Coconut Research Institute Repository

Peries, R.R.A.

The brown dwarf:a recent addition to the varieties and forms of the coconut palm in Sri Lanka

Liyanage, M. De S.

U S E S A N D M A N A G E M E N T O F N I T R O G E N 
F I X I N G T R E E S I N 
C O C O N U T P L A N T A T I O N S 
Low productivity and poor returns 
from a unit of coconut land coupled with price 
instability of the coconut crop have threatened 
the sustainability of coconut plantations in Sri 
Lanka. Over the past three decades, coconut-
based farming systems 
have been introduced by 
the CRI, for the purpose 
of increasing land produc­
tivity and generating ad­
ditional income to the co­
conut farmer. 
M de S Liyanage 
Coconut Research Institute of Sri Lanka 
erate rainfall to increase productivity and ac­
crue several benefits to the farmer. 
On fertile soils 
with favourable climate, 
farmers are encouraged to 
grow high value cash 
crops with a ready market 
such as Pineapple, Ba­
nana, Pepper, Ginger, Be­
tel, Cinnamon etc. Nitro­
gen Fixing Tree (NFT) 
species have been intro­
duced to areas where 
these cash crops will not 
perform well especially on degraded marginal 
land with less favourable climate such as those 
in the intermediate and dry zone.(mainly land 
suitability classes 4 and 5) 
Since 1987, CRI has attempt^ to grow 
several nitrogen fixing trees (NFT s) such as 
Gliricidia sepium, Calliandra callothyrsus, 
Leucaena leucocephala and Acacia 
auriculiformis, with the main objective of uti­
lizing such marginal coconut land with mod-
Figure 1.Gliricidia cultivated in between coconut rows 
Factors to be considered in selecting NFT s 
* Compatibility with coconut 
* Tolerance to partial shade 
* Ability to grow on degraded soils 
* Optimum biomass production under cocon­
ut shade 
* Ability to withstand repeated pruning 
* Good coppicing ability 
* Use minimum external inputs 
(eg. fertilizer, pesticides) 
4 
* Compatibility with coconut 
The effect of fast growing tree species 
on coconut yield is an important aspect to be 
considered in promoting their adoption in co­
conut plantations. Data collected over five 
years have revealed that despite non applica­
tion of fertilizer and water to NFT s, there was 
no detrimental effect on the palm, compared 
to control blocks. Among species, all except 
Leucaena showed an improvement in the yield 
of coconut in the range of 15-20%. 
* Tolerance to partial shade 
mass productivity in NFT s could be achieved 
by pruning trees 1.0 m above ground at 3-4 
monthly intervals. For instance.gliricidia is 
capable of producing 10-15 mt of fresh 
loppings per year from one hectare of coco­
nut land. 
* Ability to grow on degraded land 
NFT species have established well and 
continue to produce satisfactory biomass with­
out fertilizer on Andigama soil series which is 
considered marginal for coconut due to poor 
physical characteristics of the soil. 
It has been 
shown that among 
NFT s the least reduc­
tion of biomass yield 
under reduced light 
occurred in Gliricidia 
(23%) followed by 
Calliandra whereas 
biomass of Leucaena 
was reduced most 
(56%) by low light, 
suggesting that it is 
less shade tolerant. Of 
all NFT species, 
Gliricidia has shown 
to be the most compat­
ible species that could 
be grown in associa­
tion with coconut. Figure 2.Use of Gliricidia leaves as green manure 
* Optimum biomass production under co­
conut shade 
Optimum biomass production can be 
achieved by tree management. Frequency and 
height of pruning are important aspects in tree 
management. 
Experience has shown that highest bio-
* Use of minimum external inputs 
This is a clear advantage of NFT s as 
other crops will not perform well without the 
application of fertilizer and pesticides. These 
trees have the ability to meet their own nutri­
ent requirement by foraging through the soil 
profile, biological nitrogen fixation and they 
5 
are practically free of pests and diseases. 
* Ability to withstand repeated pruning 
Despite NFT species have been sub­
