Hello everyone and welcome back. Today I want to start a short section on water resources. And water management, specifically irrigation in agriculture. Everyone realizes the importance of water. We talked a lot about water, water quality. And I want to talk some now about quantity, because honestly in places like Florida, it's very, very hard to separate the two. We want to start with just a general overview of the water cycle, the Hydrologic cycle. And I've given you a fairly simplified diagram here in this slide. There are several parts of it that we want to focus on. Obviously for agriculture, we're very interested in precipitation, rainfall, snow that might accumulate and add water to the system. We've learned about how water infiltrates through our soils. Rain water can do this, especially if we get more than we want at any one particular time. We can have run off, and we've learned how to deal with run off, with some of our soil conservation practices. We'll talk a little bit later on about evapotranspiration and water requirements for our crops. So, all of this cycle goes on and the inputs and the outputs from the cycle are very much interest to us as far as talking about the water requirements of our crops. And how we can make up for deficiencies in natural sources of water by irrigation. Here's a pretty scary thought. Most all of the water on this globe is salt water. This picture, this diagram brings it home. Very much for me. About 2.5% of the water on the globe is freshwater. And you'll notice that of that, two thirds of it is locked up in ice and snow. So about somewhat less than 1% of the total water on the face of the earth is available as freshwater for us for drinking, for consump, human consumption and for growing our food. Agriculture is the largest user of this fresh water. This slide shoes water use consumption, by sectors. Agriculture is the largest, about 75 percent of the fresh water withdrawals are used for irrigating. For producing our food. Now agriculture doesn't use water in a vacuum, it's not out there just using water, it's doing it on our behalf. So, for example, our food if you like to eat vegetables and fruits, about 90% plus or minus of our fruits and vegetables are water. And so for example, if we're consuming an orange, a fresh orange, the orange is about 85 or 90 percent water. And how did that water get into that orange? It came through, probably, irrigation practices, that the farmer used, to produce that orange. So agriculture is extremely important and yes uses a lot of water but we just need to remember that, that water is being used by agriculture on our behalf for our food production. Now there are areas around the globe and it doesn't take very long to do a search and find many of these examples where water is, is, water supplies are stressed. And I, I'm going to give you an example of one on a, world basis something here in the United States we'll talk about and also Florida. We've already mentioned some areas in Florida that are stressed. On a global basis there are many areas. An, on the globe that are stressed by water. And, you can see those up here, on the orange and the yellow colors. The scale is presented here, so the darker the blue, the less the stress is, or the less vulnerable that water, supply would be. And most of the times the stressed is caused by lack of water, lack of available water and also by high demand or increasing demand in these areas, sometimes a combination of the two. For example in central Asia, the drying of the Aral sea is one of the examples that you find very frequently. Over the years the size of the sea is has declined because the water has disappeared. And there are some that argue that the drying of the sea is related to increased diversion and use of water for agriculture in the area. Just recently here in this country we've had examples of stress on water. For example, the Mississippi River, the Great Lakes. The levels of water in those water bodies, have declined. We learned about the Mississippi water, shed. In this particular case, we've been experiencing several years of, of drought conditions. And, for example, on the Mississippi River, it not only. There's not only a decline in the water for such uses in urban areas or for agriculture, but also it has a negative impact on commerce. And in this picture you can see ships moving barges up and down the river. And when the water level is so low the loads have to be reduced on those barges and they're restricted to less of the river, so fewer barges can, can move up and down the river at any one time. Water in the United States is depicted water use in the United States, is depicted in this, in this figure. The pink line is the increase in population. And one of the interesting things that you'll note at least in this country the water consumption, or the water use has fallen slightly and, and leveled off after the 1980s. That's one of the interesting things that we'll, we'll touch on a little bit here. Here's another slide that has an interesting story to tell, particularly about agriculture. Here are the total water withdrawals by several use categories. Public, for example irrigation wi-, which would be mostly agriculture. A large amount of water in this country is used to cool the electric generating power plants. And if you look at the water use, again the same kind of story is told. So for thermal power again the amount of leveling off of the amount of water that's, that's used there. Here's agriculture, the same thing, the blue, the bluish lines. A leveling off, maybe even some would argue a decline since it's peak in the, in the 1980s. That's a good story to, to tell about agriculture, and the reason is because over these years many more farmers have adopted water conserving practices some best management practices for irrigation on those farms. It's a little bit hard to tell from this particular picture because of the colors that were chosen, but the far left histogram bar, the purple one if you follow that, that's the public supply. If you follow that across with time, that's the only sector that's actually increasing in water use. So that tells