 Good morning, everyone. And thank you so much for tuning in today to the monthly animal science webinar today I'm gonna talk about using poultry litter in pastures and hayfields There are several topics that I'm gonna gonna cover today So some of the items that I'm gonna cover today is what exactly is poultry litter what it is made up of, okay? What are the benefits of litter application and then I'm gonna also discuss about the risk associated with poultry litter and Finally, I'm gonna provide a quick update on some of the research which my lab group and my students have been doing So we are I'm gonna talk about the nutrient release characteristics of different types of poultry litter So let's get started first first thing first. What is poultry litter? So poultry litter is actually a mixture of fishies, spilled feed, water, feathers and bedding materials and Of course, there are different kinds of bedding materials that are used in Chicken houses some of the common ones are peanut hulls, pine shavings or chips and One thing to remember is that the carbon to nitrogen ratios of these different kinds of bedding materials change and You know, they're very different actually and say for example, wood chips will have a much higher carbon to nitrogen ratio And and carbon to nitrogen ratio is important because you know It tells us that how fast or slow that particular material can decompose So if the carbon to nitrogen ratio of a particular bedding material is high, it will decompose slowly The other important aspect of having a bedding material is typically to kind of like facilitate the quick drying of the bird droppings and You know keeping the moisture to a really low level Now let's talk about what exactly is Chemical composition or what is the chemical composition of poultry fishes or chicken fishes? So chemically the bird dropping is You know, it is it's comprised of uric acid urea ammonia creatine and undigested proteins But majority is actually uric acid almost 70% of the bird dropping is actually composed of uric acid But this uric acid is very unstable and it quickly gets converted into urea and then urea gets quickly converted into ammonia Now once it's in once ammonia is formed it will have two Fits either it will virtualize or it will go through a nitrification process where the ammonia gets converted into ammonium and Ammonium eventually gets converted into nitrate which are the plant which which is mostly the plant Available for form So now let's talk about the benefits of poultry litter application in pasture fields or in row crop fields So there are multiple the very first one is helps to improve the soil ornate matter You know and of course it also increases the microbial activity It helps to build the soil structure That's really important especially, you know here in Alabama where we have really eroded soils So it helps to build the soil structure and keeps the soil in place and that also helps to prevent solely rosin or reduces the solely rosin and One of the major benefits of poultry litter is it saves money on costly fertilizers and We will take a look at that. What is the fertilizer value of poultry litter? So We all know that poultry litter. It has three main Nutrients from a plant nutrition standpoint, which are which are nitrogen phosphorus and potassium So let's first calculate the nitrogen value of poultry litter. Okay, so today, you know Urea I mean most most the most common source of nitrogen is urea So the current prices of urea is around 47 cents per pound of nitrogen one ton of chicken litter has 60 units or 60 pounds of nitrogen Therefore one ton of litter has a fertilizer value of around $28 and 20 cents. Okay Now let's calculate the Potassium value of a broiler litter. So Most common source again for potassium is pot ash or murid of potas the current prices of murid of potas is around 25 cents per pound and One ton of litter has around 40 pounds of phosphorus 40 40 pounds of pot ash therefore one ton of litter Has a potassium value of around $10. So Now let's look into the phosphorus. Okay, so the so say for example, you know We can calculate the phosphorus value based on the triple super phosphate Prices so the current price of super phosphate is around 40 cents per pound and One ton of broiler litter has 60 units of phosphorus Therefore one ton of litter has a fertilizer value or the phosphorus fertilizer value of around $24 So summing up together $28 for nitrogen $10 for Potassium and $24 for phosphorus. So the total Value the total nutrient value of one ton of poultry litter is $62 and 20 cents But wait a minute Most people will argue that not all of the nutrients are available during the first year So let's make some assumptions Let's say that 50% of the total nitrogen is available in year one 50% of phosphorus is available in year one And then 85 85% of potassium is available in year one and the remaining which we call as the residual Nutrients, they may be available in year two three or consecutive years So let's look or calculate the fertilizer value by using these percentages So when we do that we see that If we account for only 50% of nitrogen that is available in the year first that Translates into $14 and 10 cents as a nitrogen value for phosphorus It's $5 and for potassium. It's $20. So the the total fertilizer value of poultry litter is around $39 and 50 cents in year one But you also remember but do remember that you know the nutrient the poultry litter does supply other micronutrients such as boron, copper, zinc and manganese Which we did not accounted for in this calculation Besides, you know, you know most of the research States that commercial fertilizers are 50% efficient or the end uptake The nitrogen uptake efficiency is only 50% So this means that