 So welcome. My name is André, I'm the new assistant professor in vegetable cropping system in the department of heart culture here at Auburn University. And my talk today will be a little bit of how to use soil moisture sensors to improve vegetable production. I put this chart as to show you that most of our growers, we know the benefits of irrigation. However, we have new tools that are available for us to use it, like soil moisture sensors. And that's the case I would like to make that we might be using old tools that will not be as beneficial as the new available to see so I want to show you. I want to show you guys how to properly use that and what are the benefits that those tools are bringing. But before we start talking about the soil moisture sensors, first I will need you guys to understand what are the irrigation scheduling that we have available. So regardless of the irrigation method or the irrigation system you have in your farm or your growers have in your farm if you are a county agent. I would like to talk about the irrigation schedule because this is how you're going to properly apply water for your crop and regardless of crop vegetable nursery, or even a real crop. So currently we have six ranks of irrigation schedule. Those those ranks, they are according to the how water is applied. So the first rank is apply water whenever, which means you're going to apply water whenever you feel that it's necessary. Usually you can go there you keep the sand, as the dirt comes up. Oh, I need to apply water. That's not recommended at all. The second rank is the rank, which is ranked as rank and one is the few and appearance method. This is a USTA method offering. So this is a method that developed back in the 80s, where you're going to compare the color of your soil with a USTA chart. And by seeing the color of the soil, your soil type and the color you're going to compare with the photos you're going to determine how much water you have in your soil and then you can apply water to replace whatever was lost whatever water was lost. So that's also by your feeling. So it's not recommended. The third method which is ranked at two is the systematic irrigation method. This is the most common one used by most of the growers where you're going to apply water using irrigation panel. So you have that irrigation panel where you're going to program your water to apply your irrigation system to apply water every day for the same time or every day for the same volume. That is very common. Most of the growers who irrigate have this system and it's very common for irrigate in houses where you need to irrigate your grass, but also in your vegetable fields where you have a drip tape, you just program to irrigate everything. This is okay. However, most of the times does not account for rainfall events, they're not account for weather conditions, and that's when it comes to a problem. Finally, rank three, four and five are the one that we usually recommend because you are applying water based on the crop water demand, which is our rank three, or based on the soil water status method, which is ranking four, or a water budget method where you account the crop water demand and the soil water status method, which is ranked five. And today we're going to be talking about rank three, four and five. So let's start about the crop water demanded method, what it is also called crop evapotranspiration, the crop water demanded method, it's a simply calculation of multiplying a reference evapotranspiration and a crop coefficients, but I don't want to come to a calculation, I want you guys to see what I'm talking about. So imagine you have a field, a field, a corn field, where you have your plants there, and then suddenly you apply water, this water can be applied as rain, or as irrigation, as water applied, it permeate down in the soil profile, it's uptake your plant. But water is also lost by evaporation from the soil. So that is evaporation. When you have water loss by the plant, it's transpiration. When you combine evaporation and transpiration, you have your crop evapotranspiration or your crop water demands. So basically that is one method. You need to account how much water is lost by the environment, which is your soil, or how much water is lost by your plant. How are you going to determine those values? Luckily in Alabama, we have the albany, like we have the mesonet. The mesonet will provide you the reference evapotranspiration or your ETO. So based on your location on the stage, you just select your weather station, and you're going to have that information for you. Once you selected your reference evapotranspiration, which is a daily information in each inches of water, or which means inches of water per day, you just need to multiply by crop coefficient. The crop coefficient is already calculated by our crop, and it's according to the stage of the crop development. Here I put the crop coefficients for most of the common vegetable crops, from bell pepper to yellow squash going through watermelon, carrots, cauliflower, cucumber, most of our vegetable crop. And how are you going to determine which crop coefficient to use? It's according to crop coefficient in the initial stage of crop development, in the mid stage of crop development, and in the end of your crop development. So basically in this chart here we have the growth. So crop coefficients, based on when you transplant your plants in the field, or you have seed transplant when you have germination, it's initial. So in the case of bell pepper, 0.6, so you're just going to multiply your reference evapotranspiration from the mesonet by 0.6. If you have growth, you're going to have your mead, which basically is your vegetative stage, your flowering and your fruiting, and then you multiply your reference daily evapotranspiration by 1.05. Or in the end of the season when you have done your peak, but you still have more harvesting, plants are just up taking water for maintenance, so you're going to multiply it by 0.9. It's easy like that. You just need to check online, and then you're going to multiply it by a crop coefficient based on the growth of your crop. But how are you going to use that? So you can use the crop water demand method to calculate water daily. It's more demanding because you need to check your daily water coefficients, your reference evapotranspiration, sorry. You can do that weekly where you're going to have a sum of your entire week, and you're going to spread it over that week, or you can do historically if you get an historical weather data from last year, and you can apply