Yang Kaixin, Li Shengyi, Sun Yanliang, Cartmill Andrew D, López Ignacio F, Ma Chunhui, Zhang Qianbing
College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China.
School of Agriculture and Environment, Massey University, Palmerston North, New Zealand.
Front Plant Sci. 2024 May 28;15:1380738. doi: 10.3389/fpls.2024.1380738. eCollection 2024.
Nitrogen (N) and phosphorus (P) fertilizers change the morphological structure and effectiveness of P in the soil, which in turn affects crop growth, yield, and quality. However, the effects and mechanism of combined N and P application on the content of P fractions and the transformation of effective forms in alfalfa ( L.) production is unclear. This experiment was conducted with four levels of N: 0 (N), 60 (N), 120 (N) and 180 kg·ha (N); and two levels of P (PO): 0 (P) and 100 kg·ha (P). The results indicated that, under the same N level, P application significantly increased soil total N, and total P, available P, and content of various forms of inorganic P when compared to no P application, while decreasing the content of various forms of organic P and pH value. In general, under P conditions, soil total N content tended to increase with increasing N application, while total P, available P content, pH, inorganic P content in all forms, and organic P content in all forms showed a decreasing trend. When compared to no N application, insoluble P (Fe-P, O-P, Ca-P) of the N application treatments was reduced 2.80 - 22.72, 2.96 - 20.42, and 5.54 - 20.11%, respectively. Under P conditions, soil total N and O-P tended to increase with increasing N application, while, pH, Ca-P, Al-P, Fe-P, Ca-P, and organic P content of each form tended to decrease. Total P, available P, and labile organic P (LOP) of N application reduced 0.34 - 8.58, 4.76 - 19.38, and 6.27 - 14.93%, respectively, when compared to no application. Nitrogen fertilization reduced the soil Ca-P ratio, while P fertilization reduced soil Fe-P, moderately resistant organic P (MROP), and highly resistant P (HROP) ratios, and combined N and P elevated the Ca-P to LOP ratio. The results of redundancy analysis showed that soil total N content, available P content, and pH were the key factors affecting the conversion of P fractions in the soil. Nitrogen and P reduced the proportion of soil insoluble P, promoted the activation of soil organic P, resulting in accumulation of slow-acting P in the soil, thereby improving the efficiency of soil P in alfalfa production.
氮（N）肥和磷（P）肥会改变土壤中磷的形态结构和有效性，进而影响作物的生长、产量和品质。然而，氮磷配施对苜蓿生产中磷素形态含量及有效态转化的影响和机制尚不清楚。本试验设置了4个氮水平：0（N₀）、60（N₆₀）、120（N₁₂₀）和180 kg·ha（N₁₈₀）；以及2个磷（P₂O₅）水平：0（P₀）和100 kg·ha（P₁₀₀）。结果表明，在相同氮水平下，与不施磷相比，施磷显著增加了土壤全氮、全磷、有效磷及各形态无机磷含量，同时降低了各形态有机磷含量和pH值。总体而言，在施磷条件下，土壤全氮含量随施氮量增加呈上升趋势，而全磷、有效磷含量、pH值、各形态无机磷含量和各形态有机磷含量均呈下降趋势。与不施氮相比，施氮处理的难溶性磷（Fe-P、O-P、Ca-P）分别降低了2.80 - 22.72%、2.96 - 20.42%和5.54 - 20.11%。在施磷条件下，土壤全氮和O-P随施氮量增加呈上升趋势，而pH值、Ca-P、Al-P、Fe-P、Ca-P及各形态有机磷含量呈下降趋势。与不施肥相比，施氮处理的全磷、有效磷和活性有机磷（LOP）分别降低了0.34 - 8.58%、4.76 - 19.38%和6.27 - 14.93%。施氮肥降低了土壤Ca-P比值，施磷肥降低了土壤Fe-P、中度抗性有机磷（MROP）和高度抗性磷（HROP）比值，氮磷配施提高了Ca-P与LOP的比值。冗余分析结果表明，土壤全氮含量、有效磷含量和pH值是影响土壤中磷素形态转化的关键因素。氮磷降低了土壤难溶性磷比例，促进了土壤有机磷的活化，使土壤中缓效磷积累，从而提高了苜蓿生产中土壤磷的有效性。
