Behavior of nutrients as a function of pH

Today, at Gardenprue, we have to talk about an essential element for any crop, the soil. If we already know the texture, the percentage of organic matter and the pH, we can almost certainly predict the problems that we are going to encounter. That is to say, the future deficiencies that will appear in our crops. Let’s see it.

Alright. Some will say that the soil is not essential for a pure hydroponic culture . It’s true. But we will never doubt that the soil is the foundation of agriculture, and as such, we have to know its properties and correct its deficiencies if we want something profitable to come from there.

The pH is an element that greatly conditions a soil. Depending on it, we will have to choose the plants that we can grow since, although we can correct the acidity or alkalinity levels of a soil by providing corrections, in the long term the soil’s own buffering capacity will return to its initial pH levels.


You can correct the pH of the soil as we discussed in this article ,  but more important is to see why the soil has such levels. If it is because it is located in a wooded and humid area with a high percentage of organic matter (acidic soil) or because we carry out a saline irrigation in our plot of land (basic soil). No matter how much we make corrections, if we do not know all the changes that occur in it and that alter its properties (that is, know the origin of said alterations), it will not do us any good to make corrective amendments and it will mean a great economic expense on our part. .


The goal of this article was this. Know first-hand what alterations can arise when we grow in a soil with a certain pH. It does not mean that the same mineral deficiencies always appear since for this we need an exhaustive analysis of the soil , but it will help us to choose the plants thatwe want we can cultivate in our garden.


We will not have any nitrogen availability problem for our plants as long as the soil pH is between 5.5 and 8.


If the soil pH is normal l (close to 7), there will be no potassium assimilation problem. But yes:

pH> 8: calcium antagonism occurs.

Potassium deficiency


We have several behaviors:

  • If pH <6.5:  precipitates with iron and aluminum.
  • If pH> 7.5: it will  precipitate with calcium.
  • If pH> 8.5: it  is solubilized with sodium.


Calcium is the quintessential element in a basic or alkaline soil . A plant grown in acidic soil is susceptible to calcium deficiency problems. Everything will depend on the levels necessary for its development.


When the soil tends to alkaline pH, boron deficiencies occur .


If the pH of a soil is acidic, the plants grown in it are susceptible to molybdenum deficiencies.

Iron, magnesium, copper, zinc and aluminum

All these elements increase in solubility and availability to plants when the soil is acidic. As the pH decreases , its mobility increases. Therefore, a basic or alkaline soil is susceptible to a deficiency in iron, magnesium, copper, zinc or aluminum. Let us remember, for example, iron chlorosis (the most famous of the deficiencies) due to a lack of iron and its correction with these chelates.

Iron chlorosis in olive tree

What was said. Not because we have an alkaline soil, we will have with total solubility deficiencies of the elements that have little mobility in alkaline pH. Everything will depend on the sensitivity of the crop and the power of adaptation of these species.

To get an idea, here is a table where the pH in which the main crops in the garden should be moved is collected, extracted from the article on the pH of the plants.


An acidic or excessively acidic soil has a lower activity of microorganisms and a lower root development. The assimilation of iron improves as we have commented before, but that of phosphorus or nitrogen (very important elements in any crop) does not. However, for us to really think that we are going to have problems due to acidic pH it is from 5.5. 

Less movement we have with an alkaline pH . From 7.5 we can start to have problems due to excess iron insolubilization. Many plants in our garden show problems due to lack of iron, its detection by us is very easy and the response to chelate applications is very fast.

A pH of 9 presents, apart from a minimum mobility of iron , a high presence of sodium carbonate, with the consequent physical and chemical problems of the soil, making it very difficult to cultivate.

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