Gypsum Amendment Reduces Redox-Induced Phosphorous Release from Freshly Manured, Flooded Soils to Floodwater

The effectiveness of gypsum in reducing runoff P losses from soils and the mechanisms responsible are well documented; however, gypsum amendment effects in reducing redox-induced P losses from flooded soils are less researched and documented. We examined the effect of gypsum amendment on P release from freshly manured soils to pore water and floodwater with continuous flooding for 56 d in the laboratory. Three soils (Pembina, Denham, and Dencross series) collected from Manitoba, Canada, were preincubated with liquid swine manure. Each preincubated manured soil was packed into vessels with or without recycled wallboard gypsum in triplicates and flooded for 56 d, during which pore water and floodwater were sampled weekly and analyzed for pH and dissolved reactive P (DRP), Ca, Mg, Fe, and Mn concentrations. Change in soil redox potential (Eh) with flooding was also monitored. Wallboard gypsum amendment significantly decreased the pore water and surface floodwater DRP concentrations in all three soils for most days after flooding (DAF). The Dencross soil, which had Olsen P about fivefold greater than the other soils, showed the greatest magnitude decrease in DRP concentration with gypsum amendment, by 1.27 mg L−1 on 49 DAF and 0.99 mg L−1 on 21 DAF for pore water and floodwater, respectively. Gypsum amendment (i) delayed the Eh reduction with flooding beyond +200 mV, (ii) decreased pore water pH, and (iii) increased concentrations of Ca, Mg, and Mn in pore water favoring precipitation of P, all of which may have directly or indirectly reduced the P release from flooded soils to overlying floodwater.Funding for this research was provided by the University of Winnipeg Major Grant and a Natural Sciences and Engineering Research Council Discovery Grant to Darshani Kumaragamage, and a fellowship awarded by the Queen Elizabeth Advanced Scholar Program to R.S. Dharmakeerthi.https://acsess.onlinelibrary.wiley.com/doi/10.2134/jeq2018.08.030

Phosphorus Release from Unamended and Gypsum- or Biochar-Amended Soils under Simulated Snowmelt and Summer Flooding Conditions

Prolonged flooding changes the oxidation–reduction status of soils, often enhancing P release to overlying floodwater. We studied P release from unamended, gypsum-amended, and biochar-amended soils under simulated snowmelt flooding (previously frozen, cold flooding at +4°C) and summer flooding (unfrozen, warm flooding at +22°C) using two soils, Fyala clay (FYL-Cl) and Neuenberg sandy loam (NBG-SL), from Manitoba, Canada. Amended and unamended soils were packed into vessels and flooded under cold and warm temperatures in the laboratory. Pore water and floodwater samples were taken weekly for 6 wk after flooding (WAF) and thereafter biweekly for 10 WAF and analyzed for dissolved reactive P (DRP), pH, and cation concentrations. The NBG-SL showed a significantly higher DRP concentration in pore water and floodwater despite its low Olsen P content. Redox potential (Eh) decreased slowly under cold versus warm flooding; hence, redox-induced P release was substantially lower under cold flooding. Gypsum amendment significantly decreased the floodwater DRP concentrations in NBG-SL by 38 and 35% under cold and warm flooding, respectively, but had no significant effect in FYL-Cl, which had low DRP concentrations (<1.2 mg L−1) throughout the flooding period. Biochar amendment significantly increased floodwater DRP concentrations by 27 to 68% in FYL-Cl under cold and warm flooding, respectively, but had no significant effect in NBG-SL. The results indicate substantially less P release under cold than under warm flooding. Gypsum was effective in reducing floodwater DRP concentrations only at high DRP concentrations; thus, the effectiveness was greater under warm than under cold flooding conditions."Funding for this research was provided by a National Sciences and Engineering Research Council (NSERC) Discovery Grant and a University of Winnipeg Major Grant to Darshani Kumaragamage, and a fellowship awarded by the University of Winnipeg–Queen Elizabeth Advanced Scholar Program to R.S. Dharmakeerthi."https://acsess.onlinelibrary.wiley.com/doi/10.2134/jeq2019.02.009

Phosphate Solubilizing Bacteria and Fungi Isolated from Rubber (Hevea brasiliensis) Root Rhizosphere, Their Biofilm Formation and Phosphate Solubilizing Abilities

