In both mother and baby trials, cassava starch yield of treatment # 5 (medium rate) is highest in compared with control 2 as farmer practice with values are 6.99 and 6.8 tons per ha, respectively. The NRoI of treatment # 3 as "300 kg NPK Lam Thao 12:5:10" is highest at value of 7.47, means that for every 100,000 VND invested in fertilizer, the farmer will receive 747,000 VND in increased yield (profit). The treatment # 2, a farmer practice (control 2) as "300 kg per ha of NPK Lam Thao 5:10:3" have highest NRoI of 5.41 and 5.34, indicating the reason why local farmers there used to apply that fertilizer rate. Balanced application with medium rate as "300 kg NPK (5:10:5) + 147 kg Urea+ 158 kg KCL" gained highest root yield, and application of "300 kg NPK Lam Thao 12:5:10" could gain highest NRoI, are considered as CSA technologies on soil fertility management for cassava production. Therefore, we would like to recommend the farmers applying this NPK compost forcassava production.