Fourth Lab Report: Balsam Ballerina

BALSAM BALLERINA

LECTURER’S NAME: MADAM DIANA DEMIYAH MOHD HAMDAN

TITLES: SOIL SALINITY (AND ELECTRICAL CONDUCTIVITY) TEST

COURSE: SS11403 ENVIRONMENTAL SOIL SCIENCE

DATE OF SUBMISSION: 24^TH APRIL 2018

DISCLAIMER: We posted our fourth laboratory report 3 days later with the lecturer's permission. We have to repeat the filtration activity using vacuum pump because the required volume of our rations and saturated paste for the Soil Nutrient Analysis were insufficient.

NAME OF MEMBERS	MATRIC NO
FARLIANA BINTI PADUPAI	BS17110276
KIM MUN KIT	BS17110536
MARYELL IRISHA BINTI HILLARIAN	BS17110372
NURUL FATIEN NADZIRAH BINTI JAITULLAH	BS17110289
RATNA FAIRUZ BINTI NOOR AZAM	BS17280750
TEO YU ROU	BS17110465

1. INTRODUCTION

 Salinity is a measure of the soluble salts’ concentration in the soil. The most common salt is sodium chloride and others include bicarbonates, sulphates and carbonates of calcium, potassium and magnesium. Some salts are useful, for instance, in fertilizer form, but too much salt of any kind is detrimental to plants and other organisms.

The salinity of soil refers to the amount of salts in the soil and it can be estimated by measuring the electrical conductivity (EC) of an extracted soil solution. Soil electrical conductivity (EC) is a measurement that correlates with soil properties that affect crop productivity, including soil texture, cation exchange capacity (CEC), drainage conditions, organic matter level, salinity, and subsoil characteristics. It is measured in either decisiemens (dS/m) or microsecond (µS/cm).

Ions increase the water's ability to conduct electricity. Common ions in water that conduct electrical current include sodium, chloride, calcium, and magnesium. Because dissolved salts and other inorganic chemicals conduct electrical current,conductivity increases as salinity increases. The determining of electrical conductivity of soil sample is usually tested with different ration of soil to water (1:1, 1:2 and 1:5) and saturated paste. Saturation paste test from soil salinity is more convenient. Although EC does not provide a direct measurement of specific ions or salt compounds, it has been correlated to concentrations of nitrates, potassium, sodium, chloride, sulfate, and ammonia. For certain non-saline soils, determining EC can be a convenient and economical way to estimate the amount of nitrogen (N) available for plant growth.

Salinity can affect plant growth in several ways, directly and indirectly. As for direct damage, salinity can decrease the water uptake of plants. High salts concentration results in high osmotic potential of the soil solution, so the plant has to use more energy to absorb water. Under extreme salinity conditions, plants may be unable to absorb water and will wilt, even when the surrounding soil is saturated. Other than that, the soil will be affected by specific-ions toxicity. When a plant absorbs water containing ions of harmful salts such as sodium, chloride, and excess boron, visual symptoms might appear such as stunted plant growth, small leaves or fruit distortions.

On the other hand, as for indirect damage, salinity may interfere with the plants’ uptake of essential nutrients. An imbalance in the salts content may result in a competition between elements. This condition is called "antagonism" which refers to an excess of one ion limits the uptake of another ion. For example, excess of chloride reduces the uptake of nitrate, excess of phosphorus reduces the uptake of manganese, and excess of potassium limits the uptake of calcium. Furthermore, the soil structure could be affected by sodium content in soil. In saline soils, sodium replaces calcium and magnesium, which are adsorbed to the surface of clay particles in the soil. Thus, aggregation of soil particles is reduced, and the soil will tend to disperse. When wet, a sodium-containing soil tends to seal, its permeability is dramatically reduced, and thus water infiltration capacity is reduced as well. When dry, a sodium-containing soil becomes hard has the tendency to crack. This may result in damages to roots.

