 Well, welcome everyone to this session. This online training session organized by Glossola, the Global Soil Laboratory Network. I will have a short introduction to this webinar and then the proper training session will start. So let me share my screen. I will briefly introduce you to the session. I hope you can see my screen. So this is the, today we have an online training session on the standard operating procedure for soil-available phosphorus using Olsen method. My name is Filippo Benedetti and I work at the Global Soil Partnership of FTO, coordinating and supporting the coordination of the Global Soil Laboratory Network. I'm a member of the Global Soil Laboratory Network of the Global Soil Laboratory Network. It is called Glossola. For those of you who are not aware of this network, this is a global network grouping together soil laboratories worldwide that is structured in different regions. So we have within the global network, several regional networks, also called Resolans and these cover different regions. So we have a network for Asia, it's called SealNet, a regional network for Near Eastern North Africa soil laboratories that is called Ninalab. Then we have Afrilab for African Laboratories, Eurozolan, which is grouping together laboratories coming from Europe and Asia. Then we have Aspa for laboratories from the Pacific region. And then we have Latsulan, the regional soil laboratory network for Latin American and the Caribbean. We are also working with countries to establish national soil laboratory networks to group together all soil laboratories operating within the same country. And as you can see, the network increased a lot in the last years. And now we are currently approaching 800 members. So if you are not yet members of the network, please visit our website and I strongly encourage you to register the network because you will have the chance to join several activities such the one of today, that is the on capacity development, then there is also session on other topics. Then we have activities like internal and external quality control, harmonization of standard urban procedures. And as you can see here, this is a screenshot of our website where you can see all the different topics that Glosson is taking care of. So we take care of course of sonalities. So again, internal and external quality control, standard urban procedures. And we try also to organize several capacity development sessions, so webinars on wet chemistry, like the one of today, then dry chemistry as well. So webinars on soil spectroscopy, webinars on health and safety, and some webinars on quality assurance and quality control will be organized soon. We also take care of particular generalities via the Infa network. Glosson is also working on equipment. So we support laboratories with food chasing and the maintenance of the equipment. And we are also working on soil spectroscopy and we have initiative on soil spectroscopy. On our webpage on capacity development looks like this. So each webinar you have the link to register and another view of the training. So who is gonna give the training? So the short biography of the trainers. So you can see the background and the short abstract of the training. So you can have a look to the webinar topic, let's say. And after the implementation of the webinar, we upload online all the material. So even after today's webinar, you will be able to see again this webinar because we are currently video recording it and we will upload the video recording online. So after the webinar, you will be able to just click on the recordings and you will link to, and YouTube link where you can re-watch this webinar. If you would like to go through it again and you can also consult the presentation that will be displayed today. This is another view of all the training sessions organized by Glosson from September up to December of this year. As you can see, we on the right part of the screen we implemented several webinars on soil spectroscopy. And a new series of webinars on soil spectroscopy will be organized in the beginning of 2022. So I will invite you to have a look on our website to get all the information about that. While on the left side of the screen, you can see all the webinars that have been organized regarding wet chemistry. So we have some for Oldson, like it was implemented in Spanish in October. Then one webinar was on Elton safety in laboratories. Then we had a couple of webinars on Saturday soil test extract, both in English and Arabic languages. Then a couple of weeks ago, we had one webinar on what claim back matter for measuring soil organic carbon. And today's webinar is on soil available phosphorus by Oldson. Still, I would like to present you to invite you to register today, upcoming webinars that will be on the next ones are on handling and preparation of soil samples for chemical and physical analysis. So basically sample pretreatment and this will be implemented both in English and in French. So six and seven December. On our website, you can find the link to register. So please have a look at them. After we will have a webinar on soil electrical conductivity that will be held on 14 of December. And a webinar on internal quality control in soil laboratories is currently under organization and will be implemented on 15 December. The timing is still has to be confirmed, but we will upload all the information soon on our website. Today's training session is about soil available phosphorus using Oldson method and we'll follow the procedures, the SOP that was harmonized by Glossolan in last year. So basically if you go on our website you can download this document. It's a PDF file that guide you through all the steps of the procedures. So for sample preparation to quality assurance and quality control, health and safety measurement, all the steps of the calculations. And so I invite you to download this file. And the link is here. So you go to different website, you click on you see on the right in the screenshot. You go to analysis, then standard operating procedures. And then you can look for those on phosphorus and check the one you click here on Oldson method. You can download the SOP. So basically the webinar of today will cover all the aspects of this SOP. Again, this webinar was given already in October by in Spanish, was that in Spanish that session it was organized by some colleagues from Mexico. And today some colleagues from the Philippines are giving this more or less the same webinar in English this time. And so I would really like to thank once again the colleagues from Mexico and that held the webinar last time and the colleagues from the Philippines for the kind availability to support Glossolan in this activity and to implement this training. So today we have with us Dr. Gina Nilo that is the assistant director of the DSWM that is the Bureau of Soil and Water Management in the Philippines. There we have Mrs. Perfina Sanchez, and Mr. Bill Gilbernardo, and Mrs. Lira Espectacion still from the Bureau. So the Bureau of Soil and Water Management. So without any further ado, I will now give the floor to them. Basically, let me just give you a short overview on how the webinar will be structured. So after this short presentation, the trainers will give the presentation of the procedures. And after that, you will have time to take the floor, interact directly with the speakers, raise questions to them, bring to their attention some issues you're facing in your laboratory about these procedures. You can share your experience and your questions. You can also write such question in the chat. We will try to answer them in the chat or answer them after in the questions and answer session after the presentation. So now we'll give the floor. I don't know who each colleague from the Philippines will share the presentation, like Birgil or someone else or Dr. Gina. Maybe you are there. You want to make a short introduction to your colleagues. Thank