Spatial distribution of nutrient resource of main crop straws and its potential to replace chemical fertilizer in Hebei Province

This study aimed to quantify the nutrient resources in primary grain crop straws and assess their potential for fertilizer substitution in Hebei Province, China, which is important for promoting the efficient utilization of straw resources and reducing chemical fertilizer usage in the region. Based on data from the Hebei Rural Statistical Yearbook and the literatures, the annual production, nutrient resources, nutrient release amounts during the season, and potential for substituting chemical fertilizers of corn, wheat, rice, and soybean straws in each city of Hebei Province were estimated. The results showed that the average annual production of crop straws in Hebei Province from 2016 to 2020 was 54.90 million tons, with a distribution pattern of high in the central and southern regions, and low in the northeast region. The average annual productions of corn, wheat, rice, and soybean straws were 34.41, 19.66, 0.51, and 0.33 million tons, respectively, with corn and wheat straw accounting for 62.67% and 35.81% of the total straw resources in the province. The nutrient resources of potassium (K₂O), nitrogen (N), and phosphorus (P₂O₅) provided by major crop straws in Hebei Province were 757.3, 454.9, and 157.2 thousand tons, respectively, indicating a considerable quantity of nutrient resources in crop straws. The nutrient resources that could be provided by straws when returned to the soil during the season were 676.2, 253.8, and 111.0 thousand tons for K₂O, N, and P₂O₅, respectively, which were equivalent to 104.38%, 15.54%, and 14.52% of the chemical fertilizer application amount. The potential for straw to substitute chemical fertilizers showed a distribution trend of east > south > central > north. Therefore, when the total straw is returned to fields, the nutrients brought to soils could replace all the K₂O and some of the N and P₂O₅ in chemical fertilizers. Regional differences should be completely considered in the comprehensive management of straw resources to achieve efficient utilization of straw resources and reduce chemical fertilizer usage in Hebei Province.