me that we've got some, we've got some ways to go, with, in our urban areas and our residential areas domestically to become more efficient in using water. If you look at, a little bit more closely to Florida, obviously we have a couple major wa-, sources of our water, ground water about two thirds of our water that we use in, in Florida comes from our aqua first. And if you look at how that's divided up here's the surface water pie over here and you can see a large amount of the surface water pie is, is used by agriculture, public and power. And then the same the same sectors are large users of ground water. Here's agriculture and public. So agriculture plays a, a major role in the utilization of water, in both those pools of water in this state. In the state of Florida the management of the water resources to a large degree falls to what we call water management districts. And I've given you an outline of the state and a geographic range of these five water management districts. The water management districts manage and acquire, when needed, lands for water management purposes. For water conservation for example. They manage the consumptive use the aquifer re recharge and also well construction and permitting. They also do technical studies on the water resource. For example, some of us at the University of Florida use funds provided by the Water Management Districts to study irrigation. Particularly irrigation efficiency that will result in reductions in water consumption by our agriculture industry. And for us in Florida, this is where a lot of the advances have been made. Through this kind of public and public private with the growers working together to develop and institute and adopt best management practices for conserving water. Here's the Suwannee River, I think we have looked at this picture before, the Suwannee River runs through one of our water management districts, the Suwannee River water management districts, district. And the Suwannee River runs through an area that's heavily agriculture, oriented. And also we've mentioned before, the dominated landscape by the springs that are a major tourist attraction. So everyone has a major interest in the Suwannee River and what goes on. Around and on its banks, particularly with agriculture. And so there's a lot of emphasis in that area of the state on water efficiency and helping growers adopt best management practices to conserve water as much as, as possible. So I guess the question's boiled down to do we have enough water, and are we using it wisely? And how can we help agriculture become as efficient as possible in, in water use. As we studied before I like the idea of a budget approach. We studied budgets when we looked at nutrients, nitrogen and phosphorous in particular on farms and looked at the inputs and outputs of nutrients. On a, on a farm. We can do the same thing with the water budget. So you can find, you can describe in, the inputs, for example rainfall and snowfall. Even though I'm in Florida. We don't see snowfall, at least not very often, but for the folks, north of me, that would be a major input of water into the system. Flowing rivers that come across a particular, area that we want to describe a budget for would be another, input. Outputs, we're going to talk a little bit more about, plants and their water use. We call it evapotransporation. Well we have evaporation from the surface, from our soil surface. And we also have transporational water losses from the plants themselves. That's where the plants take up the water through their root. And it travels up through the plant and most of it exits through the leaves and back out into the atmosphere. Agriculture uses a lot of water for irrigation, for crop production. But also for other purposes, and I'll show you a list of those in a minute or two. And all of these enter into agriculture's water use portfolio or profile. And all of those areas should be areas that farmers would want to take a look at to see how they can improve their efficiency. And then also an output obviously would be where we use water in our, in our homes. Here's a, a quick look at what a budget might look like. This happens to be one for a portion or a part a region in the state of Kansas. And you can see it looks very much like the hydrologic water cycle, and in fact it really is very similar, except that we've, we've quantified those various pools of water in the, in the hydrologic cycle. So, for example, here's 2.58 inches of runoff, here's evapotranspiration loss. You can see how big they can be.. And here's the stream inflow. We have water moving through the soil and back to the aquifer. And so there's difference, different pools of water in the budget just like we learned for nutrients, and we can quantify those. Sometimes it takes estimations to get the best estimate of the of the quantification. We can do these water budgets just like we talked about nutrient budgets on various scales. There are if you search you can find water budgets for the world, the global water budget. You can find them on a regional basis, as much as this one is for Kansas, for states. There's a water budget for states like Delaware even. You can also look at water budgets on a, on a watershed scale. I found it interesting that it was very difficult to find water budgets. Where quantifications of water inputs and outputs on farms, specific farms with specific farm practices. There needs to be much work obviously down at the farm level on determining water budgets for farms. So water budget when, when the outputs exceed the inputs just like with our nutrient budgets we have problems. And if you recall back to this, the picture or the video of the Suwannee River. If we do water budgets for that particular area, we want to maintain the Suwannee River, levels. And we want to maintain the water in the springs. Because of their value, for tourists. But at the same time, we want to make enough water available in our budget for farmers in that area to carry on their business of. Producing food and, and livestock production. So as water tables drop from more output, more utilization, then in that particular case