Soil preparation: When did it become so important and how should it be done?

Soil preparation: When did it become so important and how should it be done?

A correct soil preparation may be determined by establishing it to the lifespan of a project; it is the key in monitoring the work needed to avoid possible errors that may not be correctly amended in the future.

The constant growth of the fruit production industry and use of new types of soils for its development have turned out to be a great challenge for producers over the last decades, since it has become necessary to use totally different land than what is customary to plant new orchards.

However, for many years the work preparation of soil for new projects didn’t have major modifications, this is how the Consultant, Antonio Lobato, describes it as co-author of “Manual de Preparación de Suelos Frutales (Manual for Soil Preparation in Fruit Orchards)” by Anasac, published recently in 2021.

“Until the beginning or mid-part of the year 2000 we had good soils, but we started to have complications when the fruit production industry continued to develop and went from 190 thousand to 342 thousand hectares, that meant that we had to start using more complex soils, marginal ones, rice growing soil, crude soils, with more clay than what we would like, rocky ground; and when preparing them with the standards of good soils, there were lines, blocks that never broke, the preparation of dry soil and when we did soil prospecting throughout the years we would continue to find those blocks stuck underneath, though we thought that the ploughs had broken them, or lots of humidity, and then we had things like those,” explained the consultant.

Before this, in the mid ‘90’s, it was already possible to detect problems of root asphyxia – decay-cavities in fruit trees – which was described in those same years and is represented in the loss of fine-root mass, roots growing in an upward direction, red colors, etc.

“We managed to solve (this) when we understood that not all soils irrigated by the drip system may be irrigated in high frequency,” explained Lobato. Said study was even patented in the United States and was highly publicized as it was thought that orchards would operate better with that system, however not all plants had uniform development: “Many presented twisted root systems, either from nurseries or because we twisted them at the planting time, all these defects mean unequal uniformity, low growth rates and this is what we described and published around 2009-2010”, added the consultant.

Haste and lack of awareness, among other factors, produced in different orchards superficial root systems, despite the fact that supposedly there was good soil preparation done: “The empirical evidence says that this is what we had and not in just one species, but in general… confined root systems, 90 degree root systems that showed us the impossibility of growth and development in the roots”, Lobato indicates.

It was made clear then that it was necessary to make specific soil preparation, not only at the chemical level, but also at the physical, using a certain type of machinery depending upon the type of soil, and that all this work should be considered a fixed asset of investment in a project.

“It’s necessary to prepare, to make amendments, there is no bad land, there is land that is poorly worked, all land may be worked upon (…) It’s necessary to do a good preparation and invest money on that, which is the only thing that may not be done over; one can replant the land, change the irrigation, replant the plants that are in bad conditions, but you cannot redo the subsoil so that the roots will penetrate”, advises Felipe Mayol, also co-author of the “Manual de Preparación de Suelos en Frutales”, along with Antonio Lobato, Andrés Piraino and Cristián Pino in the book that addresses techniques and strategies for correct soil preparation and to therefore improve national fruit productivity.

Soil preparation: the only work that may not be amended

When we talk about establishing a new cherry orchard it is fundamental to focus upon soil preparation where it will be established, and we should do this in two aspects: the amendments, which are the chemical part, and the physical, which is the soil preparation as such and that we will analyze below.

“The main objective of this work consists in that it is done only once in the project, afterwards I cannot amend any type of error, this is why it is so important, just like planting, doing it the right way”, points out Bruno Tapia, Avium Technical Coordinator.

It is recommendable to start with soil prospecting that will allow the inspection of the soil type and see what is the level of the water table, recognizing the moisture levels, and with that data evaluating what to do, how and when.

“What I recommend is to first clean the land if it has any grass or weeds, ploughing it, afterwards I recommend going over it with a scarifier digger or better known in Chile as a fixed leg, in a crossed fashion in order to break the first few centimeters of the soil and to not find surprises like when I am going in with a claw or a bulldozer, and find that after all this my field is full of dirt clods; you need to break about 60 centimeters of soil with light equipment, after which an excavator with a claw will come in or a bulldozer with a fixed foot, and will manage to penetrate a larger quantity and take out the clods or big material at the surface”, Raúl Salas, General Manager of Servcam, describes in detail.

