Coffee News: from Seed to Cup

A Coffee Producer’s Guide to Soil Management & Farm Conditions

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Our coffee can only be as good as the land that it’s grown on – but by my calculations, nearly 35% of coffee crops are produced in the wrong environmental conditions.

I’m talking about something called life zone, which refers to the temperature, luminosity/solar brilliance, rainfall, relative humidity, and soil characteristics that are best suited to coffee farming.

As an agronomist, allow me to take you through the ideal life zone for growing coffee – and what poor conditions will mean for your harvests.

SEE ALSO: How Harvest Rains Destroy Coffee Crops

coffee farm Healthy coffee plants grow on hilltops. Credit: Alvaro Llobet

The Ideal Coffee-Growing Conditions

According to Dr. Gloria Gauggel, the ideal life zone for Arabica coffee is as follows:

Appropriate Range Manageable Range
pH 4.9–5.6 4.5–6.0
Organic material (%) 11.4–12.6 >4.0
K (cmol/kg) 0.29–0.70
Ca (cmol/kg) 1.6–4.2 <4.2
Mg (cmol/kg) 0.5–1.4
Ratio K:Ca:Mg 01:06:02
P (cmol/kg) 6–14 <6
Soil texture Loamy (a mixture of sand, silt, and clay) Loamy (a mixture of sand, silt, and clay)
Clay (%) 8–41 >8, <41
Effective soil depth >30 >20
Annual rainfall (mm) 1,660–1,800 >1,600
Relative humidity (%) 40–80 40–80
Temperature (°C) 17–23 14–30
Solar luminosity (%) 36–60
Sunlight (hours/year) 1,575–2,400

Let’s break down some of these qualities in a little more detail.

  • Effective Soil Depth

When it comes to your soil, you need to consider both its structure (which includes the soil texture) and chemistry (essential elements and minerals).

These two factors are connected because of the coffee tree’s root structure. As the Food and Agriculture Organization of the United Nations (FAO) explains, each tree will have multiple types of roots. The tap roots will grow down deep. However, there are also many secondary roots.

The secondary roots lie within the top 30 cm of soil and their role is to recover water and nutrients from the soil. As of such, the essential elements are key – and a loamy soil of the right pH ensures that the coffee tree can absorb the nutrients well.

  • Essential Elements & Minerals

The coffee tree requires 16 essential elements for its proper nutrition. These can be divided into four groups, based on their function and importance.

Group 1: Carbon, oxygen, and hydrogen. These elements are present in water and air, which is why the life zone is so important.

Group 2: Nitrogen, phosphorus, and potassium. These are also called “macronutrients,” due to the large amount of them that healthy coffee trees need.

Group 3: Calcium, magnesium, and sulphur. These are called “secondary elements,” because they are needed in lesser amounts than the macronutrients.

Group 4: Zinc, boron, manganese, molybdenum, iron, copper, and chlorine. These are called “microelements,” because even less of them is required – although they are still essential for coffee plant nutrition.

coffee farmA coffee tree planted in an adequate life zone, allowing for strong, healthy growth. Credit: Alvaro Llobet

The importance of all these factors is visible in the plant’s harvest. Growing coffee in an adequate life zone reduces costs, makes work easier, and increases yield. In turn, this lowers risk levels and makes coffee production more financially sustainable.

For this reason, it’s important that producers plant coffee within an adequate life zone. Of course, within this life zone, there will still be variation in terms of soil conditions, hours of sunlight, rainfall, and more. These will require producers to adapt their farm management further (ideally with the assistance of an agronomist).

coffee farmGood floration is the result of an ideal life zone. Credit: Alvaro Llobet

35% of Coffee Grown in The Wrong Life Zone

From an analysis of these factors, I have calculated that nearly 35% of the world’s coffee crops are outside the adequate life zone. During the past 10 years, I’ve visited 16 coffee-producing countries across three continents (America, Asia, and Africa). On these trips, I’ve worked on farm management, project development with small and medium-sized producers, and crop research.

That research involves the analysis of 22 aspects of coffee farming, ranging from the agronomical and environmental to the economic. My team analyzes one hectare per thousand hectares of coffee plantations in each country. We take as a reference the thermal zones and compare them to the physiological behavior of coffee trees, based on temperature and rainfall as the most relevant indicators.

From here, we reached the conclusion that 35% of coffee crops are planted outside the adequate life zone. Of that 35%, 30% are completely outside the ideal life zone. The remaining 5% are where farms are mostly within the ideal life zone but the producers have extended their plantation outside of it.

So what does it mean for producers if a farm is outside of the ideal life zone? Let’s take a look.

coffee beansBean damage as a result of low rainfall between weeks 14 and 20 of fruit development. Credit: Alvaro Llobet

Growing Coffee in Poor Conditions

If a farm is in an upper marginal zone, i.e. it exceeds the figures in the table, you can expect:

  • Slower tree growth
  • Lower productivity
  • A lower fruit yield with higher weight and density
  • Higher susceptibility to diseases
  • In the wet season, a higher risk of disease and pests
  • Better sensory qualities for the coffee
  • Increased production costs compared to crops within the adequate life zone

coffee farmCoffee plants affected by the Phoma sp. Fungi. Credit: Alvaro Llobet

And if it’s in a lower marginal zone?

  • More aggressive tree growth
  • Higher productivity
  • Lower yield made up of low-density fruit
  • Higher susceptibility to pests and diseases
  • In drought seasons, a high risk of losing all or some of the plantation and/or harvest
  • Reduced sensory qualities
  • Increased production costs compared to crops within the adequate life zone

Of course, you should remember that you may also see these traits on farms in the adequate life zone if there are problems with the farm management. Healthy coffee plants are a result of many factors, including farming practices, life zone, and more.

coffee farmDamage to coffee cherries caused by drought in the final stage of ripening. Credit: Alvaro Llobet

It’s important that we consider the ideal farm location and soil condition for coffee production. Planting in the right zones can help producing families to realize greater profit margins on their crops. It can also stabilize climate conditions as the local ecosystem will be more balanced.

 For producers, there’s so much more to consider than just the farm location and soil condition: asset management, financial restructuring, varieties, processing methods, laborers… But the life zone is an important starting point.

Written by Alvaro Llobet, Founder of Lloto del Café.

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