Effective nutrient resources and fertilizer substitution potential of root biomass of major crops in China

Crop roots are an important source of organic matter in agricultural soils. Assessing the potential of crop root biomass and nutrient resources can help optimize fertilizer and irrigation management strategies and provide scientific support for improving soil structure and quality. This paper combines data from the literature, establishes an indicator parameter system for crop root-to-straw ratio, and based on the 2022 national crop straw resource account data, measures the root biomass of China’s major crops in detail, and analyses the effective nutrient resources and fertilizer substitution potential of the root system in the current season. In 2022, the total root biomass of major crops nationwide was 152 million tons, accounting for 18.63% of the straw production. The root biomass of rice, wheat, and corn alone comprised 90.2% of the total. The total nutrient resource amount from the underground root systems of these crops was 3.22 million tons, with an effective nutrient resource amount of 2.32 million tons for the growing season. Specifically, the effective nutrient resource amounts per unit area for N, P2O5, and K2O were 4.71 kg/ha, 1.39 kg/ha, and 12.85 kg/ha, respectively. The effective nutrient resources of the main crop roots in the season accounted for 5.31% of the best chemical fertilizer application amount, which was equivalent to 2.62% of the N fertilizer application amount, 1.76% of the P2O5 fertilizer application amount and 13.09% of the K2O fertilizer application amount. Crop roots are rich in nutrient resources and the contribution of their roots to soil carbon sequestration is considerable.