[Research] The Effect of Synthetic Fertilizer and Organic Fertilizer on Plant Growth (Green ribbon)

INTRODUCTION

Cityfarm Malaysia contain 2 different type of fertilizer mainly the synthetic fertilizer which is composed of the Fertilizer A&B and the organic fertilizer which contain seaweed extracts.In hydroponic cultivation, plants require significant quantities of the three primary macronutrients, namely nitrogen, phosphorus, and potassium. Additionally, they also require the following essential micronutrients: calcium, magnesium, sulfur, iron, manganese, copper, zinc, molybdenum, boron, and chlorine(Sánchez, 2023).

As the trend shifts towards organic farming, an increasing number of individuals are opting for organic fertilizers when cultivating their crops. However, there exists a common concern among farmers and gardeners that using organic fertilizers may not yield the same results as synthetic fertilizers. Their concerns include not having the same yield, quality, size as well as overall health of the vegetables is not as good as compared to vegetables planted using synthetic fertilizers.

To address this issue, CityFarm Malaysia has initiated a small-scale experiment aimed at scrutinizing the disparities in the growth of vegetables, with a primary emphasis on the Green Ribbon lettuce, when nurtured using synthetic and organic fertilizers.

METHODOLOGY

To commence this experiment, we selected "green ribbon" vegetables, which were initially planted on 10/7/2023, making them approximately 3-4 weeks old at the outset. We established two distinct Nutrient Film Technique (NFT) systems, each equipped with its own water tank containing a different type of fertilizer. Specifically, System A was supplied with organic fertilizer, while System B received synthetic fertilizer, denoted as Fertilizers A&B. The duration of the experiment spanned approximately 5 weeks, culminating in the harvesting phase. Throughout this period, we meticulously recorded the weight, height, and leaf count of each vegetable on a weekly basis.

To ensure consistent conditions, we maintained nearly identical Electrical Conductivity (EC) values in both tanks. Additionally, we aimed to keep the pH levels within the range of 5.5 to 6.5. However, an unforeseen pH drop occurred in the organic tank due to the introduction of mosquito bti. The pH dipped to approximately 4, prompting us to rectify the situation by employing calcium carbonate powder to raise the pH back within the desired range. The data collected is then tabulated and a paired T-test is then run in order to identify if there is significant difference between the 2 batches of vegetables growing from synthetic and organic fertilizer.

RESULT

Table 1 Raw data for the weekly measurement for weight,height and leave number for the lettuce

T-Test for the weight of lettuce for both system A and B

H0: There is no significant difference between the means of the weight for both lettuce from system A and B .

H1: There is a significant difference between the means of the weight for both lettuce from system A and B .

P-value calculated : 0.153961112

P-value calculated is more than the alpha value which is 0.05 which indicates that the null hypothesis, H0 is accepted , there is no significant difference between the means of the weight for both lettuce from system A and B.

T-Test for the height of lettuce for both system A and B 

H0: There is no significant difference between the means of the height for both lettuce from system A and B .

H1: There is a significant difference between the means of the height for both lettuce from system A and B .

P-value calculated : 0.969899

P-value calculated is more than the alpha value which is 0.05 which indicates that the null hypothesis, H0 is accepted , there is no significant difference between the means of the height for both lettuce from system A and B.

T-Test for the leave number of lettuce for both system A and B

H0: There is no significant difference between the means of the leave number for both lettuce from system A and B .

H1: There is a significant difference between the means of the leave number for both lettuce from system A and B .

P-value calculated : 0.00000017

P-value calculated is less than the alpha value which is 0.05 which indicates that the alternative hypothesis, H1 is accepted , there is a significant difference between the means of the leave number for both lettuce from system A and B.

Table 2 average mean for all the weekly measurements of the lettuce

Figure 2 line graph showing the average mean of the plant weight for the 5 weeks for both systems

Based on the graph displayed, it is apparent that the lettuces cultivated in System A, which utilizes organic fertilizer, initially exhibit greater weight compared to the lettuces grown in System B. However, over time, this weight disparity gradually diminishes, and ultimately, both groups converge to attain an equivalent average weight by the time of harvesting.

Figure 3 line graph showing the average mean of the plant height for the 5 weeks for both systems

The graph clearly illustrates that the lettuce plants in System A initially exhibit greater height than those in System B, particularly around the third week of growth. However, as time progresses, the height of the lettuce plants in System A levels off and appears to reach a plateau. Interestingly, by the time of harvesting, the lettuce plants in System B have managed to attain a slightly greater height compared to those in System A.