rest of that is lost. So just from a comparison standpoint we can think that We can compare these two different kinds of fertilizer, but of course, you know litter has Not it did not only provides nitrogen phosphorus and potassium, but also supplies or it's a source of Boron, copper, zinc and manganese Now let's talk about the risks associated with the use of poultry litter as a fertilizer And of course, there are several risks just like any other manure The most important risk that comes from litter application is through pathogens. We are Which are salmonella and E coli The other important risk. I'll not say it as a risk, but of course, you know It's it's a challenge is the order, you know Litter application has the order issue and then You know, it can create conditions of complaints from neighbors and so of course that is considered as a challenge and one of the other challenge is The repeated application of litter over several years lead to build up a phosphorus in the soils and which can turn into Environmental situations of water quality which can bring water quality problems. So these are some of the risks that are associated with poultry litter use as a fertilizer But I'm gonna today talk or focus mostly on the nutrient buildup, especially the phosphorus buildup So many people can think that okay So tell me how phosphorus application leads to build up of phosphorus in the soil so say for example, you are a bird manure grass hay grower and Your average yield is around six tons per acre The nitrogen requirements for a six ton Six ton of bird manure grass hay is around 300 pounds of nitrogen so and You know, we all know that a ton of litter has 60 pounds of nitrogen. So if you are putting Or me if you want to meet the nitrogen requirements of your hay production You'll have to apply five tons of poultry litter So if we apply five tons of poultry litter, of course, you're applying 300 pounds of nitrogen 300 pounds of phosphorus and 200 pounds of potassium We also need to know that the bermura grass hay removes only 12 pounds of phosphorus per ton So for a six ton But more grass hay the total removal would be 72 pounds of phosphorus All right, so now let's look look look up at the mats here So we applied 300 pounds of phosphorus, right for six tons of bermura grass hay and The total plant removal or uptake was 72 pounds So when you do the mats the balance is around 228 pounds of phosphorus So that amount of phosphorus stays behind in year one through application of five tons of chicken litter and if somebody is Raising bermura grass year after year after year and has been applying poultry litter every single year at the rate of five tons guess what? If the soil fall Previously in a medium fertility It will take four or five years for that soil to reach to a high fertility level and And we all know that when the soil reaches a high fertility level or when it's high for phosphorus You don't get any ill benefits This means at that point, you know once your souls reach to a high fertility level for phosphorus There is no benefit of adding any phosphorus or ill benefit because of the phosphorus but when the phosphorus builds up in the soil, you know, it's a challenge and It can create several environmental issues, especially You know the water quality issues. So let's let me first talk about, you know, what are the modes through which? phosphorus can get into the water so Phosphorus can get into the water through three different pathways. The first one is called is erosion when soils Kind of you see like soil coming out from your field in runoff water as sediments that's the Phosphorus is tied to the sediments and it comes out of your field via erosion The next category is of the next category for phosphorus transport is runoff So phosphorus is very reactive. It gets dissolved in water pretty quickly And when there is like severe weather and extreme rainfall events and you see like water leaving your property Or fuel and going into the creek That's where this reactive phosphorus gets into the water system. The third Important mode of mechanism of phosphorus transport water is through leaching and this happens typically in sandy soils where phosphorus moves vertically downwards and especially when there is a Water table, which is really shallow or like, you know, you know The phosphorus can get into that water and can contaminate the entire ground water For several years So these are the three common transports. So one of the questions that has been asked repeatedly like so tell me how can we minimize this excessive buildup of phosphorus in the soil and The answer to this question is you need to constantly monitor your soil test phosphorus levels You know Because that's the only way to know whether you are running into the danger zone of having a high phosphorus And if you if you see that your soil test levels are really high for phosphorus It's always a good idea to stop applying litter for a few years and then supply The nitrogen and potassium demands using the commercial fertilizer. So or Alternatively, you can rotate between your commercial fertilizer and Your poultry litter and this this way it will delay or actually reduce the risk of phosphorus loss into the environment Next I will talk about The research that we have been doing in our lab and this is research for from one of my graduate student who is studying the release characteristic of phosphorus, but also different nutrients So in her work We we collected different poultry litter samples and we classified in them into three different Categories the first category is the fresh litter The second one is the cake litter and the third one is called as composted or aged litter So fresh litter is the litter that is Collected after six months or probably