Abstract
Rice production has been monitored at 8005 plots of rain-fed paddy field in a village in Northeast Thailand for the period from 1978 to 2002. Rice crop was evaluated and classified into 4 classes, i.e. “good”, “poor”, “crop failure” and “no planting”. Distribution mapping of crop performances showed a large variability among plots, and also extreme changes among years mainly due to flood and drought. All paddy fields were classified into 8 types by cluster analysis. Lower and unstable production was observed in upper paddy fields. Areas with poor yield and no planting paddy fields have decreased in recent years owing to expanding supplementary irrigation and the direct seeding method. Supplementary irrigation is carried out by purchasing water from canals or sucking up river water using engine driving pumps at planting time or severe drought. This indicates that a gradual improvement in rice production is possible with rain-fed rice cultivation. However, large crop failure still occurs frequently especially in areas nearer to rivers.