you. Let me introduce you, Dr. Gina, the director of the BSWM. Thanks you once again, Dr. Gina, for your availability to you and your team. We really appreciate your support and your kindness, the ability to give this training and to share your knowledge with all the other gross land members. So Gina, the floor is yours. Thank you very much, Sir. Pilipo. Greetings everyone from the Laboratory Services Division of the Bureau of Souls and Water Management. Indeed, it is with great pleasure for our blessed and strong women and men. That's the meaning of BSWM. It is our great pleasure as the National Reference Laboratory of the Food and Agriculture Organization to take the lead in this training for the available phosphorus using Olsen Method. And for this evening, I am pleased to introduce our team. And with me is Ms. Florefina Sanchez. She will hand them. Ms. Flore, come on, please show yourself in the video. Yes. So Ms. Florefina Sanchez is the chief of the soil chemistry section of our laboratory. And also she will discuss on this introduction and scope of application of the analysis using available phosphorus using Olsen Method. Also for this evening in the Philippines, it may be morning afternoon to you. We have Mr. Bernaldo, Michael author for this method. He will discuss on the principle and factors affecting the analysis. And of course, our very able analyst, Ms. Lyra Spectacion, she will do the presentation for the step-by-step procedure of the Olsen Method. So indeed, we are happy to be with you this evening. And much more so, we are happy to receive your comments and questions at the end of the session. So let us all enjoy this very important session. And we hope that through this training, we can contribute to our one mission at Glossolan. That if we cannot measure it, we cannot manage it. And this is our intention. Olsen P is one of the standard test method that we promote because we want that all our data will be interchangeable and exchangeable. So all of you, welcome to this training and God bless us all. Thank you. So Berheel, you will miss Floor. The floor is yours for the introduction and scope of application of this analysis. Thank you, Floor. It seems that you are muted. Can you unmute? You can mute it, that's why Floor. Well, you can read the floor. Would you like to? Explain it. What is your opinion? Okay. Yeah, the sound is not very clear. No, not very well. At least me and other colleagues. It's okay with you, Floor, if you move here. Mahina. Okay, good morning. Yeah, thanks. Can you hear me now? Yeah, yeah, much better, thanks. Can you hear me now, sir? Phillipo? Yeah, much better now, thanks. How about the presentation? Can you receive it now? But you are not wrong, I would like to hear more. Yeah, Floor, we can hear you. Is it okay, sir? Yeah, yeah, you can proceed. Okay. So, B. Thank you, sir. Thank you, sir. Thank you, Floor. You're welcome to join us. Okay, once again, good morning, good afternoon, and good evening to everyone. So, we are going to discuss the standard operating procedure for available phosphorus using the Olsen method. For the introduction, phosphorus in soils. Phosphorus in soils is essential to all forms of life on this planet. It is an important nutrient necessary for growth and development of plants and animals wherein our food supply depends. Soil phosphorus is found in two forms, namely the organic P and B in organic P. These two forms together make up the total soil phosphorus. Organic forms of phosphorus include dead plant or animal residues and soil microorganisms. Soil microorganisms play a key role in processing and transforming the organic phosphorus into plant-available forms. The inorganic phosphorus forms can be classified to exist in three different pools. The first one is the plant-available phosphorus. This pool is comprised of inorganic phosphorus dissolved in soil water solution that is readily available for plant-uptake. The second pool is sorb phosphorus. The phosphorus pool, this phosphorus pool is comprised of inorganic phosphorus attached to clay surfaces, iron, aluminum, and calcium oxides in soil. This is released slowly for plant-uptake. The third pool is the mineral phosphorus. This phosphorus pool is comprised of primary and secondary phosphate minerals present in soil. An example of primary phosphorus minerals include apathyte, stent jive, and varicide. While the secondary phosphorus minerals include calcium, iron, and aluminum phosphates, but the release of this phosphorus from this pool is extremely slow and occurs when the mineral weather dissolves in soil water. Next slide, please. This is the effect of pH and the distribution of orthophosphates in solution. So phosphorus in solution makes this both as orthophosphates or higher polymers. Phosphorous in soil solution, however, will be almost exclusively as orthophosphates. The individual species of orthophosphates that will be in solution body with pH are shown in this figure. We have the orthophosphates, the dihydrogen phosphate, the hydrogen phosphate and the phosphates. This species, in most agricultural soils, the pH will be between four and nine and the ion species present will be dihydrogen phosphate and hydrogen phosphate. The ion species present is somewhat relevant to plant uptake of phosphorus since it has been shown that plants prefer the monovalent ions. From this figure, the concentrations of phosphorus found in soil solution may range from less than 0.127 or eight milligram per liter or PPM, depending on soil pH and the recent addition of fertilizer phosphorus and other soil factors. The maximum level of phosphorus in soil solution will be at pH between 6.5 and eight. Now we go to the brief history of phosphorus extraction methods from the soil. Soil testing for phosphorus has been formally conducted in the United States since the late 1940s and is now a well-established agronomic practice. The fundamental goal of soil P testing is to identify the optimum P concentration required for plant growth and to define the inorganic fertilization needs in the economic return and investment in phosphate fertilizer. Next slide please. These are the list of soil test P methods most commonly used today. Methods for determining soil P is various forms in availability to plants have been essential in developing principles and knowledge of the nature and behavior of possible skin soils. The purpose of these methods is to characterize the P in the soil system. Many methods exist, but they vary in principle and technical details. Continuation of P, next slide please. The Olsen P method was developed by Sterling R Olsen and four workers in 1954 to predict crop response to fertilizer P in foods and calcareous soils using the 0.5 molar sodium bicarbonate as extracting solutions adjusted at a pH 8.5. Next slide please. Higher coloration between the phosphorus extracted in the laboratory by the method and that observed by these crops and this adjusted scale for interpretations is if this less than 5 ppm the response was expected. Between 5 and 10 ppm the response was probable and less than 10 ppm response was unlikely. So values were collaborated by other researchers from similar soils and crops and had been erroneously extrapolated for other crops without taking into account the root density of the crops. Next slide please. Usually this method was used in the North Central and Western United States and this is the difference used by the researchers using this Olsen and Sauber using the authorship of Olsen and Sauber. So next slide please. In soil analysis we distinguish two types. The first one is the total analysis and the fractional analysis. The Olsen P method corresponds to the fractional type or in the fractions of this element present in the soil must be related to the response of plants to the application of phosphate fertilizer. There are numerous methods for extracting P fractions with different sets of generated values. However, these only have meaning when