What is mulch?
Mulch is generally a layer of decaying organic
matter on the ground. Which can be occurred naturally in all forests; it is a source
rich in nutrients, moisture absorbent bed of decaying forest leaves, twigs, and
branches, teeming with fungal, microbial, and insect life. This natural mulch
serves as a “nutrient bank,” conserving the nutrients contained in organic
matter and slowly releasing these nutrients, and make available to plants. All
forms of plant species from the ground layer to shrubs and trees thrive, grow,
shed organic matter, die off and decay and enter into the cycle of nutrients.
In
terms of getting those advantageous impacts to agricultural lands artificial
mulching is introduced and it is a layer of
material applied to the surface of soil. Mulch can be any material or laid
over the surface of soil as a covering; conserve soil moisture, improve
fertility and health of the soil, reduce weed growth and enhance the visual
appeal of the area in agricultural field.
Figure 1 : Difference
between mulched soil vs unmulched soil
(Source:
https://ars.els-cdn.com/content/image/1-s2.0-S0167198717300016-gr4.jpg)
Materials to use for mulching
· Organic residue: grass clippings, leaves, hay ,coir, straw, comfrey, shredded bark, whole bark nuggets, sawdust, shells, woodchips, per, cardboard, wool, but also manure (cow), etc.· Compost: This should be fully composted material to avoid possible phytotoxicity problems, and weed seed must have been eliminated, otherwise the mulch will actually produce a weed cover.
· Rubber mulch: made from recycled rubber.
· Plastic mulch: crops grow through slits or holes in thin plastic sheeting.
What is Coir Dust?
Coconut
fiber, or coir, a natural waste or the by-product resulting from the processing
of coconuts; comes from the coconut husks. The fibers are separated, cleaned,
sorted and graded.
Figure 2: Coir Dust
(Source: https://patioyarddesign.com/wp-content/uploads/2018/11/coconut-coir-for-gardening-and-the-facts-about-coco-coir-fibredust.jpg
)
Composition
Coir contains ample amount of fiber which can act to retain water. And additionally, coir possesses significant amounts of natural potassium (K) and phosphorus (P). It contains trace amounts of nitrogen (N), calcium (Ca), magnesium (Mg), boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) as well.
Table 1 : Properties of Coir
dust
(Source : https://www.ncbi.nlm.nih.gov/pubmed/28824665)
Coir
has become widely used by gardeners as a mulch, soil amendment and potting soil
ingredient in recent years.
Advantages of Coir dust Mulch
·
Environmentally friendly – Coir mulch can be considered as an environmentally friendly
resource, unlike peat moss, which comes from non-renewable, diminishing peat
bogs. As well, peat mining is not environmentally friendly, while harvesting of
coir poses no threat to the environment. It is an organic bio-waste product obtained after coconut processing. Alhough
coir mulch is a sustainable industry, there is concern about the energy used to
transport the mulch from its point of origin in places like Sri Lanka, India,
Mexico and the Philippines. So it is problematic to use coir dust as a mulching
material in Western countries.
·
Water retention – Coir mulch holds 30 percent more water compared to other
materials including crop residues. It also absorbs water easily and drains
well. This is an important benefit in drought-plagued areas, like Hambanthota
areas in Sri Lanka as it reduces the use of water in the garden by as much as 50
percent.
Figure
3 : Moisture retention by different types of mulching
materials against different temperatures
(Source:
Godawaththa V.N.A, 2014)
Coir dust can store up
to 8 times its dry weight on water. By applying a 15 cm thick C.D.M. layer
around coconut seedlings in Sri Lanka, irrigation could be reduced by 40-55 %
during the dry season.
It plays a significant
role in agricultural field as it can absorb moisture in high amounts. According
to researches the productivity has increased in some particular crops like
maize as they have used coir dust as a mulching material.
“Coir mulching resulted in decreased seasonal
evapotranspiration but significantly increased conserved 100 cm-profile soil
moisture early in the season, when compared to non-mulched control treatments.
