 °C so that cracking can occur in the raw bio-oil. Analysis of combustion results showed an increase in total CO2 volume from experiment one and experiment two of 0.966

Quail (Coturnix coturnix japonica) Fermented Manure as a Fertilizer to Support Azolla microphylla Growth Rate

Azolla (<em>Azolla microphylla</em>) is a potential livestock feed due to its fast-growing and relevant nutrient content. Quail farming generates manure as a by-product that can be used as fertilizer to support plant growth. This study aims to determine the dose effect of fermented quail manure on the growth rate of Azolla, as well as the nutritional content of the resulting Azolla biomass. The data were obtained through observation in 20 Azolla culture ponds according to the design method throughout the research for the Azolla growth rate parameters and laboratory tests to analyze manure and Azolla proximate content at the end of the study. The results showed that treatment of 50, 100 and 150 g m<sup>-2</sup> of quail manure gave similarly good effects on the Azolla growth parameters, indicating that the application of quail manure can significantly increase the production of Azolla biomass<em> </em>in culture ponds. The resulting Azolla biomass from all treatments gave a value of 93% to 95% moisture content, 18% to 19% ash content, 36% to 42% protein, 20% to 37% fiber, 2.8% to 4% fat and 5% to 6% carbohydrates. Looking at the big picture, therefore, 100 g m<sup>-2</sup> manure treatment is considered the most optimal among the rest. Based on the result obtained, this study can provide an overview of the dose of quail manure that can be used to support the growth of Azolla.

Interspecific Variability in Growth Characteristics and Phytoremediation of Cu by Free-Floating Azolla Macrophytes

The phytoremediation potential of aquatic plants, particularly for Cu, is scarcely reported in the pertinent literature. In this regard, differential growth behavior and phytoaccumulation ability of three free-floating Azolla species (A. japonica, A. pinnata, and A. hybrid) were evaluated in a climatically controlled (a temperature of 25/20 °C, light/dark 16/8 h, a light intensity of 60 µmol m−2 s−1, and a relative humidity of 65%) microcosm study. Azolla plants were exposed to solutions having three Cu concentrations (0, 3, and 6 mg L−1) under two incubation periods (4 and 8 days). Different Cu treatments significantly reduced Azolla biomass during both incubation periods and A. pinnata was the most sensitive species. Azolla plants grown in aqueous solutions showed substantial variations in Cu removal capacity. Higher bioconcentration values displayed by Azolla plants indicated that these plants can be deployed as potential plants for Cu removal from Cu contaminated water. Nevertheless, the plants exposed to higher Cu concentrations displayed color changes and root detachment due to Cu phytotoxic effects which may also ultimately lead to plant death. Significant correlations between Cu removed from the aqueous solutions and Cu contents of plant biomass indicated that Cu phytoremediation by Azolla plants was due to the phytoaccumulation mechanism because the removed Cu from aqueous solutions was accumulated in plant biomass. Introduced Azolla species, i.e., A. hybrid, displayed comparable Cu removal efficiency with naturally grown Azolla species, i.e., A. japonica and A. pinnata. Tested Azolla species proved to be suitable candidates to remediate Cu contaminated water and can be deployed for phytoremediation.

Critical evaluation of novel applications of aquatic weed Azolla as a sustainable feedstock for deriving bioenergy and feed supplement

Azolla is often considered an invasive weed because of the rapid colonization on water surfaces. It is a free-floating aquatic fern, known for its N fixing potential, short doubling time, and bioremediation potential. It has several applications as green manure, N biofertilizer, cattle, chicken, and fish feed supplements because of its high protein content. It can grow on wastewater improving its quality. Azolla biomass thus produced can be utilized for energy production. It has been used for the production of biogas. Recently, its bio-oil potential has been studied. Azolla biomass has been used for biodiesel, biogas, and biohydrogen production. The exploitation of Azolla biomass as feedstock for bioenergy needs critical evaluation.

