Effects of Biochar and Wood Vinegar on Labile Phosphorus Pool in Soda Saline-Alkaline Soil

A pot experiment was conducted to research the effect of biochar and wood vinegar on labile phosphorus fractions in saline-alkali soil. There were eight treatments, including CK(0 kg·hm^-2 biochar + 0 kg·hm^-2 wood vinegar), C1(0.6 t·hm^-2 biochar), C2(0.6 t·hm^-2 wood vinegar), C3(1.2 t·hm^-2 wood vinegar), C4(1.8 t·hm^-2 wood vinegar), C5(0.6 t·hm^-2 biochar + 0.6 t·hm^-2 wood vinegar), C6(0.6 t·hm^-2 biochar + 1.2 t·hm^-2 wood vinegar), and C7(0.6 t·hm^-2 biochar + 1.8 t·hm^-2 wood vinegar). The results showed that biochar without wood vinegar and the co-application of biochar and wood vinegar significantly increased soil total phosphorus content. Meanwhile, compared with CK, all of treatments increased resin phosphorus and sodium bicarbonate-extracted inorganic phosphorus（NaHCO₃-Pi） contents in saline-alkali soil. Especially, the contents of resin phosphorus and NaHCO₃-Pi under C5, C6, and C7 treatments were higher than those of C2, C3, and C4 treatments, respectively, indicating that the increases of labile phosphorus contents under the co-application of biochar and wood vinegar were better than those of the alone application of biochar and wood vinegar. Each treatment increased the proportion of labile phosphorus pool in saline-alkali soil and the proportion of labile phosphorus pool increased with the increase of the amount of wood vinegar. In addition, the application of biochar and wood vinegar increased the 100-grain weight of rice, and C6 treatment had the best effect, increasing the 100-grain weight by 134.35%. Therefore, the application of biochar and wood vinegar in saline-alkali soil could improve the soil phosphorus availability, increase the weight of rice grains, thereby realizing the resource utilization of agricultural waste and the sustainable development of agriculture.