In this pot experiment, poultry manure dried by Fan separator was applied at different rates N to see the effect of poultry manure on the growth and total N uptake of corn and rice. Contributions of poultry manure to A-values (available N) of soils, %NdfF (N-fertilizer). %NdfPM (poultry manure), nitrogen recovery percent of poultry manure and the quantity of poultry manure equivalent to 1 kg (NH4)2SO4 were determined by 15N trace technique. The results are summarized as follows: 1. Increasing rates N of poultry manure significantly increased the amount of corn straw, rice grain+straw and total N uptake of corn and rice plants. 2. The contribution of poultry manure to A-value (available N) of soils was significant. Increasing rates of poultry manure increased the A-values from 66.19 to 186.70 mg N/kg soil in soil where corn was grown, and from 208.59 to 382.14 mg N/kg soil in soil where rice was grown. 3. Increasing rates N of poultry manure decreased the percentage of nitrogen derived from (NH4)2SO4 labelled with 15N (%NdfF) in total N uptake of corn and rice, whereas the percent nitrogen derived from poultry manure (%NdfPM) increased from 14.24% to 47.87% in corn and from 9.19% to 33.54% in rice. 4. Maximum nitrogen recovery percentage obtained from poultry manure was about 4.61 for corn and 4.13 for rice. 5. It was found that, 1 kg N as (NH4)2SO4 was equivalent to 7.74 kg N as poultry manure in soil where corn was grown, and to 9.65 kg N as poultry manure in soil where rice was grown. Those results show that 1 kg (NH4)2SO4 is equivalent to 50 kg poultry manure dried by Fan separator containing 3.13 % N for corn plant, and to 62 kg poultry manure for rice plant.