that's not a good thing because the spring levels drop and the springs start to dry up. And that's an economic negative e, economic impact. Remember back to the triple bottom line. That's an important aspect to that part of this state. So water is extremely important to everyone in that regard. So I think knowing something about the water budget helps us make big decisions about water and where it needs to go and, and how we can, how we can try to determine best management practices to try to conserve. If you're going to far in the output direction, what is driving the output and can we do something about it? And I think that's where best management practices and knowledge about them are very important. Florida is underlain by important aquifers. The biggest of which is the Floridan aquifer system, and this is where we draw most of our ground water for agriculture and, and also for urban use. Minimum flows and levels are a way to track water in these, in the natural system, and these are established for water bodies in order to prevent significant harm as a result of. Excessive withdrawals. These minimum flows and levels are determined by the Water Management Districts, and are reviewed by Department of Environmental Protection. So here's a picture of how a, an example of how a water a minimum flow level might work. So here's a natural system might contain agriculture for example and these MFLs are designed to prevent harm to this overall system the net, the water resources or the ecology of the system by permitted withdrawals. So the idea is that you can manage and control the withdrawal by permitting so that it has no negative effect on the natural ecosystems and these MFLs then define the how long. High, how long these high, intermediate and low water flows, should occur or should be allowed to prevent, prevent harm. The water levels are going to fluctuate but the MFLs describe how they're going to or how they should be allowed to fluctuate and still maintain the natural system and so that we can prevent no harm to the, to the water bodies. Ground water because we use a lot of it in Florida. It's a major source of our water. Really doesn't recognize water boundaries. Our boundaries ca, you know for example so the, the ground water doesn't recognize boundaries, in these so called water management districts so, it's very hard to manage. The water in the ground. And, this brings us to the issue of water utilization and currently there are challenges in, in a state like Florida where you have such huge demands. On water. And so for example, if you have an area that is withdrawing water if the withdrawal is at such a great amount you can lower the water table. And that water table might be lowered enough to impact a water body, a stream or a spring. And that's, even from a long distance away. And so those are the kinds of scenarios that cause water management district officials, and other interested parties to come together,and work together, so that the withdrawal. In one particular area doesn't negatively impact, another area. And that's a tough process for everyone to come together. And, and work together to achieve. Over-pumping has another negative impact. Particularly in, state like Florida. And for coastal states up the east coast, of this country. As we. As we withdraw fresh water, if we withdraw it at such a rate that we reduce the amount of fresh water to a, a level that allows Salty water or sea water to intrude and we call this salt water intrusion and when this happens it effectively makes this source of water here where this pump is, ineffective. Because if we're using it for irrigation, we can't irrigate crops with salty water and we can't drink salty water. So that's why these, the situations or these, processes like MFLs are so important. Because we want to minimize the chances that we degrade, the source of water that we have available to us, by over, extraction. There are 44,000 plus or minus farms in, in Florida. Many of em doing irrigating but not all of em are, are irrigating. They're growing crops maybe grasses and pastures that do not require irrigation or at least a large amount of irrigation. And I've given you some figures here on water use by agriculture. Half of the, the fresh water withdrawal is due to agriculture. And half of this is due to a couple of our major horticulture sectors fruits and vegetables. Recall that these are very, very valuable. In the state there are large, make up a large portion of the state's agriculture economic value. And because of our demands that we as, as consumers put on our vegetables we want high quality and irrigation is a very important place, a very important role in producing high yields and high, high quality vegetables. So it's no wonder that we irrigate vegetables. We get 54 inches of rain in this state, plus or minus. And you might say, well that's a, that's a lot of water, and it is. This state is, very blessed with, with ample rainfall. The problem is, it seems like it never rains when you really need it and so if you think back to those vegetable farmers trying to produce high yields of high quality vegetables. And they enter into a drought period, when they're not getting enough rain. Then that's when they need the irrigation system to supplement the rainfall. You might want to take that just as an aside, you might want to take that 54 inches of rainfall and there's enough information out there, in publications on the Internet, about Florida, in other words our land area. And how much water is in an inch of rain. And figure out how many gallons of water, fall on this state, each year. And then look and compare that to the amount of water that agriculture uses every day. I think it'll be an interesting comparison. Here's some other interesting information about water. These are some values that are very interesting to me in terms of the amount of water that it takes For example 70 liters of water to make an apple. And obviously there's not 70 liters of water in that apple. But over time, in terms of growing that tree and producing the apple out in the field, then perhaps cleaning, washing the produce as it's being packed