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Smallholder Coffee Tree Management: Part 2 – Growth and Maintenance

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Watering

Your planting has been successful and now all the seedlings are in the field. One of the first challenges you will face with young, newly planted trees is the requirement for water. Young trees will require more attention than older ones as it takes time for the root structure to develop. A small root structure means a limited area in which the plant can source both water and nutrients from the soil. Regular watering, 2-3 times a week for the first few months is a must, so planting just as the rainy season arrives is a wise idea. Without that natural source of water, it will be up to you to fulfil this requirement. The options for an automatic irrigation system are likely to be limited as they are very expensive to install and have high running costs, especially if you have to pump water up a mountain. Let’s assume that the only way is a stream, a jerry can and lots of walking. This is very hard and timing consuming work so fingers crossed for that rain.

No matter how hard you try you can always expect some of the seedlings not to make it. Once it is clear that a tree won’t survive it’s important to cut your losses, take it out and plant a new one. This is known as gap filling and is crucial to do it as soon as possible to try and keep the trees in your plot at the same stage of development for management purposes.

Young trees on steep slopes with a grass cover crop. Notice the rows going across the slope. Honduras

Weeding

Regular weeding is also vital during these early stages as small trees leave large areas of exposed soil which will quickly become populated by weeds. Weeds will compete with your young coffee trees, reducing the growth rate and may even cause them to die. They can also act as host plants for pests and diseases. A weed is, by definition, any plant that you don’t want to grow there. So, although those flowers might be pretty, right now they aren’t worth having.

Weeding can be done in a number of ways. They can be slashed, dug out of the soil or sprayed off with an inorganic or organic herbicide. Slashing is quick but because the roots stay intact the weeds grow back again very fast meaning it needs to be done at least every 3 weeks. Digging is more difficult, but the total removal of the weeds means the results are felt for a much longer period of time. Using a herbicide is quick and the weeds can be left to die to form a mat over the soil. This discourages further weeds from growing and also helps to protect against soil erosion and evapotranspiration. You can use both inorganic and organic herbicides and of course using an inorganic herbicide would mean your farm is not organic. However, herbicides will add an extra cost and can be dangerous to use. To conform with health and safety best practice, a full set of protective clothing must be worn, and a number of rules followed during the spraying and for a period of time after. If you are using a broad-spectrum herbicide (rather than a selective for specific types of weeds) you also run the risk of accidently spraying your trees causing them to die as well.

Cover Crops

A popular method to reduce the need for weeding is to purposely select the plants that grow between your coffee trees. Known as a cover crop or intercrop, as it covers the bare soil and is planted between the rows of coffee. These can be anything from food crops to grasses. These help to reduce the effects of erosion and evapotranspiration, increase soil organic matter and can act as a wind break but do run the risk of affecting your trees in the same negative ways as weeds, although to a lesser extent. Food crops can be used as an additional source of income and a way of spreading out cash flow whilst waiting for your coffee to bring its first harvest. Peas, beans or other legumes are regularly selected as they are easy to grow and also have nitrogen fixing capabilities, so act an as an organic fertiliser.

Farmers work their way along the field slashing the grass between the rows of coffee trees. Honduras

Pruning

As your coffee trees grow and develop, it’s important to keep on top of unwanted branches and shoots. Pruning has a number of uses; it helps to shape the tree in order to maximise light and airflow through the branches thereby reducing the risk of disease. It helps flowering, aids accessibility when harvesting and applying Plant Protection Products and focuses growth and energy to the desired parts of the tree. It is considered as an organic method of pest control.

Pruning can be reduced to a yearly activity or can be a continuous process throughout. When the trees are small the best tool to use is a pair of secateurs. Although time consuming, they allow for the best selection of singular branches. Aim for a clean cut as close to the main trunk as possible. Jagged cuts may lead to infection.

Branches to be targeted for pruning:

  • Branches touching the ground
  • Branches growing towards the centre of the tree
  • Branches growing towards the ground
  • Branches growing above picking height
  • Diseased branches
  • Unproductive branches
  • Tertiary branches
  • Suckers aka thieves
Suckers in need of pruning. India
A coffee tree allowed to grow with lack of pruning. Kenya

Fertiliser Use

Most naturally occurring biospheres are fairly self sustaining as nutrients are recycled from plants back into the ground from where they came. However, in agriculture much of those nutrients are taken offsite in the form of crops. An easy way to look at it, for every cherry picked and taken for processing, a small parcel of nutrients that needs to be replaced has also be taken away. Like any living organism when plants are well fed, they are healthier, more productive and have better capabilities to fight against diseases and pests. Without restoring these nutrients, over time the trees will become less productive and eventually productionless.

All plants require 17 essential elements to grow, used in photosynthesis, respiration and other processes. These are divided into two categories based on the amounts needed. Macronutrients (carbon, oxygen, hydrogen, nitrogen, potassium, phosphorus, calcium, sulphur, magnesium) and micronutrients (iron, boron, chlorine, manganese, zinc, copper, molybdenum, nickel). Carbon, oxygen and hydrogen form the majority of the plant tissue and are gathered from water and air, but the remaining 13 are taken from the soil. Focus is largely placed on the application of macronutrients as they are needed in larger quantities, however, micronutrient levels are just as important to consider. The barrel analogy (pictured below) depicts Liebig’s Law of the Minimum. This law states that growth is not dictated by total resources, but rather by the scarcest resources – which act as a limiting factor. To explain it, all slats of the barrel may be tall enough to hold the water and let the barrel fill up, but if just one slat is shorter than the rest, the water will only be able to fill up so high.

