FOURTH LAB REPORT: TARAB ARAB Padi Sawah

Lecturer: Dr. Diana Demiyah binti Mohd Hamdan

Date of Submission: 24^th April 2018

Soil Analysis Test: Soil Salinity Test

NAME	MATRIC NUMBER
NG JING JIE	BS17160675
FICKRY JAJURI	BS17160677
NURUL IRINA AK DOUGLAS NYEGING	BS17110050
MARILYN LEANNE MONROE	BS17110366
EMILEY TOMPOK @ MOJINOK	BS17110145
SITI NURAZWANNI BT. WARISHAD	BS17160698

INTRODUCTION

Salt content in the soil is called soil salinity. Salinization is the process of increasing the salt content. The salinity may occurs naturally or through human-induced processes that cause the accumulation of dissolved salts. Saline soil is a term use to define as having a high concentration of soluble salts, high enough to affect the plant growth. Electrical conductivity of a water extract of a soil will be used in measurement to identify the presence of excess salt. Salinity reduces the water availability for plant use. In saline environments, the water is not held tighter to the soil, the plants will exert more energy extracting water from the soil due to the presence of salt. Therefore the excess salinity in soil water can decrease plant available water and can cause plant stress. 

Salinity of soil identified by the electrical conductivity of saturation extract of a soil, but routine diagnosis of salt problems are made on 1:1, 1:2 and 1:5 water soil ratio extract. Saturated paste extraction also a method to identify soil salinity. Plants are generally more sensitive to salinity during germination and early growth. Next, salinity affects the respiration and photosynthesis of plants. Biological N₂ fixation and soil nitrogen mineralization will decreases. Due to unfavorable osmotic pressure, the plant roots are unable to absorb the water or salts may interfere with other plant essential ions, causing deficiencies even the soil have contain adequate water. Other than osmotic influences that can harmful the plant of salts dissolved in soil water is by specific ion toxicities. The effects for paddy growth are reduced the germination rate, reduced the plant height, poor root growth and increase spikelet sterility.

OBJECTIVES

1.    To determine the electrical conductivity of the 5 different soil based on different water to soil ratio.

2.  To extract filtrate for the further nutrient analysis of the soil

MATERIALS AND APPARATUS

1.     Air dried soil samples

2.     2mm mesh size sieve

3.     200ml glass beaker

4.     Spatula

5.     Distilled water

6.     Vacuum pump

7.     Conical flask

8.     Graduated cylinder

9.     Size 42 Whatman filter paper

10.  Bottle container

11.  Electric Conductivity Meter

12.  Filter funnel

PROCEDURES

1.    Air dried soil samples from 5 different soil types were prepared.

2.    The 2mm mesh size sieve was used manually to filter and collect soils that were filtered out.

3.    The soil sample should not contain roots, barks, stones and excluded any foreign materials

4.    A saturated paste for each soil sample was made from mixture of 100 gram of each air-dried soil sample with distilled water.

5.    The mixture of 25 gram of one soil type and distilled water was also prepared with water ration of 1:1, 1:2 and 1:5. After the water was added, the mixture was swirled and mixed for at least 10 minutes.

