How the effect of humic acid application on nutrients absorption of lettuce?

Using six different concentration of humic acid were added in the  specially formula application, to test the influence of humic acid application on growth and nutrient absorption of lettuce in field. The yield and water consumption of lettuce were measured per ten days after treatments,so main mineral element content in hydroponic culture.The results showed that the fresh weight and dry weight of hydroponic lettuce increased with the humic acid concentration raising with 0~(-1).41mg·g~(-1).The 1.41mg·g~(-1)concentration humic acid,which was the concentration of the highest volume for each aforementioned index.Humic acid was cushion for the nutrient solution pH value.At the condition of 0~(-1).41mg·g~(-1) concentration humic acid,water use efficiency(WUE)and use efficiencies of mineral elements increased with the humic acid concentration rising.The effect of humic acid application on nutrient absorption of lettuce was not significant.The ability to absorb inorganic nutrients was different with different humic acid concentration treatments.Synthesize the yield and nutrient absorption factor,effect of high yield,water saving,fertilizer production would achieve when humic acid with 1.41mg·g~(-1) concentration.