Relationship between plant residue removal and soil carbon in soils of smallholder nutmeg plantations in Ternate Island, Indonesia

Abstract

A poor plant residue management in the nutmeg plantation system in the Ternate Island is claimed as the major factor causing the decline of soil organic carbon (SOC), and hence the low production of nutmeg. The present study was conducted with the aim of examining the relationship between SOC and plant residue removal activity in nutmeg croplands. An interview method was used to collect data from 140 farmers about their knowledge on SOC and the models of plant residue management adopted in their cropland. A snap-shot field survey was also undertaken at 14 plantation sites to collect soil samples from the depth of 0-20 cm and 20-30cm soil layer to be analyzed. The result of interview was analyzed descriptively, whilst the soil variable data were analyzed using regression models. The findings revealed that all the respondents remove plant residue from the soil surface and burned it. About 80% of the respondents applied it four times a year, whilst the rest 20% did it twice a year. The SOC content in the soils treated with the four times residue removal practice was lower than ones with less frequency of plant residue removal, and thereby has triggered the formation of subsoil compaction.