نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 گروه علوم و مهندسی خاک، دانشکده علوم کشاورزی، دانشگاه گیلان، رشت، ایران
2 گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه گیلان، رشت، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Considering the increasing area of acidic soils in Guilan province and the need of finding resources that can amendment soil acidity in the long term, the effect of wood ash and calcium carbonate on the amendment of two acid soils was investigated in this study. As the soil biological characteristics are also important in the long-term amendment of soil, the biological indicators of soil were also evaluated after adding lime and wood ash.
Two acidic soil samples with initial pH of 5.2 (soil 1) and 4.3 (soil 2) were taken from Fuman region in the Guilan province. Based on the lime requirement calculated according to the pH of soils, cacium carbonate, and wood ash, 4.32, 7.94 g calcium carbonate, and 7.23 and 13.24 g wood ash were added to soil 1, and soil 2 respectively, and mixed completely to attain 650 g soil-conditioner mixture. Soils without conditioners were also considered as controls. Incubation of the mixtures was done for 6 months at optimal water condition of about 70% field capacity, and laboratory temperature. pH, EC, organic carbon (OC), microbial basal respiration (MBR), and soil microbial biomass carbon (MBC) were measured, and microbial carbon ratio (Cmic) was calculated at 0, 2, 4, 7, 14, 28, 42, 56, 86, 116, 146, and 176 days of incubation. A factorial-split experiment in a completely randomized design format with three replications were done. Combination of soil type in two levels, and conditioners in three levels (lime, wood ash and control) was regarded as main plot and sampling time in 12 levels was regarded as sub-plot. Data analysis was done by SAS software package and mean comparisons by Tukey's test (p < 0.05).
After 6 month of incubation, pH was significantly higher in lime treatment compared to the wood ash treatment (p < 0.05) in both soil 1, and 2 and reached 7 and 7.2, respectively. However, pH in wood ash treatment was also increased to 5.7, and 6.3 in soil 1, and soil 2, respectively. pH variation showed that during incubation period pH trend was increasing in wood ash treatment, while it was almost constant after 3 month of incubation. The effect of lime on EC was slightly more than that of wood ash. The average soil OC content in wood ash treatment was higher than that in lime treatment. In the control and lime treatments, the trend of OC changes was generally decreasing, while it was increasing in the wood ash treatment. In wood ash treatment soil OC was increased from 1.4 and 1.7 to 2.06 g 100g-1. The trend of MBR changes was almost the same in all treatments. During 6 months of incubation, the fluctuation of Cmic was the highest in the control treatment while it was the lowest in the wood ash treatment. The effect of conditioners on the soil chemical characteristics was also dependent on the soils. However, the pH changes were almost the same in both soils and reached 6.9 at the end of incubation period.
Compared to wood ash, lime increased pH in a shorter time period, but chemical properties such as organic carbon and electrical conductivity of the soil as well as biological properties were enhanced in wood ash treatment. Therefore, it can be said that in improving the pH of acidic soils, the effect of wood ash appears gradually and at the same time it can improve the biological characteristics, so it can be more compatible with the growth of perennial plants in acid soils.
کلیدواژهها [English]
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