Guy - [00:00.120 - 00:25.470]
Okay, welcome everyone to HaifaStream podcast, presented by Haifa Group's Modern Greenhouses Task. Well, my name is Guy, I'm an agronomist based in France. And – well, I'm discussing with my colleague, Marco, and that's one of our questions today, is about how to manage the pH in the soilless crop.
Marco - [00:27.960 - 00:58.750]
Yeah, correct. Thank you, Guy, for your invitation. First of all, I shall introduce myself shortly. My name is Marco Molenaar, located in the Netherlands, but also traveling worldwide to visit growers, to help and to support them about pH in general, because this is the red line in the whole nutrigation. So let's discuss the topics which we put on the table today, Guy.
Guy - [00:59.480 - 01:27.520]
Okay. Thus far, when we're speaking about pH in the soilless crop, that you have several points where we can measure the pH. So first we can begin with the mixing tank when we are putting all the fertilizer. What can you say that's about – what is the pH level that you need in the tank for calcium, the tank with phosphorus, and what problem we can have if we don't have the proper pH in the proper tank?
Marco - [01:28.900 - 02:55.760]
First of all, I want I want to look back in the previous podcasts which we create from our group, because in every podcast, the pH is coming back. What I want to say here is that this is the whole red line in nutrigation. So in one of the previous podcasts, we say something about pH management in fertilizer tanks, because this is step number one to manage everything. One of the reasons here is to bring every fertilizer in 100% solution. Everything what is on the bottom of the tank is not good, it's not sent to the plant. So depending on the type of the water, we shall use more or less acid to decrease the number of bicarbonate. The information which we need in front is the type of the water, the quality of the water, to see the level of pH, to see the level of bicarbonate, and if needed, to decrease these kind of levels. So remember, looking to fertilize a tank, that the pH in the tanks, especially the tank where we are adding sulphate and phosphate-based fertilizer, must be below 5. So that's rule number one, to have everything back in solution. If we look to the modern greenhouse market, what you call the hydroponics, most of the greenhouses are installed with a two-tank system.
Marco - [02:56.260 - 03:46.850]
Also there, I want to review a little bit back to one of our previous podcasts where we say something about one-tank system and a two-tank system. But now looking to what we call modern greenhouse markets, most of them are installed with a two-tank system. A mixing tank, and we shall discuss, okay, what is a mixing tank? What is a two-tank system? An acid tank, because also this is common in the modern greenhouses. And we have some storage silos where we collect different types of water. Different types of water, speaking about the starting water. Collect drain water, more and more. But we shall discuss it. Let's start with the topics.
Guy - [03:47.600 - 04:03.940]
Okay, so that we're speaking about acid. What acid we can use? We hear about something about nitric acid, about phosphoric acid, sulfuric acid. So what is your experience about the different acid you can use, you can find in the greenhouses?
Marco - [04:04.450 - 05:10.260]
Yeah, in general, not especially looking to our market in the Netherlands or in Belgium, there are three main acids available in the market. So speaking about the different types of acid, we can say nitric acid, that's one, phosphoric acid, and we have sulfuric acid. So it's on grower level to choose one of these acids to decrease the pH and also to decrease the level of bicarbonate. Which acid is common? Nitric acid. So depending on the market, we have different concentrations of acid available. And especially this type of acid, we use it most of the time. I know other markets, they don't have the availability of nitric acid, so you must step to, for example, phosphoric acid. So I cannot say in the whole world we use nitric acid. It has to do with rules; it has to do with safety. But in general, these are the three types of acid which we can use to do the things which are needed.
Guy - [05:10.580 - 05:13.680]
Okay, so the most common that we find is the nitric acid. Okay.
Marco - [05:13.950 - 05:14.450]
Yeah, correct.
Guy - [05:14.680 - 05:42.280]
When we're speaking about the tank, that – we were speaking about recirculation in one of our previous podcasts. The question is that you are speaking about the clean drain water, the dirty drain water, and of course, what is the pH? What is using some acid for the UV disinfection, for example. So about this drain water, what can you say about the pH and the pH management of this drain water?
