Abundance and diversity of soil macroinvertebrates in sugarcane (Saccharum spp.) plantations under organic and chemical fertilization in Belize

Abstract

Many studies suggest that sugarcane management practices have negative impact on soil quality, especially on soil organisms, however, information on macroinvertebrate abundance and diversity in conventional sugarcane fields is scarce. This study determined the abundance and diversity of soil macroinvertebrates in sugarcane plantations under 2 types of soils, Cambisol and Fluvisol, with three types of fertilizer management: chemical fertilizer, vinasse and filter mud, and in a secondary forest (on a Cambisol). Sampling was carried out in northern Belize during two crop cycles (from May 2013 to May 2015). Soil macroinvertebrates were collected using monoliths based on Tropical Soil Biology and Fertility (TSBF) Handbook of Methods at the end of the rainy seasons. The parameters evaluated were biomass, density and diversity of soil macroinvertebrates (number of morphospecies, an ecological index for tropical soil quality based on macrofauna, and a converted Shannon index (H_exp)), yield and plant response variables (number of stool, number of stem, number of active leaves, stem length and stem diameter). A total of 7,634 individuals were identified, grouped into 52 morphospecies belonging to 16 orders and three species of annelids. No significant differences existed among management systems (application of chemical fertilizer, vinasse, filter mud and secondary forest) on abundance and diversity of soil macroinvertebrates, yield and plant variables. However, there were significant differences between soils and cycles in some evaluated parameters. Presuming that soil type and seasonal conditions, in a two years trial, had higher weight on determine the studied parameters than the different management systems.