Help required for Nutrient Solution for Citrus Trees

[DumbFalang]

I have a target NPK of 15-4-11 + trace elements to fertigate a range of citrus trees that I grow. Here is what I know:

 

Soil pH 7.1

 

EC 1:5

 

Water pH 8 to 8.85

 

Soil organic matter 0.12 (moderate)

Nitrogen 24 (high)

Phosphorus 24 (high)

Potassium 158 (very high)

Calcium 3527 (high)

Magnesium 123 (moderate)

 

Obviously, it would be great to have a 'balanced' solution, but I'd be happy with something 'in the ball park'.

 

I thought about using Ammonium Sulphate as my Nitrogen source but am not sure if it comes in soluble form. The trace elements I have are Iron Chelate, Magnesium Chelate and Copper Chelate (Librel brand). Did I miss anything?

 

Thanks in advance for any suggestions to get me started.

[DumbFalang]

Update: I also have Zinc Chelate, Borax and Sodium Molybdate

[CLW]

I'm no expert but seeing your already high nutrient values (in the soil sample?) why do you want to go the expensive way to fertigate the trees.
I see your organic matter is low, why not use some organic fertiliser for maintain the nutrients in the soil and building up organic matter.
For trace elements a premix like Utilise Max should be sufficient.
It might worth a try to split the application half to soil and foliar treatment.
That's all just my opinion and guess.

[drtreelove]

Good suggestions from CLW.

 

What is the source of your soil test, and do you know what extraction method/material was used: Mehlich 3, Ammonium Acetate (AA8.2 or other) or other extraction medium? 

 

Because it makes a big difference in reported results and interpretation/recommendations. For a soil with pH over 7.0 the Mehlich III or other highly acidic medium may dissolve excess calcium from parent soil material, changing the interpretation, and causing a miss reading of the Ca to Mg ratio, CEC and other factors. Over 7.0 an alkaline extractant like the AA8.2 test is appropriate and will be most revealing.  

 

The EC you reported must be Electrical Conductivity and not CEC, Exchange Capacity. I use CEC so can't comment on the other.

 

Are you growing in the ground or in containers? In real mineral soil or in a medium?  A %OM of 0.12 is not moderate, but extremely low as CLW observes. It may be moderate in the context of Thailand soil conditions, and common for in the ground, in the tropics, because its hard to maintain the ideal SOM of 2 to 10%.  5% would be moderate and was in fact the original minimal requirement to qualify as a certifed organic farm in the early California programs.  

 

 

[drtreelove]

Further: 

You may want to consider buffering the water with a pH reducer like citric acid. Because 8.0 to 8.5 will alter your soil and fertilizer chemistries. And also any pesticides that you use with that water. 

 

The major anions and cations measurements are related to the extraction method in this case so accurate interpretation remains to be seen. 

 

Granular Ammonium sulfate 21-0-0 that I have used is highly water soluble, but only with good agitation. Test yours in a jar sample. It has an acidic effect because of the Sulfur, which is a major anion and one of the most important plant nutrients that is readily used up with plant metabolism. But 21-0-0 is a high salt index harsh chemical that will contribute to killing off of beneficial soil organisms. For chemical growing, you may not care about that, but it is a consideration for some growers. 

 

 

[drtreelove]

Further:

You don't report on Na, sodium, which is also an important cation and plant nutrient.  What you term "trace elements" are usually called secondary or micro nutrients. And you have almost all of them all covered, B, Fe, Cu, Zn. Only Mn (Manganese is left out.) but maybe thats what you meant with the Magnesium chelate. The similarity in names is confusing sometimes.  

 

But you need to have an accurate soil analysis with ppm found in the soil sample. Only then can you get an Rx to bring the levels up if needed, based on the actual deficiencies found. And then you need to know the % of the actual elemental mineral in the product, in order to calculate how much of the product to add. And as some of these secondary mineral amendments are sulfates, you need to calculate the Sulfur you are adding and how that affects the balance. It gets complicated, but that's what I've been studying with Michael Astera the author of The Ideal Soil. 

 

Trace minerals/elements are not usually measured in a standard soil test, and they may be hard to supply with fertigation. But think about a liquid kelp product to get some of these.  

[DumbFalang]

Thank you so much guys. That information has given me a lot to think about. I will do what CLW suggests on this particular land and see what happens. I had a feeling someone might suggest this and I have already been researching how to increase organic matter.

 

My soil test was a basic Bt500 one from Mae Jo university in Chiang Mai. I dug the sample myself in a bit of a rush so the test is almost certainly not as accurate as it could be (my fault - not Mae Jo's).

 

I will want to fertigate the same variety of trees on other plots of land in the future, so I will get proper soil tests done and revisit this subject.

