Effect of biochar on greenhouse gas emissions and the growth of paddy rice masters thesis major sciences and management of the environment

− Addition of biochar alone no cow manure on saline soil increased aboveground biomass of paddy rice and the influence level depending on the type of biochar.. Saline soil is studied to

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OF BIO MISSIO

L UNIVE LIÈGE U

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OCHAR ONS AN PADD

OF HOCH SITY

ENHOU ROWTH

ANAGEM

STER IN ENT CITY

USE

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The project was completed at The Industrial University of Hochiminh City

Supervisor’s name: Dr Nguyen Thanh Binh

The thesis was taken at The Industrial University of Hochiminh City date 23 month

SCIENCE, ENGINEERING AND MANAGEMENT

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ABSTRACT

Agricultural practices affect the growth of rice and emission of methane (CH4) from the paddy field The increased CH4 concentration in the atmosphere could be contributed from the flooded regime The release of CH4 from soil is the largest source of carbon to the atmosphere

In order to examine the effect of biochar on rice growth and CH4 emission from paddy soil, an experiment was conducted with 6 treatments and 4 replicates Six treatments include (1) no manure – no biochar, (2) no manure – rice husk biochar, (3) no manure – rice straw biochar, (4) cow manure – no biochar, (5) cow manure – rice husk biochar, (6) cow manure – rice straw biochar The experiment was conducted over three months at the Institute of Biotechnology and Food Technology, Industrial University of Ho Chi Minh City Gas samples were collected and analysed with CH4 weekly The biomass of rice crop and soil properties were determined at the end of the experiment

The results showed that:

− Application of cow manure increased CH4 emission from the paddy rice Biochar reduced CH4 emissions from the treatments applied with cow manure Specifically, CH4 emissions decreased by 58% with the addition of rice straw biochar, decreased by 17% with the addition of rice husk biochar

− Addition of biochar alone (no cow manure) on saline soil increased aboveground biomass of paddy rice and the influence level depending on the type of biochar

In the current study, aboveground biomass increased to 346% with straw biochar, and to 174% with husk biochar

The addition of biochar and cow manure into saline soils also affected the nutrient content of the soil

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TABLE OF CONTENTS

LIST OF TABLES 4 

LIST OF FIGURES 5 

LIST OF ABBREVIATIONS 6 

INTRODUCTION 7 

1 The reason for choosing the topic 7 

2 Objectives of the study 9 

3 Subjects and scope of the study 9 

4 The methodology 10 

CHAPTER 1 LITERATURE REVIEW 11 

1.1 Paddy rice production in Vietnam 11 

1.2 Soils for paddy rice production 13 

1.3 Greenhouse gas emission from paddy fields 15 

1.4 Biochar with crop production 17 

1.5 Biochar with paddy rice production 17 

1.6 Current problems of paddy rice production in Vietnam and biochar solutions 18 

CHAPTER 2 MATERIALS AND METHODS 19 

2.1 Research Content 19 

2.2 Materials and methods 19 

2.2.1 Experimental procedure 19 

2.2.2 Experimental layout 22 

2.2.3 Measurements and analyses 25 

2.2.4 Statistical analysis: 27 

CHAPTER 3 RESULTS AND DISCUSSION 30 

3.1 Basic characteristics of experimental materials 30 

3.2 Variations in CH4 effluxes during experiment 31 

3.3 Rice growth 40 

3.4 Soil properties of six treatments after experiments 41 

3.4.1 Exchangeable concentrations of PO43-, NH4+, NO3-, and Cl- 41 

3.4.2 Soil pH and EC 43 

4.4.3 Soil exchangeable concentrations of Ca, K, and Mg 44 

3.4.4 Soil CEC, Na, and non-Na, exchangeable Na 45 

CHAPTER 4 CONCLUSIONS 48 

4.1 For CH4 emissions: 48 

4.2 For the growth of paddy rice 48 

4.3 For soil nutrients 48 

REFERENCES 50 

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LIST OF TABLES

Table 1 1 The paddy rice cultivated area and yield of Vietnam from 2000 to 2013 11 Table 2 1 Details of treatments 23 Table 3 1 Basic properties of experimental materials The numbers in the parenthesis are the standard deviation of the mean 30 Table 3 2 Average CH4 emission of each treatment through observations SD = standard deviation of the mean In the same column of data, different letters indicated statistically significance with probability P <0.05 31 Table 3 3 Soil concentration of PO43-, NH4+, NO3-, and Cl- of 6 treatments after the experiment SD = standard deviation of the mean 41 Table 3 4 Soil pH of six treatments after the experiment 43 Table 3 5 Soil EC of six treatments after the experiment 43 