There are several factors affect the amount and composition of salts in soils. Firstly, the irrigation water quality. The total amount of dissolved salts in the irrigation water, and their composition, influence the soil salinity. Therefore, various parameters, such as source water EC and its minerals content should be tested. The next factor is the amount of fertilizers applied. The type and amount of fertilizers applied to soil affect its salinity. Overuse and misuse of fertilizers leads to salinity buildup, and should be avoided. Besides, soil salinity is also affected by the field’s characteristics and agricultural history.  A poorly drained soil might reach salinity level that is harmful to the plants and to the whole crop. A soil that was not flushed after a previous growing cycle might contain high level of accumulated salts.

Soil salinity is an important indicator of soil health. It affects crop yields, crop suitability, plant nutrient availability, and activity of soil microorganisms which influence key soil processes including the emission of greenhouse gases such as nitrogen oxides, methane, and carbon dioxide. Excess salts hinder plant growth by affecting the soil-water balance. Soils containing excess salts occur naturally in arid and semiarid climates.

1.      To determine the salt level of the soil ( FSSA lakeside soil )

2.      To determine whether the soil salinity is suitable for planting impatiens balsamina seeds

·         Air dried soil samples

·         2mm mesh size sieve

·         200ml glass beaker

·         Spatula

·         Filter funnel

·         Test tubes

·         Distilled water

·         Vacuum pump

·         Laboratory flask

·         Graduated cylinder

·         Whatman filter paper (size 42)

·         Bottle container

·         Electric Conductivity Meter

Activity 1: Procedure for soil water ratio:

1.Air dried soil sample was used to make the ratio mixture with water of 1:1, 1:2 and 1:5.

2. The weight of the soil sample for the ratio of 1 is 25 g.

3. Distilled water was used for the mixture where 25 ml for the 1:1, 50 ml for 1:2 and 125 ml for 1:5.

4. After the water was added, the mixtures were stirred using glass rod for 10 minutes.

Diagram 1: Stirring mixture of soil and water

5. Three test tubes with a funnel on top each tube were prepared on a test tube rack. 

6. In each funnel, a folded filter paper was inserted so that the soil will not drop together with the water into the test tube. 

7. Each mixtures then poured into different funnels and let the water to finish falling into the test tube.

Diagram 2: Set up of experiment

Diagram 3: Filtrates after some time

Diagram 4: Compacted soil after water finish permeating from it

8. The filtrate were then placed into different small beakers so that it was easier to take the readings for electric conductivity.
9. The probe was rinse with distilled water before measuring the electric conductivity of each sample.

Activity 2: Procedure for saturated paste:

1. The air dried soil sample used was sieved manually which had the size of less than 2mm and were cleaned from foreign materials such as roots, bark and stones. 

Diagram 5: Process of removing foreign materials from soil

2. The total weight of soil sample used to make the saturated paste was 100 g and it was put in a beaker.
3. Distilled water was added to make the soil to be saturated with no standing water but had glisten appearance.
4. Before putting in the saturated paste into a funnel, a Whatman filter paper of size 42 was inserted.
5. After the paste was put in, a vacuum pump was used to extract the filtrate.

Diagram 6: Filtration using vacuum pump

6. The filtrate was then moved into a plastic bottle and labeled.
7. The electric conductivity of the filtrate was measured with the electric conductivity meter.

Diagram 7: Measuring the EC using electrical conductivity meter.

8. After measuring the electric conductivity, the meter probe was rinse with distilled water before putting it away.
9. The filtrate sample was kept in fridge for nutrient analysis.

RESULTS

Keywords: 

• Ave. : Average
• Temp. : Temperature

Diagram 8: First sample of 1:1 ratio

Diagram 9: Second sample of 1:1 ratio

Diagram 10: First sample of 1:2 ratio

Diagram 11: Second sample of 1:2 ratio

Diagram 12: First sample of 1:5 ratio

Diagram 13: Second sample of 1:5 ratio

Diagram 14: First sample result from vacuum pump

Diagram 15: Second sample result from vacuum pump

DISCUSSIONS

Soil electrical conductivity (EC) is a measure of the amount of salts in soil (United States Department of Agriculture, 2014). Soil electrical conductivity correlates with a lot of aspects which include of soil texture, drainage condition, cation exchange capacity (CEC), presence of organic matters, salinity and subsoil characteristics (Robert “Bobby”Grisso, 2009). Therefore, it shows apparent relationship between salinity and electrical conductivity of soil while there are still other components that will infer the results.

