Nutrient Content And Fertilizer Requirement For Jatropha Curcas Biology Essay

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Abstract: Problem statement: Biodiesel has emerged to become an eye-opener as an alternative to petrodiesel. Apart from its major potential as a green energy, other components of the plant are beneficial as well. Even so, there is still a general lacking of information on how much of the nutrients that contain and needed by J. curcas and how much of the fertilizers should be added to support the optimum growth of the plant. Therefore the objectives of this study were to determine the amount of nutrients such as N, P, K and Mg contain in J.curcas and to carry out estimation on fertilizers requirement to be added during its first and subsequent year of planting. Approach: The experiment was conducted at Ladang 2, UPM. In this study, 80 seeds of Jatropha curcas were sown in polyethylene bags at the initial stage of planting and were then transferred into the field and planted according to 2 x 2 m planting density after one week of sowing. The J. curcas were harvested after one and two years of planting and were analyzed for total nitrogen (N) using Kjeldhal method while total phosporus (P), potassium (K) and Magnesium (Mg) were done using dry ashing method. The nutrients were analyzed using Atomic Absorption Spectrophotometer. Results: The total amounts of N, P, K and Mg in 1 year old plant were 101.37 g, 9.63 g, 48.42 g and 4.01 g respectively while the amount of nutrients for 2 year old plant were increased to 104.41 g N, 11.54 g P, 55.69 g K and 4.08 g Mg due to its demand for fruit development. It was also found that potassium content in seed pod was very high (4.27%) and it can be recommended as a good source of K fertilizer. As much as 550.94 kg of urea, 122.58 kg of TSP, 242.13 kg of MOP and 61.78 kg of kieserite are required during the first year of planting while 914.15 kg of urea, 247.98 kg of TSP, 478.93 kg of MOP and 196.21 kg of kieserite were estimated for the second year of planting per hectare basis. Conclusion: It should be emphasized that all the values given here are only estimation of the actual condition in the field as well as the growth and yield of the plant recorded in this study may only be applicable to similar type of soil.

Key words: J.curcas, fertilizers, nitrogen, phosphorus, potassium, magnesium, urea, TSP, MOP, kieserite

INTRODUCTION

The exhaustive exploitation of fossil fuel has led to an increasing need to find alternative source of fuel to supply the energy for the spiralling need of industrialization and urbanization. With the increasing awareness on mitigating the global climate change with respect to the escalating emissions of green house gases, biodiesel has emerged to become an eye-opener as an alternative to petrodiesel. Developing countries such as India has been progressively growing Jatropha curcas and is taking strong initiatives to improve yields[1].

Jatropha Curcas, which falls in the family of Euphorbiaceae grows best on well drained soils with preferable pH of 6-9 provided with good aeration. However, it is also well adapted on marginal soils with low nutrient content and can tolerate well on long periods of drought. Therefore, it is largely found in arid and semi-arid regions also in areas with rainfall ranges from 200-1500 mm per year [2, 5].

The rationale on its interesting possibility for biodiesel production is attributed to its rather high oil content. Analysis from TERI found that the oil content on seed basis varied from 25 to 38% although some have claimed that it can produce up to 60 % of oil content depending on several important factors which are; the selection of high-oil-yielding breeds, advanced application of pruning techniques, moisture and nutrient content in soil, ripening stage at harvest as well as employing high quality of processing equipments [1, 2, 3].

Apart from its major potential as a 'green energy', other components of the plant are beneficial as well. The seed cake of this Euphorbiaceae family may contain a great deal of nutrients and can supplement as an alternative source of organic manure for the plant. According to Saxena[4], the seed cake produced after oil expulsion process may contain more than 5 % of nitrogen, phosphorus (>2.5% P2O5) and potassium (1% K2O). This can eventually be processed and transformed into valuable organic fertilizer to improve on the soils nutrient storage that is continuously being depleted due to the nutrient-harvesting by the plant.

However, there is still a general lacking of information on how much of the nutrients that contain and needed by J. curcas and how much fertilizers should be added to support the optimum growth of the plant[5]. These questions need to be addressed so as to achieve a more sustainable agricultural management.

Therefore the objectives of this study were:

1) To determine the amount of nutrients such as N, P, K and Mg contain in J.curcas

2) To carry out estimation on fertilizers requirement to be added during its first and subsequent year of planting J. curcas.

