Field trials undertaken 2012 and 2013 highlighted the potential of direct seeding of rice in the rainfed lowland environment in Laos as a means of helping reduce the potential impact of climate variability (particularly drought) on rice yields, while at the same time reducing labour input requirements in an environment where labour (for transplanting rice crops) is becoming increasingly expensive. There is now a lot of farmer and government agency (at national, provincial and district levels) interest in the potential of the direct seeding technology as an alternative to transplanting of rice crops. One of the issues related to the farmer adoption of the direct seeding technology in the rainfed lowland rice environment is the optimisation of fertilizer use efficiency. This study undertook an assessment of grain yield and economic returns for different fertilizer application strategies in direct seeded rice crops in the rainfed lowland environment of Savannakhet province. The soils in much of the rainfed lowland rice area of Savannakhet province are relatively infertile sandy soils. Using the recommended fertilizer application for the rainfed lowland environment of a basal application of 200 kg/ha of N:P:K (15:15:15) and topdressing with 130 kg/ha of urea (46% N), comparisons were made of fertilizer use efficiency (in terms of yield response and net returns) when the basal fertilizer was applied at the time of direct seeding, relative to the application of fertilizer post-seedling emergence. The treatments compared were: T1- basal fertilizer application with direct seeding; T2 – basal fertilizer broadcast application 2 weeks after seedling emergence; T3 - basal fertilizer broadcast application 4 weeks after seeding emergence; and T4 - no basal fertilizer applied. Using an on-farm, farmer participatory approach for the study, six farmers in Champhone district in Savannakhet province participated in the study. The improved rice variety Thadokham 8 (TDK8) was used as the test variety in the study. The final grain yield and economic efficiency of the application of basal fertilizer at the time of direct seeding (T1) was much higher than for the other treatments. The average yield for T1 was 4,235 kg/ha, compared with 3,516 t/ha and 3,534 t/ha for T2 and T3, respectively, and only 2,168 kg/ha for the unfertilized control (T4). The average gross return from the direct seeded crops were 8,472.000 kip/ha (US$1,059/ha) for T1, 7,032,000 kip/ha (US$879/ha) for T2, 7,068,000 kip/ha (US$883/ha) for T3 and 4,336,000 kip/ha (US$542/ha) for T4. In terms of net return after debiting costs for land preparation, labour and fertilizer inputs, the average returns for the different treatments were: 1,861,000 kip/ha (US$233/ha) for treatment T1, 421,000 kip/ha (US$53/ha) for T2, 457,000 kip/ha (US$57/ha) for T3, and -2,165,000 kip/ha (US$ -284/ha) for T4. The results clearly demonstrated higher potential yields and net returns from fertilizer incorporation at the time of direct seeding.The rainfall in the study area in the year that the research was undertaken (2015) was close to the long-term average in terms of distribution and amount. The results of this research are regarded as being representative of what can be expected under average seasonal conditions in the wet-season in the rainfed lowland rice environment in Savannakhet province.

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