Analyzing the Salt Level in Different Soil Textures

Jason Jarabejo
Rafael Celis
Joshua Mikael Ramos
Hagin Busto
Santos Angelo
Wesley Pangilinan

Chapter I – Introduction

BACKGROUND OF THE STUDY

The main goal of this research is to fully understand how salt level varies in different soil compositions. The first fundamental topic for this research came from The Effects of Sodium Chloride Solution on the growth of Tomato Plants (Lycopersicon esculentum) (Larsen, 2007), a study concerning the effect of high salinity level on farming and the factors affecting it.

Sodium Chloride (NaCl) or commonly known as salt or halite was used in marking territories because it yields the growth of plants on fields enforced with salt. The scientific reason for this is because salt acts as an opposing agent against the plant’s ability to sip water through the soils cracks.

This research will focus on the analysis of the salt level in different soil textures. The gathered salinity levels will be analyzed and compared to know which soil textures will have a reading precisely close to moderate regular salinity levels. Based on the procedure on measuring salinity by (Queensland, 2007) we will use, the regular salinity margin is 1.5-4 dS/m which is ranged from slightly saline that has minimal effect to moderately saline which has restricted effects. It can also be translated to 15%-40% salinity. But to get more precise readings, 27.5% will be marked as the basis of regular salinity level.

For this research, we will limit the field of measurement in a regular setting for the electrical conductivity measurement to control the level and for it to remain constant.

Using soil salt level field test, we compare reading of salt level in each soil texture.

Thus arriving at the main purpose of this research which is to analyze the salt levels in different soil textures and assess the results using Soil Salinity Field Test.

STATEMENT OF THE PROBLEM

Main Problem: Which soil texture will give a salt level that will approximately be the closest to the regular salinity level mark?
Hypothesis: The loam soil. Because it is moderately coarse, has less cation exchange capacity, and has a high water infiltration rate to wash the salt.

Sub problems:

How does the salt level of each soil composition differ from the mixed soil textures?
Does the difference between the soil compositions have relevance to its permeability?
What measurements are used when it comes to salt level?

OBJECTIVES OF THE STUDY

Main Objective: To analyze the salinity level in different soil composition
Specific objective: To assess the factors that affect the salt level in various soil textures.
Specific objective: To identify which type of soil texture can resist salt intrusions considering its bad impact on plants.

SIGNIFICANCE OF THE STUDY

When the problem about the salt level affecting wet land and dry land farming was encountered, it gave a potential to this research and formed a basic study. The main goal of this research is to gain knowledge on of the leading causes in failure of farming, and that is the high level of salts. And at the same time, it might find a better solution by finding an efficient way in controlling it through soil composition comparison. The Effects of Sodium Chloride Solution on the growth of Tomato Plants (Lycopersicon esculentum) (Larsen, 2007) Physiology of Salt Tolerance: Annual Review of Plant Physiology (Leon Bernstein and H. E. Hayward, Agricultural Research Division 2000) serves as the first fundamental research for our paper.

SCOPE AND LIMITATION

The coverage of this research is about the analysis of the salt level in different soil textures. This study covers the Properties of Sodium Chloride which includes its physical properties such as its crystalline form and hypotonic property. Also, the Effect of Level of Salinity in Wet land and dry land farming such as Dehydration and Stabilization. In relation with the part of analyzing the salinity, this research will specifically use Soil salinity yield test. Other topics which will not be covered by the said topics will be excluded from the study and will not affect the research.

Chapter II – Review of Related Literature

SALINITY

Salinity is the amount of salt in a body of water or in soil. Salinity in the soil is caused by natural processes such as mineral weathering or the gradual withdrawal of an ocean (Graaff, 2001)It can also be caused by artificial processes such as irrigation. Dry land salinity occurs when the water table is between two to three meters from the surface of the soil. Also occurs on landscapes that are not irrigated. The salts from the groundwater are raised by capillary action to the surface of the soil. This occurs when groundwater is saline and is favored by land use practices allowing more rainwater to enter the aquifer than it could accommodate. Salinity from irrigation can occur over time, because almost all water contains some dissolved salts.

