Biogeochemical cycling of some trace and plant essential elements in soil-rice system

Name: Juthamard Kaiphoem

LCSH: Kasetsart University -- Dissertations. Ph.D. (Soil Science) 2021

Classification :.LCCS: S667.R5 .J88

LCSH: Kasetsart University. -- Department of Soil Science -- Dissertations

LCSH: Rice -- Soils

LCSH: Soils -- Trace element content

LCSH: Soils -- Arsenic content

LCSH: Soils -- Zinc content

LCSH: Trace elements

Abstract: Rice (Oryza sativa) is a staple food for half of the world’s human population. Consumption of rice containing high toxic element and low essential element can jeopardize human well-being. In addition, global warming has triggered greenhouse gas emissions, threatening rice productivity. Conventional (CF) and organic farming (OF) play a pivotal role in toxic and plant essential element cycling, affecting soil fertility, rice productivity, and human health. This research aimed to provide an understanding of the biogeochemical cycling of some trace toxic and nutrient elements (As and Zn) and some plant essential elements (C and N) in soil-rice systems under CF and OF systems (n = 63) in a Jasmine rice cultivation in Thailand (Amnat Charoen province). Typical characteristics of the studied soils had coarse texture, acidic condition, and poor in organic matter, available P, exchangeable K, and cation exchange capacity. The OF soils had significantly higher pH and organic matter than those in the CF soils, whereas rice yield in the CF system was higher than in the OF system (P < 0.05). The concentrations of As and Zn in the soil (total and extractable forms) and rice parts (root, straw, and grain) were quantified under both farming systems. The results showed that most soils had low total As (0.10–11.10 mg kg–1 , median 1.20 mg kg–1 ) and total Zn (5.80–43.90 mg kg–1 , median 11.60 mg kg–1 ). Moreover, oxalate-extractable As (0.03–2.14 mg kg–1 , median 0.42 mg kg–1 ) was very low, whereas DTPA-extractable Zn (0.08–4.68 mg kg–1 , median 0.41 mg kg–1 ) indicated the Zn deficiency level for rice growth (<1.0 mg kg–1 ). The brown-rice grain As and Zn concentrations showed that all rice grain contained the safe As level (< 350 µg As kg–1 ). Conversely, the grain Zn was insufficient for recommended daily allowance (RDA) for Thai (46–51% RDA) and global (30–33% RDA) population. The rice farming systems had no statistical differences in As and Zn contents in soils and rice plants. The C and N fluxes were measured based on a detailed analysis of relevant influxes (fertilizer, manure, and biomass incorporation) and effluxes (biomass harvest and greenhouse gas emission) under both farming systems. The results demonstrated that OF system improved many soil properties (pH, OM, total N, total C and available P). The OF system enhanced root and stubble biomass, which promoted soil C input. The most C and N effluxes occurred through straw and grain harvest. Therefore, the net C depletion were observed in both CF and OF systems. However, the net N was depleted and accumulated in the CF and OF systems, respectively. Overall, low As, Zn, C, and N in soils resulted in low rice yield, containing As-safe and Zn-undernourished rice grains. Straw incorporation to soils could potentially resolve the net C depletion and greatly elevate the net N accumulation in the paddy soils. Moreover, recycling Si-rich straw into the soils could also gradually build up plant-available Si that potentially sustain rice production with the safe-As level and improve rice productivity. The effective of rice residue recycling to soils is a simple strategy to implement adaptive management for sustainable agriculture and the environment.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Worachart Wisawapipat

Role: Thesis Advisor

Name: Surachet Aramrak

Role: Thesis CO-Advisor

Created: 2021

Modified: 2025-07-27

Issued: 2025-07-27

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2564/juthamard-kai-all.pdf

CallNumber: S667.R5 .J88

eng

DegreeName: Master of Science

Level: Doctoral Degraee

Descipline: Soil Science

Grantor: Kasetsart University

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