Neem tree

Introduction

The Neem tree originated from the Indomalaysian region and is now widely grown in almost all African countries as well as in arid and semi-arid areas of the world. 
 

 

Neem trees

© A.M.Varela

Purpose and usage

• Medicinal
• Pesticides
• Cosmetics
• Gum
• Toothpaste
• Wormicide
• Fodder
• Farm tools and furniture
• Anti-desertification

Climatic conditions, soil and water management

Climate: 

Neem has a wide climatic adaptability and thrives under sub-humid to semi-arid and arid climatic conditions. It is generally found in areas with mean annual temperatures of 21 to 32°C. It can survive hot temperatures (reportedly up to 50°C), but does not tolerate frost or extended cold, although there are some reports of neem trees surviving light frost. Generally, at temperature below 4°C leaf shedding and death may occur.

The neem tree grows in areas with mean annual rainfalls of 450 mm up to 1,200 mm. It can grow in regions with an annual rainfall below 400 mm, but in such cases it depends largely on the ground water levels.

Altitude: 

Neem grows in areas from sea level up to 1200 m, however it thrives at low altitudes. Very often the neem tree is confused with the Persian lilac or chinaberry tree (Melia azedarach) a relative of neem which thrives a high altitudes. 

Soils: 

The tree grows on a variety of soils, clayey or sandy, saline or alkaline, but will not grow in waterlogged soils. It does particularly well, however, on black cotton soils and deep, well drained soils with good subsurface water. Unlike most other multipurpose tree species, neem thrives on dry, stony, shallow soils and even on soils with hard calcareous or clay pans at a shallow depth. The tree improves soil fertility and water holding capacity because it has the unusual property of calcium mining, and can thereby neutralise acidic soils. Its extensive root system also has a rare physiological capacity to extract nutrients from highly leached sandy soils. Neem can grow on soils with a wide pH range. The optimum growth is at pH 6.2 to 7, but it can also grow well down to pH 5 and survive in soils between pH 3 and . 
 

Propagation and planting

The Neem tree is best propagated from its seeds which will only germinate if less than three months old. The seeds need to be sprinkled daily while laying on a newspaper which is placed on plastic in the shade. The newspaper has to be renewed every second day. After a week the seed will crack and sprout ready to be planted in compost made of half soil and half cow manure. To propagate from a cutting, a small twig has to be stripped of its leaves and stuck into moist soil. 

Neem nursery

© A.M.Varela

Husbandry

Nutrient deficiencies: 

A lack of zinc or potassium drastically reduces growth. Trees affected by zinc deficiency show chlorosis of the leaf tips and leaf margins, their shoots exude much resin, and their older leaves fall off. Those with potassium deficiency show leaf tip and marginal chlorosisand die back (necrosis).
 

Yields

The tree starts bearing fruits after 3 to 5 years and is fully productive after 10 years. Under favourable conditions a tree can produce up to 30kg of seeds per year and 350 kg of leaves.
 

Management

• Land cropped in the first year
• Plant rows of neem in the second year
• Space the rows about 130 cm in the third year
• Alternate rows, thinned out and planted in another field, tree rows now Spaced 2.60m
• Eliminate three rows out of four rows in the fourth year
• Finally, plantation spacing of 10.4m in between rows is recommended