Based on our results, the reading of electrical conductivity of soil fluctuates drastically when the water ratio changes from 1:1, 1:2, 1:5 and even the saturated solvent extracted by using a vacuum machine. The electrical conductivity of filter soil solutionsis 1935μS, 2100μS, 851μS and 3.32μS respectively. To relate this with pH test that we have done, the pH reading is around 4.5 to 5.5 which may due to the abundance of mineral present in the soil such as iron, manganese, boron, copper and zinc. These dissolved ionized minerals may cause the high electrical conductivity of soil.

If we refer to the soil subsoil that we tested by using jar test, soil with high percent of clay and organic matter induces the increase of CEC in soil which this may affect the electrical conductivity in soil. Although there is only a small portion of clay in our soil, but undeniably that it can influence the salinity in soil. However, salinity will eventually become a problem when too much of salts accumulate in the root of plant, it will indirectly affect the growth of the plant. This is because the imbalance of solute concentration at inner and outer of root zone causes the decrease in plant available water which leads the plant stress to achieve appropriate osmotic pressure within the plant cell.

The water to soil ratio test enable us to see the dilution effect when there is increase of water to the soil, the salt concentration will be affected as well. The high reading of electrical conductivity shows that the high salinity in our soil which may also due to the soil location, land use, planting and application of fertilizer. Since our soil is collected from the lakeside that is just right beside the lake, accumulation of mineral salt may be one of the main reason why our soil is high in salinity. There is different planting around our selected soil area which may induce the use of fertilizer and pesticide and cause the store of chemical substance or artificial mineral salts in the soil, and eventually runoff from higher soil location to the lakeside soil. Therefore, it may be the reason why there are quite much amount of sulphate content in our soil.

Soil electrical conductivity (EC) is used to indicate the salinity of soil. Salinity of soil is one important factor indicating soil health, which affects activity of organisms. Soil salinity is correlated to the concentration of ions like nitrates, potassium, sulfate, sodium, chloride and ammonium. The inherent factors that affect soil salinity are soil minerals, climate and soil texture. Salinity management like land use management also affects soil salinity.

The objectives for this experiment are to determine the salt level of FSSA lakeside soil and to determine whether the soil salinity is suitable for planting impatiens balsamina seeds. According to the results obtained from saturated paste test, the ratio of water to soil of 1:1, 1:2 and 1:5 has EC of 1935μS, 2100μS and 851μS respectively. The EC of soil obtained is 3.32μS. Saturated paste test shows the immediate nutrients available in the soil. Due to the location of soil, at the lakeside, which is arid, this causes higher accumulation of soluble salts near the soil surface, resulting higher EC. Clay particles soil has higher CEC, which also gives higher conductivity of soil.

Maximum Yield, (2014, May 24th) Plant Nutrition, Retrieved from https://www.maximumyield.com/definition/637/salt-horticulture on 25th April 2018

Fernando V. (2010, January 15th), Soil Salinity Assessment of Agriculture Irrigated Lands, Retrieved from https://www.sciencedirect.com/science/article/pii/S0016706109003632 on 25th April 2018

Testing and Interpretation of Salinity and PH. (1995). Agriculturevictoria. Retrieved from http://agriculture.vic.gov.au/agriculture/farm-management/soil-and-water/salinity/testing-and-interpretation-of-salinity-and-ph on 26th April 2018

Robert “Bobby” Grisso, Mark Alley. W. G. Wysor, David Holshouser, Wade Thomason. (2009). Retrieved from https://pdfs.semanticscholar.org/e88b/d71059c64b1dac601981c439aa9708993abf.pdf. on 26 April 2018.

United States Department of Agriculture. (2014). Soil Electrical Conductivity, Soil Health – Guides to Educators. Retrieved from https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052803.pdf. on 27 April 2018.