Research on using brackish water to irrigate for some coastal upland crops

Project "Research on using brackish water to irrigate for some coastal upland crops" are conducted to meet undertaking in increasing the traditional water supply sources; reduce the pr

MINISTRY OF EDUCATION

AND TRANING

MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT

THUYLOI UNIVERSITY

LE VIET HUNG

RESEARCH ON USING BRACKISH WATER TO IRRIGATE FOR

SOME COASTAL UPLAND CROPS

Specialization: Irrigation and drainage engineering

Code: 62 62 27 01

SUMMAZY OF TECHNICAL DOCTORAL THESIS

HANOI, 2016

Thesis has been completed at Thuyloi university

Advisor: 1 A/Prof.Dr NGUYEN TRONG HA

2 A/.Prof.Dr NGUYEN THI LAN HUONG

Reviewer 1: Prof.Dr Le Dinh Thinh

Reviewer 2: Asso.Prof.Dr Pham Viet Hoa

Reviewer 3: Asso.Prof.Dr Doan Doan Tuan

The thesis will be defended to the Examination Committee at Thuy Loi University, 175 Tayson str., Dongda, Hanoi, Vietnam On 26th November,

INTRODUCTION

1 Context of the study

Vietnam is a country located on the East coast with over 3,000 km coastline, along the coast is the delta region, the coastal plains, where agricultural production has an important role in national economy Due to of climate change impact, food production in Vietnam has been being significantly risky, today Coping with climate change situation is the top priority of the government due to its negative impact on agricultural production and the livelihoods of people in recently, particular drought in South Centre; salinization in most of the coastal provinces, especially in Mekong Delta, leads to tens of thousands hectares of agricultural land become water shortages, etc

The “Agriculture Restructuring” policy created focal points for enhanced agricultural water productivity in the context of increasing in water scarcity, thus, improve the flexibility of supply to encourage crop diversification, reducing rice acreage and water used crops; increasing acreage of with high economic value and less water consumption crops is to implement the restructuring the agricultural sector policy in the context of climate change

Project "Research on using brackish water to irrigate for some coastal

upland crops" are conducted to meet undertaking in increasing the

traditional water supply sources; reduce the pressure on traditional irrigation water sources; restructuring the irrigation sector

2 Objectifies of study

- Determine the scientific basis of saline water irrigation by drip irrigation method to the growth and yield of corn and soybeans, and soil physical and chemical properties in Kim Son district, Ninh Binh province

- Assess the possibility of using saline water to irrigate crops

3 Scope and objects of the study

3.1 Objects of the study

- To study the effect of saline water using by drip irrigation methods to irrigate for soybean DT84 and corn LVN10, which are food crops and have been planting commonly in North Delta

- The experiment soil is mixture sandy to lightly silt soil of the coastal area of the Red River Delta Testing soil is common soil in coastal areas of the Red River Delta and in central coast of Vietnam

- Salt concentration of irrigation water includes 3 levels: ≤ 1 ‰ (irrigation water standard), 2 ‰ and 3 ‰ (double and triple to irrigation water standard) Water is taken from the Vac river , the salinity of the irrigation water is treated by diluting or supplementing to meet the research principles

- Drip irrigation techniques was applied in the experiments

- The coastal areas of North and North Central regions of tropical monsoon climate were selected as experiment areas Specifically, study area was at Kim Chinh commune, Kim Son district, Ninh Binh province which is located between the North and North Central of Vietnam

- Research saline water irrigation for DT84 soybean and corn LVN10 which are grown in popularity on neutral alluvial soils in coastal areas

- The study was conducted in 6 seasons (2 spring seasons, 2 rainy seasons and 2 winter seasons) in two years (2012 and 2013) However, saline water irrigation would not be applied in two rainy seasons

4 Content of study

- Identify the relationship between the salt concentration of irrigation water and the growth and yield of corn and soybean crops by applying the drip irrigation techniques

- Determine the effect of using of saline water to irrigate to physical and chemical properties of the soil

- Evaluate the possibility of using saline water to irrigate crops in limited freshwater resources condition and strong saline water areas

6 The scientific and practical significances

- Scientific significances: the thesis contributed to clarify the scientific basis

of saline water irrigation for corn and soybean crops by drip irrigation techniques in the alluvil soil in Kim Son district, Ninh Binh province

- Practical significances: The thesis had a great significance when proposing the possibility of saline water irrigation for corn and soybean crops in Kim Son district, Ninh Binh province The thesis is the premise for the saline water irrigation research in the other coastal areas of Vietnam and with different kinds of crops and freshwater water resources limitation

- The thesis contributed to guide the appropriately use of saline water irrigation in sustainable agricultural production in Vietnam and reduce pressure fresh water sources in the context of climate change and sea level rise