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LIST OF FIGURES

Figure 1 1 Distribution of national rice area in Vietnam 13 

Figure 1 2 Salinity intrusion in the Mekong Delta 14 

Figure 1 3 CH4 emission mechanism 15 

Figure 1 4 Methane formation and emission in paddy field 16 

Figure 2 1 Measure EC of the soil 19 

Figure 2 2 Collected the saline soil samples 20 

Figure 2 3 Rice husk biochar 21 

Figure 2 4 Rice straw biochar 21 

Figure 2 5 Experimental pots 22 

Figure 2 6 Experimental layout 24 

Figure 2 7 Experiment Pots when appling rice 25 

Figure 2 8 Gas sampling 26 

Figure 2 9 pH Measurement 27 

Figure 3 1 Trends of CH4 emissions in no manure treatments 34 

Figure 3 2 Evolution of CH4 emissions in manure treatments during experiment 35 

Figure 3 3 Evolution of CH4 emissions On the same measuring day, the data with the same number are not significant The statistically significant dates are represented by the letters a, b 35 

Figure 3 4 CH4 emissions from 6 treatments during the experiment Within the same measuring day, data attached with the same letter were statistically significant from the others 37 

Figure 3 5 Total methane emitted for 90 days from experimental treatments Error bars are the standard deviation of the mean Bars attached with the same letters are not significantly different from the others at P ≤ 0.05 39 

Figure 3 6 Aboveground biomass of paddy rice after 90 days from sowing Error bars are the standard deviation of the mean Bars attached with the same letters are not significantly different from the others at P ≤ 0.05 (DWT = dry weight) 40 

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LIST OF ABBREVIATIONS

ANOVA Analysis of variance

IESEM Institute of environmen Science and Environmental

Management

IPCC Intergovernmental Panel on Climate Change

ISO International Organization for Standardization

GHG Green house gas

SD Standard deviation

TCVN Standard of vietnam

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INTRODUCTION

1 The reason for choosing the topic

Global warming has been studied and reported quite frequently in recent years and

is forecasted to continue for coming decades [1] Global warming in recent years, mainly caused by the continuous accumulation of greenhouse gases, such as CH4

and N2O in the atmosphere, resulted in many negative impacts to all countries in the world In developed countries, greenhouse gas emissions (GHG) are mainly derived from industrial and energy activities, while in developing countries these could come mainly from agricultural production [2]

Currently, agricultural production was reported to emit up to 1/3 total gases, which cause greenhouse effect [3] Annually rice cultivation emitted about 60 million tons

of greenhouse gases (ranging from 20 to 100 million tons) in the world, equivalent

5 - 20% of total anthropogenic greenhouse gases [1]

In Viet Nam, agriculture annually emitted 43% of total national greenhouse gases (about 65 – 150 million tons CO2) from paddy rice production and improper handling of byproducts of some crops such as straw, bagasse, coffee pods, stems and leaves of corn, peanuts, and soybeans In 2000, paddy rice production emitted 57,5 % of total greenhouse gases from the agricultural activity of the country [4] Thus, rice production in Vietnam is emitting a large amount of CH4, N2O annually due to the flooded growing environment, creating anaerobic conditions for metabolic processes within the soil This phenomenon contributes to increasing the concentration of greenhouse gases in the atmosphere with time

The soil is also the issue of rice production in Vietnam In Vietnam, it is estimated that saline soils have nearly 2 million hectares, accounting for nearly 6% of the total natural land Saline soil is studied to improve paddy rice yield and greenhouse gas emissions [5] Biochar is the residue after an incomplete combustion (pyrolysis) of organic substances such as wood, leaves, plant remnants in anoxic conditions It is

8

the organic carbon - rich materials, which have lots of important features For agronomy, biochar can increase fertility of the soils and the growth of crops by (a) reducing soil acidification, (b) enhancing soil’s ability to hold nutrients [6], (c) enhancing soil texture, and (d) increasing soil nutrient contents of N, P and K [7] For environment, paddy rice soil added with biochar may limit methane emissions, through three mechanisms, including (1) limiting the activities of methane metabolizing bacteria (2) increasing the activity of methane oxidation process, and (3) enriching the gene pmoA of the methane using bacteria [8] After carbon dioxide, methane emissions provide the second largest contribution to historical warming, but it has the radiative forcing causing global warming as much as 25 times higher than that of CO2 [9] Human activity causes methane emissions, a major source of greenhouse gas accounting for 20% of global warming [10], and paddy rice production is a primary source of methane emissions Zhang (2012) undertaking studies on biochar, which was produced from straw for paddy rice, reported an effective improvement of soil fertility (pH, total protein, total C and density) and an increase in the crop yield The results of these authors also showed that biochar has a potential of reducing N2O emissions, but increasing emissions of

CH4 However, another study of Pratiwi and Shinogi (2016) showed that biochar, produced from rice hulls can reduce CH4 emissions, and increase the growth of paddy rice

However, there is almost no study in Vietnam and other countries all over the world reporting greenhouse gas emissions and growth of paddy rice cultivated on saline soils affected by biochar produced from by - products from rice production As a result, the current study "Effects of biochar on greenhouse gas emissions and the growth of paddy rice" is set up and conducted

The main purpose of this study is to evaluate the effect of biochar on GHG emissions and the growth of paddy rice on saline soil The findings from the current study could be useful domestically and internationally This knowledge could serve

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as a basis for sustainable development of paddy rice

