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Chapter 4
Plant nutrition & fertiliser management

Nutrients are recycled within the environment. A 'closed' environment such as a rainforest, recycles its own nutrients and is more or less self-sufficient. However, where plants are grown in a commercial situation, it is necessary to replenish the nutrients that are removed from the system. Without additional nutrients in some form of fertiliser, coffee yields will remain very low as nutrients are removed with the coffee beans. Unshaded plants of dwarf, high-yielding varieties such as Catimor, will quickly develop dieback and die if adequate nutrients and water are not added to the soil. Plants with mild to moderate dieback will recover with timely good fertilising, watering and weed management.

In India, it was found that for every 6,000 kg of ripe coffee cherry (1 tonne of green bean) removed from the plants, approximately 40 kg nitrogen (N), 2.2 kg phosphorus (P) and 53 kg potassium (K) must be replaced yearly.

There are 16 natural elements (nutrients), that are essential for plant growth (see table below). Three elements (carbon, hydrogen and oxygen) make up 94% of the plant tissues and are obtained from air and water. The other 13 elements are obtained from the soil and are divided into two broad categories - 'macro' and 'micro'. These terms do not refer to the importance of the elements; macronutrients are required in greater amounts than micronutrients for normal plant growth.

Essential minerals and their role in the coffee plant

Mineral/ Element

Chemical symbol

Main requirement/use by the plant




Plant growth; proteins; enzymes; hormones; photosynthesis



Amino acids and proteins; chlorophyll; disease resistance; seed production



Energy compounds; root development; ripening; flowering



Fruit quality; water balance; disease resistance



Cell walls; root and leaf development; fruit ripening and quality



Chlorophyll (green colour); seed germination




Chlorophyll; protein formation



Hormones/enzymes; plant height



Photosynthesis; enzymes






Development/growth of new shoots and roots; flowering, fruit set and development



Nitrogen metabolism



Photosynthesis; gas exchange; water balance

Soil and leaf analysis

The objective of sampling is to get an AVERAGE (representative sample) of soil in the block, not the best or the worst. To keep costs down, and if plantings are of the same age and appearance, three samples per two to four hectare block will be adequate, provided the three samples are composites from the 20 sites sampled.

To help determine the best nutrition practices, soil and leaf analyses are recommended. While Lao currently does not have access to these services, in nearby Thailand the Mae Jo University in Chiang Mai and Department of Land Development (DLD) can offer fee-for-service analyses. The FAO project used Mae Jo University for the soil and leaf analysis survey of Arabica coffee farms in the Bolovens in 2005.

In order to standardize procedures between farms, years and personnel involved, the following practices are suggested for soil and leaf analysis.

Soil sampling

Figure 23. Remove surface litter and old fertiliser etc., from area to be sampled but do not remove soil. Take samples to a depth of 150 mm

If possible, soil samples should be taken once per year before flowering.

Leaf sampling

The objective of leaf sampling is to get an AVERAGE (representative sample) of trees, not the best or the worst. The 40 trees per hectare samples can be bulked and three composite samples made to reduce analysis costs. A minimum of 100 leaves is needed for each composite sample.

Figure 24. Leaf sampling

Pre-flowering is preferred sampling time if only one sample is taken each year. More frequent sampling (every four months) is highly desirable for large plantations, especially if nutritional problems occur.

A soil and leaf sampling survey on 15 properties has recently been conducted on the Bolovens Plateaux; results were not available at the time of publication.

Optimum leaf and soil nutrient levels

Once the soil and leaf samples have been taken, it is important to analyse the results and compare them to levels that have been determined as optimum in coffee plantations around the world in order to devise a nutrition programme for the coffee.

Optimum leaf nutrient levels


Optimum range


Optimum range

N (Nitrogen)

2.5 - 3.0%

Na (Sodium)

< 0.05%

P (Phosphorus)

0.15 - 0.2%

Cu (Copper)

16 - 20 mg/kg

K (Potassium)

2.1 - 2.6%

Zn (Zinc)

15 - 30 mg/kg

S (Sulphur)

0.12 - 0.30%

Mn (Manganese)

50 - 100 mg/kg

Ca (Calcium)

0.75 - 1.5%

Fe (Iron)

70 - 200 mg/kg

Mg (Magnesium)

0.25 - 0.40%

B (Boron)

40 - 100 mg/kg

Optimum soil nutrient levels

Nutrient (extraction method in brackets)*

Suggested optimum soil levels

pH (1:5 soil/water)

5.5 - 6.0

Organic matter (Walkley Black)

1- 3 %

Conductivity (l:5 soil/water)