jected to pruning 3-4 times a year and this pro­
cess has been re­
peated for five 
c o n s e c u t i v e 
years,trees con­
tinue to perform 
well and remain 
productive over 
the years. 
requirement of the coconut palm, thus provid­
ing about 40% saving on the cost of fertilizer. 
It will also provide a regular supply of micro-
nutrients to the palm. 
* Coppicing 
ability 
The abil­
ity of NFT s to 
produce new 
shoots after each 
pruning is re­
ferred to as 
coppicing ability. 
All NFT s have 
shown their ability to produce coppice shoots 
after pruning. Among NFT species, Gliricidia, 
Calliandra and Acacia have shown better 
coppicing ability. 
ROLE OF NFT' S IN COCONUT PLAN­
TATIONS 
* Use of fresh biomass as green manure 
Figure 3.Gliricidia foliage as animal fodder 
* Use of fresh biomass as mulch 
Of the NFTs. prunings of Acacia fol­
lowed by Calliandra have shown a greater 
promise to serve as a surface mulch. With all 
species, mulching has shown a better effect 
against bare soil, in terms of moisture conser­
vation ability, soil temperature regulation, and 
weed suppression. 
Of the NFT species, Gliricidia and Leucaena 
foliage is particularly rich in nitrogen. It has 
been shown that application of 35 kg fresh 
Gliricidia loppings could satisfy the total re­
quirement of N and at least 20%' of P and K 
* Use of fresh biomass as animal fodder 
Mixing of poor quality grass or rice 
straw with Gliricidia and Leucaena foliage 
up to about 30% of the total feed will provide 
a balanced ratio for livestock, especially dur-
6 
ing the dry period. Feeding with high protein 
supplements has given rise to improved intake, 
better digestibility and weight gains of rumi­
nant livestock. Acacia leaf is commonly fed 
to goats. 
* Restore and improve soil fertility 
NFT species have a special ability to 
grow on marginal lands and improve soil 
physical, chemical and biological properties, 
there by improving the productivity of soil and 
facilitating better growth and yield of coco­
nut palms. 
* UseofNFT's as temporary shade 
In new plantations, species like Gliri­
cidia and Leucaena have been grown together 
with coconut seedlings to provide temporary 
shade.especially in dry areas to provide a 
favourable microclimate for initial establish­
ment and growth up to about 3 years from 
planting. 
* Use of NFT's as live support 
Of the NFT's Gliricidia is widely used 
as a live support for Pepper and Vanilla grown 
together with coconut. Application of Glricidia 
loppings arround Pepper could reduce the fer­
tilizer requirement of Pepper by about 50%. 
Considering the easy management and 
the potential use of NFT's, it is profitable to 
grow them, especially on marginal coconut 
lands. 
/ i 
Specialist Assistance to Develop your Plantation 
The Coconut Research Institute implements programme known as "Persuasive 
Extension Programme" to assist coconut growers to develop their plantations with the 
adoption of new technology. In this programme a group of scientists and extensionists 
of the Institute meet land owners in their plantations and draw up suitable develop­
ment plans in consultation with land owners. In this exercise land owners have an 
opportunity to discuss their problems and limitations and decide on future development 
activities. Officers from this institute continue to assist them in the implementation of 
the proposed development plan and monitor the progress. This is a valuable opportu­
nity for growers who wish to improve the productivity of their plantations. 
If you wish to register to obtain this service, please write to Director, Coconut 
Research Institute, Lunuwila, Sri Lanka. 
7 


Uses and management of nitrogen fixing trees in coconut plantations

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Nadarajah, N.

Amarasinghe, L.

Soil maps of Awissawella, Panadura-Horana, Aluthgama,Ambalangoda, Galle, Matara and Ambalanthota 1" sheet areas,Coconut Research Institute, Lunuwila, Sri Lanka

National Science Foundation of Sri Lanka

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