The results of this experiment may provide an overview about the impact of biochar

on GHG emissions and the growth of paddy rice, suggesting a direction for the optimal utilization of by - products, which are abundant natural resources of the country Moreover, it is the basis for further studies in the selection of organic amendments to improve soil properties, enhance paddy rice yield and contribute to reducing greenhouse gases in the atmosphere

2 Objectives of the study

This thesis is set out to address the gaps in knowledge outlined in the problem statement It aims at:

− Assessing the effect of biochar on greenhouse gas emissions from paddy rice production;

− Assessing effect of biochar on the growth of paddy rice;

3 Subjects and scope of the study

™ Time of the study

The study was carried out from October 2016 to September 2017, with 3 stages The first stage, setting the master thesis proposal from October 2016 to March 2017

4 The methodology

Measundard methods as followings:

− TCVN 5979_ 2007: Soil quality - Determination of pH;

− TCVN 6643: 2000, Soil quality -; TCVN 8466:2010: Identifying cation exchange capacity (CEC) by usinghexamincoban trichloride solution;

− TCVN 8568:2010: Method determining capacity of the cation exchange (CEC) - The method used ammonium acetate;

− TCVN 8660:2011: Methods for determination of potassium total;

− TCVN 8941:2011: Soil Quality - Determination of Total organic carbon -

Walkley Black Method;

− TCVN 8940:2011: Soil Quality - Determination of Total Phosphorus -

colorimetric method

− TCVN 6496:2009: Soil quality Determination of cadmium, chromium, cobalt, lead, copper, zinc, manganese and nickel in the soil extracts by aqua regia - The method of absorption spectrometry atomic flame and thermal (no flame)

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1.1 Paddy rice production in Vietnam

Rice is one of the most important staple foods for more than 50% of the world population Total rice production in 2015 is 1% higher than in previous year (749.1 million tons compared 741.8 million tons) and tends to increase in the following years

Vietnam has a general tropical monsoon climate regime with a long coastline, complicated topography, and varying climate regimes, forming many different farming regions Rice cultivation in Vietnam is divided into 3 main regions including the Red River delta, the central coastal delta, and the Mekong river delta Record of the paddy rice area and yield of Vietnam from 2000 to 2013 are shown in the below table:

Table 1.1 The paddy rice cultivated area and yield of Vietnam from 2000 to 2013 [11]

Spring

Spring

From 2005 to now total rice production gradually increased Apart from increased rice area, application of the science and technology in agriculture by creating new high - yield and pest resistant varieties also contribute to improving rice production

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1.4 Biochar with crop production

Today, farmers use biochar as the substrate, artificial soil amendment to grow flowers having a high economic value such as orchids … This is a method that is being promoted in growing flowers and ornamental plants as well as vegetables and crops

People in Binh Dinh Province has applied biochar to increase peanut yield on sandy soils by increasing moisture, holding fertilizers, and beneficial microorganisms, thus, improving soil quality People in many places in Vietnam such as Hanoi, Hung Yen, Hai Duong have produced biochar from by - products to apply to the soil for better crop productivities

1.5 Biochar with paddy rice production

According to a study by Vu and Nguyen , application of biochar produced from rice husk increased rice yield up 9-10% [27] Another study by Tran Viet Cuong reported that biochar produced from rice husk and straw when applied to gray soil increased the rice yield, compared to the control treatment and manure applied treatment from 1.9 to 2.9 kg/ha [28] This study also reported that biochar improved soil quality indicators such as CEC, pH and nutrient elements in the soil

Another full research project in Vietnam about biochar was conducted by Mai Van Trinh to improve the soil properties and reduce environmental pollution in Soc Son – Hanoi To start the project, the author conducted studies with 7 different production methods to produce biochar from rice hulls and straw The produced biochar from this study was applied in the soil to reduce CO2 emissions and improve rice yields Results showed that the rice yield was higher in biochar applied treatment than in inorganic fertilizer applied treatment Soil fertility indicators such

as pH, organic carbon, N, P, and porosity were also improved CO2 emissions from paddy rice soil applied with biochar were also decreased, compared to manure

In Vietnam, an experiment using biochar to grow rice in Thai Nguyen showed that biochar produced from rice straw, bamboo, and tree branches composted with animal manure increased rice yield up 130%, dependent on application rates [32] In Ninh Thuan, biochar produced from rice husk applied with NPK + manure resulted

in highest peanut yield To use biochar effectively, there should be studies specifically conducted on individual soils and locations for individual local crops s [27]

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23

block design (RCBD) with 6 treatments and 4 replicates, making 24 experimental plots in total Details of treatment are shown in Table 2.1 These treatments were replicated four (4) times to give twenty-four (24) experimental pots

Table 2.1 Details of treatments [8], [31]

weight*)

Cow manure (% by weight, *)

Inorganic fertilizer

applied (**)

Note: application rate 80 N + 30 P 2 O 5 + 30 K 2 O: kg/ha

− All other cultivation techniques on rice such as inorganic fertilizers, seeds,

weeding, and the pesticide application are the same for all experimental treatments and following regular protocol

− The soil in the experimental pots was totally flooded for the experimental period

of three months by regular irrigation

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