and shipped. So there's a lot of processes that go into, produ, producing, our food. And also 120 liters of water to make a glass of wine. So for those of us that like a glass of wine, in the evening, that's a sobering, thought. Agriculture water use, doesn't stop with what we use to produce our crops. That's the, evaprotransporation part of it, and we'll learn a little bit more about that in our next lecture. But we also use water in many other, functions on the farm. Field preparation, for example. Sometimes, we need to irrigate a field to provide, put moisture into the soil so that we can actually, for example, with vegetables, make raised beds and cover them with plastic mulch, a very important component of vegetable production. Crop establishment. Sometimes, we need to irrigate the soil to speed up or enhance or help improve the uniformity of seedling germination or transplant establishment. Cooling our produce sometime we use water, for example, to cool sweet corn when it comes in out of the field on a hot day. We want to cool that sweet corn, so that, it maintains its, sweetness, during shipping. So cooling and using water during the cooling, process is extremely important. We as a consumer, many consumers may not understand. That use of water on the farm but for some vegetable producers that's a significant use of water for just cooling the produce and maintaining that quality that we want to see when we buy that ear of corn in the food store. Sometimes Mother Nature deals some blows, at certain times of the year. For example, our fruit production, our vegetable production, our strawberry production. Freeze protection is a very important part of maintaining, a crop. Particularly here in Florida when we have those changes in weather, during the spring our strawberry industry in central Florida can be subject to freezes. And so growers use water to help protect that crop from, freezing. And that, results in a, a large withdrawal of water from the ground water to put on that crop and keep it from freezing. The, the freezing process or the freezing of water, you might see those pictures sometimes on television about growers using waters to protect their crops. And you see large amounts of ice formed on those crops. As the water freezes and gives up what's called it's latent heat of fusion and that heat helps keep that fruit or that leaf at about 32 degrees which is the mixture of water and ice. And so as long as the growers keep applying water or sprinkling water on the crop during the freeze they can protect it to some very cold temperatures. So that is the way that process works, but it requires, continual application of water. Washing and cleaning our produce and processing, our produce also requires water, on the farm. In some areas the, the country where we have dry climates and soluble salts buildup in the soil, we use fresh water to move those salts deeper and below the root, system. Leach them away. These salts are not like nitrogen. They're usually calcium carbonate or gypsum, calcium sulfate, those kinds of salts. They're detrimental to the growth, to the germination of seeds and the growth of young transplants. So water sometimes on those farms is used to move those salts deeper into the, the soil and to keep the crops from experiencing soluble salt injury. And also our animal industry you, obviously uses water for drinking. So there are many, many uses of, of water. We might think and look at irrigation and see that but behind then scenes agriculture is using considerable amounts of water. But again, remember it's on our behalf because we as consumers want readily, high value, high value and high quality vegetables and for example and that takes water. So what can we do to make sure that we're being as efficient as possible on our farms. Helping farmers to adopt best management practices for irrigation, so that those growers are using only the water that is really required. It's good for them too because growers realize that the less they have to pump, the less money that they're spending to grow the crop. So there's a return on investment issue just like we saw with fertilizer. So sustainable irrigation management is very important to farmers. And fortunately in, in this country and around the world there's been a considerable amount of research on developing irrigation systems and teaching farmers how to use these more efficient irrigation systems. And having irrigation systems change with time and become more and more efficient. We'll look at some of this information about water use efficiency on farms and how we can understand water use on farms, and help farmers adopt. Best management practices in their irrigation management and we'll take a look at that in our next, in our next lecture. But just keep in mind as we learned earlier in the course, the population is still growing in this world and the food demands are still increasing. So farmers are going to be asked to produce more and more food and irrigation is a critical, a must component of successful food production. We need to understand that as consumers and we also need to help farmers adopt best management practices so that even though they are using water on our behalf we all can be as efficient as we possibly can. So if you look at a few take homes at least from this particular part of the, the work on water. We know that water is vital to life and we also know that there is a tiny fraction of it that we can use readily on this planet and so we want to avoid overusing water. We want to conserve it as best as possible. We want to help farmers because agriculture is a large water user, we want to help farmers understand to learn and adopt. Best irrigation practices so that, so that they can produce out food in an efficient manner. So human activity is having a big impact on not only the water quality as we've spent a lot of time looking at but also on water quantity. And agriculture, again to produce food on our behalf is the largest water user. So here's where we can possibly continue to make some positive impacts on improving efficiency and conserving water, is through working with our agriculture producers.
