Effects of fertigation strategy on nitrogen (N) uptake by cotton and N use efficiency (NUE) were invest igated through a pot experiment under greenhouse conditions.According to t iming of irrigation and fertilization,four fertigation treatments were designed,nitrogen applied 1) in the beginning of the irrigation cycle (N-W),2) at the end (W-N),3) in the middle (W-N-W),and 4) throughout the irrigation cycle (N-N) in a completely randomized layout,each with four replications.Cotton was grown in plastic containers,84 L in volume,filled with a clay loam soil and fertilized at a rate of N 6.44 g per pot as ¹⁵N-labeled urea Treatment N-W was significantly higher than Treatment N-N in total dry matter (DM) and N content,but did not differ much from Treatment W-N and Treatment W-N-W Plants in Treatments W-N and N-W were found to have a significantly higher content of nitrogen derived from fertilizer (NDFF) than those in Treatments W-N-W and N-N Fert igation strategy had a consistent effect on total NUE:Treatment N-W was the highest in total NUE,and followed by Treatments W-N and W-N-W,which were quite similar to each other,and Treatment N-N was the lowest After harvesting,the residue of fertilizer N in soil was highest in Treatment W-N,and the lowest in Treatment N-W,but did not vary much between Treatment N-N and Treatment W-N-W The difference between the four treatments in total ¹⁵N recovery was not statistically significant From the aspect of nitrate leaching losses from the root zone,Treatments N-N and W-N may lead to an increase in soil residual nitrates and hence a higher risk of nitrate leaching.In contrast,Treatment N-W tends to reduce potential leaching loss of nitrate from the root zone In this study,the fertigation strategy,Treatment N-W (nitrogen applied in the beginning of the irrigation cycle) increased DM accumulation,N uptake and NUE of cotton Therefore,NUE could be enhanced by optimizing fertilization strategies with drip irrigation.