G.K. Upawansa Eco Conservation Organization, Hyneford, Nawalapitiya, Sri Lanka
Dry sowing of paddy in aswedumised fields is known as kekulama in Sri Lanka. When dry
sowing is done in highland under shifting cultivation it is called vee hena.
In the past for kekulama the fields were ploughed with a new country plough first to get a somewhat deeper tillage then kept for a few days and dry seeds were sown with the anticipation of rains soon. Having sown seeds again, farmers ploughed the land with an old worn out
plough to cover the seeds. When the fields are wet the same operations are done but sprouted seeds are sown instead.
In some paddy tracts and under some tanks certain
sections were sown to kekulama and then when the tanks were full with
rains other sections were sown having done the normal wetland land preparation
which includes:
first ploughing;
cleaning bunds;
re-plastering bunds;
second ploughing;
puddling;
leveling;
preparing a shallow channel system to drain the fields; and
sowing sprouted seeds.
This combination of above cultural practices
apparently has being adopted for centuries with the aim of controlling weeds.
Weed menace is unavoidable because of depletion of soil fertility mainly caused
by soil erosion inherent to wetland paddy cultivation. In depleted soil weeds
grow much more vigorously than paddy because the fertility level and other
physical conditions are ideal for weeds. If and when other means of weed
management are available most of the said practices can be got rid of. One of
the main attempts of nava kekulama is to manage weeds with other
innovations not requiring more water than for an ordinary highland crop.
Main features of nava kekulama are as follows:
Not clearing and re-plastering bunds:
This was intended to attract and harbor insect predators to bring about biological
control of insect pests and was very successful. When weedy bunds were
maintained for three to four seasons more and mere benevolent incidences
appeared. Those are given below.
With weedy bunds more anthills and more ants inhabit the bunds. The ants during harvest
period bring weed seeds of the field to anthills thus reducing the amount of
germinating weed seeds in the fields.
Weedy bunds are not normally subjected to making holes by land crabs.
Animals such as iguana, mongoose and rat snakes inhabit weedy places and devour rats, crabs
etc preventing the damage to the crop.
Leaving the bunds unattended for a few seasons causes a gradually change of the vegetation
in which yams and rhizomes are disappearing. At the same time the earthworm
population too get reduced. When there are no yams, rhizomes and earthworms the
wild boars are not damaging the bunds.
Damages to bunds due to flash floods during the cultivating season are not happening
when the bunds are strong due to weeds.
The fauna and flora disappeared due to continuous cultivation and cleaning of bunds
reappear in the bunds.
Cost of production is remarkably brought down owing to reduced labour, not using or
minimal use of agrochemical including chemical fertilizer and natural crop
protection.
From the above list of
benefits to farmers it is clear that keeping weedy bunds is the total crop
protection measure of paddy including some of natural disasters.
Minimal or zero tillage:
Puddling
of soil avoided in nava kekulama to prevent soil erosion, surfacing of
weed seed that would not germinated if kept burried, dispersing weed seeds over
entire field surface and and to keepa cloddy surface favoured by the plants.
Other advantages are as follows:
Main objective of minimal or zero tillage is to keep the fertile soil with its
stratified nature of microbes intact so that the chemical, physical and
biological properties of top few millimeters of soil is ideal for the
germinating seedlings. Besides this
It reduces the cost of preparatory tillage,
Reduces the ware and tare of machinery,
Minimizes the soil erosion,
Reduces the time of operation,
>Less water consumption and
Also reduction of weed population.
Observations in zero tillage shows patchy good results and expect in near future to give more
details about it. Our organization conduct experiments on zero tillage in three different methods including Fukoka
method modified to suit tropical conditions.
Mulching the fields soon after sowing: This is the most striking innovation which has
not been given any thought by thousands of scientists for many decades or even centuries.
By mulching alone a yield increase of five to eight bushels or 100 to 160 Kg. per
acre per season has been observed in Sri Lanka. The yield increase of the crop
depends on the initial fertility level of the soil.
Mulch completely check the soil erosion. It is the main factor contributing to soil fertility.
Adds organic matter substantially without much effort.
Enhances and increases the soil microbes and particularly the earthworm population.
Earthworms not only make the soil fertile but also pulverize the soil so that
it paves way for zero tillage.
Improves organic matter content of the soil season after season and as a result improves
the water holding capacity enabling the crop to withstand short water stresses.
