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Rice-Wheat
Cropping Pattern and Resource Conservation Technologies
By Iftikhar Ahmad
Shazia Iram
1. Deputy Director General, Institute of Plant and
Environmental Protection (IPEP), National Agriculture Research
Centre (NARC), Islamabad.
2. Assistant Professor, Department of Mycology and Plant
Pathology, University of the Punjab, Lahore.
The rice-wheat system has been practiced by farmers in Asia
for more than 1000 years. It has since expanded and is
currently estimated at 23.5 million ha. The rice-wheat system
covers 13.5 million ha in South Asia: India (10.0), Pakistan
(2.2), Bangladesh (0.8) and Nepal (0.5). It represents 32% of
the total rice area and 42% of the total wheat area in these
countries.
In the Indo-Gangetic Plains (IGP), which stretches across
these four countries, rice is usually grown in the wet summer
(May/June to October/ November) and wheat in the dry winter
(November/ December to February/March). Although rice-wheat
cropped area in the IGP is irrigated or has assured rainwater
in sub-humid regions, the soils and crop management undergo
drastic changes during the two cropping seasons. Several
yield-reducing and yield limiting factors, together with
delayed planting of wheat and transplanting of rice; energy,
labor, and other input shortages; resistance of the weed and
crop residue burning have contributed to the stagnating or
declining production, productivity and sustainability of this
system.
Continuous cropping of rice-wheat system for several decades
as well as contrasting edaphic needs of these two crops have
resulted in increased pest pressure, nutrient mining, and
decline in yields in some areas. In many areas, yields have
stagnated at below potential level. The input use efficiency
is low. Soil organic matter content has reduced. This can be
improved by incorporating crop residue into the soil. But
burning of crop residue is common and has increased
environment pollution. Nutrients are being mined and
transported long distances and lost permanently for the sub
region. The water table has receded at several places in the
region. Also, there is a reduction in biodiversity due to
large area coverage by a single cultivar.
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Rice-Wheat Cropping System in Punjab
The rice-wheat growing areas in Pakistan are primarily
situated in central Punjab (main districts include Gujranwala,
Sheikhupura, Narowal and Sialkot) followed by Sindh (Fig 1).
The rice-wheat cropping system in Pakistan is the major one
with an estimated area of 1.6 mha. In the system, rice is
traditionally grown by transplanting 25-35 days old seedlings
in well-puddled and continuous flooded field. This method of
rice establishment is a time-consuming, tedious and inhuman
and involves high cost of labour, water, and land preparation.
Wheat sowing after the paddy harvest is delayed, resulting
into poor crop stand and low grain yield. Wheat crop is also
badly affected by flood irrigation due to poor drainage of
paddy soils. Consequently, the productivity of the system
remains far below the potential yield levels of modern
cultivars.
The rice-wheat system, one of the major cropping systems of
the South Asia and parts of East Asia, requires special
management. Rice grows well on puddled compacted soil, whereas
wheat grows best on well-drained soils. The hardpan developed
with puddling operation is important for water retention and
weed control in rice, but compacted soil creates problems of
waterlogging for wheat. In addition to this, the traditional
land preparation after rice harvest results in later wheat
sowing dates than optimum. Due to these management differences
and traditional cultural cultivation practices, the
productivity of the rice-wheat system is stagnating and its
sustainability threatened.
This can only be possible if the planting techniques of rice
or wheat crops are improved resulting to saving of time,
cultivation cost and irrigation water. Resource conserving
technologies (e.g. zero-tillage, bed planting or direct
seeding of rice) can be helpful in the achievements of major
goals.
Resource-conserving technologies
Resource-conserving technologies are defined here as any
practice that improves the efficiency of use of natural
resources, including water, air, fossil fuels, soils, inputs,
and people.
Late planting is a major problem in most rice-wheat areas. To
improve system productivity, the wheat crop must be planted at
the optimal time.
The other major cause of late wheat planting is the long
turnaround time between rice harvest and wheat planting. Long
turnaround can be caused by many factors, including excessive
tillage, soil moisture problems (too wet or too dry), lack of
animal or mechanical power for plowing, and the priority
farmers place on threshing and handling the rice crop before
preparing land for wheat.
Coupled with the problems of late planting of wheat is the
problem of poor germination and plant stands. Most farmers in
the IGP sow wheat by broadcasting the seed into plowed land
and incorporating it by another plowing. Part of the reason
for this is residue management problems in fields following
rice. The loose straw and stubbles are raked and clog the seed
drills. Broadcast seed results in seed placement at many
different depths and into different soil moistures, with
resulting variable germination. The problems of late planting
and poor plant stand have been addressed by promoting various
resource-conserving tillage and crop establishment techniques
described below
a) Surface Seeding
Surface seeding is the simplest zero-tillage system being
promoted. In this tillage option, wheat seed is placed onto a
saturated soil surface without any land preparation. This is a
traditional farmer practice for establishing wheat, legumes
and other crops.
b) Zero-Tillage with Inverted-T Openers
Another practice involves sowing using a seed drill, without
prior land preparation. This has been tested in Pakistan and
is presently being tested in other areas of the Indo-Gangetic
Flood Plains, including India and Nepal. The practice is more
relevant in the higher yielding, more mechanized areas of
northwestern India and Pakistan, where most land is prepared
using four-wheel tractors.
c) Reduced Tillage
The Chinese have developed a seeder for their 12 horsepower,
two-wheel diesel tractor that prepares the soil and plants the
seed in one operation. This system consists of a shallow
rotovator followed by a six-row seeding system and a roller
for soil compaction. Funding from the UK Department for
International Development (DFID) and CIMMYT made it possible
to import several tractors and implements from Nanjing, China,
into Nepal, Pakistan, and India, where they have been tested
over the past few years with positive results.
The main drawback of this technology is that the tractor and
the various implements are not easily available and spare
parts and maintenance are hard to obtain. It would help if the
private or public sector in South Asian countries could import
this machinery or develop a local manufacturing capability.
d) Bed Planting Systems
In bed planting systems, wheat or other crops are planted on
raised beds. This practice has increased dramatically in the
last decade. Farmers have given the following reasons for
adopting the new system:
• Management of irrigation water is improved.
• Bed planting facilitates irrigation before seeding and thus
provides an opportunity for weed control prior to planting.
• Plant stands are better.
• Weeds can be controlled mechanically, between the beds,
early in the crop cycle.
• Wheat seed rates are lower.
• After wheat is harvested and straw is burned, the beds are
reshaped for planting the succeeding soybean crop. Burning can
also be eliminated.
• Herbicide dependence is reduced, and hand weeding and
roguing is easier.
• Less lodging occurs.
Such technologies are rapidly gaining popularity among
farmers, in as much as they increase production and lower
costs, resulting in higher profits, cheaper food, and improved
farmer livelihoods. Among other things, the efficiencies
gained include less land and time needed to produce the
required staple cereals, allowing farmers to diversify crops
and cropping patterns or pursue other gainful activities.
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