A lack of nutrients will result in visible changes in the tree when unaddressed for a long period of time. Often seen as yellowing or browning of leaves or complete necrosis this is known as a deficiency and is often confused for a disease. Dieback or overbearing is the dropping of fruit and leaves by the plant as it doesn’t have enough resources available to support all of its crop. If addressed correctly deficiencies can be easily treated with fertiliser, and the tree has a good chance of making a full recovery.

Source: Nutritional Requirement and Management of Arabica Coffee (Coffea arabica L.) in Ethiopia

It is possible to measure your nutrient content through soil and leaf analysis. Both the leaf and topsoil can be collected and sent to a laboratory in the local country where the nutrient concentrations can be distinguished and advice given on which nutrients need to be added in greater quantities to ensure maximum production from your plants. Although more readily accessible than Leaf Area Index as mentioned in part 1, analysis this is still a service many smallholder farmers do not have access to, often due to limited financial resources. Nutrient concentrations will differ across a field as a result of different plants that were situated there before or areas that are more susceptible to fast drainage, so multiple samples need to be taken from your land.

Nutrients can be added through many different types of both organic and inorganic substances. These can range from inorganic fertilisers that are preblended to ensure the optimal ratio of nutrients for coffee, to animal manure or plant material left over from other areas of the farm. Inorganic fertilisers are often more expensive and can be difficult to come by in many mountainous areas. An example is Yara Mila Java, a specific fertiliser for coffee containing a ratio of 22% nitrogen, 6% phosphorus, 12% potassium, 2% calcium and 1% magnesium and a small concentration of micronutrients, the rest is made up of an inorganic binding material. However, they are much higher in concentration than organic sources, minimising the amount of material that needs to be moved around the field.

Sources of fertiliser do not have to be independent of each other and actually a broad range of inputs is more likely to lead to a well balanced nutrition regime. Some farmers may use small amounts of inorganic types to give their plants a boost, but the main source will be animal manure which will also act as a mulch so help to maintain soil moisture and reduce risk of erosion. This leads on to the other aspects of the fertiliser regime.

Consideration must be given to not only the type of fertiliser used, but the amount applied and number of applications within a crop cycle or year. It is possible to over fertilise your land which can have serious negative effects. Most research shows that smaller, more frequent applications of fertiliser result in a better uptake by the plant and therefore a lower cost to input ratio and less wastage to the soil which can have negative environmental impacts. However, this would require more labour time, so it’s a balance that depends on the system you choose. A common recommendation would be three applications of fertiliser spread out within a year. It will be your decision whether you want to be a high input: high output farm, or a low input: low output farm. Both can be run in a sustainable manner but require different management techniques.

 Pests, Fungicide and Insecticide Use

A pest is a destructive organism that has negative effects on a plant. The most common are insects and fungi, but birds, bacteria and nematodes will also fall under the same category. There are a large number of insects that will cause damage to a coffee tree and can ultimately limit growth and yield. Some of the most common are Coffee Borer, Leaf Miner and Aphids. Fungi cause many of the diseases associated with coffee e.g. Brown Eye Spot, and Leaf Rust or Roya as it’s known in Spanish.

Pests can be controlled by cultural and non-chemical methods which fall under the umbrella of Integrated Pest Management (IPM) or by chemical pesticides sometimes known as Plant Protection Products (PPP). When used effectively IPM can help to save costs and reduce damage to the environment by reducing over-use of chemicals. Techniques include:

  • Correct plant spacing.
  • Planting tolerant varieties.
  • Adequate plant nutrition.
  • The use of natural plants and animals e.g introducing ladybirds to eat mealy bugs.
  • Cedrela Montana trees are grown in Central America. They produce a natural odour that repels insects.
  • Regular pruning.
  • Removing excess tree litter and weeds.

The term pesticide describes a series of chemicals that kill certain types of pests. These include, but are not limited to, fungicides, insecticides and herbicides. Pesticides can be inorganic chemicals created specifically to target certain pests or they can be naturally occurring chemicals produced by other plants and animals. There are two categories of chemical pesticide: preventative and curative. Preventive can be applied to the plants at regular intervals to, as the name suggests, prevent pest infestations taking hold in the first place. Copper sprays can be applied once a month during the rainy season as an effective barricade to Leaf Rust. Curative chemicals are applied once an infestation has already taken hold and needs to be ‘cured’. Although there are some effective chemicals available there is no guarantee they will work and sometimes whole farms may be lost. This can have devasting outcomes for farming families losing a source of income for many years. This can also occur on a countrywide level as demonstrated in Colombia where from 2008 to 2011 the coffee regions were swathed by a Leaf Rust epidemic. Sources state that production was reduced by 31%. Care must be taken when using pesticides of any sort as they can be hazardous to human health. As mentioned before a full set of Personal Protection Equipment must be worn.

As much as possible farmers should always aim to stop pests becoming a problem in the first place so preventative measures must be the first port of call with curative measures only being used if absolutely necessary. Of course, the use of in-organic pesticides would be that your farm would not be organic but in some instances this may be preferable over losing your entire crop and source of income for several years. Overall, the most effective method of pest control is regular crop walks. Take time to go into your field and inspect a selection of plants in different areas to identify where problems are starting to occur. Any problems identified should be recorded to a high level of detail, such as how many plants are infected to even what percentage of a singular leaf is showing symptoms. This way problems can be treated and the progress monitored to see if they are getting better or worse.

Tree completely defoliated due to Leaf Rust. Mexico
Leaf infested with Leaf Rust spores. Colombia
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