ABSTRACT

Soil carbon and microbial biomass were substantially depleted following long-term incubation for saline-sodic and calcareous soils. The objectives of the present study were to investigate changes in (i) soil CO₂-emissions and (ii) soil fertility and SOM decomposition (iii) soil enzymes activities during the incubation period under various organic and biological soil treatments. Both soils were incubated for 150 days with 9 treatments included 2 levels of spent grain, which referred to as 10 g kg⁻¹ soil (S1), and 20 g kg⁻¹ soil (S2); two levels of compost were referred to as 10 g kg⁻¹ soil (M1), and 20 gkg⁻¹(M2); Azospirillum brasilense (A1) was inoculated 5% of weight of the soil; the mix of both sources M1 and S1 (M1S1); the combination of both sources A1 with M1 and S1 (A1M1) and (A1S1); all treatments were used and compared to the control. All treatments were mixed with 400 g soil samples and incubated at 28°C. Results showed that the average cumulative CO₂ emission for both soils regarding to S2 and A1 treatments had the highest values, 548.3 and 364 (mg C100g⁻¹ soil), respectively. While the lowest value was observed for the control treatment 89.12 and 40.13 (mg C100g⁻¹ soil) for calcareous and saline soils, respectively. The dehydrogenase and urease enzymes were often decreased slightly and did not respond to adding labile substrate, and did not restrict soil breathing. The S2 treatment possessed the dehydrogenase and urease enzymes highest values in calcareous soil, 720 (μgTPFml⁻¹) and 309 (mgNH₃⁻Hg⁻¹h⁻¹), respectively, after incubation periods. In conclusion, the findings support the idea that the soil organic matter amendments increased soil respiration over long-term incubation and compensate the absence of microbial biomass and enzymes in calcareous more than saline soils and enhance soil-plant nitration.

摘要

对盐碱土和钙质土壤进行长期培养后，土壤碳和微生物生物量大大减少。本研究的目的是调查（i）土壤 CO ₂排放和（ii）土壤肥力和 SOM 分解（iii）在各种有机和生物土壤处理下的孵化期间土壤酶活性的变化。两种土壤均培养 150 天，9 个处理包括 2 个水平的糟粕，称为 10 g kg ^-1土壤（S1）和 20 g kg ^-1土壤（S2）；两层堆肥分别称为 10 g kg ^-1土壤 (M1) 和 20 gkg ^-1 (M2)；巴西固氮螺菌(A1)接种5%重量的土壤；混合源 M1 和 S1 (M1S1)；两个源 A1 与 M1 和 S1 (A1M1) 和 (A1S1) 的组合；使用所有处理并与对照进行比较。所有处理均与 400 g 土壤样品混合并在 28°C 下孵育。结果表明，S2 和A1 处理的两种土壤的平均累积CO _{2排放量最高，分别为548.3 和364 (mg C100g} ^-1土壤)。而对照处理观察到最低值 89.12 和 40.13 (mg C100g ^-1土壤）分别用于钙质和盐渍土。脱氢酶和脲酶通常略有下降，对添加不稳定底物没有反应，也没有限制土壤呼吸。在培养期后，S2 处理在钙质土壤中的脱氢酶和脲酶的最高值分别为 720 (μgTPFml ^-1 ) 和 309 (mgNH ₃ ^- Hg ^-1 h ^-1 )。总之，研究结果支持这样的观点，即土壤有机质改良剂在长期培养过程中增加了土壤呼吸，并且比盐渍土壤更能补偿钙质土壤中微生物生物量和酶的缺乏，并增强土壤-植物的硝化作用。