Aquaculture wastewater-raised Azolla as partial alternative dietary protein for Pangasius catfish

Azolla is a freshwater floating aquatic fern found in the tropical, subtropical and temperate regions with a high nitrogen-fixing rate from the result of symbiotic relationship with the blue-green cyanobacterium, Anabaena azollae. Azolla can effectively remediate aquaculture wastewater owing to its high production capacity and the ability to absorb nutrients and toxic compounds. The Azolla biomass generated as a by-product is currently underutilized and could potentially benefit the aquafeed industry in replacing the unfeasible and expensive fishmeal protein at a certain level. This study evaluates the incorporation of red tilapia wastewater-raised Azolla as a dietary protein for the growth performance, feed efficiency, survival, body indices, body composition and nutrient utilization of Pangasius catfish Pangasianodon hypophthalmus during a 90-days feeding experiment. Dried Azolla was incorporated into four isonitrogenous (30 g kg−1) and isolipidic (12 g kg−1) practical diets containing 0 g kg−1 (Control), 10 g kg−1 (A10), 20 g kg−1 (A20) and 30 g kg−1 (A30) fishmeal protein replacement. One hundred and twenty juveniles with an initial mean weight of 45 ± 15 g were distributed into 12 tanks representing four dietary treatments in triplicates. Results showed significant (p < 0.05) improvement in weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and feed conversion ratio (FCR) in Pangasius catfish fed 10 g kg−1 Azolla protein. Beyond that, WG, SGR, PER and FCR decreased to the lowest value when fed with 30 g kg−1 Azolla protein. No significant (p > 0.05) effects were recorded for feed intake, survival, body indices and nutrient utilization amongst all dietary treatments. In conclusion, Azolla raised from red tilapia aquaculture wastewater can replace fishmeal protein up to 10 g kg−1 in the diet of Pangasius catfish juveniles having better growth, feed efficiency and nutrient utilization without affecting its survival, body indices and body composition.

Assessing the Plant Phytoremediation Efficacy for Azolla filiculoides in the Treatment of Textile Effluent and Redemption of Congo Red Dye onto Azolla Biomass

In this work, Azolla filiculoides was used for the bioremediation of a textile effluent and as a potential sorbent for the rejection of Congo red (CR9) dye from a synthetic aqueous solution. The sorbent was characterized, and a pot culture test was carried out to assess the physiological responses in a controlled environment. The response of the plants to the exposure to the emanating pollutants was subordinate. The BOD, COD, and TDS removals were found to be 98.2%, 98.23%, and 90.29%, respectively. Moreover, the dried biomass was studied for the expulsion of CR9, and the process variables were optimized. The maximum CR9 removal was 95% at the optimal conditions of 2 g/L of the sorbent dose at acidic pH. Equilibrium data for adsorption were analyzed using a two-parameter isotherm model. It was observed that the Langmuir isotherm fit with the data (R2 = 0.98) and also had satisfactory lower error values, with its maximum sorption capacity reaching 243 mg/g. The pseudo-second-order kinetics were well fitted (R2 = 0.98). The mass transfer models and the thermodynamic parameters of the system were evaluated. The regeneration studies also showed that the uptake efficacy in the fifth cycle is reduced by 20% when compared with the first cycle. The results show that the biomass was a capable sorbent for the removal of CR9.

Biohydrogen Production from Aquatic Plant and Algae Biomass by Enterobacter cloacae Strain DT‐1

AbstractProcess parameters were optimized for enzyme (textile‐grade enzymes) hydrolysis of Azolla, water hyacinth, and algae biomass for recovery of maximum sugar to be used as feed for biohydrogen production by Enterobacter cloacae strain DT‐1. Under optimum temperature and pH, the hydrogen yield in mole per mole of sugar from enzyme‐hydrolyzed water hyacinth biomass, Azolla biomass, and Spirulina and Scenedesmus biomass was determined with regard to cellulase, hemicellulase, amylase, pectinase, and xylanase. The maximum hydrogen yield was observed with hemicellulase‐treated Spirulina, Azolla, and Scenedesmus biomass.

