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Rice production in Southeast Asia is significantly affected by root-parasitic nematodes (RPN). The Green Revolution has encouraged new agricultural practices (e.g. intensive monoculture, high yielding rice variety) to respond to the high rice demand; however, these methods have promoted the spread of these pests. The recent banning of chemical nematicides resulted in a need for alternative sustainable control strategies. In the present study, we assessed the effects of a direct-seeding mulch-based cropping system (DMC) vs conventional plough-based tillages (CT) on soil properties, rice yield and RPN communities during a two-year trial in Cambodia. Our results show that on average the population densities of RPN were significantly higher in DMC than in CT. Molecular identification revealed only two RPN species associated with roots: Meloidogyne graminicola, not previously reported from Cambodia, was predominant and was present throughout the plant's development, whereas Hirschmanniella mucronata was only found at the tillering and milky stages. We conclude that DMC had a significant positive impact on rice yield, despite higher RPN short-term pressure. In order to increase the efficiency of such cropping systems, further studies and an evaluation of the long-term relationships between DMC, the nature of cover crops used, the soil biota including RPN, and rice yield should be conducted. [ABSTRACT FROM AUTHOR]

Upland farming in Northwest Cambodia has developed rapidly over the last 20 years, with limitations to the plough based system now apparent, including soil degradation and reductions in yield and profitability. A survey was conducted in order to prioritise the main constraints to production, to aid in future research planning, and to identify potential beneficial modifications to the current system. Three hundred and ninety one farmers were interviewed regarding their current farming system constraints, knowledge of conservation agriculture and their future plans in the Districts of Samlout in Battambang Province and Sala Krau in Pailin Province. Perceived major problems in the farming system were extreme climate events such as droughts and heavy rain, declining crop yields, and cash flow shortages, particularly in the pre-monsoon period. This is a plough based farming system, yet 66% of farmers had heard of conservation agriculture, and 59% wanted to learn more about conservation agriculture practices. Two thirds of farmers were interested in how to grow crops in the post-monsoon dry season on residual soil moisture. The survey highlighted opportunities for farmer education and adoption of farming system modifications to improve productivity and sustainability of the farming system in Northwest Cambodia, and assist with climate change adaptation. [ABSTRACT FROM AUTHOR]