洱海流域高肥力土壤的碳磷比特征及调控途径

Characteristics of C∶P Ratio in High Fertility Soil in Erhai Lake Basin and Its Regulation Approach

为提高高肥力土壤磷素安全可持续利用,探究高肥力土壤碳磷比特征。选取洱海流域3种典型作物类型(粮食作物—玉米、地方特色高值经济作物—烤烟和高值高投入作物—蔬菜)作为研究对象,采集27个样点土壤,测定土壤碳磷含量并计算碳磷比。结果表明:(1)土壤有机碳(SOC)含量为31.91 g/kg,种植不同作物类型土壤SOC含量无显著差异;(2)土壤有效态无机磷(NaHCO_(3)提取态无机磷,简称NaHCO_(3)-Pi)含量为156.7 mg/kg,有效态有机磷(NaHCO_(3)提取态有机磷,简称NaHCO_(3)-Po)含量为63.43 mg/kg,种植不同作物类型的土壤有效态无机磷/有机磷含量(NaHCO_(3)-Pi/NaHCO_(3)-Po)无显著差异,均表现为蔬菜地>烤烟地>玉米地;(3)洱海流域农田土壤C/NaHCO_(3)-Pi比为321.42,C/NaHCO_(3)-Po比为1138.25,土壤C/NaHCO_(3)-Pi比显著低于全国和西南地区,种植不同作物类型土壤中,蔬菜地碳磷比(C/NaHCO_(3)-Pi)显著低于玉米地。综上所述,洱海流域土壤碳磷含量较高,尤其磷含量高,造成土壤碳磷比显著降低,投入高的蔬菜地碳磷比显著低于玉米地,影响土壤微生物对磷的转化,同时也带来磷污染问题。因此,可通过调控碳磷比实现高肥力土壤中磷素的安全可持续利用,添加高碳磷比物料以提高土壤碳磷比,增加微生物对土壤磷的固持,将土壤磷储存在微生物磷库中,减少土壤磷素向水体的流失。

In order to improve the safe and sustainable utilization of phosphorus in high-fertility soil,and explore the C∶P ratio of high-fertility soil.Soil of three typical crop types(grain crop-maize,local characteristic high value economic crop-tobacco and vegetables with high value and high nutrient input)from 27 sample sites in Erhai Lake Basin were selected to analyze the characteristics of soil carbon and phosphorus content and C∶P ratio.The results showed that:(1)The soil organic carbon(SOC)content was 31.91 g/kg,and there were no significant difference in SOC content among the different crop types.(2)The contents of available inorganic phosphorus(NaHCO_(3) extracted inorganic phosphorus,NaHCO_(3)-Pi)and available organic phosphorus(NaHCO_(3) extracted organic phosphorus,NaHCO_(3)-Po)were 156.7 mg/kg and 63.43 mg/kg,respectively.There were no significant difference in the contents of available inorganic and organic phosphorus(NaHCO_(3)-Pi/NaHCO_(3)-Po)among the different crop types,and the results were as follows:vegetable field>tobacco field>maiza field.(3)The C∶NaHCO_(3)-Pi ratio and C∶NaHCO_(3)-Po ratio of farmland soil in Erhai Lake Basin were 321.42 and 1138.25,respectively.The C∶NaHCO_(3)-Pi ratio of farmland soil in Erhai Lake Basin was significantly lower than the China and the southwest China.The C∶NaHCO_(3)-Pi ratio of vegetable field was significantly lower than that of maize field.Our results showed that the soil carbon and phosphorus content in Erhai Lake Basin was high,especially the high phosphorus content,leading to a significant decrease in soil C∶P ratio.The C∶P ratio of high input vegetable land was significantly lower than that of maize field,which not only impacted the transformation of phosphorus by soil microorganisms,but also brought about phosphorus pollution.Therefore,the safe and sustainable utilization of phosphorus in high fertility soil can be achieved by regulating the C∶P ratio.Adding materials with high C∶P ratio,such as crop straw,can increase the soil C∶P ratio,increase the immobilization of soil phosphorus by microbes,and store soil phosphorus in microbial phosphorus pool,which can reduce the loss of soil phosphorus to water.