"From the tree roots you can make soil"

ILEIA Newsletter • 4 nº 1 • March 1988

‘From the tree roots you can make soil’

Pak Wagimin from Kali Putih on Mount Semeru now plants Albizia in stead of Leucaena trees.

Budi Haryono and Meine van Noordwijk

It's not so easy to reach Kali Putih at the end of a road leading up to Mount Semeru, at 3676 m above sea level the highest volcano of Java, Indonesia. Kali Putih means 'white river', suggesting that erosion was limited when the name was given. Recently the remains of an old Hindu temple were found, which show that the area was inhabited long ago. Every twenty minutes Mount Semeru erupts with a small puff and lava flows Pak Wagimin from Kali Putih on Mount Semeru now plants Albizia instead of Leucaena trees constantly from one side of the volcano. Frequent light earthquakes remind one of the possibility of a big eruption any time, but the fertile ash rains make up for that risk. The rainfall is heavy and the soil porous; erosion is a major risk.

Because the area is difficult to reach, especially in the rainy season, farmers are less integrated in the money economy than in the rest of Java. They grow many types of vegetables and food crops in their home garden and keep goats in a stable near the house. Cash income mainly comes from high valued, low volume perennial crops: clove, coffee, tea and some pepper. Shade trees grown in between these crops may give a considerable income from timber, as we learned from Pak Wagimin. Recent attempts to introduce large-scale horticulture for the city markets lead to severe soil erosion, as can be seen on other mountains of Java as well: will the Kali Putih stay clear? Our spokesman does not want to say much about this problem, but lets us hear more about his own experience using trees.

He has experience with several tree species in combination with clove, tea and coffee. A bushy type of Leucaena has been known in this area for many generations as 'Lamtoro biasa'; about fifteen years ago it was largely replaced by the new fast-growing taller variety 'Lamtoro gung'. This became a valuable shade tree: it grows well, the leaves and branches are good fodder for the goats (Indonesian goats have stomach bacteria which can deal with the toxic mimosine compound) and the pods and young seeds are suitable for human consumption as a vegetable. According to Pak Wagimin, however, the branches decompose slowly and attract termites, which is not good for the coffee trees. The wood is mainly suitable as fire-wood; it is sold for Rp 4.000 per cubic metre to merchants who drive up the mountain with a truck. Now most Lamtoro gung trees have to be cut, because the 'Kutu loncat' beetle (Heteropsylla cubana) destroys the branches and leaves.

Pak Wagimin luckily does not depend on one tree species only. Albizia falcata (known locally as 'Sengon') has been used as a shade tree for a long time and is now gaining a more prominent place. Sengon grows faster than Lamtoro and it adds more to the fertility of the soil. Sengon is grown from seedlings; after about five years stems can be cut and sold to match factories for about Rp 9.000 per cubic metre. Six months before cutting new seedlings are planted in between to take over the shading function. After cutting, Sengon trunks will regrow but do not give valuable stems again. The trunks are regularly pruned for feeding the goats, until the trunk dies. When dead the trunk and roots decompose rapidly and leave fertile soil behind: 'Dari akar bisa menjadi tanah', 'from the roots you can make soil'.