MATERIALS AND METHODS

Planting material

The experiment was conducted at Ladang 2, UPM. Data collected were analyzed at the Fertility Laboratory, Land Management Department, Faculty of Agriculture. Nutrient analyses were conducted at the Atomic Absorption Spectrophotometer Laboratory. In this experiment, 80 seeds of Jatropha curcas were sown in polyethylene bags where each bag contains 4 seeds at the initial stage of planting. After one week of planting, the seedlings were then transferred into the field and planted according to 2 x 2 m planting density. Watering and weeding were done manually. Plant nutrient analyses were done according to the standard methods.

Plant analysis

The J. curcas were harvested after one and two years of planting and the collected samples were separated according to its plant parts (leaf, stem and root). The fresh and dry weights were recorded according to each of the plant components. All the plant parts were then placed in the hot air oven at 60°C for 48 to 72 hours. On the other hand, fruits harvested following the second year of planting were collected and separated according to their components (seed pod, kernel and seed coat). These samples were then stored in air-tight containers after the process of drying and grinding. All of the samples from the fruit and vegetative components were analyzed for total nitrogen (N) using Kjeldhal method [6], while total phosporus (P), potassium (K) and Magnesium (Mg) were done using dry ashing method [7]. The nutrients were analyzed using Atomic Absorption Spectrophotometer (AAS).

For the determination of total N by Kjeldhal method [6], as much as 0.1g from the samples was used. Then, about 5 mL of sulfuric acid with 5% salycylic acid were added to the samples and heated at 100 °C using block digester and placed in the fume hood. After an hour, as much as 0.3 g of sodium thiosulfate were added and then left for about half an hour for the digestion to take place. Then, one Kjeldhal tablet was placed into each of the digested sample while increasing the temperature to 300°C for further digestion. The solutions of the samples eventually turned colourless and were left to cool before filtering and made up to 100 mL volume. Finally the samples were sent to the Auto Analyzer (AA) for nitrogen analysis.

For the analysis of total phosphorus (P), potassium (K) and magnesium (Mg) by dry-ashing method [7], as much as 0.5 g of tissue samples were placed in a porcelain crucible and heated at 300°C for an hour. After that, the temperature was raised to 520°C for 5 hours until the samples turned white. Samples were then left to cool in a desiccator. Then, 2 mL of distilled water and 2 mL of hydrochloric acid were added and the samples were heated using a hot plate placed under the fume hood to dry. Next, about 10 mL of 20% nitric acid were added into the samples and placed in the water bath for an hour. Afterwards, the sample mixtures were transferred into 100 mL volumetric flasks by rinsing the crucible several times to ensure all mixtures were completely transferred into the volumetric flasks, made up to volume with deionized water and filtered into plastic vials. Finally, the samples were analyzed for nutrient content by Atomic Adsorption Spectrophotometer.

RESULTS AND DISCUSSUONS

Concentration of nutrient uptake in J. curcas

The nutrient contents in leaves, stems and fruits were analyzed and the concentrations of N, P, K and Mg indicated that the highest was N in all plant parts. Details on the nutrient concentrations are shown in

.

The highest content of N, P, K and Mg were discovered in kernel where the oil is extracted with concentrations of 5.05%, 0.86%, 1.15% and 0.49% respectively. In contrast, the lowest concentrations were located in the seed coat as it forms a small portion of the seed. However, it was found that potassium content in seed pod was the highest (4.27%). This suggests that seed pod can be a good source of K fertilizer that can be recycled back to the plant to replenish the soil K storage therefore reducing the reliance on chemical fertilizers.

The amounts of nutrients in 1 and 2 year old plants are summarized in Table 2 and 3 respectively. In addition, the dry matter weight of leaves and stems are also given. The nutrient content in the roots were calculated using the root-shoot ratio at 3.78 for 1 year old plants and 4.03 for 2 year old plants.

Table 2: Amount of N, P, K and Mg (g per plant) for 1

year old of J. curcas

The total amounts of N, P, K and Mg in the 1 year old plant were 101.37 g, 9.63 g, 48.42 g and 4.01 g per plant respectively. Whereas the amounts of nutrients for 2 year old plant increased to 104.41 g N, 11.54 g P, 55.69 g K and 4.08 g Mg. From the results given, it was observed that there were not much differences in the amount of N and Mg contained in both planting age. However about 20% increase was found in P content while 15% increase in K after 2 years of planting.

