Impact of Combined Application of Swine Manure Liquid and Phosphorus Fertilizers on Soil Phosphorus and Microbial Communities

The rapid increase in pig production has become a major contributor to environmental issues due to the mismanagement of organic waste. The sustainable and effective transformation of this waste into a fertilization resource has become an urgent topic for environmental protection, and new regulations have been imposed. The present study aimed to investigate the effects of different ratios of swine manure liquid (SML) and chemical fertilizers on soil phosphorus forms and microbial communities through field experiments cultivating spring wheat (cultivar “Jinqiang 10”) in Hebei, China. The results indicated that the application of SML in portions with traditional fertilizer can enhance soil pH and electrical conductivity (EC), as well as available phosphorus, particularly when the proportion of SML is high (SML ≥ 75%). Compared with CK, the available phosphorus content of group C3 increased by 22.3%. SML facilitated the transformation of stable phosphorus to unstable phosphorus, as well as the conversion of organic phosphorus to inorganic phosphorus. Additionally, SML increased the soil content of H 2 O-P, NaHCO 3 -Pi, and NaHCO 3 -Po, and promoted the conversion of NaOH-Po to NaHCO 3 -Po. Studies on bacterial diversity indicated that different fertilization treatments have no significant impact on the bacterial diversity in the 0–20 cm soil layer, whereas the dominant bacterial and fungal genera were positively correlated with the available phosphorus. The present study may facilitate the combined application of SML and chemical fertilizers for soil improvement and improve phosphorus availability.