this year. So let's see what's happening if we are growing watermelon in the spring season in South Alabama. If you plant March 1, March 15, April 1 and April 15, those are the curves you're going to have off water demand in inches of water per week. So let's just give another example, because here we have four planting dates, but if you have an average of those four planting dates, you're going to have exactly the amount of water that it's required as an average. So let's say in the first week, we just transplant our plant. We need about only 0.3 inches of water in that week because plants are still small, we don't have much water requirement, so we're just going to have like low water demand. Next week, plants grow a little bit more, so we need 0.36 inches of water. That's just basically on whatever is the plant is losing and how much water your environment is losing as well. But then you have a peak of your growth because our temperatures start to raise, you have more water demand by the plants, they start to grow their vines, they start to flowering, so that's when you have a peak of water. And from the week three to week 10 is when it's more critical for you to apply water. So you're going to apply from 0.9 inches of water up to 0.34 inches of water. So that's what you're going to consider. That volume of water from 1.02 or 1.14, you're going to be applying during the entire week. If you have a drip irrigation system, then you can apply it daily so you are spoon feeding your plants. But if you have an overhead and center pivot or even stationary gas, you don't need to apply water every day. That's going to increase your cost for electricity. So you can do, you can spread it in two or three applications. The only thing you need to do is divide this number by two or three, which are the number of applications. And you just apply that amount for that week. You can do that every Monday, Wednesday and Fridays, or you can do that Monday, Thursday and Sundays, whatever it's easier on feet on your scheduling during the growth of your crop. But then we are growing now cabbage in the fall season in North Alabama. So you have a decrease of water consumption. Usually I would ask you guys, why do we have that reduction in water demand? But just going straight to the point, water demand is reduced in the fall season. And it doesn't mean that water is for cabbage. It doesn't mean that it's only for cabbage. It's going to be for all the crops. The reason why is because when you enter in the fall season, you are coming from warmer conditions of the end of the summer to the winter to the cold conditions of the fall, which means that you don't have much water being lost by the environment. You don't have evaporation. Remember in the first slide where we have this the sweet corn losing water by evaporation. So here in the fall, you don't have that much water being lost. So your water is not, the water is not much required. It doesn't mean your crop doesn't need water. It's mean you don't have water being lost by the environment. On the other hand, in the spring, you come from the cold conditions to warmer conditions. And that's when you have more water. So just keep in mind, you probably will be irrigating more in the spring and the summer during the fall, but it doesn't mean your crop require less water. It means you are losing less water to the environment by evaporation. So, if you guys understood what is the crop water demanded method. That's how you can do that. If you have any question you can just contact me we can come through that or you can easily go to the mesonet and calculate how much water your crop required, based on the crop that I presented here. So moving gears to the soil water status method, which is the focus of our talk today, I'm going to be talking about how to properly use soil moisture sensors. But before we start doing that, I need you guys to understand a little bit of soil physics, but I don't take it wrong. It's very simple. So what I need you guys to understand are three main characteristics of your soil. Fertilization, field capacity and permanent to wilting point. Saturation is when your soil is full of water, and you start to have deeper percolation or an extremely conditions erosion. Field capacity is when your soil is full of water and is the maximum water your soil can hold, while permanent to wilting point is when your soil is dry enough that your plants cannot update your water. Then you have a sponge that you do your dish wash. When you get that sponge there and you put a sponge under the water, and you remove it, it's leaking. When that sponge is leaking, that is saturation. However, when you squeeze it, and there is no water more coming out of that sponge that your field capacity. Finally, when that sponge is dry enough that is hard and you can break it in half. That is your permanent to wilting point. So now that you know that basically by field capacity, the water available for your plant means you have field capacity is between field capacity and permanent to wilting point. And in this chart here, we have the soil moisture content for each type of soil, where you're going to have your field capacity, the top line here. That is your permanent to wilting point, the dot line in the bottom. So everything below field capacity is an available water. Everything above field capacity is saturation and everything between field capacity and permanent to wilting point is your available water. And that's what I need you guys to know what is field capacity and permanent to wilting point. Now that you know those characteristics of soil, and you can identify what is your field capacity and your permanent to wilting point. So in this chart, we can start talk about soil moisture sensors. So much your sensors, there are a ray of availability for you guys, you have as cheap as 1050 as $50 with tensiometers, or $2,000 as the ones that you can control your irrigation by your phone, and they are very accurate. And some examples that I put here were to install and how to install that those are TDRs, and those are more they can go on store are very good and reliable soil moisture sensors. So they are available for you to use. I don't want to promote any company and not talking about some water sensors, but teach you guys how to interpret the data. And that's why I put that graphic here, although a little bit busy. It's easy to understand what is going on in this graph. So here we have volumetric water content in the y axis in days after planting. Here is our rainfall event. And I'm going to explain what are those lines and