The present invention relates to a quantitative NPK nutrient management system for ICT-based smart farms, which enables accurate determination of liquid manure application rates to target farmland by automatically calculating the amount of manure generated and the nutrients contained therein when the number of livestock by rearing stage is input, thereby accurately predicting the nutrient content contained in regionally generated livestock manure and automatically computing the fertilizer application rates in terms of NPK (nitrogen, phosphorus, and potassium) when the generated manure is recycled to farmland.

Specifically, the system comprises: a terminal configured to input livestock information via a web-based interface and request calculation of manure quantity and nutrient content, or to input crop type and request fertilizer recommendations; and a livestock manure recycling means which, when livestock information or crop type is input and a fertilizer recommendation is requested through the terminal, predicts manure production and calculates its nutrient content, recommends fertilizers suitable for the soil in which the crop is to be cultivated, and calculates and provides the appropriate liquid manure application rate, thereby implementing a quantitative NPK nutrient management system for ICT-based smart farms.