From the study Effects of Different Ammonium and Nitrate Ratios on Lettuce Growth and Accumulation of Plant Nitrogen,Phosphorus and Potassium, in China vegetables, from LEI Yu-ling，CHEN Zi-yan，SONG Shi-wei*，CHEN Ri-yuan，LIU Hou-cheng，SUN Guang-wen.
Under hydroponic condition, it is studied the effect of different rates of ammonium : nitrate in the nitrogen application on lettuce (Lactuca sativa L.) growth and N, P, K accumulation:
ammonium: nitrate
CK 0:100
T1 10:90
T2 25:75
T3 50:50
The results showed that compared with the CK, T1 significantly promoted the lettuce growth, increasing the fresh weight and economic yield, while the fresh weight of aerial part and economic yield in T2 and T3 treatments were significantly reduced. The N, P, K accumulation in lettuce plant were behaved as T1>CK>T2>T3 under different ammonium and nitrate ratio treatment.