they are associated with the response of the plants. Next slide please. This correlation and this figure shows the correlation between the extractable phosphorus and the percent of maximum yield for soybeans, corn, and wheat. The intersections of the dotted and dotted and solid lines indicate the critical point for further fertilizer additions will not economically increase yields. Next slide please. The scope of application. The method, this Olsen P method is best suited for carcarose soils, particular with those greater than 2% calcium carbonate, but it has been shown in some search to be reasonably effective for moderately acidic soils according to the fixian and rogue in the year 1990. In the Olsen method, best phosphorus is extracted using 0.5 so the sodium bicarbonate solution adjusted at the pH of 8.5. As shown, the calcium phosphates will react to the sodium bicarbonate at the pH of 8.5 to produce a precipitate of calcium carbonate and the phosphate ions that we are determining. This method is based on the use of bicarbonates, carbonates, and hydroxyl ions to decrease the solution concentrations of soluble calcium ions by precipitation as calcium carbonate and soluble aluminum ions and iron ions by formation of aluminum and ferric oxyhydroxides, which does increase the solubility of phosphorus. The increased surface negative charges and or decreased number of sorption sites and iron and aluminum oxide surfaces at high pH levels also enhance the sorption of available phosphorus in two solutions. As discussed by the, that they've been during 1980 and other authors, different methods give variable results according to the type and concentration of the extractant, the soil solution ratio, time of shaking and temperature. Results obtained with different P methods are seldom comparable. So these tables use these soil properties to consider when selecting a method to determine the phosphorus and recommended methods according to El Rashidid in the year 2010. So results obtained, therefore, analysis of P and soil must always be provided with the name of the analytical method used. For a given method to be useful, the laboratory data must also be correlated with crop production data from field experiments. Typically, the laboratory test methods that gives the greatest correlation with plant growth and yields under defined conditions, sorption climates are selected. This will vary with crop type and density of planting. As a result, a wide range of analytical methods as shown in this table is used to determine available phosphorus in soil throughout the world. So now I'm going to turn over to floor two, one of my colleague, Mr. Virgil Bernaldo to discuss about the principles of the Olsen-Meco. Now Mr. Virgil, now the floor is yours. Thank you. We cannot hear you. Can you hear me now? Yeah, now, yes, thanks. Okay. So thank you to Mom Floor for her wonderful discussion on the brief introduction and the scope of this glossoled SOP. Now for my part, I will discuss the principles of the Olsen method extraction and also some other important details when it comes to the effect of time, the size of the vessel and agitation when you do the shaking part. Also, I will discuss some important points when you start to analyze the soil using this method and some review of our basic chemistry. So to proceed, let me go into my presentation. Can you go to the next slide? Okay, so let us understand how P, is located in the soil. So as you can see in our picture, in the picture presented in our screen, usually P is available in inorganic or organic forms which are somewhat readily available for uptake by the plants through the roots. But usually the inorganic phosphorous forms are more available for plant uptake than the organic form. Inorganic phosphorous forms are primarily mixtures of aluminum and iron phosphates, as you can see in this yellow figure. And also it is also available in calcium phosphates. Then the relative percentages between these three forms in soil are a function of soil pH. With higher percentages of aluminum and iron phosphates in acid soils and higher percentages of calcium phosphates in neutral to alkaline soils. That is why we qualify Olsen as a method of extracting phosphorous for alkaline soils. Neutral to alkaline soils while for the Bray 1 and Bray 2 is a method for extracting phosphorous for acidic soils. So next slide. The Olsen method also uses sodium bicarbonate extract. I think it's in the next slide. So for this one, what phosphorous does the Olsen method extract from the soil? So we should be the P extracted by Olsen method from the soil. It mostly comes from as what I have said earlier, mostly from P unsorbed on the surface of iron and aluminum minerals with the different crystalline tea and on calcium carbonate particles. And also from organometallic and phosphate complexes of relatively high solubility. But for this one for the Olsen method, the most common type of P is analyzed from soils which have higher percentages of calcium phosphorous. Next slide. Okay. So why and how does Olsen extract and solubilize phosphorous? So how do these extract and get the available inorganic phosphates from the soil? So as you can see in our simple diagram and the left part of the figure, you can see that those type of phosphates enclosed in the rectangle are present in the soil. When we now add the sodium bicarbonate in 0.5 molar, the sodium bicarbonate now releases the ions below as you can see the bicarbonate, the carbonate and the high c-lions at pH 8.5. So the solution is maintained or buffered at 8.5. Later you will know the importance of having the solution buffered at 8.5. And after that, when you now put the sodium bicarbonate, the type of phosphates present in the soil are now released and readily available for analysis using the UVV's spectrophotometer. Later on the presentation of this slide, I will visualize how it happens. Okay. So usually the hydroxide and can you go back first? Okay. So usually the hydroxide and carbonate ion can see the sodium bicarbonate solution controls the activity of aluminum and iron in the soil by precipitation of calcium as carbonate and aluminum and iron as hydroxides. As a result, the phosphate concentration can also increase. Next slide please. So there are numerous factors that can affect the analysis of phosphorous. So there are four, extraction solution, extraction time, vessel size and type of agitation. Also extraction temperature. And also spectrophotometric measurement. So it is important to note that let us be careful when we analyze the soil using this method because there are numerous factors that may affect the analysis. So let's go to the first factor that may affect or during the analysis. Okay. So the effect of extraction solution are meaning the pH of the extracting solution. As you can see in our table, table one, this table comes from the book by Beeler 2002, Influence of pH on Bicarbonate Extractable Phosphate. So as you can see in the first row, we maintain the 0.5 normal or it is also equivalent to molar, letter M, sodium bicarbonate. So as we prepare that 0.5 molar or normal sodium bicarbonate solution, we intend to maintain the pH only to 8.5 plus or minus 0.05. So meaning 8.55 will do, 8.54. Also, we can also reach, for example, up to 8.45. So we should take note of the deviations when it comes to the pH of the solution because in this table you can see the table shows that the pH was, the researcher tried to determine the factor of having high pH of the extracting solution. So you will see 8.5, 8.75, and pH 9. You can see that there is a significant increase in pH. So if you have a solution that is more than 8.5 plus or minus 0.05, 0.05, automatically it's either you will be positively or negatively biased, meaning you will extract more phosphorus or you will not extract the phosphorus that this method provides. So let's go to the next factor. So we have the effect of time, vessel size and type of agitation. So