like, you know after four or five Flocks, you know when the growers clean out their houses So that's the kind of litter which we are calling it as fresh litter Then the other category is cake litter which where you know Growers remove or de cake After two years and then then remove it. So that is the de cake litter cake litter And the third category is the compost where the litter has been stored in the pile for a couple of years It stays there and is undergoing the natural composting process. So that's what we call it as the age litter So we are studying the Phosphorus and other nutrient release characteristic of these three different kinds of litter So let me provide you a brief Background about what are the different kinds or forms of phosphorus that are present in any poultry litter So, you know, in Paul whenever we send a poultry litter samples We always get the total phosphorus analysis, but total phosphorus analysis is actually comprised of several different categories of four or forms of phosphorus and The important forms are there are three important forms one is called as dissolved reactive phosphorus DRP and These are like mostly plant available phosphorus, you know, like orthophosphorous Or pyro or meta phosphates the second form of phosphorus that is present in litter is called as dissolved Non-reactive phosphorus. So this form of phosphorus is not accessible by the plants, but it is accessible to the microbes and Microbes can break these when they need them and and some of the common dissolved forms of non-reactive phosphorus lipids or DNA or RNAs Which are out, you know in the environment in the natural soil solution Then the third part is It's called as the recalcitrant organic phosphorus and these form or pool of phosphorus is very hard to break I mean, it takes a quite a bit of energy by the microbes to break these and it's very slow to become So very slow to degrade or decompose So most of the phosphorus that is available to plants is the dissolved reactive P and the dissolved non-reactive P whereas the recalcitrant phosphorus is a very Stable kind of phosphorus that stays in the soil for a long period of time. So for in this particular experiment we studied the Release characteristic of these three different forms. So the most important form is the dissolved reactive phosphorus, okay? So again a little bit about a background about our materials and methods So we collected these different kinds of litter from houses poultry houses in different parts of the state in Alabama And then we conducted a wasp experiment in the laboratory where we watched we did a repeated extraction of phosphorus from this poultry litter and then we analyzed it for All these three different categories which were the reactive the dissolved reactive the dissolved non reactive and the recalcitrant organic P So let's first we can also think about, you know about, you know, say for example a producer applies poultry litter, okay? And when there is a series of rainfall, especially like when we enter into the winter month, you know, we see like A series of rainfall events. So say for example a farmer applied poultry litter and then the first and after he applies We got the first rain. So how much phosphorus can we expect that? You know that will be released from the poultry litter Then also how much phosphorus can we expect that would be released during the second rainfall event and third and fourth And so on and so forth So that's how we are trying to mimic this or trying to understand the release rates of different kinds of phosphorus under different rainfall events So this is a graph that tells the release characteristic of the dissolved reactive phosphorus remember, I just mentioned that the dissolved reactive phosphorus is the phosphorus form which is readily available or accessible to the plants so And we are comparing and contrasting the release rates of these three different kinds of poultry litter, one is six months old litter, the cake litter and the compost litter What we see here, a very interesting finding here is that the release rates of the release rate of phosphorus differs between these three kinds of litter and and Actually, the cake litter releases the most dissolved reactive phosphorus in the first wash cycle or the first rainfall event Compared to the six months old litter or a composted litter The other important thing to note is like this release rate follows Exponential decay order meaning that initially it releases the phosphorus fast and as We move on or as with subsequent rainfall events This release rates decrease down or slows down considerably So most of the phosphorus as you can see is released during the first second third and fourth Rainfall events or wash cycles after fourth, you know The amount as well as the release rate decreases down considerably So now let's look into the percentages Let's talk in terms of percentage of like how much of the reactive phosphorus was released compared to the total phosphorus content In the litter. So what we see here is in the first wash cycle or first rainfall event Six months old litter released 14 percent of the total P as the plant up level or the dissolved reactive P Whereas compost litter they release 21 percent of the total phosphorus amount And then I'm sorry, excuse me the one two three year old or cake litter release 21 percent Whereas compost release 12 percent of Of the total phosphorus as a dissolved reactive P An interesting feature is that of course the cake litter has the highest amount of Phosphorus that is released during the first wash cycle or first rainfall event and as we go And then with consecutive wash cycles or rainfall event You can see here that these percentages drop down But the significant drop happens after the fourth