Decay and erosion-related transport of sulfur compounds in soils of rubber based agroforestry

Sissou Zakari; Wenjie Liu; Junen Wu; Ashutosh Kumar Singh; Xiaojin Jiang; Bin Yang; Chunfeng Chen; Xiai Zhu

doi:10.1016/j.jenvman.2020.111200

Decay and erosion-related transport of sulfur compounds in soils of rubber based agroforestry

J Environ Manage. 2020 Nov 15:274:111200. doi: 10.1016/j.jenvman.2020.111200. Epub 2020 Aug 17.

Authors

Sissou Zakari¹, Wenjie Liu², Junen Wu³, Ashutosh Kumar Singh³, Xiaojin Jiang⁴, Bin Yang³, Chunfeng Chen³, Xiai Zhu³

Affiliations

¹ CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Yunnan, 666303, China; Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Menglun, Yunnan, 666303, China; Laboratory of Hydraulics and Environmental Modeling (HydroModE-Lab), Faculté D'Agronomie, Université de Parakou, 03 BP 351, Parakou, Benin.
² CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Yunnan, 666303, China; Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Menglun, Yunnan, 666303, China. Electronic address: lwj@xtbg.org.cn.
³ CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Yunnan, 666303, China; Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Menglun, Yunnan, 666303, China.
⁴ CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Yunnan, 666303, China; Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Menglun, Yunnan, 666303, China. Electronic address: jiangxiaojin@xtbg.ac.cn.

PMID: 32818828
DOI: 10.1016/j.jenvman.2020.111200

Abstract

Elemental sulfur is intensively used to control weeds and rubber leaf diseases. However, the mechanisms contributing to elemental sulfur dissipation and decay (hereafter decay) in rubber agroforestry remains unclear. This study relates hydrological processes such as runoff and soil loss to the changes in soil total sulfur (S_tot) and sulfate (S-SO₄) in typical hillslope rubber agroforestry intercropped with cocoa in Xishuangbanna. The elemental sulfur decay kinetics were studied at two slopes (top and bottom) and three agrosystems (weed, no-weed and mixed). The results show that soil moisture and hydraulic conductivity was uniformly distributed in the experimental rubber agroforestry settings. Higher soil loss and runoff occurred in the bottom slope than the top slope, and in no-weed agrosystem than the herbaceous agrosystems (weed and mixed). The soil loss was mainly driven by runoff. Moreover, S_tot and S-SO₄ in runoff water were higher in weed agrosystem than no-weed agrosystems. Soil S_tot best fit a two-compartments kinetics model, with lower kinetic rates in elemental sulfur applied treatments than in the no-added elemental sulfur treatments, particularly for the weed agrosystem. The soil S_tot dissipation time 50% (DT₅₀) was 10-14 times higher in top slope than bottom slope; but 4 and 20 times higher in mixed and no-weed agrosystems, respectively, compared to the weed agrosystem. The soil S_tot and S-SO₄ contents negatively correlated with soil microbial respiration (CO₂ efflux), indicating an adverse influence of elemental sulfur on soil microbial activity. In short, elemental sulfur decay and its S-SO₄ transformation depended on soil moisture, runoff, soil erosion and soil CO₂, which are in turn affected by slope and agrosystem. This study not only clarifies the mechanisms of elemental sulfur dissipation and decay for its use as an environmental friendly agrochemical; but it also provides information to understand the contribution of runoff and soil loss on these mechanisms in rubber agroforestry.

Keywords: Elemental sulfur; Kinetics; Land slope; Runoff; Soil loss; Soil microbial activity.

MeSH terms

Rubber*
Soil*
Sulfur
Sulfur Compounds
Water

Substances

Soil
Sulfur Compounds
Water
Sulfur
Rubber