commonly this method allows for 30 minutes of agitation or shaking period. By study, if you, for example, forgot to turn off the shaker or if you did not consider the timer, if you shake the samples for around five to six minutes, there is no significant increase in the phosphorus that you will extract. But if you extracted it far more than 30 minutes, let's say this one, 40 minutes, the increase in shaking time also increases the amount of phosphorus by 5%. So it is to call this directly proportional. Another factor is the vessel size. So it is critical that the extraction vessel contain a minimum of 25% dead space occupied by air to provide sufficient agitation while you are shaking the samples. Next is, it is also recommended that the reciprocating shaker be used for the extraction to allow proper contact of soil and the solution while it is shaking in the shaker. Other laboratories, I think they also use what you call this type, the orbital shaker. But for this method, we recommend the use of reciprocated shaker. Now we go to the effect of extraction temperature. So by inspection, you will see that when you look at the X axis, which is the temperature, and the Y axis, which is the concentration of the extracted phosphorus, you will see that there is a direct proportion. When you increase the temperature of the environment or the solution where you are shaking the samples, automatically you will have greater amount of phosphorus that will be extracted by this method. So it is important that you maintain the temperature of the room to around 20 to 22 degrees Celsius or 20 to 25 degrees Celsius at ambient or normal room temperature to avoid overextracting the phosphorus content of the soil. Next slide. Another is the spectrophotometric measurement. As you can see in this figure, also by Miller 2002, you will see that there is an influence in the spectrophotometric wavelength on phosphate sequence. You will see that there is a comparison between 616 nanometers and 882 nanometers. So this method only uses 882 nanometers because by study, it is found that 882 nanometers wavelength is superior and does not have a soil-soluble organic interference that is noted for the 616 nanometers wavelength and originally the method for Olsen was developed for 616 nanometers but eventually the researchers found out that 882 nanometers is a better option for this method. And also using 882 nanometers will also prevent you from high bias of phosphorus when you are measuring. Next slide. Now I will go through the measurement or quantification which is part 2 of the brief introduction to the UVA-based spectroscopy because this method uses that technology measuring the pea content. Next slide. Okay. So this is a short review of our basic chemistry. So usually electromagnetic radiation is a form of energy and it can be described in both waves and particles. The interaction of electromagnetic radiation which is in this case is light with matter is what we call the spectroscopy. So there are regions of the electromagnetic spectrum and in this analysis we will be dealing with the UVA-based region only with a wavelength of 882 nanometers. So as you can see 882 nanometers is on the right most part of this figure around the red color. But as we studied in our chemistry usually what you can see is the color of the solution which in this case is color blue. The detected wavelength is the complementary of that one. So it is actually on the red part of this color scheme. Next slide. So what are the processes that occur when the electromagnetic radiation or the EMR affects the matter? So in the figure, usually in spectroscopy the light energy interacts in different ways with matter through first absorption, emission, deflection, transmission, scattering, or diffraction. So each interaction in this closed certain properties of matter and different type of information about the matter can be obtained. And magnitude of those light gradations absorbed or emitted by matter are measured with the help of instruments like spectrophotometer. So in this case the principle is absorption. So for this one it's just a figure or application of the beer lumbered slough where you will see that in this method we measure the transmittance or the amount of light transmitted through a sample by rationing the intensity of the incident light to the intensity of the transmitted light. So absorbance measurements are frequently used by an unknown samples concentration by exploiting the beer lumbered slough. That describes how light is attenuated based on the materials it passes to. Next slide. Okay, so this is the basic structure of a spectrophotometer. So it is relatively straightforward. First there is a light source and a wavelength dispersive element. Third there will be a detector. I mean fourth there will be a detector because the light passes through first here in the number three which is the sample solution. Then there is the detector and last would be the digital display or the meter. Basically we just measure the amount of light that passes through the solution because the solution containing the complexes already absorb part of the light that is coming from the light source. So it is very straightforward explanation. Next slide. So chemical reactions in the colorometry of phosphorous. So the measurement or the determination of phosphorous we'd expect through phosphopic methods is based on color development. In the coloration process the molybdenum blue methods are the most sensitive and as a result they are widely used for soil extracts containing small amount of phosphate as well as for total P determination source. These methods are based on the principle that in acid molybdenum solution containing or toposphate ions the phosphomolive date complex is formed which can be reduced by ascorbic or other reducing agents which for example is tannous chloride in the presence of potassium antimony tart rate to form a blue-pollard complex. So the product of this analysis is a blue-pollard complex which will be measured using the UV spectrometer. Next slide. So there are some questions in measurement. So when we measure the phosphorous extracted you should take note that the correlation coefficient between the concentration of the standards and the absorbance of the collared solution on the calibration curve should be greater than or equal to 0.995. And if the absorbance of the samples is greater than that of the peak of the curve or the highest standard you just dilute the extract with the extraction solution and record the dilution factor. Then you can take a new alicone and repeat the operation. Next is you should verify the preparation of the agents standards and the instrument configuration and operation if it is correct because it may also take part in the random bias during random errors during the analysis. Next is in PO sender are frequent contaminations that may arise or detected by a slight coloration of the blank. You should take special care in washing the glassware if you can purchase phosphate free detergents it is much better to avoid contamination of your blank solution. Next slide. Okay, so next is there are some cases that there will be some interferences in the color of the solution because of the organic matter. So sometimes there are solutions that are dark blue or you cannot really classify or qualify if it is a color blue because the organic matter has an effect to it. So what you can do is that you can put activated carbon in the soil when you shake it and you can also filter the solution so you can have a clear blue color solution when you now put the mixed reagents. Next. So there are also interferences due to the ion solution. So the antimony and potassium tartrate form usually the color hetero polymolipid complex or the molipid blue color. So the antimony accelerates the development of the blue color and usually it stabilizes it for 24 hours and there is no interferences expected from silicon. Also the final pH