Figure 4 line graph showing the average mean of the leave number of the lettuces for the 5 weeks for both systems

The graph provides a clear visual indication that the lettuce plants cultivated in System A, which incorporates organic fertilizer, consistently display a higher number of leaves when compared to the lettuce plants in System B. The disparity between these two groups of vegetables is quite pronounced. In particular, the lettuce plants in System A eventually reach an average leaf count of approximately 31 leaves, whereas the lettuce plants in System B only manage to achieve an average leaf count of around 20 leaves.

DISCUSSION

Based on the data presented, it can be concluded that there is a subtle distinction between lettuce plants grown using organic fertilizers and those cultivated with synthetic fertilizers.The  lettuce plants nurtured with organic fertilizers tend to have shorter stature but boast a higher leaf count in comparison to their counterparts grown with synthetic fertilizers. This indicates that while organic fertilizers may result in smaller plants, they compensate by yielding more leaves.

Besides, both sets of lettuce plants, whether cultivated with organic or synthetic fertilizers, appear to yield similar weights at the time of harvesting. This suggests that the choice of fertilizer does not substantially impact the overall weight of the lettuce. A notable discovery is that lettuces cultivated with organic fertilizers tend to possess a sweeter taste, while those grown with synthetic fertilizers may exhibit a more bitter flavor profile. This taste disparity is attributed to the potential overabundance of certain nutrients associated with chemical fertilizers, which can lead to bitterness in vegetables(Thomas, 2023).Another facts to take note is that It's essential to acknowledge that lettuces grown with organic fertilizers present certain challenges, such as smaller leaves and a softer plant texture. In contrast, lettuce nurtured with synthetic fertilizer is characterized by a crunchier and firmer texture. Another observable distinction lies in the coloration of the lettuce. Lettuce grown with synthetic fertilizer typically displays a lighter green hue and a fresher appearance, whereas lettuce cultivated with organic fertilizer tends to exhibit a darker green color and may not appear as fresh.

Figure 5 the difference in the size of the leaves growing from synthetic fertilizer(left) and organic fertilizer (right)

Figure 6 the difference in the overall size and color of the lettuces growing from synthetic fertilizer(left) and organic fertilizer (right)

In addition to its other attributes, an intriguing discovery is that CityFarm's organic fertilizer incorporates seaweed extract. This extract is derived from various brown seaweeds, including Sargassum, Laminaria, and Ascophyllum, and it boasts not only essential macro and micro nutrients, vitamins, and antibiotics but also a medley of growth hormones like auxin, gibberellin, cytokinin-kinetin, and cytokinin-zeatin. These growth hormones, richly present in seaweed extract, play a pivotal role in promoting plant growth by facilitating processes such as increased production, enhanced protein synthesis, cell division, and differentiation. Additionally, they contribute to fruit cell development and regulate overall plant growth, fostering optimal growth trajectories. Moreover, studies have demonstrated that the application of seaweed extract can augment nutrient content within leaves, ultimately leading to increased plant weight. This effect is attributed to the involvement of growth hormones in nutrient absorption and transportation processes within plants. Notably, seaweed extract also contains growth hormones like indole-3-acetic acid (IAA) and cytokinins, organic compounds known for stimulating growth through mechanisms such as protein synthesis, cell division, and nutrient metabolism. These findings underscore the multifaceted benefits of seaweed extract as an organic fertilizer, promoting robust plant growth and bolstering crop production (Yusuf et al.,2021) .

REFERENCES

R Yusuf et al 2021 IOP Conf. Ser.: Earth Environ. Sci. 828 012011

Sánchez, E. (2023). Hydroponics Systems and Principles Of Plant Nutrition: Essential Nutrients, Function, Deficiency, and Excess. Retrieved from https://extension.psu.edu/hydroponics-systems-and-principles-of-plant-nutrition-essential-nutrients-function-deficiency-and-excess

Thomas, R. (2023, May 7). 5 Reasons Organic Fertilizers Grow Better Vegetables. Dengarden. https://dengarden.com/gardening/Best-Garden-Fertilizer-For-Vegetables#:~:text=Chemical%20fertilizers%20can%20lead%20to,bland%20or%20bitter%2Dtasting%20vegetables.

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