Coffe

Coffe

Coffee belongs to the Rubiaceae family. It comprises more than a 100 species, among which the main are: Arabica (Coffea arabica, with of 80% of the total world production) and robusta (Coffea Canephora, with a 20% of the total). Its fruit is a berry and its seeds have a great economical value, mainly used as nutritive and stimulant beverage.

Coffee is a medium size shrub of semi-conic shape, with opposite and alternate branches that can auto-shade. Roots are present up to 60 cm of the soil depth, but 90% of the total root volume is above 30 cm. The plant has woody taproot, with secondary, tertiary and absorbent roots. The stem is woody and has a vertical growing.

The coffee shrub grows under a wide rage of rainfall conditions. Optimum rainfalls are between 1,200 and 2.800 mm annually with a good distribution during the year. A short drought period is considerate as a favorable factor for the development and flowering of coffee.

In relation to soil requirements, coffee is a crop that behaves well in moderate acid soils. Even though, it is frequently cultivated in soils from very acid to extremely acid pH. These soils are influenced by the climatic characteristics (high and very concentrated rainfall), nutrient extraction without reposition and high use of ammonium nitrate fertilizers. It is important to have a soil with good drainage and physical structure, and with a 5.5 and 6.5 pH rage. When the pH is lower than 5.5, it is necessary to evaluate the manganese (Mn) and aluminum (Al) contents, since in these levels they are in high concentrations which cause physiological disorders. It is recommended to apply fertilizer amendments such as agricultural lime or ideally, dolomite lime.

In relation to irrigation, it should be adequate for obtaining a high yield and good quality coffee. Different irrigation types (central pivot, furrow and drip irrigation) can be used but must consider good water management. On the other hand, since the coffee root system is concentrated under the plant canopy, fertigation can be used in order to directly place the nutrients in the roots´ absorption zone.

Obtaining a good quality coffee will depend on: the selection of a high genetic potential variety, good planting location, the implementation of good crop management and adequate post-harvest processes.

Main Nutrients
The application of balanced nutrition aims to ensure adequate aerial and root growth to store as much carbohydrate in specialized organs. Adequate nutrition of the crop is a key factor in obtaining good harvests.

To achieve an appropriate nutrition plan in coffee is necessary to know the nutrient demand in quantity and type of nutrient. It is also important to know the role of each nutrient for crop growth, yield and quality of production.

The key elements for obtaining an optimum result in coffee are: N-NO3, P, K, Ca, Zn y B.

Nutrient

Main nutrients in the Coffee crop and their characteristics

Nitrogen

The greatest Nitrogen demand coincides with the largest vegetative growth of the tree. Nitrogen is the principal nutrient responsible for foliar area development of the plant, which is important for obtaining a high coffee production per hectare and of high quality.

Neverthless, in the fruit formation period, the Nitrogen excess is not desirable, since it prolongs the vegetative period of the crop and interferes with the photosynthates accumulation in the harvestable product. This affects the yield and seed quality.

Given the short period in which the absorption must occurs, the Nitrogen supplied as fertilizer must be immediately available for the plant. Ideally this fertilizer should be in high percent in form of Nitrate (NO3), since this is the preferential Nitrogen form absorbed by the plant.

This is the element of greatest production response in coffee. Normally it applies 250 kg/ha/year; even though, a fertilizer application of 200 – 300 kg of N/ha/year, divided in three application periods, produces good results.

Phosphorus

Coffee seems to be very efficient in utilizing the Phosphorus available even though it is found in small quantities in the soil. It is advisible to apply doses of 50 - 75 kg of P205/ha/year for supplying the plant requirements in order to maintain nutritional balance.

A good nutrition with Phosphorus and Calcium improves flowering and its uniformity.

The crop has the greatest Phosphorus requirments after harvesting, when the tree does not concentrate carbohydrates in the fruit and allows root growing in this period.

Potasium

Potassium is absorbed in greater quantity by the plants, Practically no soil, were coffee is cultivated in the present day, is able to produce high yields and of good quality, without applying Potassium fertilizer.