of the colored solution remains within the plateau of maximum stability of the complex. The final acidity of the solution contributes also to the precipitation of suspended materials. Alright, so for the next part of our presentation I will turn over the floor to Miss Lyra Expectation. Thank you everyone for listening. Okay, thank you Sir Virgil for the kind introduction. Again, good morning, good afternoon and good evening to everyone and thank you for attending this webinar. At this moment I will be presenting the step-by-step procedure for the determination of the available phosphorus using the AllSense method. So let me start my discussion with the presentation of the equipment and laboratory wares that we need to prepare before the analysis. So here are the list of equipment and laboratory wares for the AllSense analysis. So for the laboratory wares we have Eileen Mayer-Flast 125 ml, Fanel for the filtration process, Vickers for the preparation of our agents, polyethylene bottles with lead, wide-mouth type 125 ml capacity, as mentioned earlier by Sir Virgil, and then volumetric flests for the preparation of our solutions and working standards. And graduated cylinder test tubes, micropiped and volumetric pipettes. For the equipment we should have a UV-Vis spectrophotometer that we will be using for the quantification of the extracted phosphate in our soil sample and then analytical balance with a precision of at least 0.001 gram and the reciprocating shaker and vortex mixer. For the reagents and required chemical solutions, here are the list of reagents and chemical solutions that must be prepared before the analysis of AllSense method. So all of these chemicals and reagents must be of at least analytical grade. So first we have the extracting solution. So this extracting solution, as mentioned earlier, is the Sojong bicarbonate solution with a concentration of 0.5 molar, adjusted to pH 8.5, using the 1 molar sodium hydroxide. Another reagent is the mixed reagent. So the mixed reagent composed of 200 ml of the ionized water, 50 ml of 4 molar sulfuric acid, 15 ml of 4% ammonium molybdate solution, and 30 ml of 1.75% ascorbic acid solution, as well as 5 ml of the 0.0275 potassium antimony 33 solution. So the mixed reagent must be prepared fresh daily as the ascorbic acid solution is not stable and will degrade over time. So next is the ionized water that we will be using for the preparation of these reagents. The phosphate free activated charcoal and ours working standard series. So for the preparation of standard solution, we first have to prepare a 100 ppm standard phosphate solution. So we can do this by using an NISD traceable 1000 ppm of the phosphorous stock solution. So alternatively we can also use the potassium dehydrogen phosphate dried for two hours at 110 degrees Celsius. Next is the preparation of the 4 ppm secondary standard phosphate solution. So to prepare this, we should pipet for example we prepare 250 ml volumetric flask for the secondary phosphate solution. We can pipet 10 ml of the 100 ppm standard solution and then make it up to volume with the extracting solution. So lastly is the preparation of our working phosphate standard series. So in a 100 volumetric flask we will pipet 10, 20, 30, 40 and 50 ml of the 4 ppm secondary standard phosphate solution and make it up to final volume with the use of our extracting solution. Then our working standard series will have a 0.4, 0.8, 1.2, 1.6 and 2 ppm. So please also note that the range of the standard series or our working phosphate standards can be adjusted according to the equipment specification and the expected concentration of phosphorus in the analyzed soil samples. So for the caution in the preparation of reagents seems almost every log uses the chemicals and in this case we use many chemicals for the analysis of also never. So chemical safety rules are amassed and following these policies helps us to avoid steels and other accidents as well as to damage the environment outside of the laboratory. So here are the list of the caution and safety rules that we must follow while working in the laboratory, especially when conducting this analysis. Since the OZMP procedure involves the use of hazardous chemicals we should always refer to the safety guidelines or the safety data sheet before proceeding with the analysis. And we should always wear PPE. So what is PPE? PPE is already proper personal protective equipment includes the use of a laboratory coat, gloves, shoes, dust or dust mask and appropriate gloves as well as safety glasses when we are performing chemical analysis to mitigate the harmful effects of chemical exposure. Next is to observe careful and proper handling of chemicals when using strong alkali bases such as in this case we use sodium hydroxide and strong acids for example the sulfuric acid that we use for the preparation of the mixed reagent and oxidizing agents and to avoid mixing incompatible chemicals to reduce risks of fire and explosion inside the laboratory and of course always pour the acid into water to avoid splattering. So as mentioned earlier we should always refer to the safety data sheet of the chemicals that we will be using in this analysis before proceeding. So here is the summarized information on the chemicals, chemical hazards from the safety data sheet of the chemicals that we should be aware of. So first is the sulfuric acid. So sulfuric acid is a clear color less and it is extremely corrosive and causes severe burns if not handled properly. So we should always dilute it by adding a small portion of acid to a large amount of water and of course we should always work under a fume hood to avoid inhaling its vapor. Next is the ammonium molybdenum solution which is also a corrosive liquid and contact of dissolution with the eyes or the body may cause serious health injuries and reaction with metals reduces hydrogen and in a fire reduces sulfur oxides. So as we all know sulfur oxides are pollutants that contribute to the formation of acid or particulate pollution and they are harmful to our lungs and it makes us difficult to breathe. Another caution in the preparation for agents for the asporic acid it has no known effect on the skin or body and it should be stored in light resistant containers because it is light sensitive and we should always step it away from incompatible materials such as oxidizing agents. For the potassium antimony turret rate it is hazardous in case of contact with our skin or body and we should not dispose it down the drain and it is also incompatible with strong acids bases and oxidizing agents. For the activated charcoal it is also hazardous in case of contact with skin or body and may cause eye and respiratory irritation if inhaled. So we should always keep it away from heat sparks, open flames and hot surfaces. So for the sample preparation for the preparation of our soil samples it must be air dry or dried in a in an air force oven at a temperature of 35 plus minus 5 degree Celsius and then grind and sieve to less than or equal to 2.0 millimeter size. So we will now proceed with the step-by-step procedure for the analysis of this ALSEN-P method. So the ALSEN-P analytical procedure is divided into two parts. First is the extraction process wherein as mentioned earlier the carbon dioxide from the bicarbonate is driven off and the pH increases and the bicarbonate will then be converted to carbonate. So the calcium, magnesium, aluminum and iron in the soil the activity of these of these ions are reduced as the calcium, magnesium and aluminum hydroxides are formed and increasing the quantity of the phosphates in the extracted solution. Second is the quantification or the measurement of the extracted phosphates of the UVVS spectrophotometer which was explained also earlier by Mr. Burjil. So for the extraction process the first part of the procedure is to weigh 5 grams of the air-dried soil sample into a wide-mouth 125 ml capacity shaking bottle. So we then