 

Once again - much appreciated advice ;-)

[drtreelove]

I too listen to CLW.  He's humble, but did you know he has a degree in Tropical Agriculture from the top Ag U in Thailand.

 

As an experienced grower you know that one the most cost effective ways to manage soil organic matter is with green manure cropping/inter-cropping. 

 

The more expensive but with instant results is a high quality compost that you make yourself, or from a regular forum member pig farmer who can PM you if they have it available, or from Natural Agriculture in MaeTaeng.  http://www.thai-organic-compost.com/

 

Raw rice hulls, rice straw and coconut fiber are readily available, but raw materials should not be incorporated, only used as mulch. And what Cooked has pointed out before, even mulching with raw materials can in some cases draw soil minerals for the decomposition process.  

 

[IsaanAussie]

This is a conversation to keep an eye on. My kind of stuff. 

[drtreelove]

8 hours ago, IsaanAussie said:

This is a conversation to keep an eye on. My kind of stuff. 

A bit off topic from Not So Dump Farang's stimulating post, but not off the compost topic: you may enjoy this article that Island Guy sent me: 

No, change my mind. This climate change world view deserves it's own Discussion. 

[DumbFalang]

In case anyone is interested, here are the soil test results from Mae Jo:

 

 

[DumbFalang]

The land being discussed is only 1.5 rai but it has been free from pesticides for around 5 years now - and it will stay that way. We only grow 'high end' crops and we are happy to share 10-20% of our crop with the birds and insects. Consumers are much more educated these days (Facebook and Google aren't completely evil) and the price they are willing to pay for 'clean' food more than makes up for the losses caused by pests.

 

I heard the missus talking with the current renter of the 3 rai next to us and  after 2 decades of abusing the land he has decided to throw in the towel. He is going to inform the owner that we want to take it over and I can't wait to see the soil test results from that toxic wasteland. We would use 1 rai for our citrus trees and the other two rai for rice.

 

We already proved last year that we can grow a successful rice crop in 'abused' paddy fields without the use of any chemical fertilizer or pesticide, so two of the three rai are not a concern. I've thought many times over the years on the best way to 'repair' abused rice paddies but have yet to come with a cost effective solution.

[drtreelove]

I just noticed that you posted the MJU soil test report.  I'm going to look it over and see if I can offer any insight.  I'm fully immersed right now in soil testing and trying to determine the best labs to use for organic program oriented analysis and recommendations.  I used MJU and CMU in the past, but it's been over 10 years. CLW took me to the Kasetsart U Soil Science Department and I submitted a soil sample there to experience their process and pricing.  3500 baht for the test items I wanted, which I get for $25 (775 baht) at the lab I use in the US.   So today I'm sending a sample to that lab by EMS ThaiPost, to see how it all compares. 

 

It's really confusing with all the different ideas and approaches to soil management. Most are oriented to the chemical fertilizer industry.  After Rice555 introduced us to Michael Astera's The Ideal Soil book through this forum several years ago, I have been using that approach very successfully for my customers trees and landscapes in the US, and for my own veggie garden.  So don't give up on the soil testing and prescription amendments based on actual deficiencies found with your specific soil.  Organic matter is vitally important, but it decomposes and is rapidly lost in this climate. OM is better utilized, enhances beneficial soil biology and forms humus better when the soil minerals are adequate and balanced. 

 

Your intention to grow without hard chemistry pesticides is admirable, but how practical it is would be the big question, especially if you don't differentiate from "bio-pesticides" that can be quite useful if used preventively, and are organic program compatible. How do you repel Asian Citrus Psyllid that carries HLB bacterial disease?  Or Citrus Leaf Miner, or scale and aphids.  You will have much less need for pest and disease control if you balance the soil minerals along with the organic matter inputs. Plant resistance to pests and diseases is enhanced with high nutrient density growing practices.  

 

https://www.newsociety.com/Books/I/The-Intelligent-Gardener

 

http://www.soilminerals.com/

 

[kickstart]

2-3 years ago Farmerjo sent some soil to be tested, they were very fussy about the way the samples were taken, the results were interesting, all minerals and trace elements where tested.

Have a word with him for information. 

[drtreelove]

The MJU soil test is really minimal and only addresses a selected list of major minerals, for the objective of NPK  fertilizer recommendations.  There is not nearly enough information to assess all the major plant nutrients and balancing.  There is no Sulfur, a major anion and no Sodium, a major cation. And you can't calculate CEC from this.  A complete analysis should not just list amount of the mineral available, but % saturation and also the relationships and ratios, like Ca:Mg ratio which is so important. 

 

The minor nutrients products that you have available may be useful if you knew the current levels. But to add them without an Rx would not be wise. 