Marco - [05:44.240 - 07:15.140]
What we see more and more is that growers who are using disinfection equipment, for example, UV, this is one of the disinfection equipment which are common in the modern greenhouses. So we collect drain water coming directly from the in the greenhouse. This is what we call the dirty drain water. Tomatoes and more and more also other crops are having disinfection equipment. And what we said, UV is one of them. So we collect the drain water coming back from the greenhouse called dirty drain water. Then we disinfect it via UV. And in this system, there is also a need for an acid, and also there the most common acid which we is nitric acid. And we know that if we use acid that we decrease the pH, and also to destroy a little bit, or sometimes all levels of bicarbonate. So saying this, there is a difference between dirty drain water collected in the greenhouses and after disinfection, looking to pH, looking to bicarbonate level. So you can imagine that if you disinfect all the dirty drain water via UV, that there is a difference in pH and the level of bicarbonate. In the end, the clean drain water after disinfection, this is the type and the quality of the water which we shall reuse it again in our new recipe.
Marco - [07:17.560 - 08:03.040]
And we don't say anything about the iron chelate. I remember in one of the previous podcasts, also there, that we do something in this equipment on the iron chelate. If it's not in a good, let's say, environment, we also kill most of our iron chelate in this disinfection equipment. There is one way to manage this, to refresh in the fertilizer tank a good amount of iron chelate. So in this process, there is happening a lot. pH is going down, the level of bicarbonate is going down or destroyed completely, and the level of iron chelate is going down. So remember, these are interesting and important topics to know in front.
Guy - [08:04.100 - 08:22.180]
So we're speaking that we are destroying (indistinct) all the bicarbonate in clean drain water that we use for watering the crop. So that's the question is, if we have water without bicarbonate, what pH do you want in the drip line to the crop?
Marco - [08:22.640 - 09:46.480]
That's a good question, but I cannot say in general, this is the pH which we want in the drip lines. It's, of course, it has to do with which crop is behind. But okay, we are present in the markets mainly in the vegetables. So speaking about tomatoes, peppers, cucumber, aubergine or eggplant. So let's focus on these big crops, which are also present more and more worldwide, of course. I want to see a pH, let's say between 5 and 5.5 in the drip. Below 5, it's not good. You lose also here some elements. Up to 5.5, so in the direction of 6, we also lose here the availability of different elements. Main elements which we are losing when the pH is rising up to a pH of 6 is iron, phosphorus, and manganese. These three elements are sensitive for a high pH, and there are solutions for that. But for good solubility, for no precipitation in the drip lines, we want to focus on a pH between 5 and 5.5. This is the range which we want to see every time back on paper when we bring these drip samples to the lab.
Guy - [09:47.500 - 10:01.490]
Okay. This is the only reason that you want to manage properly your pH in the drip system? The drip is only for the availability of, for example, phosphorus, iron, and manganese, or do you have other reason to manage properly your pH?
Marco - [10:02.820 - 10:48.740]
When you're speaking about drip, Guy, then I also want to prevent my system. If we have a too high pH in the water which we send to the plant, there is also a reaction between some elements, and calcium and phosphorus, magnesium and phosphorus, are easily precipitate with each other when the pH is rising. This is another very important thing to know. So looking to starting water, looking to the tanks where you are adding the fertilizers, everything must be managed to have in the end, in the drip lines, the water plus fertilizers which you are sending to the plants, a pH between 5 and 5.5. Also for these reasons.
Guy - [10:49.620 - 10:49.740]
Okay.
Marco - [10:50.240 - 11:06.020]
To avoid precipitation, to protect your system, and to protect in the end also the problems which you can have in the drip membranes to clogging. This is not what we want in the end, of course.
Guy – [11:06.660 - 11:10.820]
No, if the drip is clogged, I think you should have a big problem on your crop after that.
Marco - [11:11.120 - 11:11.413]
That's correct. Yeah.
Guy - [11:12.660 - 11:33.760]
Yeah. That was speaking a lot about bicarbonate that you are explaining that you are destroying the bicarbonate when you are adding acid, for example, for UV disinfections. So how can you say about the management of the bicarbonate level in the starting water, the drainage water, or maybe in a drip solution?