In order to determine if it is appropriate to break the soil using a bulldozer or an excavator, you must take into account its moisture, the presence of rocks, among other aspects.

If we have soil with lots of rock presence I don’t recommend, under any circumstances, according to my point of view, getting an excavator in there or a claw because what you will achieve is getting out all the rock, over-mixing the soil and it will be an eternal gathering of rocks; the claw is much better when we have moisture in the soil, because we are able to get more out of it, break the ground, which with the bulldozer, when we have that moisture, we will only accomplish cutting out slices that will later join together and we will not attain turning it over, breaking the soil is what is sought after”, Salas explains.

The following decision is how the plantation of the new orchard will be done, whether it be on the ground or with a cover sheet, with the purpose of having better isolation of the plants and collecting all the soil nutrients to only one area; in this case the cover sheet acts as a planter for the trees.

“Optimum soil preparation will determine the lifespan of a project, as well as the ability of its establishment, since it will help me in water infiltration and, primarily, in breaking physical impediments that it might have, this is why constant monitoring is key in this work once it has started in order to avoid possible mistakes, because then afterwards they can be amended in a good way in the future”, concluded Bruno Tapia, Avium Technical Coordinator.

Only physical preparation?

«Do not forget that the concept of “soil preparation”, doesn’t only refer to the use of machinery, it also considers the physical preparation, since the chemical and biological preparation of the ground are also important from the point of view of nutrient recuperation up to putting together the organic material and even giving options to improve the soil micro-fauna respectively», explains Carlos Tapia, founder and Technical Director of Avium.

We shouldn’t underestimate what it means to mend the sufficiency levels of the soils in nutritional terms.

There are very important base nutrients that we should recognize and be able to make corrections before planting, since the subsequent work to this is to be able to maintain adequate levels, and when the orchard is in production, to be able to maintain these levels according to the use that it had in function with production. This is an exercise that must be done every year with important adjustments in the post-harvesting stage.

An important case in many soils is Phosphorus (P), an immobile element in soil, with which is very important to take to sufficiency levels prior to planting. However, this element is not always a problem in cherry production.

Without a doubt, Calcium (Ca) and Potassium (K) are the ones that we should have more concern with at the time of making these corrections.

Both elements are part of the Cation Exchange Capacity (CEC) and of the fertility of these soils and respond to an equilibrium dynamic between other nutrients like Magnesium (Mg) and Sodium (Na), where Hydrogen (H) and Aluminum (Al) also participate.

In this case, we must respect a range of participation of the CEC that is around 70% for the Ca and 2-3% for K (Table 1).

Any imbalance in the Ca affects the balance of the other cations. This means if we apply Ca to the soil without true necessity and this is above 70% of the participation of the CEC, it will automatically affect and decrease nutrients that are below the participation line as is the case of Mg and K respectively, having an imbalance of these in terms of deficiency. 

It has become common that in chemistry amendment applications Ca Sulfate (Fertiyeso) is used to “improve” soil structure. However, if the soil has adequate levels of Ca or ones that are higher than normal, the indiscriminate use of this fertiyeso, which contributes Ca to the soil, will increase the participation of this element in CEC, not being necessary and automatically creating an imbalance with the other cations (Mg, K and Na), so the correct use of this time for calcium amendments must only be reserved in order to form the nutritional standards, and if it were necessary, parallely, in second place, it will help the soil by physical means.

«It is different in the case of K and that its participation in the CEC is so low (but so necessary), that high levels of K are not capable of unbalancing upwards the Mg and Ca. K is an element that is not very mobile in soil and its not phytotoxic, therefore it may be applied without risk of waste. Consider also that this is the element that is most consumed in cherry growing (even exceding 10 units of K2O per ton of fruit production), so it becomes very important that, prior to planting, the levels of sufficiency are secured so that then, during the seasons, the exercise be that it is replenished by use through a consumption rate with respects to production», Carlos Tapia, specialist in cherry production and Avium Technical Director, analyzes and concludes.

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