Effect of metal nanoparticles on microbial community shift and syntrophic metabolism during anaerobic digestion of Azolla microphylla

Supplementation of anaerobic digesters with conductive nanoparticles (NPs) is considered as a potential approach for augmenting methanogenesis, however, their impact on microbial diversity, methanogenesis routes and metabolic pathways appear to differ depending on the substrate and operational conditions. Hence, in the present study, using metagenomics and KEGG pathway analysis, an attempt was made to gain an insight into the influence of two NPs viz., Fe3O4 and Ni, on the microbial composition and metabolic pathways during anaerobic digestion (AD) of Azolla microphylla. Results showed that addition of both Fe3O4 and Ni NPs at optimal concentration significantly accelerated the substrate degradation rate (89.8%) thereby enhancing the biomethane yield by 49.1% in anaerobic reactor (M3) supplemented with NPs as compared to control (M0). The dominance of microbial species (Enterococcus sp.) belonging to Firmicutes phylum in M3 reactor, indicated an efficient hydrolysis of Azolla biomass, owing to abundance of glycoside hydrolase (GH)-coding genes in their genome. Metagenomic analysis showed the enrichment of Geobacter sp. and Methanosaeta harundinacea in NPs-amended reactor confirming syntrophic metabolism of AD intermediate products that could have resulted in enhanced hydrogenotrophic methanogenesis via DIET. Predominance of Fe (III) reducing acetoclastic methanogen Methanosarcina acetivorans in NPs-fed reactor might also have been attributed to enhanced methane production. KEGG pathway analysis also showed an enhancement of major metabolic pathways viz., Carbohydrate metabolism, Methane metabolism and Lipid metabolism, in M3 reactor which further signifies the stimulatory effect of NPs.

Azolla Biomass as Liquid Biofertilizer to Improve Yield and Productivity of Paddy Plant Using Efficient Monitoring System

Azolla Filliculoides has been utilized as biofertilizer to increase productivity and yield of paddy. Azolla was used as a good source of nutrient to the paddy plant. In this study, we investigated the growth and productivity of paddy plant supplemented with liquid Azolla biofertilizer. The preparation of Azolla was monitored under several parameters such as pH, dissolved oxygen, temperature, and salinity in an aquaponics system. Water quality analysis of the aquaponic system was monitored by using the Arduino system which the customized design that consists of a microcontroller to record the parameters directly to the computing device in a single optimum and efficient system. The nutrient composition of liquid Azolla biofertilizer was analyzed by using Inductively Coupled Plasma Mass Spectrometry (ICP/MS) and CHNS elemental analysers. hows that liquid Azolla contents 0.958% nitrogen, 15.5 ppm phosphorus and 159.8 ppm potassium. After four months, the yield of paddy on Azolla was 149.12 kg/he with the productivity of 63.157 kg/he/year. This application helped to an efficient monitoring system for measure high yield and productivity of biofertilizer by Arduino software monitoring. This study can act as an initial step for the web-based automated control and monitoring of the food production system.

Comparison of hydrothermal carbonization and torrefaction of azolla biomass: Analysis of the solid products

The effect of torrefaction and hydrothermal carbonization has been studied on Azolla filiculoides, which is a potential aquatic biomass feedstock for renewable energy sources. Hydrochar and torrefied azolla samples were prepared at three temperatures (260, 280, 300 °C) with 15 min residence time. The thermal behavior and the volatile content of the raw and thermally treated biomass samples were determined by thermogravimetric analysis, while the detailed composition of the volatile contents was analyzed by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The major pyrolysis products were phenolic compounds, monocyclic and condensed aromatic hydrocarbons, nitrogen heterocycles, nitriles, carbohydrate decomposition products, phytosterols, and fatty acid derivatives. Principal component analysis on Py-GC/MS data revealed that the pyrolyzates of the samples differed significantly depending on the temperature and type of pretreatment. Hydrothermal carbonization resulted in more severe decomposition at each temperature than torrefaction. The volatile content of torrefied azolla decreased gradually with torrefaction temperature, while 280 °C was a sufficient temperature to remove the majority of the volatile content during HTC. The amounts of phytosterols decreased to the highest extent during both treatments. The thermally less stable carbohydrate components of azolla were decomposed during torrefaction, while hydrothermal carbonization affected other constituents of the biomass (e.g., proteins), as well. During pyrolysis, the formation of aromatic compounds (phenol, benzene, pyridine, and pyrrole derivatives) was more favored from hydrochars than from torrefied azolla.

