施肥和豆禾混播对松嫩平原退化草地修复的影响

Effects of fertilization and mixed sowing on restoration of degraded grassland in Songnen Plain

摘要:

【目的】探索适合松嫩平原中度退化草地的最佳修复模式，为松嫩平原退化草地的保护修复提供技术支持。【方法】设置紫花苜蓿（Medicago sativa）与羊草（Leymus chinensis）2 种混播比例，结合不同 N 施用量，分析土壤养分含量、牧草品质和产量之间的关系。【结果】施肥水平显著影响群落物种丰富度（P＜0. 01），施肥水平、混播比例及二者交互显著影响土壤有机质、Shannon‐Wiener 多样性指数、牧草粗蛋白含量及产量（P＜0. 05）。土壤全氮、牧草粗蛋白含量与施氮量存在极显著正相关性（P＜ 0. 01）。两种混播比例下，土壤全氮含量变化与 N 施用量一致；N 施用量 300 kg/hm² 的牧草粗蛋白含量高达 20. 22%，与其他处理差异显著（P＜0. 05）。【结论】 N 施用量 200~250 kg/hm² 在试验当年秋季和第二年春季均获得最佳产量；豆禾 1∶2 混播的群落丰富度和多样性优于 2∶2 混播，其中 N 施用量 150 kg/hm² 表现最佳。

Abstract:

【Objective】To explore the best restoration mode suitable for moderately degraded grassland and provide technical support for the protection and restoration of degraded grassland in Songnen Plain.【Method】 The study examined two types of mixed sowing，involving Medicago sativa and Leymus chinensis（legume∶grass interrow patterns of 2∶2（B1）nand 1∶2（B2）），along with seven levels of nitrogen fertilization of 0，50，100，150，200，250，300 kg/ hm² . The aim was to identify the optimal restoration model for moderately degraded grassland in Songnen Plain by analyzing soil nutrient content，forage quality and yield.【Result】 Fertilizer levels significantly affected community species richness （P＜0. 01）. Additionally，fertilizer levels，mixed sowing proportions，and their interaction significantly affected soil organic matter，Shannon‐Wiener diversity index，crude protein content and forage yield （P＜ 0. 05）. Significant positive correlations were observed between soil total nitrogen，forage crude protein content and nitrogen application （P＜0. 01）. The variation in soil total nitrogen corresponded to the nitrogen application rate under both mixed sowing proportions. Forage crude protein content with 300 kg/hm² N reached 20. 22%，significantly higher than other treatments （P＜0. 05）.【Conclusion】 Nitrogen application rate of 200~250 kg/hm² yielded the best results in the autumn of 2021 and the spring of 2022. The Margalef richness index and Shannon‐Wiener diversity index of legumegrass in the 1∶2 configuration were higher than those in the 2∶2 configuration，with 150 kg/hm² N identified as optimal.