6.    Size 42 Whatman filter paper was put on the filter funnel before putting in the saturated paste.

7.    The funnel was then put over a graduated cylinder as the water from the soil are being extracted or filtered. 

8.    Step 5 to 7 was repeated for 4 other different soil types.

9.    The saturated paste was then used to extract its filtrate from the soil using a vacuum pump.

10. The filtrate would then be extracted using the vacuum pump into a larger conical flask. 

11. The electric conductivity of the filtrate was measured by using the electric conductivity meter.

12. The probe was rinsed by using distilled water before measuring every samples.

13. The filtrate extracted from the vacuum pump was placed into a bottle container with label.

14. Step 13 is repeated for all the filtrate extracted from the paste with water to soil ration of 1:1, 1:2 and 1:5.

15. All the bottles were then labelled.

RESULTS

Soil Type	Soil Ratio
	1:1		1:2		1:5		Saturated
	Electric conductivity (µS)	Temperature ˚C	Electric conductivity (µS)	Temperature ˚C	Electric conductivity (µS)	Temperature ˚C	Electric conductivity (µS)	Tempeature ˚C
Odec	13.56	23.80	7.35	22.30	3.06	22.50	30.90	15.30
B1	114.40	23.90	112.40	24.20	97.20	23.40	213.00	23.80
Kampung E	265.00	22.90	203.00	23.30	134.10	23.60	693.00	19.20
Ums Peak	273.00	23.30	239.00	24.90	116.30	23.30	179.70	18.50
Tanah Hitam	55.40	22.20	51.30	22.60	39.70	22.10	30.90	15.80

Table 1: Electrical Conductivity of 5 different type soils mixtures and their respective ratios.

Soil	Volume Extracted from the Vacuum (ml)
ODEC	50
Compounds of Residential College E	20
Block B1	9.5
Garden Soil	7
UMS Peak	10

Table 2: Volume of filtrate extracted from each soil through the vacuum method

DISCUSSION

Soil salinity is usually assessed by determining the electrical conductivity (EC) of either a 1:1, 1:2 and 1:5 distilled water (soil dilution) or a saturated paste extract. Electrical conductivity analysis is an indicator of soil health. It 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. Electrical conductivity of sand which is coarser contains high soluble salt content, followed by loam soil and silt soil. Clay soil has the least soluble salt content.

Based on the results, soil from ODEC has the highest reading of electric conductivity for water ratio of 1:1 (13.56 ms), 1:2 (7.35 ms), 1:5 (3.06 ms) and saturated paste (30.9 ms). Soil pH also affects the solubility of salts. These indicate that ODEC highest salt content causing the conductivity to be the highest among all. Based on previous experiment, recorded average pH of ODEC is 6.96 which is near to alkaline. Based on the plant observation, the paddy only grows in ODEC’s soil due to its pH which is 6.96 which is almost neutral. Even with high salt content, paddy can grow on ODEC’s soil because the optimum pH for paddy to grow is 5.5 until 7.0. Usually, soil with high soluble salt content can decrease the ability of the plant to take up water that lead to decreasing of growth rate (Munns, R. n.d).

Meanwhile, the reading of electrical conductivity for the soil from Garden Soil is 55.4 µS for 1:1, 1:2 and 1:3 is the lowest. This shows that garden soil has the low soluble salt content. Even with a low soluble salt content, due to its pH which is 4.34, paddy plant cannot grow on it because it is acidic. For saturated, the soil from UMS Peak is the lowest which is 179.7 µs. The texture of soil from UMS Peak is clay loam and it is dominated by clay minerals that have a low electrical conductivity.

Other than pH, the presence of organic matter was also important as the Mason Jar test showed that other than the ODEC soil, most of the soil consists of organic matter which plays an important role for the seeds to germinate and continue to grow. 

One of the most brutal environmental factors limiting the productivity of crop plants is salinity because most of the crop plants are sensitive to salinity caused by high soluble salt content in the soil, and the area of land affected by it is increasing day by day. Salinity can effect in decreasing of agricultural production of most crops, soil physicochemical properties, and ecological balance of the area. The impacts of salinity include—low agricultural productivity, low economic returns and soil erosions, (Hu and Schmidhalter, 2002). High salt levels in the soil can upset the nutrient balance in the plant or interfere with the uptake of some nutrients (Blaylock et al., 1994). Even with high salinity, pH of the soil also determines the plant growth. Soil pH influences how easily plants can take up nutrients from the soil. Some plants can tolerate grow well in acidic soil while some can grow well in slightly acid to moderately alkaline soils. The soil pH can also influence plant growth by affecting the activity of beneficial microorganisms. Bacteria that decompose soil organic matter are hindered in strong acid soils. Organic matter is prevented from breaking down, lead to the accumulation of organic matter and the tie up of nutrients. 

CONCLUSION

From the analysis of the 5 types of soil, ODEC sand proved to be the soil type with the highest electrical conductivity. The electrical conductivity plays an important role in determining the physical and chemical properties of a soil. It allows us to identify the various contents in the soil through further analysis of the soil.