NOVELTY - Liquid fertilizer comprises (in %): inorganic nutrient (6-10), organic nutrient (10-15), and additive containing microorganism and amino acid.    USE - The liquid fertilizer is useful for cultivating poplar.    ADVANTAGE - The fertilizer is environmentally-friendly. The microbes present in fertilizer generates various organic acids, and hence insoluble phosphates and potassium formate in alkaline land soil can be decomposed effectively so as to supply nutrients to plants roots, and reduces usage amount of inorganic phosphorus and potassium.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for method for preparing the above-cited fertilizer, which involves (a) dissolving potassium hydroxide in protein solution, adding cane sugar to the dissolved product, and mixing the mixture uniformly at 15-40 degrees C, (b) adding microorganism to the mixture, stirring and pulping the mixture in the fermenting tank, and fermenting the mixture, where the ratio of cane sugar, microorganism and water is 1:1:18, (c) mixing fish remnants, microorganism and cane sugar in the ratio of 18:1:1, and fermenting the mixture to prepare fish essence protein fermenting solution, (d) adding the fermenting solution to the fermenting tank, and stirring the mixture uniformly once every two days to obtain organic fertilizer, (e) mixing (in kg) urea (0.3-0.6), diammonium phosphate (0.2-0.6) and nitrate of potash (0.05-0.01) in measuring cup, stirring the mixture using glass rod, adding distilled water to the mixture, dissolving the mixture, and pouring the mixture into a 10 kg rubber barrel, extracting 100 ml of ammonium phosphate (AP) solution using glass sucking tube and rubber pump, adding humic acid solution (1 kg) into the rubber barrel, adding distilled water until the rubber barrel reaches 10 kg, where the content of urea is 3-6%, diammonium phosphate is 2-4% and nitrate of potash is 0.5-1%, covering the rubber barrel, and dissolving all the materials to form inorganic fertilizer, and (f) mixing the prepared organic and inorganic fertilizer in the ratio of 7-8:2-3.