English

Azolla tissue contains 5% N, which is slowly released into the soil upon decomposition. Timing of incorporation is therefore important for maximum benefit to a crop. The effect of time to incorporate Azolla biomass on growth and yield of rice was investigated in Mwea-Kenya. Treatments consisted of 7.5 t ha-1 Azolla biomass applied at transplanting, 7.5 t ha-1 Azolla applied at 21 days after transplanting (DAT) and 30 kg N ha-1 inorganic N applied in splits at O, 21 and at 55 DAT. There were control treatments without Azolla and without inorganic N application. The treatments were laid out in a Randomized Complete Block Design (RCBD) with three replications. Phosphorus and potassium were applied at 50 Kg ha-1 each as P2O5 and K2O. Plant height and tiller numbers were recorded at 21 (rooting/tillering), 32 (tillering), 42 (maximum tillering), 60 (flowering) and 75 DAT (heading) while yield parameters were determined at physiological maturity (120 DAT).&nbsp; Data were analysed using SAS software and means separated using the least significant difference test (p&le;0.05). Azolla incorporation at transplanting significantly enhanced panicle m-2, grain weight and grain yield while incorporating it at 21 DAT only significantly enhanced panicle m-2. Higher environmental temperatures enhanced Azolla effect. The effect of Inorganic N significantly increased plant height, tiller number, grain weight and spikelets panicle-1. However, percentage grain filling was reduced. The effect of interaction between Azolla application and inorganic N was significant on spikelets panicle-1 and grain weight. Observations therefore indicate that the effect of Azolla on yield and yield components was more when incorporated at transplanting. Key words: Azolla, incorporation time, inorganic fertilizer, rice yields. &nbsp

Azolla Fern in Mwea Irrigation Scheme and Its Potential Nitrogen Contribution in Paddy Rice Production

Azolla fern is invasive in Mwea Irrigation Scheme in Kenya and its management in paddy rice fields is a challenge to farmers. A survey was undertaken to establish farmers&amp;rsquo; knowledge and potential nitrogen contribution by Azolla in the paddies. The Scheme was stratified into seven sections and a questionnaire administered to 250 farmers. Data were collected on awareness levels, source, trend of infestation, abundance, fertilizer regimes and management practices. Five farms from each of the sections were also sampled for Azolla coverage and tissue N levels analyzed. Survey data were analyzed using SPSS software and interpreted using descriptive statistics. Biomass sampling data were analyzed using SAS software and means separated using the least significant differences at P &amp;le; 0.05. &#x0D; &#x0D; The results demonstrated that Azolla has infested nearly all the paddy farms in Mwea. Azolla invasion occurred more than 10 years ago and coverage per unit area was on a decline and stood at 25%. Water shortage and herbicide use were the main reasons associated with this trend. Azolla is conspicuously noticed at transplanting and weeding times. The presence of Azolla in Mwea is enhanced by widespread use of P and K fertilizers and continuous paddy cropping, thus providing a suitable environment for Azolla growth. Azolla was reported to enhance soil fertility, rice yield and yield components. The maximum Azolla biomass coverage was 14.92 t/ha, with a potential nitrogen contribution of 37.6 kg N/ha. Azolla is invasive in Mwea, widespread, beneficial to paddies and with a high potential N contribution.