Padi Sawah Week 4

For Week 4, the frequency of watering is reduced down to once a week with the same volume of water per watering session which is 500ml per pot.

Heavy Metal Analysis

Soil A: Mengkabong

ELEMENT	Concentration Sample 1 (mg/L)	Concentration Sample 2 (mg/L)	Concentration Sample 3 (mg/L)
Pb	0.014008413	0.002694417	0.003863217
As	-0.004957411	-0.015532467	-0.013303132
Cd	-0.000916353	-0.0010518	-0.001297817
Ni	0.004269601	-0.000323979	-0.00189394
Cu	-0.000190151	-0.005004651	-0.007049157
Mn	0.058932387	0.040371796	0.022724504
Fe	10.1544198	6.53118537	4.512930647
Zn	0.047445893	0.016755812	0.010892636
Mg	2.689317604	1.408097462	1.203621294
Ca	25.33700356	1.413638271	8.879992482

Soil B: Kg E Parking Lot

Element	Concentration Sample 1 (mg/L)	Concentration Sample 2 (mg/L)	Concentration Sample 3 (mg/L)
Pb	0.016859046	0.011719172	0.008474511
As	-0.013937892	-0.011844154	-0.007125657
Cd	-0.001000405	-0.001609932	-0.000745093
Ni	0.016589244	0.005770265	0.009374053
Cu	0.019619676	0.003180055	0.00755583
Mn	0.069652632	0.031951332	0.04337258
Fe	17.38350594	7.54151051	10.76769967
Zn	0.071774909	0.032541482	0.039898066
Mg	3.600086408	1.741994328	2.194362233
Ca	2.182807405	1.447029887	1.537269574

Soil C: ODEC

Element	Concentration Sample 1 (mg/L)	Concentration Sample 2 (mg/L)	Concentration Sample 3 (mg/L)
Pb	0.034108373	0.016938404	0.014879866
As	-0.014831497	-0.009602942	-0.014928663
Cd	-0.001471046	-0.001575582	-0.001450439
Ni	0.002639702	-0.003772476	-0.002710286
Cu	-0.004514014	-0.008854971	-0.009196772
Mn	0.175387851	0.079937844	0.063138778
Fe	7.92380651	3.223682831	2.880858733
Zn	0.052893795	0.020930451	0.014655389
Mg	4.036395659	2.346598506	1.856296147
Ca	190.5499666	135.221588	101.0084711

Soil D: FSSA Garden

Element	Concentration Sample 1 (mg/L)	Concentration Sample 2 (mg/L)	Concentration Sample 3 (mg/L)
Pb	0.023163616	0.012702458	0.004278169
As	-0.000992438	-0.001299157	-0.010279218
Cd	-0.001183789	-0.001596694	-0.001248602
Ni	0.017371732	0.005663495	0.005214698
Cu	0.014324932	0.002784504	-0.000458302
Mn	0.59368353	0.331655579	0.25556267
Fe	23.61708169	12.20601149	10.14707401
Zn	0.085585869	0.0386312	0.046453833
Mg	1.950157951	1.124537283	0.810986678
Ca	2.687650714	15.61181985	2.264993052

Soil E: 1B

Element	Concentration Sample 1 (mg/L)	Concentration Sample 2 (mg/L)	Concentration Sample 3 (mg/L)
Pb	0.005028751	0.001152354	0.003338012
As	-0.010652342	-0.017967004	-0.01682043
Cd	-0.001073568	-0.001608099	-0.001055397
Ni	0.005952083	0.00022175	0.002401394
Cu	-0.002252883	-0.006078029	-0.004446652
Mn	0.117481337	0.061454924	0.06290585
Fe	9.674508242	5.330201709	6.262510817
Zn	0.083358545	0.015041843	0.018363894
Mg	1.959683796	1.108059231	1.309824158
Ca	1.252989769	0.612166861	0.519958911

Discussion

     The determination of heavy metals and metalloids in soil may be carried out for a variety of reasons. That is soils from metal-contaminated industrial sites may be analysed for legislative purposes. Next is to access risk to human health or the environment. Beside to monitor the success of remediation strategies. Agricultural chemists may wish to access the availability of metals in soil, either as an indicator of potential plant deficiency of toxicity. Last but not least, to determine the likelihood of metals entry into the food chain of animals and man.

