Bio-resource flow in integrated agriculture–aquaculture systems in a tropical monsoonal climate: a case study in Northeast Thailand

The degree of integration and intensification in integrated agriculture–aquaculture systems (IAAS) varies with the variation in the pattern of bio-resource flow among various enterprises. Bio-resource flow in IAAS in Northeast Thailand was studied across four different agroecologies, one irrigated and three rainfed (drought-prone, rainfed lowland and rolling land). Only the irrigated and one rainfed (drought-prone) agroecology had easy market accessibility. Patterns of bio-resource flow clearly varied between IAAS as most enterprises in the irrigated agroecology functioned independently with a low degree of integration based on bio-resource flow among the enterprises compared with a high degree of integration among enterprises in the rainfed agroecologies. However, market accessibility played a crucial role in intensification of IAAS regardless of agroecology. Households with integrated systems in irrigated and drought-prone agroecologies applied adequate chemical fertilisers to fruit and vegetables to realize high gross incomes from these enterprises. In contrast, households in rainfed lowland and rolling land agroecologies operated subsistence IAAS as they relied more on organic manure from on- or off-farm sources with corresponding low gross income. Fish culture in farm ponds was a low-input system in all agroecologies but resource-use efficiency based on assessment of total N in pond inputs and N removed in fish harvest appeared to be relatively high. A combination of resource base and market accessibility can be envisaged to play the key role in the development of viable IAAS in Northeast Thailand.