Planting

vietnam newsList Item:
I. Coffee Plant Overview:
Coffee Plant Growth and Development
Coffee Plant Root System
Coffee Leaves

II. Growing Coffee Beans:
Coffee Plant Propagation
Coffee Bean Germination Process
Growing Coffee Seeds in Nursery Beds

III. The Optimal Coffee Environment:Best Climate Conditions for Growing Coffee Beans
Climate for Growing Arabica Coffee Beans
Climate for Growing Arabica Coffee Beans
Soil Analysis Examples and Coffee Nutrients
Analysis of Soil: Correcting Problems
Coffee Fertilizer

1. Coffee Plant Overview: P1.JPG

The coffee plant is a woody perennial evergreen dicotyledon that belongs to the Rubiaceae family. Because it grows to a relatively large height, it is more accurately described as a coffee tree. It has a main vertical trunk (orthotropic) and primary, secondary, and tertiary horizontal branches (plagiotropic).
The Difference Between Arabica and Robusta Coffee Beans
While there are several different coffee species, two main species of coffee are cultivated today. Coffea arabica, known as Arabica coffee, accounts for 75-80 percent of the world's production. Coffea canephora, known as Robusta coffee, accounts for about 20 percent and differs from the Arabica coffees in terms of taste. While Robusta coffee beans are more robust than the Arabica plants, but produces an inferior tasting beverage with a higher caffeine content. Both the Robusta and Arabica coffee plant can grow to heights of 10 meters if not pruned, but producing countries will maintain the coffee plant at a height reasonable for easy harvesting.

Coffee Plant Growth and Development

Three to four years after the coffee is planted, sweetly smelling flowers grow in clusters in the axils of the coffee leaves. Fruit is produced only in the new tissue. The Coffea Arabica coffee plant is self-pollinating, whereas the Robusta coffee plant depends on cross pollination. About 6-8 weeks after each coffee flower is fertilized, cell division occurs and the coffee fruit remains as a pin head for a period that is dependent upon the climate. The ovaries will then develop into drupes in a rapid growth period that takes about 15 weeks after flowering. During this time the integument takes on the shape of the final coffee bean. After the rapid growth period the integument and parchment are fully grown and will not increase in size. The endosperm remains small until about 12 weeks after flowering. At this time it will suppress, consume, and replace the integument. The remnants of the integument are what make up the silverskin. The endosperm will have completely filled the cavity made by the integument nineteen weeks after flowing. The endosperm is now white and moist, but will gain dry matter during the next several months. During this time the endosperm attracts more than seventy percent of the total photsynthesates produced by the tree. The mesocarps will expand to form the sweet pulp that surrounds the coffee bean. The coffee cherry will change color from green to red about thirty to thirty-five weeks after flowing. See Flash movie on Coffee Bean Development.

Coffee Plant Root System

The roots of the coffee tree can extend 20-25 km in total length (Malavolta, 195) and the absorbing surface of a tree ranges from 400 to 500 m2 (Nutman). There are main vertical roots, tap roots, and lateral roots which grow parallel to the ground. The tap roots extend no further than 30-45 cm below the soil surface. Four to eight axial roots may be encountered which often originate horizontally but point downward. The lateral roots can extend 2 m from the trunk. About 80-90% of the feeder root is in the first 20 cm of soil and is 60-90 cm away from the trunk of the coffee tree (Mavolta, 195-196). However, Nutman states that the greatest root concentration is in the 30 to 60 cm depth. The roots systems are heavily affected by the type of soil and the mineral content of the soil. To be thick and strong, the coffee roots need an extensive supply of nitrogen, calcium and magnesium. During planting the main vertical roots are often clipped to promote growth of the the horizontal roots, which then have better access to water and added nutrients in the top soil.

Coffee Leaves

The elliptical leaves of the coffee tree are shiny, dark green, and waxy. The coffee bean leaf area index is between 7 and 8 for a high-yielding coffee (Malavolta, 195). The coffee plant has become a major source of oxygen in much of the world. Each hectare of coffee produces 86 lbs of oxygen per day, which is about half the production of the same area in a rain forest (source: Anacafe).