It was suggested that 2 x 2 m (2,500 plants/ha) is the recommended spacing used for J. curcas although it has been reported that a spacing of 3 x 3 m (1,100 plants/ha) was also found in India and elsewhere [3]. Thus, the annual nutrient uptake per ha for N, P, K and Mg by 1 year old J. curcas were 253.43 kg, 24.08 kg, 121.06 kg and 10.04 kg respectively. With the same number of plant per ha, the annual nutrient uptake for 2 year old J. curcas were 420.53 kg of N, 48.72 kg of P, 239.49 kg of K and 31.91 kg of Mg respectively which are given in Table 4. Almost 50% of the increment was due to the development of fruits.

From the values shown here on the nutrients content in fruits, it is possible to provide estimation on the amount of nutrients removed from the harvested portion of J.curcas as well as the amount to be added in following year of planting. From the results shown in Table 4, it was found that about 160 kg of N, 20 kg of P, 100 kg of K and 22 kg of Mg per hectare basis are contained in the fruits.

The total amount of nutrients in Table 4 was calculated by multiplying the values in Table 3 with the number of planting density per hectare basis (2500 plants/ha). It should be emphasized that all the values given here are only estimation of the actual condition in the field as well as the growth and yield of the plant may only be applicable in growing J. curcas on similar type of soil.

Nutrient requirement and fertilizer recommendation of 1 and 2 year old J. curcas

One of the approaches for making fertilizer recommendations is by nutrient accounting where the amount of nutrients taken up by plant and the portion which is being removed should be replenished equally. According to the buildup and maintenance philosophy described by Black[8], the nutrient supplies in soil should be increased in 1 or 2 years to high soil test levels followed by maintaining the supply during subsequent years by only adding the quantities of nutrients that is being removed from the plant.

Nevertheless, it should be reminded that not only the nutrients are being removed through the harvested portion, but losses through leaching and run-off should be taken into account as well. However, only the loss through crop removal is being considered in this study.

According to the findings by Saxena[4], a well established plantation of J. curcas could produce on an average of about 5 tons of seed/ha/year which equals to 2 kg of seeds per ha at 2 x 2 m spacing giving 1500 kg/ha oil and 2500 kg/ha seed cake. The amount of nutrients in the form of N, P2O5, K2O and MgO required by 1 and 2 year old of J. curcas are presented in Table 5. The results indicated that J. curcas requires more N compared to other nutrients due to its highest content in the plant tissue in contrast to other nutrients.

Recommendations on the fertilizer formulation based on the ratio of N, P2O5, K2O and MgO are shown in Table 6. Urea was proposed as a source of N while TSP, MOP and MgSO4 (kieserite) as a source of P2O5, K2O and MgO respectively. Conversely, the amount of fertilizers to be added after crop removal is shown in Table 7. It is shown that after 2 years of planting, as much as 348 kg of Urea, 102 kg of TSP, 200 kg of MOP and 133 kg of kieserite are required to be added after fruit harvesting.

CONCLUSION AND RECOMMENDATION

The total amounts of N, P, K and Mg in 1 year old J. curcas were 101.37 g, 9.63 g, 48.42 g and 4.01 g respectively while the amount of nutrients for 2 year old increased to 104.41 g N, 11.54 g P, 55.69 g K and 4.08 g Mg due to its demand for fruit development. It was also found that potassium content in seed pod was very high (4.27%) and it can be recommended as a good source of K fertilizer. As much as 550.94 kg of urea, 122.58 kg of TSP, 242.13 kg of MOP and 61.78 kg of kieserite are required during the first year of planting while 914.15 kg of urea, 247.98 kg of TSP, 478.93 kg of MOP and 196.21 kg of kieserite were estimated for the second year of planting per hectare basis. It is also estimated following the subsequent year of planting, as much as 348 kg of Urea, 102 kg of TSP, 200 kg of MOP and 133 kg of kieserite are required to be added after fruit harvesting. It should be emphasized that all the values given here are only estimation of the actual condition in the field as well as the growth and yield of the plant recorded in this study may only be applicable to similar type of soil.

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