This conserved moisture was available later in the season for increased dry
matter and grain yields. Coir mulching increased WUE by 8.4%. The study showed
that adoption of a simple agronomic practice of applying a 10 cm thick layer of
coir dust mulch could increase maize productivity by 10.4% and help improve livelihoods
of people in Coastal region.”
(S. M. Muti ,
A. M. Kibe , W. Nge’tich and E. Muindi, 2017 )
·
Soil amendment –
Coir is a versatile substance which can be used to improve difficult soil. Because
coir mulch helps sandy soil to retain nutrients and moisture. As an amendment
for clay-based soils, coir will improves soil quality, preventing compaction
and allowing freer movement of moisture and nutrients.
In Sri Lanka the productivity of coconut has limited due to poor
nutrient retention and moisture availability for the growth of coconut palm. It
is suggested that using old coconut dust as a mulch can improve the structure
of the soil and then increase the yields in coconut triangle (L,,1997)
·
Favorable pH –
Coir has a near-neutral pH level of 5.5 to 6.8, unlike peat, which is
highly acidic with a pH of 3.5 to 4.5. This is an ideal pH for most plants,
with the exception of acid-loving plants like rhododendron, blueberries and azaleas.
·
Low biodegradation - Coir dust consists mainly of lignine,
cellulose and hemicellulose. About 90 % is organic matter and the C/N ratio is
extremely high (> 130). The low pH of 4.5 - 5.5 offers an extra protection
against biodegradation, as many microorganisms do not survive once the pH drops
below 4. Slow biodegradation of organic mulches has been recently more and more
looked for, especially in the humid and sub-humid tropics, where fast
mineralization of the humic substances and outwash are big problems. Coir dust
can therefore be applied as a mulch or incorporated in the soil to improve soil
structure
Beside above importance it is found that
adding coir dust as mulch can suppress weeds and increase the production as
well. Weeds in cashew plantations in
India suppressed by 75% by using coir dust mulch which is applied around the
trees in circles with 1.5m of radius and 7.5cm thickness. ( D.
Kalaivanam, T.R. Rupa , 2017)
Different types of crop species performed better on saline soils
after application of coir dust as a mulching material
The germination of cashew seeds (Anacardium occidentale) has improved after the application
of coir dust mulch. The roots are not damaged and reduced the transplanting
shock.
In Sri Lanka,
this kind of mulch is mainly used in semi-perennial crops
like pineapple (Ananas comosus) and
ginger (Zingiber officinale). In a pineapple intercrop under coconut, weed flora changes
were observed with the use of C.D.M., in that there was a clear tendency
towards moist loving
weed species as Borreria latifolia and Commelina nudiflora. Coir dust,on the other hand, suppressed weeds
which are defined as some of the world's worst weeds, namely goatweed
(Ageratum conyzoides), purple nutsedge (Cyperus rotundus) and the sensitive plant Mimosa pudica. Therefore, coir dust promotes the growth of some (weed)
species on the other hand,
while suppressing other species. (Alwis, A.J. and Herath, H., 2012)
A final point related to this, is
the positive effect on the establishment of cover crops. As such,
thehigh incidence of Pueraria
phaseoloides coincides
with the cover cropping practices under coconut in Sri
Lanka. This herbaceous legume is, however, suppressed by weeds under dry
weather conditions. The application of coir dust tackles this
problem and positively influences the leguminous
cover crop during the dry season. The easy establishment of cover crops on pits and
trenches filled with coir dust has also previously been reported.
Coir dust, besides of being
important to control weeds, improve soil physical conditions and increase water
retention capacity, therefore has a direct effect on the sustainability of
cover
crops during the dry season, and an indirect effect on the
soil N-level. C.D.M., therefore, can be regarded
as an important tool for soil conservation and sustainable land use in many integrated
cropping systems.