Marco - [11:34.340 - 13:01.160]
This is really an interesting point because I say something now about disinfects the drainage water. We say something about the type of the starting water. If I look to my territory, most of our growers are working with clean water, so there is nothing inside. But I know also that there are places who don't collect the rainwater, or there are places there is no rain available, let's say, during the whole year. So they must work with water coming from the soil, what we call well water. If we look to this type water, well water, it contains also a level of bicarbonates. So that's one. Another one – one step back, when we are collecting drain water and we visit also some growers without any disinfection equipment. So the drain water is collecting, and we shall reuse this type of water also in our new recipes. We also learned and know that if we collect this type of water, that it also contains sometimes a lot of bicarbonate. So we have two water streams which can contain, I must say, bicarbonate. The higher the number, the more invest you must do to decrease a little bit the amount of bicarbonate.
Marco - [13:02.860 - 14:26.460]
And in the beginning, we say something about, okay, A and B tank, it is what it is. We manage everything in a good way. And then we have the mixing tank. And the mixing tank is in the end, the water, what we call the drip water. In this small tank, everything is coming together. Starting water, an amount of A and B tank, or what we call the calcium tank, sulfate and phosphate tank, and an amount of the drain water. And if this water is containing bicarbonate, we think and expect that everything, what is happening in the mixing tank is managed at pH. So the modern greenhouses, they have investment to add acid where needed, also in this mixing tank. So we have a measurement system to measure the pH. So the computer is saying to us, we have a pH of 6, and we say to each other that we want to have a pH in the drip between 5 and 5.5. So the measurement system is saying we want to have a pH of 6, so there is a need for an acid. We expect that in this small tank, the mixing tank, that we manage everything in a very short moment, because this is an automatic system, and in a very short time, we must manage everything.
Marco - [14:27.780 - 15:30.410]
And from our experience, we can say we cannot manage everything in front in this small mixing tank. So if you can manage in front of this mixing tank, the pH, the level of bicarbonate, it is better, and the last need for an acid is happening in the mixing tank. But don't expect that if you have, let's say, 2 millimoles of bicarbonate in the starting water and in the drain water, that we want to decrease it to, let's say, 0.5 millimoles of bicarbonate, it shall not be happening fully in the mixing tank. So if you can manage in front the level of bicarbonate, it is better. Otherwise, what we see is that the drip in the pH, on the computer, we say between 5 and 5.5, but then we shall see that the pH is rising in the drip up to 6, and then you have the problems which we discussed. This is not what we want. So managing that is important.
Guy - [15:31.320 - 16:00.640]
Okay. Yeah, you are speaking a lot about the mixing tank. The pH, that it could be quite difficult to manage properly if the job is not done before the mixing tank. The question is, of course, that there is the pH of the water. But what is happening in the root system? Because the pH near the root system is quite important for the availability of the different nutrients. So is there a way to manage this pH? What can we do with the problem?
Marco - [16:01.060 - 16:03.780]
Yeah, it's again a good question, Guy.
Guy - [16:04.780 - 16:06.200]
I always have good question.
Marco - [16:08.780 - 17:32.290]
So okay, we manage everything in front. We have starting water, we have A and B tank, we have mixing tank, we have drain water, everything is managed. But then the next step, okay, we send a good drip value, looking to pH, bicarbonate, to the plant, but then the plant is growing, and also there is happening something. So when the plant is growing, we see it directly back on the numbers on paper. The bicarbonate levels is rising, and we know that if the pH is also rising, and I want to bring an example, if it's okay for you, on the table, looking to the pepper market. The pH is rising when the plant is growing. Also, the level of bicarbonate is rising. And if these two compounds are rising, we know that we lose availability of phosphorus, iron, and manganese. The numbers on paper are going down. So here we try to manage the pH also. The ideal pH in general to have everything in a soluble way for up taking by plants is around 6. So this is a little bit different than what we want in front in the drip line. So in the root system, we want to have a pH around 6.
Marco - [17:32.560 - 18:34.600]
Then everything normally is available for the plant. Every element which we want to bring to the plant is available. But our knowledge is that, in the pepper market, for example, is that we measure a pH of 7, which is a little bit higher than the 6 which we put on the table. So how can we manage? Is not with an acid, because we use nitric acid or phosphoric acid or sulfuric acid to manage everything in front. But in the root system, we use other products. And if we say something about this, which type of products do we have available to manage this in the root system? Then we are going to products which are containing ammonia or urea. And then we have different types of fertilizer available to decrease the number of pH and also to decrease the number of bicarbonate. So this is my answer to the market to manage also this one.