(http://www.coffeeresearch.org/agriculture/coffeeplant.htm)

2. Growing Coffee Beans

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Coffee Plant Propagation

For propagation of arabica coffee, ripe red cherries are collected, pulped, and the mucilage is removed by fermentation. The freshly picked coffee seeds (typically referred to as beans) can either be planted immediately or dried for later use. Coffee drying takes place on wire mesh trays in the shade. Correctly storing coffee beans is essential for a longer seed life. Dried coffee seeds can be used up to a year or more if properly stored.

Coffee Bean Germination Process

There are two basic methods for the germination of seeds. In one method, coffee seeds are pregerminated by spreading on a sand bed and covering with moist burlap bag sacks or straw. The seeds are watched closely and removed as soon as radicals emerge. An alternative method of germinating coffee beans is to mix the seeds with moist vermiculite or expanded polystyrene and keep in the polythene bag (Mitchell, 46). Coffee seedlings are grown in nursery beds or polybags and are planted in the coffee fields when they reach 20-40 cm.

Growing Coffee Seeds in Nursery Beds

Once pregerminated, the coffee seedlings are planted in nursery beds containing soil consisting of well rotted cattle manure (10-20 liters per meter) and phosphate fertilizer (100 g per meter) (Mitchell, 47). Nursery beds should be built to be 1 meter wide and 50 cm deep and seedlings are spaced between 12-15 cm apart (for 20 cm tall plants) or 20 cm apart (for 30-40 cm tall plants) (Mitchell, 47). The nursery beds are shaded 50 % for the first couple months. Shading is reduced slowly and completely removed the last two months before planting coffee seedlings.
For more information about growing coffee seeds in nursery beds, visit the United Nations Food and Agriculture Organization.

3. The Optimal Coffee Environment: Best Climate Conditions for Growing Coffee Beans
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For growing Arabica coffee beans, there are two optimal growing climates:
1. The subtropical regions, at high altitudes of 16-24° (Illy, 21). Rainy and dry seasons must be well defined, and altitude must be between 1800-3600 feet. These conditions result in one coffee growing season and one maturation season, usually in the coldest part of autumn. Mexico, Jamaica, the S. Paulo and Minas Gerais regions in Brazil, and Zimbabwe are examples of areas with these climate conditions (Illy, 21).
2. The equatorial regions at latitudes lower than 10° and altitudes of 3600-6300 feet (Illy, 21). Frequent rainfall causes almost continuous flowering, which results in two coffee harvesting seasons. The period of highest rainfall determines the main harvesting period, while the period of least rainfall determines the second harvest season. Because rainfall is too frequent for patio drying to occur, artificial drying with mechanical dryers is performed in this type of coffee growing environment. Examples of countries that have this climate are Kenya, Colombia, and Ethiopia (Illy, 21).
Robusta coffee is grown at much lower altitudes (sea level-3000 feet) in an area 10° North and South of the equator (Illy, 22). It is much more tolerant to warm conditions than Arabica coffee.

Climate for Growing Arabica Coffee Beans

Arabica coffee is grown in relatively cool climates in the region between the Tropic of Cancer and Capricorn. The optimum temperature is between 15-24ºC (59-75ºF) year round. Photosynthesis is slowed above these temperatures and frost damage can occur when temperatures hover around 0ºC. Ideally, 1500-2500 mm of rain will fall over a nine month period with a three month dry season coinciding with the harvest (Mitchell, 44). Areas with less rainfall can use irrigation to compensate. A period of moisture stress (rain after a dry spell) helps cause a homogenous flowering and therefore premotes a clearly defined harvesting season. Coffee producing countries with more than one wet and dry season will have more than one harvesting season.
There is a direct relationship between extremes of day and nighttime temperatures and coffee quality. Experimental evidence has indicated that a large gap between day and nighttime temperatures is beneficial to the flavor of fruits. Since a coffee cherry is a fruit and the seed is in contact with the fruit, these benefits will be passed onto the seed and therefore into the cup.

