Innovation in rice (Oryza sativa) productivity improvement is a major goal for rice research. However, many studies have tended to analyse the various factors that affect productivity separately, while farmers invest their scare resources in farm inputs that impact on multiple factors in the real farm. This study assessed the effectiveness of integrated pest management practised during farmer field school (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 in 3 years to analyse the production practices and productivity using six cost-related factors: 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 (TRs) than with traditional farmer practices (FPs). However, the reverse was true for production costs due to the overuse of seed and pesticides in FP, neither of which are correlated with yield increase for both FP and TR. Thus, the FFS approach is a knowledge-intensive field management tool that enables the rational use of farm inputs and that is expected to be highly effective for sustainable rice production improvement.

Rice (Oryza sativa) is the staple crop of Cambodia. The heavy use of pesticides has caused significant financial losses to local farmers. This study examined the necessity and economic viability of insecticide use for rice cultivation, and the multiple interactions between the populations of both insect pests and natural enemies in dry-season rice fields. The outcomes of calendar-based insecticide-sprayed and non-sprayed 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 did not suffer significant damage by insect pests or by diseases and had similar yields to those treated with insecticide application in two provinces. Although the occurrence of caseworm was observed in the third province, this was successfully controlled by an integrated pest management (IPM) treatment without using insecticides. Insufficient 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 control potential pest expansion in the other two provinces. Natural enemy populations were significantly decreased by insecticide applications. Reduced insecticide input in the insecticide-free 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.

This study aims to compare the grain yield, gross return above fertilizer cost (GRAFC: (paddy sales)–(fertilizer cost)), and several parameters relating to the quality of white rice cultivated with different soil-specific nutrient management in 14 provinces where different soil types are distributed. The grain yield tended to increase with increased fertilizer application; however, the relationship between the fertilization rate and the yield was not linear in areas where clay soil dominates. In cases of popular varieties cultivated from the northern to southern province, the amount of fertilizer applied was up to 163 kg ha−1 (sum of N-P2O5-K2O), and the GRAFC and the fertilization rate showed a nonlinear relationship, with a peak of around 120 kg ha−1 fertilization. The nitrogen concentration recognized as a negative factor for the quality of rice tended to increase with an increasing fertilization rate, and the carbohydrate concentration and carbohydrate/protein ratio that are a positive factor for the quality were related negatively with the fertilizer rate. The amylopectin concentration in white rice was positively related with the carbohydrate concentration, which decreased with an increasing fertilization rate. The levels of fertilizer application required to achieve a higher yield, GRAFC, and the maintenance and improvement of parameters relating to grain quality were different.