This study analyzed the effects of two water-saving rice production techniques - alternate wetting and drying (AWD) and direct seeding of rice (DSR) - on crop health and yield compared to farmers' regular practice of continuous flooding (FPR). Over six seasons, AWD showed no yield penalty compared to FPR, while DSR yields were significantly lower. AWD and DSR both resulted in lower levels of weeds, insect damage, and certain diseases compared to FPR. However, AWD is a better option than DSR as it saves more water, emits less methane, and results in higher yields for farmers. The study provides evidence that AWD can be adopted by farmers without negatively impacting

1. Analyzing the effects of water-saving technologies to rice
crop health
Normally, rice production requires about 5,000 liters of water to produce a kilogram of rice grain. However, with increases in domestic demands
and the changing climate, water has become scarce, thus, putting pressure in rice production systems. Direct seeding of rice (DSR) and alternate
wetting and drying (AWD) are two techniques known to reduce water use in rice production. AWD can reduce consumption by 15-30%, whereas
DSR can save up to 30% more than traditional methods. Flooded rice fields also emit huge amounts of methane (CH4), a potent greenhouse gas.
AWD, which promotes periodic aeration of the soil, inhibits methane-producing bacteria. The adoption of AWD and DSR by farmers strongly
depends on the perceived benefits of adopting these technologies, among which is for improved crop health, which has not been scientifically
assessed.
Jerico Stefan R. Bigornia and Adam H. Sparks
International Rice Research Institute, DAPO Box 7777, Metro Manila 1301, Philippines
Email address: j.bigornia@irri.org
Methodology
Experiments were conducted to assess the effects of AWD and DSR on crop
health under farmers’ field conditions. The experiments were conducted in
Sta. Cruz, Laguna, Philippines, from 2009-2011 for six consecutive seasons in
three farmers’ fields each season. The farmers’ practice (FPR) of continuous
flooding served as the control. The percentage of weed cover and incidence
of injuries caused by animal pests and diseases were assessed every 2 weeks
starting from maximum tillering until harvest. Data on yield were collected
at harvest from three sampling areas.
No yield difference was observed between AWD and FPR over the six
seasons, but DSR yields were significantly lower (Fig. 4).
Fig. 4. Average yield of the different treatments across
seasons.
Conclusions
Producing rice with less irrigation water is one of the core research
objectives of natural resource management at IRRI. The promotion of
AWD as an adaptation and mitigation option in coping with the effects of
climate change has been gaining momentum. The results of this study will
give the farmers more incentive to adopt AWD. Aside from showing no
yield penalty compared with continuous flooding, it also saves water,
emits less greenhouse gas, and has fewer problems with pests and
diseases. AWD is also a better option to save on irrigation costs than DSR
because it results in higher yield.
P-314
Results
Multiple analysis of variance on the entire set of injuries leads to a large and
significant (P < 0.01) Wilk's Λ, indicating that the different treatments indeed
led to different crop health syndromes. There were large differences in the
levels of injuries between seasons. These levels often differed between the
dry seasons 2009, 2010, and 2011 (DS09, DS10, DS11) and the rainy seasons
2009, 2010, and 2011 (RS09, RS10, RS11). As a result, a strong interaction
between treatments and seasons occurred in the levels of injuries.
Weed coverage and rat damage were significantly higher in DSR than in FPR
and AWD (Fig. 1a, 1b).
AWD and DSR had significantly lower incidence of insect damage than FPR
(Fig. 2a, 2b, 2c).
Results also showed that diseases such as bacterial leaf streak and rice
tungro were lower in both AWD and DSR compared with FPR (Fig. 3a, 3b).
There were also no difference detected on some major diseases such as
sheath blight and brown spot among the treatments (Fig. 3c, 3d).
A B
C D
Fig. 2. Average of injuries caused by stem
borer (A), whorl maggot (B), and leaf folder
(C) to the different treatments across all
seasons.
A B
C
A B
Fig. 1. Average of weed coverage (A) and rat damage (B) of the different treatments across
seasons.
Fig. 3. Average of injuries caused by bacterial leaf streak (A), rice tungro (B), sheath blight (C),
and brown spot (D) to the different treatments across seasons.