Wu Jiangqi, Wang Haiyan, Li Guang, Hou Fujiang, Xu Guorong
State Key Laboratory of Aridland Crop Science Gansu Agricultural University Lanzhou China.
College of Forestry Gansu Agricultural University Lanzhou China.
Ecol Evol. 2024 Oct 30;14(10):e70501. doi: 10.1002/ece3.70501. eCollection 2024 Oct.
Global climate change and agricultural practices have increased atmospheric nitrogen (N) deposition, significantly affecting the nitrogen cycling process in grasslands. The impact of different N forms on key soil enzyme activities involved in N nitrification, particularly in the saline-alkali grasslands of the Hexi Corridor, using natural grassland as a control (CK) and adding three N treatments: inorganic N (IN), organic N (ON) and a mixed N treatment (MN, with a 4:6 ratio of organic to inorganic N). Our study assessed the effects of these N forms on soil properties and enzyme activities crucial for N cycling. The findings indicate that different N forms significantly enhance soil mineral N content, with ON treatment leading to the highest increases in nitrate and ammonium content 92.44% and 35.6%, respectively, compared to CK. Both IN and ON treatments significantly boosted soil nitrate reductase and urease activities ( < 0.05), while MN treatment decreased nitrate reductase activity, with ON treatment showing the greatest sensitivity to enzyme activity changes. Soil pH slightly increased with N addition, but soil nitrite reductase activity remained relatively unchanged (0.372-0.385 mg g). Correlation analysis revealed that soil mineral N content and pH are key regulators of enzyme activities in saline-alkaline grasslands. These results suggest that different N forms should be considered in nutrient cycling models, with organic N addition potentially enhancing soil N conversion and mitigating nutrient limitations in grassland ecosystems.
全球气候变化和农业活动增加了大气氮（N）沉降，对草原氮循环过程产生了显著影响。以天然草原为对照（CK），添加无机氮（IN）、有机氮（ON）和混合氮处理（MN，有机氮与无机氮比例为4:6）三种氮处理方式，研究不同氮形态对河西走廊盐碱化草原氮硝化过程中关键土壤酶活性的影响。本研究评估了这些氮形态对氮循环至关重要的土壤性质和酶活性的影响。研究结果表明，不同氮形态显著提高了土壤矿质氮含量，与CK相比，ON处理使硝酸盐和铵含量分别最高增加了92.44%和35.6%。IN和ON处理均显著提高了土壤硝酸盐还原酶和脲酶活性（P<0.05），而MN处理降低了硝酸盐还原酶活性，其中ON处理对酶活性变化最为敏感。施氮后土壤pH略有升高，但土壤亚硝酸还原酶活性相对保持不变（0.372 - 0.385 mg g）。相关性分析表明，土壤矿质氮含量和pH是盐碱化草原酶活性的关键调节因子。这些结果表明，在养分循环模型中应考虑不同的氮形态，添加有机氮可能会增强土壤氮转化并缓解草原生态系统中的养分限制。
