Author : Ngin Chhay

Summary : Rice is the staple food of Asia and is central to the food security of about half of the world's
population. Rice production is an important source of livelihood for approximately 140 million
rice-farming households. As Cambodia's staple food crop, rice has provided income to majority
of the rural population and has contributed to the national economy. It is predominantly grown
on more than 3 million hectares comprising 75% of the agricultural land in Cambodia.

Major challenges include the need to produce more rice to meet the rising demand from
population growth that is expected to reach 9.6 billion in 2050; environmental degradation;
decline in rice biodiversity; climate change and increasing competition for land, labour and
water. Increase in crop yield has often been attained through the exhaustive application of
pesticides and fertilizers. However, the indiscriminate use of these chemicals damages the
environment and human health while jeopardising agricultural production.

Therefore, new ways need to be explored to increase crop production profitability while
reducing the risks from pesticides to humans and the environment. One of the ways to achieve
this is by implementing suitable IPM practices to reduce reliance on pesticide use and moving
towards food production methods based on the effective use of ecosystem services that are
regenerative and that minimize negative impacts.

FFS is a participatory approach to train farmers to apply the principles of IPM. The
Cambodian National IPM Programme was established in 1993 and FFS programmes started in
1996. The main objective of the FFS is to improve the technical capacity and enhance field
observational and analytical skills of farmers and enable informed decision making in crop
management so as to reduce reliance on pesticides, and increase yield and incomes from rice
production. Approximately more than 200,000 farmers have been trained in FFS on different
crops and they are currently applying the knowledge and experiences in farming, of which more
than half accounts for rice farming.

The study on Sustainable Integrated Pest Management consists of four main objectives:
(1) assess the effectiveness oflPM practiced during FFS training on the production efficiencies,
yields and profitability of rice farming; (2) evaluate the impact of farmer education through
FFS on pesticide risk reduction and productivity improvement in Cambodian rice farms; (3)
assess the impact of insecticide application on arthropod predators and plant feeders in
Cambodian rice fields; and (4) investigate the response of rice plant to defoliation and
detillering at different growth stages during dry season in Cambodia.

In pursuit of the aforesaid objectives, four field studies were conducted from September
2014 to June 2017. The following results were obtained:
Study-1 assessed the effectiveness of application of technical recommendations during
FFS training in Cambodia on the production efficiencies, yields and profitability of rice farming.
In total, 270 FFSs on rice cultivated in the early wet, wet and dry seasons were randomly
selected from three provinces over 3 years to analyse the production practices and productivity
using six cost-related factors, namely, seed, planting methods, field management, fertilizer use,
pesticide application and harvesting. It was found that yields and profits were significantly
higher with the technically recommended practices (TR) than with traditional farmer practices
(FP). In contrast, the production costs due to the overuse of seed and pesticides were higher in
FP, neither of which correlated with yield increase in both FP and TR. Thus, the FFS approach
is a knowledge-intensive field management tool that enables the rational use of farm inputs,
and it is expected to be highly effective for sustainable rice production improvement.

Study-2 examined impacts of FFS on improved practices of rice farmers by comparing
baseline data (O-year) with follow-up investigation of datasets from short-term (3-year) and
long-term (7-year) surveys. Three subsets of data were analysed: FFS-trained farmers (FFS
farmers), non-FFS-trained farmers (non-FFS farmers) in an FFS-implemented village, and nontrained
farmers (outer farmers) in a village where FFS was not implemented. It was found that
FFS farmers had a reduced pesticide usage over the short-term and continued to reduce their
usage over the long-term. By contrast, although non-FFS and outer farmers had a reduced
pesticide usage over the short-term due to a spill over effect, this later increased, albeit to a
lesser extent for non-FFS farmers. By reduction in pesticide usage, the use of proper protective
equipment, and the increase in the application of alternative pest-control methods, FFS-farmers
have significantly reduced the exposure risks from pesticides while gaining significant benefits
from rice production compared with non-FFS and outer farmers. Therefore, working towards a
non-toxic environment is a viable option for achieving sustainable rice production, maintaining
a healthy environment, protecting human health, and attaining income security for smallholders
in Cambodia.

Study-3 examined the necessity and economic viability of insecticide use for rice
cultivation, and multiple interactions between both the populations of insect pests and natural
enemies in dry-season rice fields. The outcomes of calendar-based insecticide-sprays and nonsprayed
rice fields were compared at three provincial research stations in Cambodia in terms of
rice growth, economic returns, damage caused by insect pests, and population dynamics of
insect pests and arthropod natural enemies. The results showed that rice fields without insecticide application suffered no significant additional damage by insect pests or by diseases
and had yields similar to those treated with insecticide in two provinces. Although, the
occurrence of caseworm was observed in the third province, this was successfully controlled
by an IPM treatment without using insecticides. Insufficient population densities of natural
enemies appeared to correlate with the caseworm outbreak in this location, whereas high
densities of natural enemies relative to those of insect pests contributed to controlling potential
pest expansion in the other two provinces. Natural enemy populations were found to be
significantly decreased by insecticide applications. Reduced insecticide input in the insecticidefree
control and IPM plots resulted in higher net profits than those in insecticide-applied plots,
except for plots in the region with a caseworm outbreak (insecticide-free). Overall, this study
provides encouraging insight into cost effective and environmentally-friendly pest management
in Cambodian rice fields.

Study-4 investigated the impact of mechanical-simulation of insect-caused defoliation
and detillering on irrigated rice during dry season in three locations in Cambodia. Defoliation
treatments included 0% (control), 10%, 25% and 50% defoliation at 30 days after transplanting
(DAT) at the tillering stage, and 10%,30% and 50% defoliation at 60 DAT at heading stage.
The tiller damages were simulated at 10%,20% and 30% at 30 DAT and 5%, 10% and 15% at
60 DAT compared to the control. The number of tillers/m2, number of panicle/m2, weight of
1000 grains, number of full grain/panicle, and grain yield (kg/ha) were examined. The results
revealed that no yield losses occurred up to 50% defoliation at 30 DAT and up to 30%
defoliation at 60 DAT. However, 50% defoliation at 60 DAT resulted in a significant reduction
in the number of full grain/panicle, and on the grain yield, amounting to 13.5% yield-reduction
(from 4,422 to 3,824 kg/ha) on an average. For simulated stem damages, no difference in rice
yield was observed up to 20% tiller removal at 30 DAT and up to 10% stem loss at 60 DAT.
Nevertheless, significant yield losses occurred when 30% and 15% of tillers were removed at
tillering and heading stages, respectively. These results highlight the ability of rice plants to
compensate and tolerate certain levels of foliage and tiller loss at different growth stages. For a
sustainable IPM, it is important to understand the inherent ability of rice cultivars, and their
interactions with the ecosystem to compensate and tolerate foliage and tiller losses along with
host plant resistance and to apply appropriate cultural practices together with the conservation
of biological control agents in the field.