Climate for Growing Arabica Coffee Beans

Arabica coffee is grown in relatively cool climates in the region between the Tropic of Cancer and Capricorn. The optimum temperature is between 15-24ºC (59-75ºF) year round. Photosynthesis is slowed above these temperatures and frost damage can occur when temperatures hover around 0ºC. Ideally, 1500-2500 mm of rain will fall over a nine month period with a three month dry season coinciding with the harvest (Mitchell, 44). Areas with less rainfall can use irrigation to compensate. A period of moisture stress (rain after a dry spell) helps cause a homogenous flowering and therefore premotes a clearly defined harvesting season. Coffee producing countries with more than one wet and dry season will have more than one harvesting season.
There is a direct relationship between extremes of day and nighttime temperatures and coffee quality. Experimental evidence has indicated that a large gap between day and nighttime temperatures is beneficial to the flavor of fruits. Since a coffee cherry is a fruit and the seed is in contact with the fruit, these benefits will be passed onto the seed and therefore into the cup.
Soil Analysis Examples and Coffee Nutrients
When buying soil for growing coffee, the following values are recommended for coffee soil (Malavolta, 201):
P (resin) - 15-30 µg/cm3.
P (Mehlich 1): 10-20 ppm
SO4-S: 10-15 µg/cm3.
K% CEC (pH 7.0): 10-15%
Ca% CEC (pH 7.0): 40-60%
Mg% CEC (pH 7.0): 10-15%
V%: 60-70%
CEC (pH 7.0): 7-10 meq/100 cm3.
B (hot water): 0.4-0.5 ppm.
B (0.05 N HCl): 1.0-1.2 ppm.
Cu (Mehlich 1): 2-3 ppm.
Zn (Mehlich 1): 4-7.

Analysis of Soil: Correcting Problems
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Lime is often used to help correct acidic soils to a pH between 4.5-5.5 in the first 20 cm of soil. When planting coffee, the holes should be covered with 250-500 g of limestone per meter (Mavolta, 199). Production increases of up to 500% have been observed by adding limestone. In Brazil the highest producing plantations had a pH from 6.0-6.5, a cation exchange capacity of 40-50%, and the base saturation in the upper 20 cm was 60% (Malavolta, 198). The requirement for lime can be calculated as follows:
Lime needed = (T(V1-V2)/RPTN)p where
T - meq/100 cm3 of exchangeable H+Al+K+Ca+Mg
V1=S/T*100
RPTN=Relative Power of Total Nutrition. The average is 75%.
p=factor of compensation for depth:
= 0.5 for 0-10 cm.
= 1.0 for 0-20 cm.
=1.5 for 0-30 cm.
(From Malavolta, 198).

To correct problems with acidity below 20 cm deep phosphogypsum is often applied. Mavolta suggest that phosphogypsum should be applied when aluminum saturation is higher than 20% or the participation of Ca in the effective CEC is lower than 40% (Malavolta, 200).

Coffee Fertilizer

Since the coffee hullls and pulp are rich in nutrients, many people often use coffee grounds as fertilizer. One 60 kg bag of coffee contains 1,026 g of nitrogen, 60 g of phosphorous, 918 g of potassium, 162 g of calcium, 90 g of magnesium, 72 g of sulfur, 0.96 g of boron, 0.80 g of copper, 3.6 g of iron, 1.2 g of manganese, 0.002 g of molybdenum, and 0.72 g of zinc (Malavolta, 197). The pulp resulting from processing contains 1,068 g of nitrogen, 84 g of phosphorous, 2,250 g of potassium, 246 g of calcium, 78 g of magnesium, 90 g of sulfur, 2.04 g of boron, 1.08 g of copper, 9.0 g of iron, 1.80 g of Manganese, 0.004 g of Molybdenum, and 4.20 g of Zinc (Malavolta 197).
Mineral deficiencies in mineral content can usually be detected visually from looking at the coffee bean leaves. See Coffee Bean Leaf Analysis for more information on laboratory tests available.

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