Guy - [18:36.120 - 18:54.160]
Okay, so that was speaking about the pH in the root system. What do you think we are speaking about analysis for the water, the fresh water, the drain water, etc. And what do you think about analysis from the slab, something like that? What is your opinion? Is it something that we need or something that we cannot not do?
Marco – [18:55.320 - 19:50.570]
Most of the time, look, let's say the experience from me in the markets from grower level is that they also take water from the slab. This is the first impression to see, okay, are we on track? Yes or no? Must we correct something? Yes or no? Most of the growers are taking slab water as a reference. Are we on a good level? My advice is, okay, this can give us good information. But drip water, take a sample of the drip, collect it, bring it to the lab to see if the amount, what we are sending and collecting, and what we put in a mixing tank, is this on a good level also? So today it's a combination of slab water and drip water. And then we have normally fully information available to give our recommendations for the crop behind.
Guy - [19:51.540 - 20:12.580]
Okay. And that as well. Okay. Well, that's the question. That's most of the problem, as you were saying, that's generally a pH increasing in the slab, in the drainage water. So for you, what should the good reaction for the grower if the pH is increasing too much or maybe decreasing too much, is the same effect?
Marco – [20:14.580 - 21:39.840]
This is really a topic which we discussed, I can say, most of the time every day. So the pH is rising up to 7, in the example of the pepper. You see less availability of manganese or phosphorus, and a normal reaction of the grower, consultants also, is that we are adding more and more from this type of products. So speaking about phosphorus, more MKP or more other phosphorus-based fertilizers or extra manganese. And I think this is not the good way. I think that the drip water must contain a good level of phosphorus and a good level of manganese, for example. And if the number in the slab, the high pH is going down, in my opinion, the drip must be good organized. If you are adding more phosphorus and if you are adding more manganese, you are asking for problems in the end because extra phosphorus in your recipe or extra manganese in your recipe can react easily with calcium, for example. So the chance of precipitation of these type of elements is there. Be aware of extra adding phosphorus or extra adding manganese because in the end, it costs you a lot of troubles and money in the end to clean your system.
Guy - [21:40.880 - 21:50.520]
So for you, that's increasing the phosphorus, the manganese, iron, etc, is not the right way to react if you have problem with pH in your solution.
Marco - [21:51.100 - 21:51.340]
Yeah, correct.
Guy - [21:52.840 - 22:13.540]
Okay. That's what we're speaking a little about this. But for you, what can have influence on the pH in the root environment? So we are speaking about, of course, that the acid you can add, that, of course, the fertilizer with urea or ammonia, is there something else that we can advise to the growers?
Marco - [22:14.080 - 23:30.000]
Yeah. Also here looking to the crop behind, and it's always a discussion with growers. So let's stay in the example of peppers. If we see a pH of 7, some growers are asking me, okay, what can we do about the pH? And I said, the only way to manage this is to work with products which containing ammonia. But then directly they say, are you sure? I said, yes, you can work with products based on ammonia. But the other side is, when we are bringing ammonia in the recipes of peppers, sometimes there are problems coming back. Blossom-end rot is one of them. So we can do something with these type of products. To give you an example, calcium nitrates, the soluble calcium nitrate, contains a level of ammonia. MAP, monoammonium phosphate, contains a level of ammonia. So you can do something with this type of products to balance, let's say, the pH in the root zone. And this is my answer to the markets. If you want to do something, this is the solution. Not too much, but an acceptable level, you can work with.
Guy - [23:30.880 - 23:57.500]
Okay, thank you, Marco, very much to share your knowledge and experience about the soilless crop, the management of the pH in the whole soilless crop, from the tank to the slab to the drip solution. Well, this is all for today for the Haifa Stream podcast. I invite you to register for the next podcast that for sure will be with a lot of information like today. Goodbye.
Marco - [23:58.760 - 24:10.330]
Thank you, Guy. It was my pleasure to give a lot of insights in this, in my opinion, important line in nutrigation. Thank you.
Guy - [24:10.390 - 24:10.676]
Thank you.
