ABSTRACT

This study investigated the effects of a eucalyptus-based compost on soil microbial community and enzyme activities of soils under avocado plantations in Limpopo, South Africa. It was hypothesized that compost application rate and time-post application would determine the abundance of biological organisms and enzyme activities. Experiments were conducted on 8-year-old ‘Hass’ avocado orchards. A repeated measures design with four compost treatments (0, 5, 10, and 15 ton ha⁻¹ year⁻¹), replicated three times was used. Thermophilic compost was prepared from locally sourced Eucalyptus wood chips (40%) and sawdust (20%), chicken manure (20%), and cattle manure (20%) stock feed. Soil samples were collected at three-month intervals for a period of nine months and analyzed for soil biota and enzyme activities. The results showed that compost application led to improved soil microbial counts and the effects were compost application rate and time dependent. The highest microbial counts were realized at 15 tons ha⁻¹ and increased with time post compost application. Phosphatase, β-glucosidase, and urease were slightly increased at 10 and 15 tons ha⁻¹ whereas fluorescein di-acetate was not affected by compost application rates. Compost application rates did not show a consistent effect on soil enzymes activities across sites and time.

摘要

本研究调查了基于桉树的堆肥对南非林波波鳄梨种植园土壤微生物群落和土壤酶活性的影响。假设堆肥施用率和施用时间将决定生物有机体和酶活性的丰度。实验是在 8 年历史的“Hass”鳄梨果园中进行的。使用重复测量设计，采用四种堆肥处理（0、5、10 和 15 吨公顷^-1年^-1），重复 3 次。嗜热堆肥由当地采购的桉树制成木屑 (40%) 和锯末 (20%)、鸡粪 (20%) 和牛粪 (20%) 饲料。在为期九个月的时间里，每隔三个月收集一次土壤样品，并分析土壤生物群和酶活性。结果表明，堆肥施用导致土壤微生物数量增加，其效果取决于堆肥施用率和时间。在 15 吨 ha ^{-1 时}实现了最高的微生物计数，并且随着堆肥施用后的时间而增加。磷酸酶、β-葡萄糖苷酶和脲酶在 10 和 15 吨 ha ^{-1 时}略有增加，而二乙酸荧光素不受堆肥施用率的影响。堆肥施用率对不同地点和时间的土壤酶活性没有表现出一致的影响。