Disadvantages
of coir dust mulch
·
Contamination
Coir dust may be contaminated with
cow dung and other animal wastes because coconut husks are gathered in areas
where cows graze freely. This could contaminate the mulch with cow manure that
may have salmonella. Also it may contain organisms like mites. Additionally,
green coconuts are processed using brine, which makes the husks very saline. It
may also dehydrate plants and stunt their growth.
·
Acidity
Coconut mulch is slightly acidic.
So it is not considered as a choice for mulching most vegetables
·
Cost
Because coconut mulch cannot be
produced every country, it must be imported to those countries. This makes
coconut mulch cost more for the countries other than Asian countries .The
countries like USA can produce other mulching materials domestically. If cost
is the consideration, they will compare the prices of various mulches locally
before deciding on what type to buy and use.
·
Inconvenient
Coconut mulch comes in compact
bricks in international market. Unlike other types of mulch, coconut mulch must
be soaked in warm water for at least 30 minutes before using, to allow it to expand
up to nine times the original size. This could be quite a hassle if you have a
large area to mulch.
·
Not readily available
Coir dust is not readily available in the
market when we need to buy it. It is limited to areas with coir dust industry
otherwise it needed to be transported to desirable place.
Figure 4 : Coconut husks
Figure
5 : Coir Industry
(
Source : https://upload.wikimedia.org/wikipedia/commons/thumb/1/19/Coir_segregation.jpg/300px-Coir_segregation.jpg )
New trends in Coir dust
mulching
Coir
dust is compacted and exported from countries like Sri Lanka
Figure 4: Compacted Coconut
Coir for exporting ( Source : YouTube Screenshot )
Bibliography
1. Mulching
( A blanket on the soil ) [Online] Available from : https://www.daff.gov.za/Daffweb3/Portals/0/Brochures%20and%20Production%20guidelines/Poster%20Mulchin.pdf [Accessed 10th February 2019]
2. Sample records for coconut coir dust [Online] Available from : https://worldwidescience.org/topicpages/c/coconut+coir+dust.html [Accessed 15th February 2019 ]
3. Anand H. S , Suseela Devi L., Nagaraju H.R
(2002) Chemical and bio-chemical characterization of coir dust composts as
influenced by pretreatment and enrichment [Online ] Available from : https://pdfs.semanticscholar.org/f334/def6bc1336c56200926fa0f2978bd083f07d.pdf [Accessed 15th February2019]
4. Van Mele, P. (1997). Utilization of
Coconut Coir Dust Mulch in the Tropics. 13(1), pp. 3-4.
5. S. M. Muti , A.
M. Kibe , W. Nge’tich and E. Muindi, ( 2017)Journal
of Agriculture and Ecology Research International Effects of Coir Dust Mulch on
Evapotranspiration of PH4 Maize in Coastal Region of Kenya 10(3): JAERI.29611
6.
D. Kalaivanam and T.R Rupa (2007) Organic Cultivation of
Cashew, Chapter 17
7. Utilization of coco-peat in coconut
production (2003 ) ,
Department of Agriculture, PHILIPPINE COCONUT AUTHORITY, Research, Development &
Extension Branch,Zamboanga Research Center,Davao Research Center
8.
LN
Mulumba, R Lal,(2008) Soil and Tillage
Research Mulching effects on selected
soil physical properties 98, 1 p
106-111 [Online] Available from : https://doi.org/10.1016/j.still.2007.10.011 [Accessed 25th February 2019]
9.
Alwis,
A.J. and Herath, H. (2012) Impact of Mulching on Soil Moisture, Plant Growth
and Yield of Mauritius Pineapple (Ananas
comosus. L. Merr)
9. Regional Agriculture Research and Development Centre,Makandura,
Gonawila( NWP).
10. What is Coconut Coir: Tips On Using Coconut
Coir As Mulch [Online
] Available from : https://www.gardeningknowhow.com/garden-how-to/mulch/using-coconut-coir-mulch.htm [Accessed 31st January 2019]
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