Land-use impact on soil carbon, nitrogen, neutral sugar composition and related chemical properties in a degraded Ultisol in Leyte, Philippines

Abstract

Over the past several decades, the conversion of native forest to agricultural land use has accelerated and featured in the development of Philippine landscapes. This study evaluated the effect of land-use change on soil carbon, nitrogen, neutral sugar composition and other related soil chemical properties in a degraded soil (Typic Hapludult) in Leyte, Philippines. Using a space-for-time substitution (paired-area) approach, soil samples were collected and examined from secondary forest (SF), mahogany plantation (MP), rainforestation farming (RF), coffee plantation (CP) and grassland (GR) of comparable geology, parent material, soil type and climate. Soil pH, exchangeable Ca and Mg, and cation exchange capacity (CEC) tended to be higher after the conversion of deforested cultivated land into MP and RF land-use types. In contrast, land conversion decreased the soil carbon, nitrogen and carbohydrate-C in the order of SF, MP, CP, RF and GR, and the decrease was more marked in RF and GR sites that had been under intensive cultivation for a long period of time. Arabinose and xylose (mainly of plant origin) constituted the major non-cellulosic neutral sugar and represented 31-54% of the total soil carbohydrate-C. Soil carbohydrate-C content contributed 2-8% of the total soil organic carbon because of rapid decomposition of sugars. This suggests an adverse effect of land-use change leading to degradation of soil quality. The results of this study suggest that under the humid tropical climate of the Philippines, high temperature and favorable moisture enhanced the carbohydrate decomposition and, thus, affected the content and composition of neutral sugar in the soil.

Application of categorical information in the spatial prediction of soil organic carbon in the red soil area of China

“…Owing to the effect of complicated soil‐forming factors and human activities, SOC exhibits high spatial variability (Matsumoto et al. 2008; Navarrete and Tsutsuki 2008; Zhang et al. 2009).…”

Humus composition and the structural characteristics of humic substances in soils under different land uses in Leyte, Philippines

“…Conversion of PF to other land uses has led to a decrease in FAs (Table 1), which was more appreciable at the RF and GR sites under intensive cultivation (Navarrete and Tsutsuki 2008). In contrast, the HA contents in the soils were small even in the PF.…”

“…There have been very few studies examining the effect of land use on humus composition in the Philippines (e.g. Navarrete and Tsutsuki 2008; Ohta 1990). Ohta (1990) reported that conversion of forest into grassland (GR) has resulted in a considerable decrease in soil organic C, humic acids (HAs) and fulvic acids (FAs).…”

“…Ohta (1990) reported that conversion of forest into grassland (GR) has resulted in a considerable decrease in soil organic C, humic acids (HAs) and fulvic acids (FAs). Navarrete and Tsutsuki (2008) reported that conversion of secondary forest to other land uses has led to a decrease in soil C and N contents. They reported that land use affected not only the content, but also the composition of neutral sugars.…”

Chemical and Spectroscopic Properties of Soil Hydrophilic Fulvic Acid Purified by Tangential Flow Ultrafiltration

“…Some neutral sugars that are associated with the soil mineral matrix (i.e., bound to iron and aluminum oxides) are resistant to biodegradation as documented in Andosol [6,14,36,37] and Acrisol [14]. Although the amount of mannose was not statistically different between HiFA and HoFA, the slightly higher mannose in HoFA suggest that mannose is relatively stable against microbial decomposition.…”