From World Bank blogs

The Global Food Crisis: Will Investments in Agricultural Technology be enough?:
"During the early 1990s, Bangladesh experienced widespread diffusion of green revolution technology in rice, its main crop. As a result, rice production has more than doubled since the early 1970s. The spread of green revolution technology is usually expected to boost wages for farm workers. But we found regional differences in rural wages that run counter to the traditional argument.
The North-West region of Bangladesh (Rajshahi Division) has some of the highest agroecological endowments in the country (Figure 1). But, surprisingly, real agricultural wages were much lower in the Rajshahi Division (Figure 2). Similarly, the probability of employment in the high-wage, non-farm sector was also lower in the North-West (Figure 3). This is puzzling in light of the traditional argument that productivity growth in agriculture raises agricultural wages and also boosts non-farm employment through various production, consumption and labor market linkages. These linkages between the farm and non-farm sectors are assumed to create a virtuous cycle of growth and development in rural areas.
Our study found that access to large urban markets (as in Dhaka and Chittagong) is by far the most important determinant of high-return, non-farm activities: people are more likely to be employed in better paid wage employment and self employment in the non-farm sector if they are closer to urban centers. The impact of agricultural potential depends on how far the village is from the main urban centers: those who are further away from these centers are even less likely to be in well-paying non-farm jobs even if they are living in areas with greater agricultural potential. This suggests that poor connectivity to major urban markets greatly weakens farm-non-farm linkages. And lack of expansion of better paid non-farm jobs in turn slows down the movement of workers from agriculture to other activities, depressing agricultural wages and impeding long-term growth in agricultural productivity itself."
From Wade into the paddy field yield figures at your peril...:
"Most sources (FAO and USDA both pdf files) indicate an average rice yield of a little under 5 tons/hectare (or 5t/ha) in Vietnam in 2006/2007. My rice farmers claimed to be harvesting twice that amount per season: 1ton per "cong" or 10t/ha."
Apparently the discrepancy comes partly from difference of measuring straight paddy or milled rice, measuring in different seasons, location and size of plots used in the samples etc. There is also link to a nice slideshow 'describing the impact of a Bank-financed water resources management project in the Mekong Delta.'