The ability of some soil microorganisms and their biofilm combinations to convert insolubleforms of phosphorus to an accessible form is an important trait associated with plant Pnutrition. The phosphorus solubilizing potential of bacteria and fungi isolated from Hevearhizosphere and their effective biofilm communities were evaluated using solid and liquidmedia under in vitro conditions. Phosphate solubilization ability of them were tested oncalcium phosphate media by analysing the soluble P content after incubation at 28±2°C. Outof the microbial isolates, 10 bacterial colonies and one fungal colony formed haloes (clearzones) around the isolate growing on solid media containing calcium phosphate as the solephosphate source. Spectrophotometric quantification of phosphorus solubilization in theliquid media showed that the ten bacterial isolates, and ten fungal isolates solubilizedinsoluble calcium phosphate in to the liquid media in the range of 200 – 450 and 200 – 300mg P L-1 respectively. Biofilm showed significantly higher P solubilization (853.3±25.17 mgP L-1) than their bacteria and fungi counterparts alone. Phosphate solubilization of bacteria,fungi and their biofilm could be attributed to the secretion of organic acids. A significant dropin the pH of the broth media (4.7 to 5.6) compared to the pH of the control treatment (6.8-7.0)was observed. pH change in the media could be due to secretion of organic acids bymicroorganisms and/or utilisation of compounds in the broth media. Although there was asignificant synergistic effect on P solubilization due to biofilm formation, pH in the liquidmedia of their mono cultures and biofilm were not significantly different. This observationwarrants further investigation

Agent based solution for artificial neural network optimisation

Artificial neural networks are highly used in the areas of pattern recognition, feature extraction, function approximation, scientific classification, control systems, noise reduction and prediction. Feed-forward and back-propagation neural networks are the most commonly used artificial neural networks. Many researchers face difficulties when selecting a proper ANN architecture and training parameters. The manual ANN training process is not the best practical solution because it is a much time consuming task. Also most of the people conduct the manual process in an ad-hoc manner without having a proper knowledge about artificial neural networks. At the end of this research project a multi-agent system: MASAnnt (Multi Agent System for Artificial Neural Network Training) was developed to automate the neural network training for feed-forward and back-propagation neural network. Interaction among agents enables emergence of quality training sessions which cannot be archived by an ad-hoc training sessions conducted by humans. It is straight forward to recognize training parameters such as number of hidden layers, number of neurons in each hidden layer, momentum, learning rate, Emax (Error goal) and activate function of an ANN as a set of agents. Inherent features of agents including coordination, communication and negotiation are able to mimic the ANN optimizing and training process by manipulating theses parameters. Our experiments show that the more rational results can be obtained from the system with both simple data sets like XOR as well as with real life data sets. We can conclude that the neural network optimization and training tasks are successfully accomplished by the agent based approach by analysing the results of the evaluation

Exploring the Response of Paddy for Varying Levels of Soil Phosphorus in Tropical Soilscapes

Better management of soil Phosphorus (P) in crop cultivation leads to environmental and economic benefits. Proper understanding of the crop response to inherent soil P is important to develop site-specific recommendations. The objective of this study was to assess the yield response of paddy for varying levels of inherent available soil P in Alfisols and Ultisols. Surface soil (0-15 cm depth) P content was measured in 71 paddy fields in three districts of Sri Lanka, namely Anuradapura, Kurunegala and Polonnaruwa. Experiment plots (3x6 m) at each site comprised of ample application of N, P and K and an omission treatment plot of P. Total yield of each plot was recorded at the end of the season. The available P showed a large variability (range=from 2.7 ppm to 34.2 ppm, CV=78%) meanwhile 31% of the experimental sites were below the optimum soil P level for paddy (5 ppm).Omission plot treatments did not show a clear yield response for added P. Very low correlation coefficient between the yield of the omission treatment with the inherent P level (0.05), indicated that inherent P level will not determine the yield. The yield response was plotted against the Olsen P, and very low R2 value (0.03) indicated the Olsen P content does not clearly reflect the actual P requirement in every experimental sites. Short term availability of P from soil reserves cause to mask the effects of spatial variability on yield response and it was concluded that further studies are required to assess P dynamics to take SSNM decisions.Keywords: Paddy, Phosphorus, Site specific nutrient managemen

Stability cogitated electric vehicle charging infrastructure planning

Electrification of the transportation is taking place at an accelerated rate. Even though, electric vehicles (EV) evidently bring numerous environmental and economic benefits, their impact on power systems should not be overlooked. It has been identified that EV load characteristics can significantly affect power system voltage stability and small signal stability. Hence, it is important to consider mitigating of stability impacts right from the planning stage of bulk EV charging stations. However, unavailability of suitable stability evaluating indexes that could fit into planning algorithms is a hindrance. This study proposes two computationally efficient indexes to compare stability status in different planning options. The developed indexes have been tested, verified and utilized in a multi objective planning algorithm to identify a comprehensive solution, which satisfies the grid operator, EV customer and the charging facility investor optimally