bars in your graph in this graph. So the bars are our rainfall events. Our blue line here represent our field capacity. Our red line here represent our permanent wilting point and everything between our field capacity and permanent wilting point is the available water for the plant. The orange line here represent a threshold that we must to determine in order to tweak our irrigation event. So usually for vegetables, it's 70 to 80% of our available water. For row crops, you can be more flexible because they have a deeper root system. So you can go for 60 to 50% of your available water. But for vegetables, we need to be precise. So that's why we have 80%. So this is 80% of our available water, which is the difference between field capacity and permanent wilting point. So the black line represent our soil moisture. So we start our season, we have two rainfall events, we have a boom of our soil moisture content above our field capacity, no need to irrigate. Water is start to being uptick by the plants or percolation, and then we have an irrigation event. Finally, we have a 0.4 inch of water applied a little increase of water we are good and then water moving down again by upticking off plants, then we irrigate 0.4, 0.8 inches of water we pick at our moisture up to our field capacity. We are keeping our moisture, which is the black line between our threshold and our field capacity, make sure that water is plenty for plants to uptake. Rainfall events are common in our mainly not right now during the summer you see how much water we have so we're going to have peaks of water content. This means we're going to need to terminate our irrigation for some time until we have the water, the soil moisture coming back for our ideal condition. And here, when we don't have rainfall events, or only one rainfall event, it was perfectly for us to manage our moisture in ideal conditions. So that's when we have an ideal condition of soil moisture in the field for a vegetable crop or for any crop where we can control our moisture between field capacity and our threshold, which I also call readily available water for the plants. So how should it be? So that period of days here is demonstrated in our field bed here. So imagine we have a vegetable bed here, six foot center to center with a drip line in the middle so this black dot represents our drip tape and what's going to happen during the day and during the night. So during the night, we don't have much water going on, but we have irrigate at 8am. So every day we irrigate at 8am, water is being applied and uptake by the plants. So look this case right now, 3am, 4am, we don't have much 8am, water being applied, distributed in the bed, being uptake during the day by the plants, during the night a little bit of recharge, and then it's not much activity. But again, during the day at 8am, we have water being applied, water moves in the bed and then it's being uptake by the plant. So basically that's how water distributed in the soil and how should be a proper irrigation management using soil moisture sensors. But what are the benefits of it? So I put a study of case here that we have conducted some years ago in a sandy soil and where we have a fixed irrigation. And remember I mentioned in my first slide there where we have the systematic irrigation where you control water with irrigation panels. So that's a fixed irrigation where water was applied two hours continuously to every day to supply 0.2 inches of water, versus a controlled irrigation using soil moisture sensors where water was applied based the field capacity when it reached 80% of our available water, which is our threshold. So just for you to understand, every day from 12 to 2, we applied water with fixed irrigation, or five times in the day we applied water when necessary using soil moisture sensors. What are the benefits? Just saving in water. With the controlled irrigation, we spend about 175 gallons of water per acre, while we spend almost 450 gallons of water per acre. So we reduce it 60% of water using soil moisture sensors. Plus, you imagine the same with power that it was reduced. So this is the first benefit of using soil moisture sensors. Second, we start to see different in colors of the plant where we have squash, zucchini as our crop of study. Controlled irrigation showed a greener, a darker green plants when compared to fixed irrigation, which was more yellowish. And as you know, this yellowish means nitrogen, lack of nitrogen, so you have problems with fertility. And in this case, we saw we sample plants over the day daily to show how much water was being uptake in the plant tissue. And as you can see in this graph, we have a higher uptake of nitrogen by the controlled irrigation, which is the blue dots here compared to the fixed irrigation, which is the orange bud. So here is the second importance of using soil moisture center or the second advantage of that, which is a better nutrient uptake efficiency. Finally, you're going to see increasing of yields because you have a better increase of nutrients where we have an increasing of 26% of yield for controlled irrigation. So savings in water with savings in pumping, savings in nutrients with a better nutrient uptake and increasing in yields that's very important for a grower. So these are the main benefits of a water using soil water status method. But just to illustrate what's happening the soil, you can painting you can use a blue dye to inject in your drip line, and that's what we did here. So we injected a blue dye in the first irrigation in the soil moisture and in the fixed time treatment as you can see here 24 hours, compared to 24 hours. So later we were still in the root zone with the blue dye on the soil moisture sensor, but it was deeper in the fixed time you can even see the difference in the soil layer here. Finally, seven days later, we found blue dye at 60 inch of that in the soil moisture basis, but they 38 inch in the fixed time irrigation. So you can save imagine that this dye is your nutrient. That's how you explain the better nutrient uptake. With that, I would like to end and show you a take home manage of the importance of irrigation strategies, you can reduce of irrigation water applying, you can maintain or increase vegetable yields by doing a better uptake nitrogen uptake or nutrient uptake efficiency. So I would like to say as well that tools for water scheduling or irrigation scheduling are available. You just have to use it. And if you have any questions and you would like any any guidance I can come and I can help you guys just let me know. Thank you.