cycle. So basically, you know after the fourth rainfall event You know only one point six eight or one point or one percent of phosphorus is released as dissolved reactive P or out of the total phosphorus The same same principle applies to the six months old litter as well You can see here that the percentage of the reactive P falls down Significantly and especially after fourth cycle. There is not much phosphorus or just Very less amount of phosphorus that is released after the first rainfall event We also looked into the distribution of different P forms So remember like we classified our total phosphorus into a dissolved reactive phosphorus dissolved non reactive phosphorus and Then the recalcitrant phosphorus or the residual phosphorus, which is very difficult to break down What we observed here is that in lit the composed Sorry that the cake litter, you know, 46 percent of the nitrogen is Present as a reactive phosphorus whereas 54 percent is present as as Recalcitrant organic Phosphorus but in six months old litter We are getting less of the total reactive phosphorus and more of a residual phosphorus of recalcitrant phosphorus and Same principle applies to compost. So it's quite You know, you can imagine that out of the total phosphorus only 46 percent gets released and is available to the plant You know, whereas the remaining like 54 percent is Not available to the plants and it's actually not even and it's very hard to degrade or decompose them so The rule of thumb here is like whatever the phosphorus Percentage is almost like 40 to 45 percent is only the reactive phosphorus that would be available to the plants Whereas the rest is a recalcitrant form and that will not be available to the plants and It's very hard to degrade them as well Now let's talk about the potassium release characteristics of litter and potassium release is very different than phosphorus In potassium what we observe is that most of the potassium is released right after the first rainfall or first wash cycle But after second you don't see any action basically So most of the potassium is released after the first rainfall and second rainfall events Third and fourth you don't see any or very little amount of potassium That would be released from poultry litter that tells me that potassium is present in a highly dissolved state and it easily gets it's easily released after the rainfall event and Of course, we see the differences as well Most of the potassium is is released Or a higher amount of potassium is released from a cake litter Whereas the compost releases the least amount of potassium So this is very interesting here that the amount of potassium that is present in Composed or a aged litter is very low compared to a fresh litter or like a cake litter and Their release rates are also very low Now the other question is what are the other nutrients besides phosphorus and potassium that gets released during these rainfall events and we found that some of the major Nutrients are sulfur, magnesium, calcium and aluminum But sulfur is the one that is released at the highest rate among all these three different litter types The next one is the magnesium and again You know, it's so important especially in in pasture fields because you know, we often think about the magnesium tetanus situation But poultry litter application and rainfall does help to actually release magnesium In the soil solution and that is a little bit of plants And yeah, so so so looking at all these different release rates of Nutrients it really helps us to think about the timing of litter application because You apply the litter and if it rains the next day and you haven't planted your crop or the forage is not growing You know all the nutrients that is released after the first rainfall basically is lost So it's very important to time the litter application And and you know again the percentage of nitrogen phosphorus and potassium That will be utilized by the forage In the first year will basically depend on the type of pasture that is present I mean, is it the cool season pasture or is it a warm season grass? Okay, I mean This is a chart that tells you the relative growth rate of a winter annual or a cool season or perennial Grass warm season perennial grass So it makes us think that if you are growing a cool season perennial grass and the maximum peak or the peak biomass production is between April and May we should time over litter application sometimes between between You know early January or like early sorry late January Mid-January to early February time period so that we can match the demand here For the cool season, but again like there are two cycles here You know, I mean we see a little bit of growth again back from October number time period So we can consider a second application probably here in the August timeframe When it comes to warm season perennial grasses I feel like the best timing of application is March to early April March to an early April time period because that's the time period when the plant demand in trees is So I believe like, you know, if we time over little application close to March or April you know and You know, there will be a better utilization of the new friends that is Released but again keep in mind. We have to also think about, you know, the rainfall events and you know in context of when the litter was applied and when the rainfall So all these things go into the decision of like when to apply Little so with that I like to thank you for your time and you know, I hope that you have learned something new about the The way the litter releases new trends And of course we post some of these interesting topics time to time at our Facebook page So do check us out at this Facebook link and thank you all for being here today