     The total 10 elements content provides base-line knowledge of soil composition, with respect to which changes due to natural or anthropogenic process can be assessed. The 10 element are Pb, As , Cd , Ni , Cu , Mn , Fe , Zn , Mg and Ca . Heavy metals are elements that exhibit metallic properties such as ductility, malleability, conductivity, cation stability, and ligand specificity. They are characterized by relatively high density and high relative atomic weight with an atomic number greater than 20. There are total 3 replicate that have been done for each soil. Some of these heavy metals such as As, Cd, and Pb are not essential for plants growth, since they do not perform any known physiological function in plants. While, for other heavy metal such as Cu, Fe, Mn, Ni and Zn are essential elements required for normal growth and metabolism of plants, but these elements can easily lead to poisoning when their concentration greater than optimal values

     For the first soil, that is from FSSA. Based on the graph, from the element Pb to Cu the value of concentration replicate of the 3 soil remained the same. In the environment, Pb is known to be toxic to plants, animals, and microorganisms. Effects are generally limited to especially contaminated areas. Pb contamination in the environment exists as an insoluble form, and the toxic metals pose serious human health problem, namely, brain damage and retardation, while for As its Ac is one of the contaminants element found in the environment which is notoriously toxic to man and other living organisms. Then, from the graph Cu the value is slightly increase. Plants require Cu as an essential micronutrient for normal growth and development, when this element is not available plants develop specific deficiency symptoms, most of which affect young leaves and reproductive organs. Then, from Mn to Fe there are dramatically increase value of the concentration. The peak value that we can see from the graph is element Fe. Fe is involved when a plant produces chlorophyll, which gives the plant oxygen as well as its healthy green color. This is why plants with an iron deficiency, or chlorosis, show a sickly yellow color to their leaves. Fe is also necessary for some enzyme functions in many plants. But, then there a noticeably change of value of Zn where the value is decreasing. Zn is involved in the synthesis of auxin, a plant hormone that helps plants determine whether to focus on growing tall or becoming bushy. Then for the element Ca there are only gently increase value of concentration replicate. Plant relies on the process of transpiration in which the plant roots take up the soil solution (which contains the needed calcium), transports it to new growth where the calcium is used and the excess water vapor escapes out through holes in the leaves called stomata. Overall, for the highest value of concentration replicate between the 3 replication that is for the first replication. While the lowest value is from the third replication.

     Second sample of soil provided that is from Mengkabung. From the graph, we can see from the element Pb to Mn the value of concentration is stabilised. In the environment, Pb is known to be toxic to plants, animals, and microorganisms. Effects are generally limited to especially contaminated areas. Pb contamination in the environment exists as an insoluble form, and the toxic metals pose serious human health problem, namely, brain damage and retardation, while for As its Ac is one of the contaminants element found in the environment which is notoriously toxic to man and other living organisms. Then for Mn is used in plants as a major contributor to various biological systems including photosynthesis, respiration, and nitrogen assimilation. Mn is also involved in pollen germination, pollen tube growth, root cell elongation and resistance to root pathogens. But then, there are noticeably increase change for the element Fe. Fe is involved when a plant produces chlorophyll, which gives the plant oxygen as well as its healthy green color. This is why plants with an iron deficiency, or chlorosis, show a sickly yellow color to their leaves. Fe is also necessary for some enzyme functions in many plants. Next, we can see for the Zn element the value of concentration is dropping. The function of zinc is to help the plant produce chlorophyll. Leaves discolor when the soil is deficient in zinc and plant growth is stunted. Zinc deficiency causes a type of leaf discoloration called chlorosis, which causes the tissue between the veins to turn yellow while the veins remain green. Chlorosis in zinc deficiency usually affects the base of the leaf near the stem. Next, element Ca there are increasing value of concentration replicate. Ca, in the form of calcium pectate, is responsible for holding together the cell walls of plants. When calcium is deficient, new tissue such as root tips, young leaves, and shoot tips often exhibit distorted growth from improper cell wall formation. Calcium is also used in activating certain enzymes and to send signals that coordinate certain cellular activities. The plant relies on the process of transpiration in which the plant roots take up the soil solution (which contains the needed calcium), transports it to new growth where the calcium is used and the excess water vapor escapes out through holes in the leaves called stomata. Anything that slows transpiration, such as high humidity or cold temperatures, can induce calcium deficiency even if the calcium levels are normal in the growing medium.  Overall, the highest value of concentration replicate is the first replication, while the lowest value is from the third replication.