When a mulch applied to a thickness of about 7 to 8 cm (3 inches), complete weed control can be expected.
Picking the sawn seeds by birds is prevented.
Though not scientifically proved, it appears
that wet straw fixes nitrogen as in the rice roots. With a material like straw
with very high C/N ratio when applied as mulch, yellowing of the crop due to
nitrogen starvation is expected. This condition does not occur with nava
kekulama but vigorous green growth observed for about one month.
Those who are not
experienced with kekulama might wonder whether the paddy seeds would
germinate and immerge through the thick mulch. There is nothing to be feared.
The seeds germinate almost 100 %.
Water management: In nava kekulama all attempts in water management is to keep the soil at field capacity and
avoid inundated situation except at the panicle initiation stage which falls
around two months before the expected harvesting. This way of water management
results in an extensive root system growth.
Advantages and Potential of Nava Kekulam Method of Paddy Cultivation
Kekulama: a way of exploiting the potential of paddy seed and plant
Pre-sowing germination
A practice in certain parts of Sri Lanka is to germinate the seed paddy, dry and store for a few weeks before
sawing. Research into this practice shows that the radical is protected by a
layer of cells not allowing to dry as one sees. Once the sufficient moisture is
available this layer ruptures and begins growing. This potential is utilized in four ways:
If a water shortage occurs soon after germination the seeds
remain dormant until sufficient moisture is available for growth. The dormant
period can even be more than four weeks under favourable conditions. The
dormant period gets added up to the normal age of the crop. For instance if age
of the crop is four months and the dormant period is three weeks the crop would
take three more weeks to ripe. This is an advantage because the crop can be harvested during dry period following
rains. When the rains are delayed normally the rainy season get extended and
harvest falls within the rainy period if age of the crop remains same.
For germination it requires minimum of four days. When germinated seeds are sawn
just before rains in anticipation of rains or with the rains the crop comes up
four days earlier than when sawn normally. It is important under scanty
rainfall conditions.
When flood occurs at the time of sowing the seeds can be dried and stored till the weather
is suitable for sowing.
It is a reliable germination test.
Primordial protection
In some years a drought occurs when the paddy crop is around four to five weeks old. Then the
shoot dries but the under ground stem and some roots with primodia intact
remains hardened and dormant or hibernated condition As in the case of
germinated dried seeds with rains or when there is sufficient water is
available plant begins to grow. Dormant period gets added up to the age of the crop.
I and II above brings forward a strong case to change cultural practices now adopted in order
to save water and bring about a natural crop protection measure.
Paddy straw mulch has a weedicide effect. Mulching the soil, soon after sowing not only manage the weeds but also
check the erosion completely.
It is known that there are a few spirillums in the roots of paddy plant fixing
atmospheric nitrogen. Same effect is observed when the mulched straw is kept
moist. In fact paddy seedlings grow vigorously for about a month without any
nitrogenous fertilizer with wet mulch. This is a paradoxical situation.
Normally with material of wide C/N ratio when used as mulch the crop tends to
yellow due to nitrogen starvation.
The most important character of the seed is the ability of the radical to immerge through a grass
mulch of three inches. Though most seeds cannot germinate with a mulch of this
thickness, paddy seedlings immerge out in six days as in the case of normal
sowing. The importance of the mulch does not need any description as it is well known in farming.
All these
potentialities are being made use of in kekulam method of rice
cultivation to bring down the cost of production, enhance normal eco system and
sustain yields by improving the soil fertility.
Water economy
Though the precipitation, intensity of rainfall and spread over months vary annually, in
the long run annual average rainfall remains constant. Because of this factor
maximum amount of water available for storage with reservoirs and tanks in Sri
Lanka has a limit. There is no purpose of going beyond this storage limit as
there would not be water to fill any more tanks and reservoirs. A good example
is the reservoir at Lunugamvehera which hardly fills in any year with the average annual rainfall. Then further
expansion of farming or extent of farming land depends on economizing water or
improving water (or irrigation) efficiency. The simplest and most efficient
ways of economizing water are offered by the kekulam method of paddy
cultivation. They are as follows:
If seeds are to be sown dry no water at all is needed. The amount of water required for land
preparation under wetland condition is approximately three and half acre-feet
of water or fifty percent of total water requirement of the paddy crop. Paddy
field bunds are cleaned and plastered to retain water. The fields are puddle to
level the field so that a uniform depth of water can be maintained in the
entire field. This practice of maintaining inundated condition is adopted as a
weed control measure. Due to seepage average water requirement of a paddy crop
rises resulting in very low water (irrigation) efficiency.
