Effects of organic phosphorus replacing chemical fertilizer phosphorus on wheat growth and soil nutrients at seedling stage

【Objective】The purpose of the study was to study the effects of different proportions of tung oil cake organic fertilizer phosphorus replacing chemical fertilizer phosphorus on wheat growth and soil nutrients at seedling stage， and to provide reference for the rational application of tung oil cake organic fertilizer in wheat cultivation.【Method】Using wheat variety Qianmai 22 as the experimental material，six treatments were set up，including conventional chemical fertilizer phosphorus treatment（T1）and five organic fertilizer phosphorus replacing chemical fertilizer phosphorus treatments（organic fertilizer phosphorus replacing amounts were 10%，20%，30%，50%，and 100% respectively，represented as T2， T3， T4， T5，and T6 in order）. The effects of different fertilization treatments on soil nutrient content，soil enzyme activity，root morphology，and nutrient absorption of wheat during seedling stage were analyzed.【Result】The appropriate proportion of tung oil cake organic fertilizer phosphorus replacing chemical fertilizer phosphorus treatments could significantly increase the nutrient content and soil enzyme activity in the rhizosphere soil of wheat（P＜0.05，the same below）. Among them，T2 treatment had the highest content of hydrolyzed nitrogen and rapidly available potassium in the rhizosphere soil，as well as the highest activity of neutral phosphatase，urease，and sucrase in the soil，with increases of 34.51%，30.60%，115.94%，60.98%，and 92.68% compared to T1 treatment respectively. The appropriate proportion of tung oil cake organic fertilizer phosphorus replacing chemical fertilizer phosphorus treatments could also significantly increase the dry weight of wheat stems， leaves and roots， root morphology indicators， and the absorption and accumulation of nitrogen，phosphorus，and potassium nutrients by wheat. Among them，T2 treatment had the highest indicators，with wheat stem and leaf dry weight，root dry weight，root to shoot ratio，total root length，root surface area，and root volume increasing by 18.11%，102.56%，71.50%，109.76%，59.02%，and 105.26% respectively compared to T1 treatment. The contents of wheat plant nitrogen，phosphorus and potassium increased by 70.92%，98.04%，and 79.19% compared to T1 treatment respectively. The correlation analysis results showed that the total root length， root surface area， and root volume of wheat roots were extremely significantly positively correlated with the accumulation and absorption of nitrogen，phosphorus，and potassium by wheat（P＜0.01）. 【Conclusion】The appropriate proportion of tung oil cake organic fertilizer phosphorus replacing chemical fertilizer phosphorus can improve soil nutrient status，increase soil enzyme activity，and promote wheat root growth and nutrient absorption and utilization during the seedling stage. Overall，tung oil cake organic fertilizer phosphorus replacing 10% chemical fertilizer phosphorus is more conducive to meeting the needs of wheat seedling growth and maintaining soil fertility in the wheat area.