< 0.2 dsm

Nitrate nitrogen (1:5 aqueous extract)

> 20 mg/kg. Leaf tests more relevant

Phosphate (Colwell or bicarb)

60 - 80 mg/kg

Potassium (Ammonium acetate)

> 0.75 mg/kg

Sulphur (KCl-40)

> 20 mg/kg

Calcium (Ammonium acetate)

3 - 5 meq/100 g

Magnesium (Ammonium acetate)

> 1.6 meq/100 g

Aluminium (Potassium chloride extract)

Unknown but very low

Sodium (Ammonium acetate)

< l.0 meq/100 g

Chloride (1:5 aqueous extract)

250 mg/kg

Copper (DPTA)

0.3 - 10 mg/kg

Zinc (DPTA)

2 - 10 mg/kg

Manganese (DPTA)

< 50 mg/kg

Iron (DPTA)

2 - 20 mg/kg

Boron (hot calcium chloride)

0.5 - 1.0 mg/kg (sandy loams)

1.0 - 2.0 mg/kg(clay loams)

Cation exchange capacity

3 - 5 sandy soil

> 10 heavy soil types

Cation balance

Potassium (< 10%)

Calcium (65 - 80%

Magnesium (15 - 20%

Sodium (< 5%)

Aluminium (< 1%)

Calcium: Magnesium ratio

3 - 5

* Different extraction methods would give different results and different optimum levels.

Fertiliser programme

Fresh manure or non-composted pulp should never be used as they can burn the plants and tie up nitrogen in the soil during break-down. They also are a source of Orchratoxin A (OTA) moulds.

Coffee soils in Lao PDR are low in a number of essential plant nutrients; therefore these must be supplied to promote high yielding, high quality coffee. Manure, bio-fertiliser, cover crops, compost, legume tree leaves and shoots and chemical fertilisers all supply nutrients.

Manure and compost such as coffee pulp and husks have a low nutrient content. When utilised as a source of nutrients, they must be used in large quantities to supply sufficient nutrients for coffee plants. Manure and compost help improve soil structure and organic matter.

Chemical fertilisers are higher in nutrient content than organic fertilisers and are a more effective method of applying nutrients. For optimal results, it is best to apply a combination of manure and compost and chemical fertilisers.

At present, there has been little or no soil and leaf analysis services available for Lao coffee growers. When such services are available, a detailed coffee fertiliser programme can be devised. Meanwhile the following fertiliser programme is suggested for Arabica coffee in Lao.




Year 1

(Up to 12 months in the field)

Before rains finish


30 g/tree of NPK 15-15-15

Year 2

April/May (with first rains)

30 g/tree of NPK 15-15-15


30 g/tree of NPK 15-15-15


30 g/tree of NPK 15-15-15
500 g/tree of Dolomite

Year 3

April/May (with first rains)

60 g/tree of NPK 15-15-15


60 g/tree of NPK 15-15-15


60 g/tree of NPK 15-15-15

Year 4

April/May (with first rains)

90 g/tree of NPK 15-15-15


90 g/tree of NPK 15-15-15


90 g/tree of NPK 15-15-15

500 g/tree of Dolomite

Year 5


April/May (with first rains)

120 g/tree of NPK 15-15-15


120 g/tree of NPK 15-15-15


120 g/tree of NPK 15-15-15

Note: NPK is nitrogen, phosphorus, and potassium


1g N


1,288 g N (Urea)

1g Ca


1,399 g calcium oxide (quick burn lime)


1,780 g calcium carbonate (lime or limestone)

1g Mg


1,658 g magnesium oxide

1g S


3,750 g magnesium sulphate

Higher yielding coffee plots may require 25% more fertiliser.

Use lime or preferably, dolomite (Ca + Mg) at 500 g per plant every two years and apply before the end of the rainy season. Use the last rains to wash the lime into the soil or water in well by hand or irrigation. The following table shows the nutrient uptake and consumption by different parts of coffee tree (expected yields / ha: 1000 kg green beans).

Nutrient uptake of a coffee tree

Elements (kg)

Parts of tree










































It is obvious from this table that leaves need the major part of the uptake - more than the flowers or fruits. However, nutrients are returned to the soil when the leaves drop. The early years of root development are very important as branches and roots store nutrients for a long time.

Nutrients accumulated in the fruits will be removed when cherries are harvested. This loss needs to be compensated by the addition of fertilizers, organic manures, leaf fall or prunings and leaves from shade trees. Recycling of pulp to the soil after composting can help to reduce the additional (chemical) fertiliser needed.