When the plants use the water, the salts are left behind in the soil and eventually begin to accumulate. Since soil salinity makes it more difficult for plants to absorb soil moisture, these salts must be leached out of the plant root zone by applying additional water. Salinization from irrigation water is also greatly increased by poor drainage and use of saline water for irrigating agricultural crops. Salinity greatly affects agriculture because of the fact that salinity in soil produces salt that dehydrates the plant. Buildup of salt within the plants itself also has great effect on them, it shows older leaves which has long exposure to excess salt. The signs that indicate salinity is too high for a plant are slow and stunted growth, small stunted fruits, increased in succulence of leaves, leaves may be darker green or bluish green and leaves may turn yellow or brown, mottle and drop off from the plant.

According to (Blaylock, 2004) it happens when too much salts accumulate in the root zone, causing the plants to exert more energy to extract the water from the soil that also gives plants stress. The salinity in the soil is dependent in soil type, climate, weather, use and irrigation routines. As the plants absorbs the water and also the loss of water due to evaporation, the soil salinity then increases because salts become more concentrated. Thus, evapotranspiration between irrigation periods can further increase the soil salinity. Salinity can also affect the physical property of soil by causing fine particles to bind together into aggregates that is known as Flocculation. Flocculation is beneficial in terms of soil aeration, root penetration and root growth. Although soil salinity has a positive effect on soil aggregation and stabilization, but too much salt can negatively affect them and potentially lethal to plants. The primary physical processes associated with high sodium concentrations are soil dispersion and clay platelet and aggregate swelling.

According to (J.D, 1977), salt is a clear to white crystalline mineral that is orthorhombic. It has a boiling point of 1,413 °C and a melting point of 801 °C. Also have a hardness of 2.5 according to the moh’s scale and a density of 135 lb/ft. Salt is also the product of salinity which affects the growth of plants. Sodium Chloride or salt is essential to plant and animal life but can be harmful to both if used at excessive amounts. Salt is also used in food preservation which is called salting and is also one of the oldest known seasoning for foods. In humans, salt is needed in order for the body to survive but as stated earlier, too much salt may cause harmful effects such as high blood pressure in some sensitive individuals. Sandy soil is simply a type of soil that contains visible large particles to the naked eye, usually light in color and stays loose allowing moisture to penetrate easily. It is granular and contains very small rocks and mineral particles. It is formed by disintegration and weathering of rocks and is easier to cultivate when rich in organic material. It is good for plants since it lets the water go off so that it does not remain near the roots and lead them to decay.

SOIL TEXTURE

(P., 2009)The forces that bind clay particles together are disrupted when too many large sodium ions come between them. When this separation occurs, the clay particles expand, causing swelling and soil dispersion. Soil dispersion causes clay particles to plug soil pores, resulting in reduced soil permeability. Increased amounts of calcium and magnesium can reduce the amout of sodium-induced dispersion. Soil dispersion hardens soil and blocks water infiltration, making it difficult for plants to establish and grow. The decrease in decomposition causes soils to become infertile, black alkali soils. The main concerns related to the relationship between salinity and sodicity of irrigation water are the effects on soil infiltration rates and hydraulic conductivities. Essentially, the swelling factor predicts whether sodium-induced dispersion or salinity-induced flocculation will more greatly affect soil physical properties.

As said in (A.L., 2000). Soil composition plays an important role in all aspects of irrigated agriculture, and the role of soil texture with respect to effects of salinity and sodicity is no exception. Soil texture helps determine how much water will be able to passthrough the soil, how much water the soil can store, and the ability of sodium to bind to the soil. The three main clay types are montmorillonite, illite, and kaolinite clays. On the microscopic scale, each of these clays has a different lattice structure, i.e., different building blocks. This directly affects the ability of sodium to bind to each type. Basically, the more

Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. May be found as a soil or settled under a body of water. Silt has a moderate specific area with a typically non-sticky, plastic feel. Silt usually has a floury feel when dry, and a slippery feel when wet. Silt can be visually observed with a hand lens. It is a loose sedimentary material with rock particles usually 1/20 millimeter or less in diameter also contains 80 percent or more of such silt and less than 12 percent of clay.

