Transitional upland rice cropping systems in Northern Thailand: priorities for research and development, on the basis of on-farm crop diagnosis.

Abstract

Abstract This chapter revisits the methodology and key findings of a comprehensive empirical on-farm diagnostic survey that was conducted in a remote Red Lahu highland village in Fang district, Chiang Mai province, in the western part of upper northern Thailand. The survey covered four successive cropping years (1993-96) and an extensive range of upland-rice farming situations. The objectives of this diagnostic survey were fourfold: (1) to characterize the crop population, crop environmental conditions and farmers' practices along the upland-rice crop cycle and across several climatic years; (2) to develop and test a boundary-line approach for on-farm upland-rice yield-gap analysis; (3) to identify and rank the key periods of yield differentiation, or limitation, in upland rice under actual farmers' conditions and management practices; and (4) to identify, rank and explain the major on-farm yield-limiting factors affecting upland rice at the study site. The results show a revived global interest in yield-gap studies and in robust diagnostic methods to assess the magnitude of yield gaps and explain their causes in crops grown across a wide range of agro-ecological and market situations. Among such methods, boundary-line analysis of large yield datasets across sites, seasons and management practices is increasingly recognized as a powerful tool for on-farm yield-gap diagnosis. The broader adoption of on-farm diagnostic surveys by agronomic researchers and policy-makers is being encouraged in order to advance more productive and sustainable food-production systems, especially for smallholder farmers in less favourable agroecosystems.