should include two blanks and three quality control materials or other check samples in your laboratory. Next is the addition of the 100 ml sodium bicarbonate solution which was adjusted at pH 8.5 and then the addition also of the half teaspoon phosphate free activated charcoal. After that we can mechanically shake it for 30 minutes for mechanical shakers ranging from 180 to 200 oscillations per minute and the shaking bottles must be placed horizontally to provide the sufficient agitation or mixing of the soil and our solution. After that we can filter it through a filter paper what number 42 or with an equivalent acid-drated identical porosity filter paper. The second part of the analysis of all sentry is the spectrometric measurement or the quantification of the extracted phosphorous. So for this process we should biped 3 ml of water and the sample extracts into test tubes. After that we can slowly add the mixture agent by pipetting and homogenize it using the vortex mixer. Then we can allow the solution to stand for at least one hour for the blue color for the colorimetric determination of phosphorous. We can read after the standing time of the extracted in the mixture agent, we can then read the absorbance of the calibration standards the blunts and the QCNs in the samples in a spectrophotometer set at 882 nanometer wavelengths. So if the absorbance of the samples is too high, as mentioned earlier, we can dilute the extract with the extracting solution and record the dilution sector. So the acceptance criteria for the correlation to efficient of the calibration must be greater than or equals to 0.995 to proceed with the analysis of the samples. So otherwise, we should verify that the standards and the agents have been correctly prepared and that the instrument is functioning properly or the instrument setup is correct. So following the beard lumbered slope the amount of light absorbed will be then directly proportional to the calculation of our sample. So for the calculations of the results of the analysis, here's how we can calculate the result of the analysis by following this equation. So the result is reported in mg per kilogram P and the calculation is A minus B where in A is the concentration in the extracted sample and B is the concentration in the target. Multiply with the volume of the extracting solution which is in this case we use 100 ml of the extracting solution and if we have a dilution sector multiply again with the moisture correction of the dilution sector over the weight of the sample which is 5 grams. So the concentration as mentioned earlier the concentration of the phosphorus will be in mg per kilogram P and it should be reported in an open dry basis with two decimal bases. So in this case, we need to implement the procedure that we should implement for the analysis of the ALSEN-P method. For the accuracy test we can participate in an interlaboratory proficiency test at least once a year and the evaluation is that the P2 score must be less than two or more than the P2 score. If not, we should identify the possible causes and perform corrections and develop corrective actions to solve the problem if we have a failed PT and the records must be the records of the actions taken must be kept. We can also perform replicate analysis of the certified reference material and the quality reference material that you have in your laboratory and compare the results with those of other laboratories as indicated in the certificate of analysis of the CRM which in this case the acceptance criteria the result of your analysis must be within the 95% confidence interval or the target value of the certificate of analysis of the CRM. For the precision test we can perform a replicate analysis of 10% of the samples in the test batch. For example we have a 50 samples in a batch every 10 samples we can perform a replicate analysis of the 10th sample so the evaluation of the replicate analysis is that we calculate the percent relative standard deviation to determine if the precision of the replicate analysis is within the specifications and compare the result with the target precision for the analyte concentration as given in the AOAC table for the expected precision. So here is the expected accuracy or repeatability as a function of analyte concentration given by AOAC. So for example we have a result of 10 ppm for the of our soil sample and the calculated RST for the replicate analysis is to we can say that those replicate samples are precise since it is within the acceptance criteria of this table that is the 7.3. Another quality control procedure that we can implement is the use of the control chart so the control chart is another tool to monitor the trend of our daily analysis. So we can analyze at least a replicate of the quality control materials external or internal per batch and then construct the control chart with the results and monitor the control chart for out of specified limits. So if there are any issues with the control chart we should also take action of it and identify the possible causes perform corrections or develop corrective action plan to solve the problem. Here are the references of this method and that is all for my presentation thank you for listening but I would like also to thank Dr. J.D. Itzvers and Dr. Claudia Hidalgo Mariano from Mexico as this presentation material was adapted from their presentation during the Spanish online training session of the All-Sentee method. So if you have any comments, questions or suggestions you may let us know through the comment section or you can raise your hand again Thank you, thank you very much. To all colleagues from the Philippines, from the Bureau thanks a lot for the nice presentation and for the clear overview of all these steps thanks for giving instruction on all the aspects of the measurements including quite assurance and quality control and all the measurements. I see there are lots of questions in the chat actually I will try to start from the first one and some of them the first one I see is from 1025, it's from Dr. Sajid Hussain asking what are the possible storage conditions for pH sustaining pH 185 extracting solution I know if you have other colleagues who like to answer on this Hello, good afternoon or good evening I already answered Dr. Sajid Hussain Hussain's question in the chat box so usually the storage of the extracting solution can be placed in number of bottles and it is preferable to prepare the extracting solution fresh or before the analysis you can also prepare it in advance provided that check the pH of the solution as it tends to increase over time if you see that the pH became 9 over time just adjust it manually to 8.5 again using diluted solution hydrogen fluoride okay so I just now I'm reading the tools already I just noticed that you already answered I see the tools to answer the other questions from Padua in Ladin I received a private message from Alisa asking if the question is in analyzing soil for available phosphorus is it necessary to analyze the soil using the methods Bray 1 and Knudsen method despite of the pH given the fact that Knudsen can also be useful in analyzing soil with acidic pH gladly acidic and alkaline we know that as you also showed we are concerning about the pH for this measurement so if you have come back to this point so stressing it in which method to choose according to the pH or if there is any advantages okay let me answer the information also usually what we do in our laboratory when we started also to apply the gloss on the SOP for Olsen we qualify our soil samples which is acidic and which is alkaline soils so we we set a pH if we analyze our soils using the Olsen method if we determine that the pH of the soil is 5.6 and above and we also analyze our soil samples using the Bray 1 method when we determine that the soil samples are 5.5 and below but you can also do try us in your laboratory you can compare your results if there are significant differences