Wang Zhi-Kang, Xu Zi-Heng, Chen Zi-Yun, Fu Xiang-Xiang
Co-Innovation Center for the Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing 210037, China.
Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
Ying Yong Sheng Tai Xue Bao. 2020 Oct;31(10):3413-3423. doi: 10.13287/j.1001-9332.202010.023.
Understanding the dynamics of phosphate-solubilizing and N-fixing bacteria on soil nutrient and related enzyme activity under different organic fertilizer proportions (OFP) could provide references for screening appropriate inoculant type, OFP, and fertilization period. Here, we set four OFP levels (mass ratio: 0%, 4%, 8%, 12%) and inoculated two phosphate-solubilizing bacteria (, ) and two N-fixing bacteria (, ) in the subtropical yellow-brown barren soil. After a 60-day soil incubation under controlled conditions (28 ℃, darkness), we examined the impacts of single/mixed applications of beneficial bacteria on soil available nutrients and related enzyme activities at different OFP levels and different sampling times (3rd, 8th, 16th, 30th, 45th, 60th day). The results showed that soil available nutrient contents increased with the elevated OFP levels, and exhibited as 12%>8%>4%>0%. With the extension of culture time, soil nutrient contents in all treatments first increased and then decreased. Compared with the single application of organic fertilizer, combined application of organic fertilizer and bacterial inoculants resulted in higher and longer improvement of soil nutrient contents and enzyme activities. The effects of inoculants on soil nutrient properties varied across four OFP levels. When the OFP was low (0-4%), inoculation significantly increased soil available nutrient contents, with no the differences between inoculants at the initial stage. However, with the extension of the culture time and the elevation of OFP, phosphate-solubilizing bacteria (especially for ) significantly increased available phosphorus content while N-fixing bacteria (especially for ) significantly increased available nitrogen content. The mixed inoculant with four strains showed phosphate-solubilizing effect on soil and performed better than the single application of phosphate-solubilizing bacteria, but without prominent effect on nitrogen fixation. Soil nutrient contents were positively correlated with enzyme activity, which was affected by both cultural time and carbon-nitrogen ratio. Bacterial inoculations could significantly increase nutrient contents in the short term, but the specific functions of beneficial bacteria on soil were highly dependent on organic carbon input and carbon-nitrogen ratio. Coupled application of inoculants and organic fertilizer at an appropriate OFP level (8%-12%) could increase and extend the soil-remediating effects, while the inoculation should be conducted with an interval of 45-60 days to ensure the survival rate and the consecutive effect on soil.
了解不同有机肥比例（OFP）下解磷细菌和固氮细菌对土壤养分及相关酶活性的影响动态，可为筛选合适的接种剂类型、OFP和施肥时期提供参考。在此，我们在亚热带黄棕壤荒地设置了四个OFP水平（质量比：0%、4%、8%、12%），并接种了两种解磷细菌（，）和两种固氮细菌（，）。在控制条件（28℃，黑暗）下进行60天土壤培养后，我们研究了不同OFP水平和不同采样时间（第3天、第8天、第16天、第30天、第45天、第60天）下有益细菌单施/混施对土壤有效养分及相关酶活性的影响。结果表明，土壤有效养分含量随OFP水平升高而增加，表现为12%>8%>4%>0%。随着培养时间的延长，所有处理的土壤养分含量先增加后降低。与单施有机肥相比，有机肥与细菌接种剂混合施用能使土壤养分含量和酶活性提高得更高且持续时间更长。接种剂对土壤养分性质的影响在四个OFP水平上有所不同。当OFP较低（0 - 4%）时，接种显著增加土壤有效养分含量，初期接种剂之间无差异。然而，随着培养时间的延长和OFP的升高，解磷细菌（尤其是）显著增加有效磷含量，而固氮细菌（尤其是）显著增加有效氮含量。四种菌株的混合接种剂对土壤有解磷作用，且比单施解磷细菌表现更好，但对固氮作用不显著。土壤养分含量与酶活性呈正相关，酶活性受培养时间和碳氮比的影响。细菌接种在短期内可显著增加养分含量，但有益细菌对土壤的具体功能高度依赖于有机碳输入和碳氮比。在合适的OFP水平（8% - 12%）下，接种剂与有机肥配合施用可增强并延长土壤修复效果，同时接种间隔应为45 - 60天，以确保存活率和对土壤的持续作用。