     Third sample soil is collected from 1 Borneo. Based on the graph, the result of 3 replicates shows a dramatic increase in the concentration of Iron (Fe) and also a slight increase in the concentration of Magnesium (Mg) and Calcium (Ca). There’s no visible result can be seen for the rest of the heavy metals on the graph as there are only a small concentration that were present in the soil. This result indicate that this soil is very good for plant to grow as it contained high concentration of Iron (Fe) that enable the plant to grow chlorophyll to undergo respiration process. Magnesium (Mg) also function the same way as Iron (Fe) does as it assist in chlorophyll formation. Whereas, Calcium (Ca) prevent the plant from distorted growth that is caused by improper cell wall formation.

     Forth sample soil that is been collected is from ODEC. Based on the graph, the result of 3 replicates shows an increase in the concentration of Calcium (Ca). In this graph, there’s an Iron (Fe) deficiency occurred, and it can be proved by the colour of the plant’s leaves where it shows sickly yellow colour. As for the other heavy metals, the concentration is not visible in the graph as Iron (Fe) and Calcium (Ca).

     Lastly, fifth sample soil is from parking lot Kg. E’s. Based on the graph, Iron (Fe) shows a dramatic increase compare to Magnesium (Mg) and Calcium (Ca) in all 3 replicates. This indicates that this soil is very good in assisting the growth of chlorophyll that gives the plant’s leaves its green colour.

Weekly Measurement of Plant Height

Note: Since for Week 4, the plants are only watered once per week, some plants are starting to show signs of dehydration, especially Soil B as the volume of soil used in this study is lesser compared to other soils, therefore the volume of water retained will be lesser as well.

Soil A: Mengkabong

Average Height: -

Soil B: Kg. E Parking Lot

Average Height: 27.84cm

Soil C: ODEC

Average Height: 29.85cm

Soil D: FSSA Garden

Average Height: 37.0cm

Soil E: 1Borneo

Average Height: 25.12cm

Plant Mass

Soil	Initial Weight(g)	Final Weight(g)	Change in weight(g)
A	-	-	-
B	0.0865	0.0831	0.0034
C	0.2307	0.1376	0.0931
D	0.1265	0.0948	0.0317
E	0.1621	0.0934	0.0687

Questions from Week 3:

1.  Did the group confirm the result of soil texture type from jar test, textural triangulation with the sieve analysis test?

Did the results for soil texture from jar test and sieve analysis test correspond with each other?

Answer: No. As shown in Table 1 below, the results from jar test and textural triangulation did not correspond with sieve analysis test. This could be due to several reasons when conducting the jar test and textural triangulation such as the colours of different soil components appear similiar, therefore the proportions of different soil components are not differentiated well enough, the shape of the jar are not angular enough so the proportions of soil component isn't accurate, along with the possibility of parallax error when measuring the soil components.

 Table 1: Results of jar test(JT) and sieve analysis(SA) of the 5 soils used

Soil Soil component	A		B		C		D		E
	JT	SA	JT	SA	JT	SA	JT	SA	JT	SA
Sand	42%	87.41	23%	64.03	85%	83.21	39%	52.76	50%	77.83
Silt	22%	7.11	38%	15.04	12%	9.39	58%	23.49	43%	15.56
Clay	37%	5.47	38%	20.94	4%	7.40	3%	23.75	7%	6.61

2.  How does nutrient and heavy metal content have relationship with soil pH?

Answer: 

     According to Dr. Thomas L. Jensen, most ideal soils have a pH that is near neutrality, which is from 6.5(slightly acidic) to 7.5(slightly alkaline). The majority of plant nutrients are also available in the pH range of 6.5-7.5. Nutrients such as nitrogen, potassium and sulphur are plant nutrients that aren't that affected by soil pH, on the other hand phosphorus is a nutrient that is directly affected as when pH is higher than 7.5, phosphate ions will react with ions of calcium and magnesium to form less soluble compounds, while pH is lower than 6.5 phosphate ions will reach with aluminium and iron ions to form less soluble compounds. 

     As for soil heavy metal, it is also influenced by soil pH. Based on a study conducted by Raymond N. Yong and Yuwaree Phadungchewit in 1993, it is found that high soil pH values can initiate precipitation mechanisms which will influence the retention mechanism of heavy metals in soils. At pH values about 4 or 5, heavy metals such as lead, copper, zinc and cadmium will be precipitated into compounds such as hydroxides while in low pH soils that isn't the case.

References:
http://www.nrcresearchpress.com/doi/abs/10.1139/t93-073#.WTPJc2iGPIW
http://www.ipni.net/ipniweb/pnt.nsf/5a4b8be72a35cd46852568d9%20001a18da/97c1b6659f3405a28525777b0046bcb9