7 Achievements

1 This research showed that saline water with 2 ‰ salinity (ECiw = 2,8dS /

m) can be used to irrigate, by drip irrigation methods, that did not significantly affect the growth and yield of corn LVN10 and soybean DT84

on alluvial soil in Kim Son district, Ninh Binh province

2 On the northern coastal, north central and islands regions, under conditions

of force majeure, 3 ‰ salinity water (4.3 dS ECiw = / m) could be used by drip irrigation methods for maize LVN10 and soybeans DT84 Then, maize yield of maize and soybean was reduced <10% and <7% compared to freshwater irrigation

3 Saline irrigation by drip irrigation methods in 3 ‰ concentrations of salt (salinity triple than the normal irrigation water) did not significantly affect the chemical and physical properties of the soil Especially, the index of Na+, sodium adsorption ratio (SAR) and the elements related to saline of irrigation water

8 Thesis structure

The thesis includes: Introduction;

Chapter 1 Overview of saline water use for irrigation

Chapter 2: Research Methodology

Chapter 3: Results and discussions

Conclusions and recommendations;

CHAPTER 1 OVERVIEW OF SALINE WATER USE FOR IRRIGATION

1.1 Classification of saline water

Suitability of saline water for irrigation depends on the using conditions such as: crops, climate, land, irrigation methods and management methods

To determine the salinity of the water, making a classification scheme is practical significant

Table 1.1 Classification of saline water

Type

Electrical conductivity (ds/m)

Salt concentration (mg/l)

Type of water

No salt <0,7 <500 Drinking water and

irrigated water Slightly

salt

0,7-2 500-1500 Irrigated water

Just salt 2-10 1500-7000 Salty water and primary

groundwater Much salty

water

10-25 7000-15000 Consumed and groundwater

levels Very salty 25-45 15000-35000 Very salty underground

water Salt >45 >35000 Sea water

(Source: FAO Irrigation and Drainage Paper 48)

1.2 The saline water use for irrigation in the world and Vietnam

The saline water used to irrigate successful in the countries which had a freshwater scarcity, salinity ground water and low rainfall during the year Some countries had successfully used salt water to irrigate for several decades, including:

USA: successfully used the saline water to irrigate for in many parts of the Southwest including Colorado River Valley of Arkansas in Colorado, Arizona, New Mexico and West of Texas state Depending on type of crops, saline water with different salt concentration was applied, such as irrigated

cotton with saline water EC salinity up to 8dS/m, grass-fed cattle irrigated with EC from 3-5dS/ m that did not effects to productivity

Israel: the most countries of using saline water for irrigation, almost of groundwater had salt concentration from 2-8dS EC / m Salt water was diluted before use, crops were irrigated by rainy and drip methods In the Nahal Oz region, irrigating cotton was irrigated by groundwater with EC = 5DS / m

Tunisia: Used saline water with salt concentration was 3dS/m to irrigate dates, barley, grass and artichoke Rainwater was used for washing the saline soils

India: Gupta and Pahwa (1981) showed that can be used to saline water can

be used to irrigate with EC 8dS / m was used to irrigate for 9 districts of Haryana state

Egypt: Salt water with EC 2 - 3DS / m was used to irrigate crops including clover, rice, wheat, barley, sugar beet and cotton in the northern Delta district where was lack of fresh water Crop yields were often reduced about 25 to 30% compared with irrigated by saline water

Vietnam: There was a few of study about using saline water for irrigation Generally, the study focused on salt-tolerant varieties such as salt-tolerant rice varieties of Institute of Vietnam Agricultural Science, Can Tho University and acidification, desalination projects

1.3 Foundation of saline water used to irrigate for crop

- Some countries in the world had succeeded in using saline water to irrigate crops

- A long time ago, in the coastal areas also used to irrigate by saline water (surface and ground water less saline) or cultivate in the affected salinity land

- Currently, fresh water must be used to develop of economic sectors thus water for agricultural development has been declining

- Due to climate change, the pressure of water sources (water quality and the amount of fresh water reduce) that had a good quality for agriculture fell sharply, especially in the central coastal provinces and islands

1.4 Summary of chapter 1

1 Irrigation water in the world and in Vietnam had shortage due to increasing demand, pollution and climate change Saline water is natural resources should be considered and exploited effectively

2 Saline water typically reduced the growth, productivity of crops and increase salinity Use drip irrigation techniques had limited the rational phenomenon

3 Coastal salinity water has high levels of sodium ion that has hydration strongly, weak absorption capacity, thus it should easily be washed off and difficult to accumulate than the other elements in the soil The high rainfall areas such as the humid tropics of Vietnam, sodium ion is easily washed off

by rainwater and flood runoff This is the scientific basis for using saline water in certain concentration as irrigation water for crops

