南方长期不同土地利用方式下土壤肥力变化特征——以湖北省长阳县火烧坪乡为例

【目的】南方草山草坡分布区气候湿润、温度适宜、适合牧草生长，具有很高的生产和生态价值。土地利用方式的改变会造成土壤肥力的差异，因此探究南方草山草坡不同土地利用方式下的土壤养分特征，对南方草山草坡合理开发利用具有深远意义。【方法】湖北省长阳县的天然草山草坡、人工草地、农田在中国南方的分布具有代表性。本研究在该县的火烧坪地区采集3种土地利用类型0—10、10—20和20—30 cm土层深度样品，测定其土壤物理和化学性质。采用单因素方差分析和多重比较方法，探究了土地利用方式及其不同土层之间养分的差异，并利用主成分分析评价了各土地利用类型的土壤质量水平。【结果】1)草山草坡3个土层的土壤有机碳(SOC)、全氮(TN)含量显著高于人工草地和农田(P<0.05)，而土壤全钾(TK)、碱解氮(AN)含量则显著低于农田和人工草地，pH没有显著区别。天然草山草坡土壤养分含量随土层的加深而降低，人工草地和农田的养分含量在0—30 cm土层无显著变化。2)天然草山草坡土壤过氧化氢酶(CAT)活性高于农田和人工草地，且CAT活性随土层深度的增加逐渐递减。农田脲酶(URE)活性高于人工草地和天然草山草坡，...

Characteristics of soil fertility under different long-term land-use patterns in south China: A case study in Huoshaoping Township,Changyang County,Hubei Province

  【Objective】  The southern grassy hills and slopes have a humid climate and suitable temperature for high forage production with ecological value. Therefore, it is important to investigate the soil nutrient characteristics of the southern grassy hills and slopes under different land use for sustainable development and utilization.  【Methods】  Changyang County, Hubei Province, has the most representative natural grassy hills and slopes (WL), artificial pastures (GL), and cropland (CL) in southern China. We collected soil samples (0?10, 10?20 and 20?30 cm layer) from the three land use patterns in Huoshaoping Town as a pilot area and measured the physicochemical properties. Further, each land use type’s soil quality level was evaluated using principal component analysis, one-way ANOVA and multiple comparison methods.  【Results】  1) The organic C and total N in the three soil layers of WL were (P<0.05) higher than GL and CL. The total K, available N, were (P<0.05) lower than CL and GL. However, pH did not differ across the treatments. The nutrient content in WL decreased with the increasing soil depth. In contrast, the nutrient in GL and CL did not change within 0?30 cm layer. 2) WL had higher peroxidase activity than CL and GL, which decreased with soil depth. CL had higher urease activity than WL and GL, and urease activity did not vary across 0?30 cm soil depth. Protease activity was less affected by land use patterns and soil depths. The converting enzyme showed the highest activity among the four enzymes, decreasing with soil depth in WL and GL. 3) CL had higher N-fixing bacteria than WL and GL. However, the number of denitrifying and cellulolytic bacteria in the 10?20 cm soil layer was higher than in WL and GL. N-fixing, nitrifying, and cellulolytic bacteria did not differ (P>0.05) across soil layers in the three land types. 4) From the principal component analysis, soil nutrients, microorganisms, and enzyme activities contributed 39.8%, 30.8%, and 10% to the total soil quality score. The total soil quality score follows the order of natural grassy hill and slope (WL)>artificial grassland (GL)>farmland (CL).   【Conclusions】  Following the transformation of the natural grassy hill slopes into artificial grassland and farmland in southern China, soil total carbon, organic carbon, and total nitrogen declined. In contrast, the total and available phosphorus and potassium in the natural grassy hill slopes were lower than in artificial grassland and farmland due to the absence of chemical fertilizers. The organic matter and total nitrogen decreased with soil depth in natural grassy hills and slopes, with no change in 0?30 cm depth in artificial grassland and farmlands. The topsoil of the natural grassy hills and slopes had higher enzyme activities, while artificial grassland and farmlands had a higher microbial population. Total soil fertility comprised 39.8% nutrient content, 30.8% microbial population, and 10% enzyme activities. The fertility order was natural grassy hill and slope>artificial grassland>farmland.