Fertiliser placement

While good for the soil, manure or compost may not supply the full range and amount of nutrients required by the coffee tree and some mineral fertiliser or micronutrients or other organic fertilisers may be needed occasionally.

Figure 25. Place a band of fertiliser around the drip line

Spread fertiliser evenly on the soil around the drip line (the outside edge of the canopy) of the coffee tree, as this is where most feeder/hair roots are found (Figure 25). Keep fertiliser at least 100 mm from the stem of the plant; fertiliser applied closer than this can damage the coffee tree.

Manure (if not using fertiliser). The minimum amounts to apply are:

Year 2

0.7 kg/tree

Year 3

1 kg /tree

Year 4

2 kg /tree

Year 5 onwards

2.5 kg/tree

Legume shade trees, ground covers and suitable intercrops supply nutrients and organic matter through litter and leaf fall and through prunings added as mulch to the surface of the soil.

Nutrient deficiency symptoms

The overall rate of coffee growth and production depends on the least available plant nutrient. Plants will grow and produce only as much as the least available nutrient will allow them to. It does not matter how much of the other nutrients are available to the plant because it is the least available nutrient that limits growth and development. This is well illustrated in the following 'Barrel Analogy', where the barrel can hold only as much water as the shortest plank will allow (Figure 26). This is known as the 'Law of the Minimum' and is explained thus:

Figure 26. 'Barrel Analogy' using nitrogen as the least available nutrient

The level of water in the barrel represents the level of crop yield that is restricted by the most limiting nutrient, nitrogen. When nitrogen is added, the level of crop production is controlled by the next most limiting factor (in this example, potassium).

Poor nutrition is a major cause of coffee dieback. Plants lacking sufficient N (nitrogen) and K (potassium) suffer from dieback, especially where there is poor shade cover and insufficient water. Low soil calcium and phosphorus will hinder root development and contribute to dieback. Dieback causes loss of yield and when severe, plants can die, especially high yielding, dwarf Catimor varieties.

Each nutrient has unique deficiency symptoms. These are briefly described below and can be seen in the photographs.

Coffee nutrient deficiency symptoms

Symptoms originating in older leaves or generally on the whole plant.

Deficient nutrient

A. Uniform yellowing over whole tree or light yellowing between the leaf veins.

Lower leaves exhibiting slight yellowing, young leaves remaining darker green; faint yellowing between the veins of older leaves at advanced stages; small dead spots may be present.


Early (left); advanced (right)

B. Localised dead tissue or yellowing between the veins on older leaves.

Initial yellowing on the leaf edges followed by development of dead spots. Dead tissue increases until the whole leaf edge is covered. The veins and midrib remain green.


Early (left); advanced (right)

Faint yellowing on leaf edges with sunken, yellow-brown to light brown dead spots developing in a wide band along leaf edges; yellowing between veins evident in affected leaves, particularly along the midrib.


Yellowing in older or middle leaves; mottling, stippling between veins; necrotic spotting along main vein.


Bright yellow mottling between veins; leaves wither, curl and margins collapse; leaves distorted and narrow; older leaves affecter first. Rare deficiency.


Symptoms originating in younger leaves near shoot tips

Deficient nutrient

A. Uniform yellowing over whole leaf or faint yellowing between leaf veins; plants with sparse vegetative growth.

Leaves rapidly becoming pale green; new leaves uniformly pale green with a dull green sheen. Entire plant becoming pale green, with sparse vegetative growth; leaves becoming yellow-green at advanced stages; whitish veins may be present in lower leaves.


Healthy plant (left); deficient plant (right)

Leaves light green to yellow-green, with faint yellowing between veins; deficient leaves retaining shiny lustre.

Whole plant may show symptoms.


Advanced symptoms

B. Sharp yellowing between veins of youngest leaves; older leaves

Leaves expanding normally, with vein network remaining green and clearly visible against the light green to yellow-green back ground; background becoming nearly creamy white at acute stages.


Leaves not expanding normally; narrow, often strap-shaped; veins visible against a yellow-green background; failure of inter-node to elongate properly, giving plants a compact appearance.


C. Bronzing, mottling or death of youngest leaves; dieback of terminal buds.

Leaves bronzed along edges, cupped down-ward; new leaves dead; eventual dieback of shoot tips.


Deficient roots

Healthy roots

Youngest leaves light green, mottled, with uneven edges and asymmetric shape; new leaves with dead spots or tips.


Young leaves die back, chlorosis sets in; leaves curl and roll. Shoots are weak and restricted; may be rosetted. Not common if copper sprays are used in nursery and for leaf rust and Cercospora in field.


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