Article developed by plant nutrition and soil management advisors, Lucas Ferrada and Antonio Lobato.
Chilean agriculture has undergone significant evolutionary changes over the past 20 years. As time has passed and cities have expanded, many of the ideal agricultural soils previously used for fruit production have become real estate alternatives with values that make farming unfeasible. Consequently, fruit cultivation has been moving toward other areas with often less-than-ideal climates, unfriendly soils, and many limiting factors.
This new reality compels us to develop techniques and soil preparation work that will allow orchards to be economically sustainable over time in terms of both quantity and quality of fruit.
Soil preparation represents the beginning of a long-term productive journey. For this reason, the work of preparation and habilitation must be meticulous and unhurried, to mitigate future issues that could complicate the productive life of the orchard.
Often, climatic conditions do not allow consistent progress through the various stages of quality soil preparation. However, planting deadlines, plant reservations, and, of course, associated anxiety often lead to this crucial and important initiation being conducted in a deficient and rushed manner, failing to achieve optimal conditions for a successful orchard establishment.
It’s crucial to highlight that proper planning of tasks can take a considerable amount of time, ranging from winter outings until the autumn of the following year, depending on the required habilitation type, and it involves the development of several stages.
1.- Water Evacuation
If the planting site has not previously seen agriculture, it’s important to identify the behavior of winter waters to diagnose inputs and undertake necessary work on drainage, surface water evacuation, and cleaning of internal and neighboring channels that could cause flooding in the future orchard. This is an integral part of what we call “Soil Preparation for Establishing Fruit and Vineyard Orchards.”
2.- Physical Soil Preparation
The physical preparation of the soil involves a significant level of detail achieved through decades of research, using different types of machinery and implements tailored to each scenario, determining appropriate moisture levels based on soil texture, and employing combined work strategies.
The initiation of this work is based on soil profile pits to define the different strata of the soil, the textural and structural classes of each, the presence of layers, and the moisture behavior of the soil. This will define the strategies to be implemented, the most suitable machinery, necessary tools, the number of passes, and the time between tasks.
Working with sandy soil is different from working with rocky or clayey soil; the work and machinery used will vary for each type.
The capabilities of a Caterpillar bulldozer model D8 versus a D9 (or similar models from other brands) differ significantly. Depending on the task’s requirements, poor machinery selection can lead to improper soil tillage and the desired depth not being achieved.
There are also differences when selecting an excavator; the work produced depends on the size of its hydraulic system and its weight. The market offers a wide range of excavators weighing between 21 and 45 tons, with power ranging from 147 HP to 350 HP. (Table No. 2), along with more brands and models available.
The most important factor for proper physical soil preparation is the moisture content at the time of preparation. This occurs in two stages: the first is the preparation of the arable layer (0 to 30 cm), conducted between September and October, and the second corresponds to subsoiling, which typically begins when the soil moisture is friable and delayed for irrigation based on a qualitative touch criterion, usually between January and March.
There are ideal moisture levels for good soil preparation, which will vary according to texture, structure, and regional rainfall (Table 2).
Significant differences in the results of various tasks depend on the soil’s moisture content; neglecting this factor often results in machinery failing to achieve proper tillage and depth.
In cases of excessively high moisture, techniques can be employed to accelerate the process, such as the construction of chimneys.
Considering this, for example, in clayey soil with a moisture content of 40%, subsoiling will not produce sufficient breaking, resulting in the loss of the machinery’s pass.
3.- Chemical Soil Conditioning
In this stage, it’s essential to add amendments to address any chemical deficiencies that may exist in the soil, such as base saturation, low or high pH, deficiencies in potassium, magnesium, calcium, phosphorus, and low levels of organic matter. This is the opportunity to correct these issues with more economical amendments.
Opting to solve such problems later can be costly and often operationally challenging.
Laboratory analysis is fundamental at this stage. It’s important to request comprehensive analyses, including physical and chemical analyses, total porosity, macro and microporosity, incorporating Cation Exchange Capacity (CEC) and base sum. Without these data, performing optimal work is very difficult (this applies to already planted orchards as well).
3.1.- pH Levels: To correct low pH levels through liming, it’s important to send soil samples to the laboratory for a liming curve analysis. This result will establish the amount of lime that should be incorporated into the soil to adjust the pH effectively.
3.2.- Organic Matter: Depending on the levels of organic matter present, adding guano or compost at this stage is essential. Organic matter is consumable and degradable, so incorporating a volume that ensures adequate levels for several years is ideal at this phase.
3.3.- Cation Exchange Capacity (CEC) and Base Sum: It is quite common for soil analyses requested by various agricultural entities to not include these indicators. It is essential to have this information because, based on the results, the levels of cations that need to be incorporated into the soil system (Cations = calcium, magnesium, potassium, and sodium) can be calculated. These cations must exist in a proper relationship to avoid chemical synergies and antagonisms that could lead to issues.
3.4.- Phosphorus Levels: In many soils that have been exploited for years, phosphorus levels are extremely low. Phosphorus, as a nutrient, is the most economically costly and the most immobile of all elements. In this phase, it is important to incorporate phosphorus through more economical sources, calculated according to the results of the soil analyses.
The success of establishing high-productivity cherry orchards greatly depends on the thorough preparation of the soil, addressing both its physical and chemical properties. Following a meticulous plan and adjusting based on soil analysis not only helps in achieving better yields but also ensures the long-term sustainability of the orchard. Proper attention to soil characteristics leads to optimal growth conditions for cherry trees, contributing to a successful and productive agricultural venture.
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