Potassium participates in the carbohydrates transport from the leaves toward the fruit, Consequently, its higher or minor percentage in the leaves will have direct relation with the yield and the final grain quality.

In addition, adequate Potassium concentration in the leaves will help the plant to use water more efficiently, improve the frost tolerance and excess or lack of moisture in the soil.

The Potassium requirements are greater during the growing and grain maturing periods. A high Potassium content in the leaves is synonymous to high crops quality.

In cultivated areas that present low Potassium contents, the use of 100 - 200 kg of K2O/ha/year has achieved a positive economical response.

Magnesium

In soils with deficiency of this element, positive responses with the use of 40 - 80 kg of MgO/ha/year have been obtained.

Zinc

Results from diverse research studies with different Zinc doses of foliar sprays, suggest conducting foliar sprays once or twice per year, particularly in new planting areas.

Boron

Practically in all coffee producing areas, very good results have been obtained with Boron application to the soil, as part of the integrated elements of the so called “complete formulae” Besides, it is considered that the foliar applications are an adequate fertilizer complement to the soil. Nevertheless it must be made clear that the excessive use of Boron could induce phytotoxicity, consequently it is recommended to use doses not above 30 kg of B203/ha/year.

Phenological stage of Coffe
The physiological maturity of the seed is reached approximately in 220 days after flower opening.

The following figure shows the growing stages of the coffee crop until it becomes productive.

Growing stages of coffee crop.
Growing stages of coffee crop.

Stage I: Flowering and fructification.

Stage II: Fruit development. In this stage the plant passes through two critical periods: a critical period of moisture requirement, and a N availability.

Stage III: Grain filling. The coffee fruit development takes an average of 34 weeks after fertilization. In this period a high dry matter accumulation is produced, and then the plant requires a great quantity of available nutrients, in addition of an adequate water supply and a good phytosanitary control.

In addition, it is important to consider that coffee, as many fruit trees, presents an overlap of events occurring simultaneously which strongly affect the present year or the next year production. Example, in the grain filling and maturity periods, the tree is also in the floral induction and branch growing periods. Therefore, the plant is required to focus its products toward these stages, creating a competition for resources. This situation, often results in high productions in the present year and very low in the following year.

Stage IV: Uniform maturity. For obtaining a good quality coffee, it is important to obtain a uniform maturity, particularly if the harvest is mechanized.
Nutritional Requirements
It is possible to observe that N, P and K requirements increase as the plant grows during the years, reaching a maximum level around the 5th year. Furthermore, N and K are both required in similar and high quantities by the plant.

Figure 1 shows the N, P and K extraction by the plant (a) and the coffee fruit extraction (b) along the crop years.

Extraction of N, P and K by the coffee plant
Figure 1a. Extraction of N, P and K by the coffee plant.
Extraction of the coffee fruit along the crop years
Figure 1b. Extraction of the coffee fruit along the crop years.

Figure 2 shows the percentage distribution of the N, P and K fertilizers in function of the requirements of these nutrients, according to the different phenological stages in a 3 to 4 year crop.

Percentage distribution of N, P and K fertilizers in function of the requirements of these nutrients, according to different phonological stages, in t 3 to 5 year crop
Figure 2. Percentage distribution of N, P and K fertilizers in function of the requirements of these nutrients, according to different phonological stages, in t 3 to 5 year crop. - Source: Carbajal (1984), mod. Malavolta, 1993.

As it was indicated in the roles of the main nutrients, the greatest N levels are required by the plant during the vegetative growing period. On the other hand, fruit growth requires a greater K availability in order to obtain high quality grains together with larger crop yield.

In relation to P, its requirement is high before and after flowering, consequently its availability must be assured so that this process can be achieved in a correct and uniform fashion. Furthermore, the nutrient availability after harvesting (once carbohydrates are not going to the fruits), P is necessary since it is the period when the roots are growing, thus it plays a fundamental role in normal root development.

