Abstract
Ultisol as a marginal soil has become ‘a hope’ by farmers in Indonesia due to land use change, lately. However, the soil is susceptible to degradation since it has low soil aggregate stability (SAS) as affected by low soil organic matter (SOM) content. A pot trial about application of fresh organic matter (FOM) was aimed to improve SAS of Ultisols under wet tropical rainforest. Three types of FOM (Tithonia diversifolia, Chromolaena odorata, and Gliricidia sepium) at different size (8, 6, 4, 2, and 0.5 cm) were applied for 1% (20 g 2 kg-1 soil), then mixed and incubated for three months. The experimental units were allocated in a completely randomized design at a glasshouse. The results showed that FOM generally increased SOM content, percent aggregation, as well as SAS of the Ultisol. Among the organic matter (OM) sources, tithonia gave the highest SOM content after a 3-month incubation. Within the types of OM source, the smallest OM size applied showed the highest SOM content. Tithonia at 0.5 cm in size gave the highest SOM (3.47%) of the Ultisol and SAS increased by 68% compared to the initial soil. Overall, there was a positive correlation (R2 = 0.43) between SOM content and aggregate stability index, but no correlation (R2=0.04) between SOM content and percent aggregation of the Ultisols.[How to Cite : Yulnafatmawita and F Anggriani. 2013. Fresh Organic Matter Application to Improve Aggregate Stability of Ultisols under Wet Tropical Region. J Trop Soils 18 (1): 33-44. doi: 10.5400/jts.2013.18.1.33][Permalink/DOI: www.dx.doi.org/10.5400/jts.2013.18.1.33]
Highlights
Aggregate stability of soils in wet tropical regions seem to be a key factor to determine soil degradation, especially in the sloping areas such as in West Sumatra
Some physical properties of Ultisol from wet tropical area especially in Limau, West Sumatera, are presented in Tabel 1. It shows that the soil had clay in texture with approximately 68% of particles
It is found to be true since the sampling site is located under wet tropical rainforest, receiving up to 6500 mm rainfall annually (Rasyidin 1994) and mean annual temperature > 18°C
Summary
Aggregate stability of soils in wet tropical regions seem to be a key factor to determine soil degradation, especially in the sloping areas such as in West Sumatra. Up to 6500 mm (Rasyidin 1994), combined with wavy and hilly topography in the region has caused the soils become very susceptable to degradation mainly through erosion process. This is primarily found under annual cropping systems, in which farmers during preparing seed bed, tend to cultivate the soils intensively that causing the SOM was oxidized.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