Clay is heavy, sticky, fine grained soil that combines one or more clay minerals with traces of metal oxides and organic matter. It is mainly composed of fine particles of hydrous aluminum silicates and other minerals, and that is used for brick, tile, and pottery. Clay, a fine grained soil, also differ with the other fine grained soils by means of size and mineralogy.

Sand is a granular material that is mainly composed of finely divided rocks and minerals that is very tiny and loose. It came from the disintegration of rocks, consists of particles smaller than gravel but coarser than silt, and is used in mortar, glass, abrasives, and foundry molds. The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica usually in the form of quartz.

Loam is the mixture of sand, silt, and clay. Specifically, 40% silt, 40% sand, and 20% clay. These proportions can vary to a degree however, and result in different types of loam soils. This type of soil is good for growing plants because it contains more nutrients, moisture, and humus than sandy soils, have better drainage and infiltration of water and air than silt soils, and are easier to till than clay soils.

ELECTROMAGNETISM/ELECTROMAGNETIC INDUCTION

It is produced when electricity and magnetism were `unified’. The existing connection develops from the fact that an electric current (the flow of electrons in a metal) produces a magnetic field. Electromagnetic induction is the production of a potential difference of voltage across a conductor when it is exposed to a varying magnetic field.

SOIL SALINITY FIELD TEST

SSFT is a procedure done by (Agriculture, 2000) to measure the salinity level in your soil. It is a test verified by NSW Agriculture in November 8, 2000 but claimed to be less accurate than lab tests by estimated 10%. Its objectives are to assess the salinity level of salinity and texture of the soil sample.

A research by (Larsen, 2007) explained the effect of sodium chloride solution on the growth of tomato plants. Its primary objective is to determine how different concentrations of a solution of sodium chloride affect primary growth in tomato plants.

CATION-EXCHANGE CAPACITY (CEC) CEC s the number of exchangeable cations, an ion that has a positive charge per dry weight that a soil is capable of holding at a given pH value, and available for exchange with soil water solution. It is used to measure of soil fertility, nutrient retention capacity, and the capacity to protect groundwater from cation contamination.

BASE SATURATION

The Fraction of exchangeable cations that are base cations (Ca, Mg and K ). The higher the amount of exchangeable base cations, the moreaciditycan beneutralizedin the short time perspective. Thus, a soil with high cation-exchange capacity takes longer time to acidify (as well as to recover from an acidified status) than a soil with a low cation-exchange capacity (assuming similar base saturations).

UNIT OF MEASUREMENT FOR CEC – meq/100g. or lb/acre. – translation from meq/100g to lb/acre, for available nutrients, can be made by calculating, that considers the ion’s valence, atomic weight, and by estimating the soil depth and its density. THINGS THAT AFFECT CEC pH Level CEC is dependent on pH level, due to the Hofmeister series, which describes the relative strength of various Cations’ absorption to colloids. When soil acidity increases, pH decreases, more H+ ions are attached to cations. Inversely, when soil becomes more basic, pH increases, the available cations in solution decreases because there are fewer H+ ions to push cations into the soil solution from the colloids ( CEC increases ). ORGANIC MATTER Organic matter increases the CEC in soil by increasing its available negative charges. Organic matter in soil gives, usually, a positive impact on soil fertility. LIBRARY DETERMINATION – extraction with ammonium acetate -Silver-thiourea method (one-step centrifugal extraction )

Chapter III – Materials and Methods

METHODOLOGY

COLLECTION

Gather and prepare 7 containers. After, collect soils of different soil textures with at least 150g each. After collecting the soil textures, prepare 50g of sodium chloride for each sample.

PREPARARATION

Prepare the gathered materials. The 3 experimental setups will each have 3 containers which will contain the main soil composition and the other mixture of soil composition. Classify each container according to soil composition. Put at least 500 grams of assigned soil composition.

To control extraneous variables between each soil, each will be given respective amounts of water in accordance to their usual hydraulic level. And all will be exposed to the same environmental features. And since Silt Soils are most common in successful farming, it will serve as the control group.