Nutrient

Low

Sufficient category

High

Nitrogen

2.7 - 3.9

3.2 - 5.5

>5.5

Phosphorus

0.2 - 0.29

0.30 - 0.75

>0.75

Potassium

1.5 - 1.99

2.0 - 4.0

>4.0

Calcium

0.7 - 0.99

1.0 - 2.5

>2.5

Magnesium

0.2 - 0.24

0.25 - 0.75

>0.75

Sulphur

0.25 - 0.29

0.3 - 0.75

>0.75

Boron

25 - 29

30 - 100

>100

Copper

3 - 5

5 - 15

>15

Iron

50 - 69

70 - 300

>300

Manganese

20 - 24

25 - 200

>200

Zinc

20 - 34

35 - 200

>200

Desired nutrient levels in a foliar analysis in the coffee crop.
Source: Jones, J.B. Jr., Wolf, B. Y Mills, H.A. (1991). “Plant Analysis Handbook. Micro-Macro Pubs”. Athens, Georgia, USA.
Nutrient Deficiency Symptoms

Nutrient

Nutrient deficiency symptoms in the coffee crop

Nitrogen
Nitrogen

Adult leaves: Uniform chlorosis from the base to the leaf apex and from the central vein toward the borders. When deficiency is severe, chlorosis is more evident covering the whole leaf blade.

Young leaves: chlorosis along the leaf borders, similar to a yellow ribbon approximately 1 mm wide.

Chlorosis is first presented in older leaves. Fruits turn yellow, little grow and fall easily.

Phosphorus
Phosphorus

Leaves with slight, uniform and green lemon opaque color chlorosis. Older leaves turning more yellow up to tanned color.

Generally chlorosis is presented in older leaves. Spots are from different size and can cover the whole leaf.

In sever cases, branches with maturing fruits fall completely.

Potassium
Potassium

Generally chlorosis is presented in older leaves. Firstly appears a yellow color, and then becomes a dark brown color, only in the borders and the tips of the older leaves. A yellow line limits the necrotic border and the foliar apex.

Affected leaves´ borders turn toward the superior leaf blade.
An inadequate K supply can produce empty grains.

Sulphur
Sulphur

Generally it is present in young leaves which show a green yellowish color starting along the main.

Veins appear sunken and limiting sections outstand in a concave surface. Chlorosis turns yellowish in larger size leaves.

Affected leaves have a mottled appearance similar to Zn or Fe deficiency symptoms.

Calcium
Calcium

The deficiency appears in the superior part of the plant.

Young leaves present a green pale color near the borders, and a long the central vein remains a green color. The margins become undulant.

Adult leaves, without reaching abscission, remain hanging down.

When deficiency progresses, leaves become with a spoon similar shape, with irregular margins.

In a few cases chlorosis is presented in brown color and this is associated to the cultivation in very old red soils or in very weathered volcanic soils.

Magnesium
Magnesium

Adult leaves: chlorosis, in severe cases leaves turn to a yellow mate color.

Generally it is present in old leaves as tanned color spots. Main veins always retain the green color.

Skin yellowing begins in the branch’s base and continues toward the tip producing leaves losses.

Zinc
Zinc
Zinc

Generally chlorosis is present in the young leaves. These leaves grow little, in elongated form, with undulated borders and appear with a uniform green pale color chlorosis.

When the deficiency progresses, a rosette growing type occurs, with short internodes; the chlorosis increases and is specially localized between the secondary veins.

It is present in soils with high pH and in eroded soils with low fertility.

Generally deficiency symptoms are more visible in the tip of the branches.

Iron
Iron
Iron

Generally it is present in the young leaves, which are of larger size than normal, and the whole plant shows a complete chlorosis from a yellowish green to whitish color, on top of this the green color veins clearly stand out.

Boron
Boron

It is present in young tissues and generally appears in very dry periods. Characteristic symptoms are the following.

Adult leaves: mate olive green color chlorosis, which progresses from the apex toward the base, covering one third or more of the leaf.

Young leaves: growing in form of “palmilla” can appears chlorosis, remaining the veins green. The yellowish color is initiated in the tip and progresses until a little far from the leaf middle.