but in our case we use that limits to qualify which method are we going to use in our soil samples now in the case of the TRUG method we don't usually recommend it because it does not qualify the type of soil that it is applicable you might encounter over extracting or under extracting the available solution so it is better to check first what is the pH of your soil and now you qualify if you will use the Olsen if it is 5.6 and above or the Bray 1 method if it is 5.5 and below usually there are just minor differences in the results thank you thanks a lot for coming back to this point I see there are some questions now from Portugal if you already answered this they are asking if we are having to confirm the pH of extractors before the second point quantification or should we I know if colleagues from Portugal want to address this question to one particular speaker or if anyone from the Bureau want to answer to this one can we ask what time stamp it is so we can locate it in the chat box in Portugal you can take the floor also if you want to better explain your question or to specify who would like to address this one in the meantime there is another one I see from sorry ok thank you for the presentation ok actually I think this regards another procedure and we will provide another training another online training on nitrogen measurement in separate session let's just focus on available phosphorus today Luis asks what is your view on the range raising method is there universal methods for both acid and alkaline soil compared to water and rain I don't know if you or your colleagues have experienced this method or maybe Luis can you explain it to us so we can share this or do you know this one Miss Laira would like to answer the question from Portugal let's start with that I think the question is we haven't confirmed the pH of extract first before the second point or would you like to clarify it a little bit Laira I think they're asking if they should adjust first the pH of the extract ok Laira as mentioned earlier we should adjust first the pH of the extracting solution before the analysis since the first part of the analysis is that we add the 100 ml extracting solution before the quantification of the extracted phosphate so yes the pH of the extracting solution must be adjusted first before the quantification thank you Laira I think I also answered some of the questions in the chat box you can go back to it after this meeting I believe that Pilipo will be giving out the record of this meeting or will be posted at the FAO once further questions or clarifications sorry I got some problems thanks for the clarification I don't know if you really answered the other question about the raising one otherwise we can ask the colleagues from Luis to explain it better if you colleagues from the Philippines are familiar with this raising methodology Luis I see you have the hands up yeah thanks the reason for this is across all soil types so alkaline and acid because you're extracting basically at the native pH of the soil some have argued that that's a better option than trying to use a brave for acid also for alkaline but it's obviously a very tedious method for a long extraction time so I just want to know if your colleagues are here to explain it I know the result is quite popular but not so much in other parts of the world thank you thanks thanks for sharing this input Brigille or other colleagues from the Philippines are you familiar with this methodology I don't I to call this it's being referred to the method using high performance liquid chromatography if it is a expensive type of analysis because we use expensive kind of equipment and also very in use process but if we just would like to measure the only the pea content of soil we can up it using also using UVV spectroscopy okay thanks there is a question from Tobi asking what is the recommended temperature for the extraction solution okay thank you Mr Tobi for this question for the temperature of the extraction solution it must also be the same with the temperature of the working temperature so as in this case since it is recommended to have a temperature of 22-2 degrees Celsius for the working time for the extraction process of the outside method so I guess the temperature of the extraction solution must also be within that range thanks thanks a lot for the clarification I would like to check if there are other questions from the chat I don't know if I need someone to answer the question but I think again that the presentation will be uploaded online and together with the video recording of this session so you can say consult this material once again we'll upload this in maybe next week and we will try to send certificates to participants in the upcoming weeks we'll delay with that but we will do our best to send the certificates as soon as possible if you have any questions please if you want to share your questions feel free to raise your hand and you can take the floor mute your microphone so you can take the floor if you want I think all previous questions have been answered let me check if someone is waiting more Nur Azarina Abubakar is asking if there is any difference from Bray and Kurtz method do you know this methodology? colleagues? for the question of Nur Abubakar this method that we discussed is for the all cent method which analyzes for alkaline soils while the Bray and Kurtz method you mentioned is actually the Bray 1 method so the Bray and Kurtz are the one who developed the method so the Bray and Kurtz method or referred as Bray 1 method is a test method for estimating phosphorus in acidic soils so that's the difference between the two types of methods thank you I'm asking if is it mandatory to dilute samples with extracting solution or if laboratories can dilute it with water in case of high absorbance for this case we recommended you dilute it with extracting solution so that the matrix of the working standards and your samples are the same when you read it in the UVVS spectrum photometer thanks for the clarification is there any more questions from you can write it in the chat or raise your hand, you can take the floor please take advantage of this chance I highly encourage you to take the floor because you can share your experience with other colleagues or raise your questions to the experts so I think it's a unique possibility please feel free to take the floor is there any more questions once again if you feel like contacting the trainers after this session they wrote their email address in the presentation colleagues from Philippines you can write in the chat as well if you have any questions those participants who would like to contact you for any further clarification they may contact you directly in the meantime maybe let me show you once again those on the website while we are waiting for the last questions let me share my screen I will share with you here you have a clear overview of all our activities so some opportunities are here you can see all the increasing number of laboratories where the laboratories are displayed in the map you can even contact them information about our meetings and some key documents here such even the Global Soil Laboratory Assessment providing a nice overview of the needs you can see here on the left side of the menu you have less part of the screen you have a menu on our main areas of work so if you click on soil analysis for instance you see the address of the web page where all our activities concerning soil analysis are reported so you can consult the standard operating procedures where harmonized you can find the standard operating procedures for instance if you go on the standard operating procedures web page if you go down here you click on soil chemical analysis and you click on phosphorus then here you can find all the SOPs that glows and harmonize all of these SOPs last year we have a PDF file with all the procedures it was presented today so all the information about