TREATMENT

To ensure the regularity of the amount of soil, the researchers will conduct first observations after applying controlled variables. Using soil salinity yield test, measure the amount of salinity of the 3 main soil composition. Then after ensuring their regularity, do the same procedure to the control group which will be the silt soil and the remaining set-ups of mixed soil compositions. After recording the salinity level, apply 5 parts of water per 1 part of soil. At least 2.5 liters of 25% saline water must be added to each experimental unit. After letting the mixture set, apply the Soil Salinity Field Test. Take a soil sample and leave it to dry as long as possible (leave sample bag or container open for at least a day to let moisture escape). It can be oven-dried on a tray in a cool oven. The samples must be crushed and dried so there are no large aggregates (clods of soil 2mm or larger). You may need to crush these aggregates with a mortar-and-pestle, rolling pin or hammer. Remove any foreign Matter, plant material and stones from the sample. The test involves adding one part soil for every five parts of water. So if you add 50g of soil (weighed on scales) to the testing container, then you need to add 250ml of water. Shake the container for three minutes to make sure the salts dissolve. For clay loams and clay soils, more shaking (for one minute every 3 minutes repeated three times) will bring more salts into the solution and increase the accuracy of the test. Allow the solution to settle for a minute before testing. Place the salinity meter in the solution (but not in the soil in the bottom of the jar) and read the display once it has stabilized. Wash the meter electrodes and sample jar with distilled or rainwater, and dry. Convert your salinity meter readings to soil salinity (ECe) by multiplying the value by the Conversion Factor based on the texture of the soil sample. For sand multiply it to a factor of 17. For Loams multiply by factor of 9.5. Clay loams and light loams will be multiplied by 8.6 and sandy loams by 13.8. After replications of procedures, increase the salinity level content of the water applied to the soil by 25% until it reaches a max percentage of 75% salinity level. At the end of the experiment, gather the data that was recorded. Analyze and compare the gathered data as to which soil composition gave a salinity reading that is approximately the closest to the regular salinity level mark.

Flowchart

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Statistical Treatment: One-Way ANOVA

Bibliography and Sources

A.L., M. (2000). Role of Soil Composition in agriculture. Retrieved from Soil compositions.

Agriculture, N. (2000, October). How to Texture Soils & Test for Salinity. Retrieved from Salinity notes: http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0008/168866/texture-salinity.pdf

Blaylock, A. D. (2004). How Salinity can greatly affect Soil Production. Retrieved from Effects of Salinity level on Soil.

Graaff, V. d. (2001). Salinity : Overview. Retrieved from Salinity.

J.D, R. (1977). Salt or Sodium Chloride Properties. Retrieved from Salt.

Larsen, S. (2007, October 15). The effects of Sodium Chloride (NaCl) Solution on the growth of tomato plants (Lycopersicon esculentum). Retrieved from https://www.pcc.edu/library/sites/default/files/sodium-chloride.pdf

P., S. (2009). Soil composition properties. Retrieved from Soil Composition.

Queensland. (2007, July). Natural Resources. Retrieved from Facts Land Series: http://222065430381538974.weebly.com/uploads/1/1/5/2/11520542/measuring_salinity_-_derm.pdf

Chapter IV – Data Analysis and Research Findings

Soil

Texture

Loamy sand

Coarse

4.95

Sandy loam

Moderately coarse

10.49

Loam

Medium

4.32

Silty clay loam

Moderately fine

7.06

Clay loam

Moderately fine

10.48

Silty clay

Fine

7.87

Clay

Fine

17.15

Chapter V – Discussions and Recommendations

Summary

Purpose of the Study

The purpose of this study was to analyze the salt level in different soil textures. For the researchers to be able to identify which soil composition/s give salt level that is approximately the closes to the regular salt level mark.

Restatement of Research Questions

The research questions for this study were: (1) To identify the variability of salinity level when two soil compositions are mixed. (2) How does the salinity level of each soil composition differ from the mixed soil compositions? (3) Does the difference between the soil compositions have relevance to its permeability?

Research Methodology

The researchers used qualitative research method.

Conclusion

The findings in this study indicate that loamy sand has the most salt tolerance than the other samples we have gathered and clay having the lowest.