A cork tissue is developed over the leaves; leaves are deformed appearing crooked, wrinkled or with irregular borders. Brown color points appear in the tender leaves and branches show a fan appearance.

Manganese
Manganese

It is present in plant’s young tissues. These leaves are of excessive growth with partial or total chlorosis over which a fine reticulate green color band stands out, which contains secondary and tertiary veins.

It occurs in high pH soils and a yellowish color is produced in the whole leaves from the tip of the branches with certain mottled appearance.

Cloro
Chloride

Yellow leaves along the main veins. Death of the roots.

In the younger leaves, the veins remain out standing. The leaf blade can be deformed. In young plants, the leaves can be down curved starting from the base.

Causes: Lack of K in the soil, excess of dry matter and a lot of rainfall.

Molibdeno
Molybdenum

 

It is present in older leaves. It appear yellow spots and after dark brown spots between the veins. As time pass by, these leaves are curved down along the main vein and the opposite borders get together.

The main deficiency cause is the soil acidity.

Physiological disorders

Physiological Disorders

Physiological disorders in the coffee crop

"Crespera of coffee"

Originally the studies indicated as cause agent of the disease to a phytoplasm (parasite of plants), actually is believe that it is caused by the Xylella fastidiosa bacteria.

The symptoms are visible in the younger leaves which are of inferior size than normal, with undulated borders, small fruits and very short internodes of the branches.

Sprouts present a severe Zn deficiency symptomology characterized by narrow long leaves, with yellowish borders and green central vein. If symptoms are very severe, sprouts can grow, developing a new tree with very short internodes, narrow and small leaves, with undulating borders and scarce or nil fruits formation. In the same tree can appear healthy branches and branches affected by “Crespera”.

Some times the anomaly is so severe that the appearance of the leaves remind damages caused by some herbicides.

The disorder is present if coffee crops established in soils of sedimentary, agglomerated and conglomerated coluvio-aluvial andesitic origin, and in soils derived from volcanic ashes.

Physical-chemical factors which apparently are associated with the problem are: The excess of humidity in the soil, high aluminum exchange % (> to 40% saturation), low pH (< 5.0 in water and < 4.5 in KCL), low zinc contain in the soil, relatively high P soluble content in the soil and low temperatures.

Even though the exact true causes of the problem is not known, it is recommended to adopt measures for eliminating or reducing the considered predisposing factors.

Phytoxicity by Biuret

The Biuret is a compound form by two molecules of urea which is condensed with an elimination of an ammonium molecule. It is a harmful compound for the plants, and its toxicity hazard is greater when urea that contains Buiret is used in foliar sprays. Particularly if it is used in a mixture with Bordeaux broth with excess of lime and in high environmental temperature conditions.

The toxicity symptoms for Buiret are presented as mottled chlorosis between the secondary veins and toward the borders of the leaves. If the applications continue, the leaves in formation remain in a reduce size and these as well as the older leaves form a sharp concavity toward the underside. Firstly, the damage appears in the tender leaves and the produced chlorosis does not disappear when applications are suspended, but the leaves borne later on are normal.

Studies conducted in India report that a maximum of Buiret concentration of 2% in the urea is critical for a foliar spray in coffee. Other experiments carried on in Colombia for determining the critical Buiret concentration in the granular urea used in repeating foliar sprays in nursery coffee plants, indicate that up to 1% of Buiret contamination can be apply. Besides, the spray intervals cannot be inferior to 15 days. Also, it was found that the Biuret damage can be accumulative.

In Coffee, Soluble NPK They replace the NPK Granulated Half of Applied Dose

The treatments were applied manually in accordance with the standard practices at the farm. The treatments T1 and T2 consisted of granular fertilisers (Fig. 1); T3, T4 and T5 were performed with water-soluble fertilisers (Fig. 2). The fertiliser variants under study implied 5 treatments which were arranged in a completely randomized design with 10 repetitions each Read More.
Phenological Stage



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