the preparation the parameters needed, the material and some preparation measures the procedures and the calculations and the reference and the quality assurance and quality control section and these you can do it for if you go on quality assurance and quality control for instance you find all our material so some guidelines to prepare quality control samples and auto-reverse samples for proficiency testing if you click here on the capacity development web page you will find the information on all the trainings we are currently organizing so if you click on wet chemistry part you will see all the details of the training implemented by Glowson if you scroll down you will reach the today's session so webinar on the implementation on cell phosphorus by outside methodology you will see a review of the trainings that we are presenting today and then here we will upload soon the presentation and the video recording of today's session so in upcoming week we will upload all the information, all the material of today's webinar and then we will have a preview session for all the information here and I would like to take the opportunity to show you the upcoming webinar so as mentioned already there will be one webinar on handling and preparation of soil samples for chemical and physical analysis so sample pre-treatment basically that will be held on 6th of December in English and then we will have a preview session on soil electrical conductivity done by some colleagues from Philippines and from Syria while this one will be done by colleagues from Afrilab and then another webinar on internal quality control will be organized soon so really please have a look at this web page because you can attend other meetings, other webinars of course all for free and I see Brigille continuing to answer in the chat so thank you a lot for taking care of that is there any more questions? Coming from the chat or from the floor please let me know let me thank once again all the colleagues from the Philippines who joined this webinar so Brigille, Dr. Gina Lira and Florfina we have a very nice participation and an active participation of course in answering all the questions there is a question in the chat and we now sometimes have received results for the old samples available or old samples modified what is the difference in case if the difference exists or if there is a difference between solvable phosphorus and soil phosphorus, let's say modified to answer the question of Mr. Husserabon so for the Modified Authentic Method I guess you are talking about the since the Authentic Available Method is the standard method when we say Authentic Modified Method there has been a modification in the analysis of Authent E from the standard method so yes they are different because in the Modified Method there is a modification in the analysis so if the Modified Method yet but I guess it also undergoes a method validation what is your thanks Lira I hope Husserabon answered your question is there any more questions from the participants please feel free to write your question in the chat or you can even raise your hand and check the floor here in the meeting you can ask your question directly to the trainers well if there is no more question let me thank once again all the trainers really thank you for your availability let me stress, I really like to stress this point every time we have these webinars I really think that when experts and soil laboratory staff members are ready to share their experience with other colleagues this is where Glossoma Network is successful I really like and I really think this is really a good story, a successful story and a success for all members of the network meaning that experts meet they share their experience on the methodology they adopt in the lab and again our purpose is to ensure that all the laboratories reach the same level and by collaborating and mutual support because we would like laboratories to produce reliable, interpretable and comparable data because these are the basis to produce maps these are the basis to make decisions and make sure that all the test-takers really celebrities are playing a crucial role especially today where soil is really giving like kind of governments are giving more and more importance to soil science and management so please be aware that your job as soil staff members is really crucial in this perspective so thanks again Yeah, thanks a lot for the training. So I don't know if you want to have some closing remarks. Before closing the sessions, I would like to invite you all to the World Solid Day Celebration. That will be, there are many events online organized, but the one taking place here at FAO at Coordination Room will be on Friday at 12.30 room time. I will now give you the link in the chat to register. So please register and join the webinar. They are in the session for the World Solid Day. That will be one hour long, and many key speakers will take the floor. And we will also have the chance to talk a little bit about our laboratories as we will have the chance to present the global assessment that was released and published in 2021. So I will now put the link in the chat to register to the World Solid Day and let me give the floor to the colleagues of Philippines to close the sessions and to provide final remarks. And thanks a lot again to all of you for your participations and especially to the trainers for the kind of availability. We cannot hear you, Dina. I think you're muted. Yes, okay. So thank you very much, Sir Pilipo. And again, as always, we thank the Food and Agriculture Organization for this privilege and indeed an opportunity to share with you all the standard test methods that we also do in our own laboratory being the National Reference Laboratory of the FAO and the lead convener of the Philippine National Soil Laboratory Network. I would like to share that in the case of the Philippines, there are 43 members of the Philippine National Soil Laboratory Network. And I would like to share this as an encouragement to all other laboratories that indeed the harmonization of test methods is something that will be very useful to all of us. And in the Philippines, as we are implementing the National Soil Health Program, it gives us the opportunity that all laboratories will be capacitated even through this training and that they share with us the responsibility to analyze voluminous data that are being generated all over the country and that all this data can be exchanged. So if that is happening within the Philippines, I would like to encourage all other members of the Global Soil Laboratory Network that we join hands, we unite with FAO in our efforts to harmonize test methods. So indeed, we are grateful, we are thankful to FAO for giving us this platform to be able to share our methods. And for this evening, morning or afternoon in your case, I would like to especially thank our presenters and my blessing at the Laboratory Services Division. They are all very capable. Our Chief of Soil Chemistry section, Ms. Florfina Sanchez. Thank you, Flor. And Mr. Berheel Bernaldo, the co-author for this post-poruse method using Olsen. And may I request Lyra, maybe you would like to show your beautiful face. I have very young, energetic, active people at our laboratory. That's one encouragement, Ms. Lyra Spectacion. So to all of you who stayed with us up to this time, who actively participated in the Q&A, indeed, we are very encouraged because of this interest that you have shown to this training. So keep on participating. We still have upcoming trainings. We will not get tired supporting this kind of activity. It is for all of us. Always our pleasure to serve. Maraming salamat po. God bless us all. Thanks, thanks a lot. Thanks a lot, everyone. So have a nice day, evening or afternoon, depending where you are. And thanks again for your participation. See you to the next training session of Rosalind. Have a nice day. Thank you. Thank you. Bye.