 

BTW, I noticed that you had reversed a couple of the reported amounts: 

 

Most significant is "Soil organic matter 0.12 (moderate)" [Actually it is 2.45 % on the report, which is quite high in relation to the climatic conditions, and a really good starting point for building fertility. This reduces any urgency with your compost requirement and CLW's observation] 

 

To give you an example of a complete report, attached is a sample Logan Labs report and Michael Astera Rx that I facilitated for my friend in San Sai, CM with a small integrated permaculture farm, including 9 rai of rice. 

 

Michael Astera offers these free first 2 chapters of his latest version of The Ideal Soil: A Handbook For the New Agriculture

 

http://www.soilminerals.com/TIS_Ch1.htm

 

http://www.soilminerals.com/Cation_Exchange_Simplified.htm

 

 

 

DonCox_Walliingford1_June2011[1].pdf

[IsaanAussie]

DrTreeLove,

I like your report a lot. It is very similar to the recommendations we developed in Australia for some grazing land. We analysed the pasture and the compost that was to be applied and then developed a blend of organic approved additives to be combined with the compost. I hasten to add some MAP was suggested in that case as well but not used.

We also had the current grasses tested as a further check. 

I want to try taking the composting a step further by using biology to improve the plant nutrient availability from some of the minerals etc.. added to the compost. This follows the results I had making up fertiliser from compost, rock phosphate, dolomite and lime for our rice crop a few years ago. 

I hope that a bit more science and knowledge of the on farm resources available should help reduce the chemical requirement and improve the nutritional value of the crops whilst reducing external costs. Love to have a local agronomical service supporting my small farming efforts. Let me know if you find one (in Isaan would be great).

 

 

 

[drtreelove]

3 hours ago, IsaanAussie said:

Love to have a local agronomical service supporting my small farming efforts. Let me know if you find one (in Isaan would be great).

This should really come first of all from a university extension service.  I meant to ask CLW if he knows what farm advisory service is available through Kasetsart U. 

 

Not many farmers can afford to hire a consulting service, and if they do, they are usually selling something, which may be appropriate, or not. Most farmers are at the mercy of peer word of mouth (which isn't always bad) and the chemical salesmen. It's hard to get educated unbiased information that way.

 

I was fortunate in the US to have had access for many years, to the University of California Cooperative Extension, with its farm and environmental horticulture advisors associated with each County Agricultural Commissioners office.  They have advisors that go out to farms and landscape sites on request, put on seminars and have publications and online information available, often for free. 

 

Greame Sait of Nutri-tech says in the following article:  "we are working with a team of agronomists in over 45 countries. We continue to expand our influence and achieve impressive results, and cation balancing is an integral part of our strategy. "

If you are working with that organization in OZ you might ask them about Thailand reps. --- or become one. 

 

This excellent blog article is applicable to this discussion, and supports the work of The Ideal Soil and Intelligent Gardener books. 

http://blog.nutri-tech.com.au/in-defense-of-albrecht/

[drtreelove]

On 5/9/2018 at 2:14 PM, kickstart said:

2-3 years ago Farmerjo sent some soil to be tested, they were very fussy about the way the samples were taken, the results were interesting, all minerals and trace elements where tested.

Have a word with him for information. 

Yes it's important to take soil samples in a way that provides the lab with good representative sampling. 

www.loganlabs.com/customer-tools.html

 

BTW, I sent a soil sample to Logan Labs in Ohio, USA yesterday, Thai Post EMS 1600 baht. There may be a cheaper parcel post service that takes longer to get there.  If anyone is interested, I can coach you through the process with worksheet, permit and recommendations based on the results. Most of the amendment materials are available in Thailand.  For strict organic growers its a little harder to find some things.  

[drtreelove]

It's ancient knowledge that soil fertility is the foundation of plant health and human nutrition, but the science of testing and balancing is experiencing a new flush of growth. 

10 million dollars in grants for this research project:

 

https://soilhealthinstitute.org/north-american-project-to-evaluate-soil-health-measurements/

[drtreelove]

On 4/21/2018 at 8:47 AM, DumbFalang said:

In case anyone is interested, here are the soil test results from Mae Jo:

 

 

I ran this by my soils guru, Michael Astera author of The Ideal Soil.  This may be of interest to others also: 

Don-

First step would be to determine, if possible, the testing method used. Probably AA7.0, but could be Mehlich 1 or 3. 

The test lists Ca, Mg, and K so you could calculate approximate CEC from that.

I would explain that this is good and important information, but doesn't cover all of the major plant nutrients, which are just as important as those shown. Plants also need S, B, Fe, Mn, Cu, and Zn and will not grow well without optimum levels of those nutrients as well. 

As a side note, the probable reason that many labs do not test for more elements is because they don't know what is a desirable level for them. Soil testing is still in the dark ages. ?