Land preparation is done either wet condition or dry condition the fields are not inundated
when kekulam method is adopted as the weeds are managed by other cultural practices like mulching.
Mulching the crop lowers the evaporation from surface thus increasing the irrigation interval.
It has been observed that crops cultivated to kekulam method reach maturity twelve days
earlier than conventionally grown crops. Reasons for this phenomenon is not
clear but it can be due to non use of weedicides which retards the growth rate.
Sowing pregerminated and dried seeds can shorten the maturity by another four days.
Reaching maturity early is very critical because of water shortages occurring
often at the end of the season. 04 and 05 together is a guarantee against crop
failure due to water shortage at the end of the season.
Kekulam method improves the organic matter content of the soil over time. As organic
matter imbibes large quantities of water the crop can withstand a reasonably
long dry period on one hand and increase the irrigation interval on the other.
Practical experience shows that nava kekulam method saves forty to sixty percent of water
needed during the two seasons of a year. This indicates that the acreage under
paddy cultivation in Sri Lanka can be doubled when nava kekulam method
is adopted. Instead of constructing new dams and tanks to increase the extent
of land under paddy, popularizing nava kekulam method among farmers will
be much more cost effective and also ecologically favorable.
Ecological and environmental impact of nava kekulam:
In Sri Lanka as in all Asian countries wetland paddy cultivation is the common practice. In
newly cultivated fields no vegetation other than paddy plants are seen. It is
complete devastation of the marshland vegetation. Along with the vegetation all
animals and insects except those animals, insects and other organisms live on
paddy disappear. The repercussion of this devastation is ecologically
intolerable and unacceptable. The insect pest damage to the crop and subsequent
insecticide application is inevitable. In nava kekulam method the bunds
are not cleaned or re-plastered in order to establish the natural vegetation.
Very few weeds that grow with straw mulched paddy crop too are not removed. The
bunds account ten to twenty percent of the total extent of the paddy fields and
retaining natural vegetation on the bunds establishes the insect pest predator
balance thus avoiding the use of either chemical or organic pesticides
application. Further with time plants and insects inhabited earlier but
disappeared due to continuous cultivation begins reappearing. As such the
easiest, an inexpensive, effortless and most effective way of rehabilitating
marshland eco system in paddy fields is the adoption of nava kekulam
method of paddy cultivation.
When weeds, stubble and roots get submerged under the normal wetland paddy field
preparation methane gas is formed and liberated to the atmosphere. As paddy is
treated as a highland crop in nava kekulam no more water than field capacity is
maintained methane emission to the atmosphere is eliminated or minimized to a very
great extent.
Non-use of pesticides and minimal or non use of chemical fertilizer prevents atmospheric
pollution and ecological damages as well as ground water pollution.
Minimal or zero tillage adopted in nava kekulam and mulching the land completely controls
the soil erosion and enhances the soil life.
Social and economic advantages of nava kekulam
The author, G.K. Upawansa
Hyneford
Dekinda, Nawalapitiya
Sri Lanka
tel +94 8 223012 / 054-22580
fax +94 8 232517
e-mail: pasasa@sltnet.lk
Reduced labour and inputs reduces the cost of production
Improvement of family income due to high yields, escalate the quality of life of farm families.
Poison-free and healthy food reduces health hazards on one hand improves the health of family
members on the other.
Many farmers in Sri Lanka commit suicide owing to indebtedness caused by borrowing for farming.
As no borrowing is necessary in nava kekulam due to low labour requirement and
external inputs there is no need for borrowing and therefore suicide rate should come down.
Price of paddy is at the lowest at the time of harvest. Still the farmers sell their produce at a low price in order to pay
up the loans. When loans are not raised with kekulam produce can be stored till the prices are good.
The rituals and ceremonies involved in kekulam enhances the social integrity and morality of
the society.
Mind fullness about ecology and environment can be a great assert for local conservation.
Incorporation of indigenous concepts and practices fosters the unity of the society and quickens
the favourable social changes.
Foreign exchange spent on agrochemicals can be saved.