4 Indeed, saline water irrigation (6 ds / m) by drip irrigation in some areas such as in South Africa, tomato yield was 31.5 Mg / ha (tonnes / ha) In high rainfall areas, even saline water at 9 dS / m by drip irrigation, tomato yield reached 100 kg / ha

5 Saline water irrigation by common methods could alter certain soil properties, especially to increase the electrical conductivity (EC), reducing permeability and change the structure of the soil

6 Saline water irrigation by drip irrigation technique for crops would get significantly effective if combined with fertilizer, seed and appropriate management

CHAPTER 2 RESEARCH METHODOLOGY

2.1 Natural condition of study areas

The experiments were carried out at Kim Chinh commune, Kim Son District, Ninh Binh province that located in the tropical monsoon climate with cold winters and dry, hot, humid and rainy summer

2.2 Characteristics of the soil and water in the study areas

2.2.1 Characteristics of soil

The particles distribution of the soil at the experimental zone in coastal areas

is mixture sandy and slightly silt, highly porous, weak alkaline reaction, high organic matter content and high total N The concentration of other nutrients

as N, K, Ca and Mg is in the medium level However, Na+ exchange concentration is relatively high in relation to the critical cation such as K, Ca and Mg Soil salinity is relatively high, but still not classified as saline soil The characteristics of studied areas soil reflects basic characteristics of coastal alluvium soil Vietnam

2.2.2 Characteristics of irrigation water

In this study, controlled formula (CT1) was the salinity irrigation water ≤ 1

‰ river water (standard water), salinity of the experimental formulas are created by mixing surface water from the river or adding sodium chloride to reach 2 ‰ salinity (CT2) and 3 ‰ salinity (CT3)

2.3 Arrangement of experiment plots

The study had been carried out during two years (2012- 2013), with three irrigation formulas CT1, CT2, CT3 with ECiw conductivity respectively 1.4, 2.8 and 4.3 dS / m corresponding to the level of salinity ≤1 ‰, 2 ‰ and 3 ‰

to irrigate for corn LVN10 and soybean DT84 with three replications

There were 18 equal size plots, each plot had an area of 2.2 m2 Brick walls with 0.7 m height was used to separate between two plots with 0.2 m higher

than surface ground Around the experiments area were the system drains, road transportation and irrigation tanks Experimental diagram was shown in Figure 2.2

Figure : Cross section of experimental corn furrow

Figure 2.2: Field experiment diagram of corn and soybeans

tank with the the 1,0m3 capacity and located at 1.5m high compared to ground surface

2.5 Soil moisture measurement system

The experimental formulations were irrigated to maintain soil moisture in arrange of field maximum humidity (moisture maximum pressure from -10 to -50kPa) and suitable moisture for plants (pressure minimum humidity from -

25 to -50kPa), using soil moisture measuring devices Tensiometer 2080 that put at a 0.25 m depth just below the hose In the experiment, when the 2080 Tensiometer measuring equipment obtained value at -25kPa then operate the drip water supply system to supply water the experiment When measuring equipment obtained valued -10kPa, the irrigation must be stopped

Figure 2.3 Pictures of Tensiometer devices at experiment corn field

2.6 Measuring, sampling and analysis

- Number of leaves / tree is countted the total number of plant leaves during growth duration

- Leaf area index (CSDTL) is carried out the measurements at milk maturity, measure the length from the base to the top of leaf, the width at the widest part of the leaf blade All the green leaves are measured and then applied the formula of leaves the area:

Leaf area (m2) = Length x width x 0.75

CSDTL (m2leaf / m2soil ) = DTL / tree x number of plants / m2

2.6.2 The growth and development criteria

- On flowering flag: is calculated from sowing until 50% of tree / branch appeared last branch of flag

- Launched chalk date: is calculated from sowing until to 50% of the plants / launched chalk plots

- Spray beard date: is calculated from sowing to 50% of the plants / cell with

a long beard beyond leaves around 2- 3 cm

- Maturity date is recorded number of days from sowing to 70% of the corn / grain with seed black legs

2.6.3 The yield components criteria

- Counting the total number of trees, counting the total number of corn, weight of 2 rows of harvest corn (kg)

- The number of seed on the row: is counted in rows with average length of grain /corn

- Weight 1 000 seeds (g) at harvest moisture: counting 2 samples, 500 seeds

of each sample, weight of 2 samples are M1, M2, if the difference between the two time scales (heavy sample minus slight sample) is no over 5% compared to the average weight of 2 samples, then the M1 + M2 = P1000 seeds