 

I calculated an approximate CEC of 19 meq, based on the major cations reported, but without Sodium (so I estimated a moderate amount). This is an ok CEC indicating a good amount of exchange sites available, so improvements can be made.  You can read more about the importance of CEC in balancing major minerals here:  http://www.soilminerals.com/Cation_Exchange_Simplified.htm

 

I'll work out some limited recommendations based on the available information. 

 

[drtreelove]

On 4/21/2018 at 8:47 AM, DumbFalang said:

In case anyone is interested, here are the soil test results from Mae Jo:

 

 

I ran this by my soils guru, Michael Astera author of The Ideal Soil.  This may be of interest to others also: 

Don-

First step would be to determine, if possible, the testing method used. Probably AA7.0, but could be Mehlich 1 or 3. 

The test lists Ca, Mg, and K so you could calculate approximate CEC from that.

I would explain that this is good and important information, but doesn't cover all of the major plant nutrients, which are just as important as those shown. Plants also need S, B, Fe, Mn, Cu, and Zn and will not grow well without optimum levels of those nutrients as well. 

As a side note, the probable reason that many labs do not test for more elements is because they don't know what is a desirable level for them. Soil testing is still in the dark ages. ?

 

I calculated an approximate CEC of 19 meq, based on the major cations reported, but without Sodium (so I estimated a moderate amount). This is an ok CEC indicating a good amount of exchange sites available, so improvements can be made.  You can read more about the importance of CEC in balancing major minerals here:  http://www.soilminerals.com/Cation_Exchange_Simplified.htm

 

I'll work out some limited recommendations based on the available information. 

 

[drtreelove]

On 4/21/2018 at 8:47 AM, DumbFalang said:

In case anyone is interested, here are the soil test results from Mae Jo:

 

 

 

 

I ran this by my soils guru, Michael Astera author of The Ideal Soil.  This may be of interest to others also: 

Don-

First step would be to determine, if possible, the testing method used. Probably AA7.0, but could be Mehlich 1 or 3. 

The test lists Ca, Mg, and K so you could calculate approximate CEC from that.

I would explain that this is good and important information, but doesn't cover all of the major plant nutrients, which are just as important as those shown. Plants also need S, B, Fe, Mn, Cu, and Zn and will not grow well without optimum levels of those nutrients as well. 

As a side note, the probable reason that many labs do not test for more elements is because they don't know what is a desirable level for them. Soil testing is still in the dark ages. ?

 

I calculated an approximate CEC of 19 meq, based on the major cations reported, but without Sodium (so I estimated a moderate amount). This is an ok CEC indicating a good amount of exchange sites available, so improvements can be made.  You can read more about the importance of CEC in balancing major minerals here:  http://www.soilminerals.com/Cation_Exchange_Simplified.htm

 

I'll work out some limited recommendations based on the available information. 

 

[DumbFalang]

Thanks for your time and advice.

 

All I am adding to the top of the soil around the trees is cow manure, coffee grinds, slow release organic fertilizer pellets and rotten leaves. I will eventually mulch with straw from our rice fields.

 

I am using a foliar spray about once a month that contains the usual trace elements. The trees are progressing well and as I 'trust' the soil, I don't worry about this particular batch of trees.

 

We have just taken over the 3 rai of 'toxic wasteland' next door (typical scenario where nothing has been put back into the ground for decades). Rather than trying to repair the land, we have decided to grow in large bags and just use the newly available space.

 

The challenge now is how to prepare a good soil for the bags and how to continually rejuvenate the soil over the years. Again, I will not add chemical fertilizer to the soil for trees grown in bags and will give them everything they need through their leaves. Well, that's the plan at least.

[drtreelove]

13 hours ago, DumbFalang said:

The challenge now is how to prepare a good soil for the bags and how to continually rejuvenate the soil over the years. Again, I will not add chemical fertilizer to the soil for trees grown in bags and will give them everything they need through their leaves. Well, that's the plan at least.

Funny that you should mention it; I was just working on trying to put together a formula for a "Complete Organic Fertilizer", like outlined in the chapter of the same name in The Intelligent Gardener by Steve Solomon. Or Michael Astera's super mix:  http://www.soilminerals.com/Agricolas 4-8-4_MainPage.htm  He sells this for vegetable beds, potting and regenerating container plantings. Cannabis growers in the know love it now, in the happy land of legal weed.   

But a lot of the ingredients just aren't available in Thailand. That's what I'm working on, trying to find what is available to blend a reasonably good, general purpose, affordable, mineral balanced, organic fertilizer for planting beds and container gardening. 

 

 

 

[DumbFalang]

11 hours ago, drtreelove said:

 

But a lot of the ingredients just aren't available in Thailand.

 

Please let me know what ingredients you are unable to get hold of and I'll try to help. We have some really good contacts ?