Sugarcane Bagasse Ash as a Seedling Growth Media Component

Bagasse is the fibrous material remaining after removing the sucrose, water, and other impurities (filter mud) from the milable sugarcane. Louisiana sugarcane mills use a portion of the sugarcane bagasse for fuel producing over 20,411 mt of sugarcane bagasse ash (SBA) as a by-product. The purpose of this research was to investigate the use of SBA as an amendment to soilless planting media for the production of vegetable seedlings. The SBA was combined by volume with a commercial soilless growing media into 5 combinations (0%:100%, 25%:75%, 50%:50%, 75%:25%, and 100%:0%, SBA and growing media, respectively). Squash var. ‘Straightneck’ and cantaloupe var. ‘Magnum Hybrid Melon’ were planted in each of the 5 different planting mixtures. The research indicates that the addition of SBA can enhance squash and cantaloupe seedling growth depending on the percentage of the ash added to the growth media. Squash plant stalk lengths and total plant fresh weights (stalk, leaves, tops, roots, and total plant) overall responded best at the 75% SBA. Squash dry weights were consistently greater when SBA was added to the soilless media compared to no SBA. The 25% and 50% SBA media produced the greatest cantaloupe leaf fresh weights. Cantaloupe leaf dry weights followed a similar trend, where the 25% and 50% SBA media produced greater plant weights with lesser yields observed at the 75% and 100% SBA levels. This data suggests that the 75% SBA and 25% SBA were certainly suitable potting media combinations for squash and cantaloupe seedling production, respectively.


Sugarcane Bagasse Ash Production
It is very common for Louisiana sugarcane mills to use a portion of the sugarcane bagasse to produce steam power to run equipment within the mill and/or as a boiler fuel for the clarification, evaporation, and crystallization processes.Sugarcane bagasse ash (SBA) is a by-product of the thermoconversion of the sugarcane bagasse.Depending on the source of the sugarcane, harvesting methods and thermoconversion efficiency at the mill, the percentage of ash produced from bagasse typically represents a small percentage, 1.5 to 3.0% by weight, of the original sugarcane bagasse (Amin, 2011;Garcıà-Pèrez, 2002).And, although SBA content is low (1.5-3.0%)compared to other agricultural sources such as rice straw, 14.5% (Guo et al., 2009) and wheat straw, 8.6% (Biricik et al., 1999), the large volume of bagasse used for fuel results in massive amounts of SBA that needs to be economically and environmentally handled.If the estimated 50% (Pandey et al., 2000) of the 3 million tons of bagasse produced each year in Louisiana is used for energy conversion at the sugarcane mills, the SBA produced in Louisiana each year would range from 20,411 to 40,823 mt, and an estimated 2.25 to 4.5 million mt of sugarcane bagasse ash globally.
Five seedlings from the center of each tray were harvested 21 days after planting.Each seedling was divided into above and below ground portions.The above ground portion was measured for plant length by measuring the distance from the soilless media surface to the apical meristem.The upper portion of the plant was further divided into leaves and stalks.The soilless media was removed from lower portion of the plants (roots).The fresh weight of the leaves, stalks, and the roots were then determined.The plant portions were then oven dried for 2 days at 60 o C and then reweighed to determine dry weights.All data were subjected to ANOVA and mean separation using LSD with P = 0.05 (SAS Inc., SAS, Ver.9.0, Cary, NC).

Statistical Analysis
Statistical analysis determined that there were significant interactions among plant species (squash and cantaloupe), experiments, and plant growth medium (0%, 25%, 50%, 75% and 100% SBA); therefore the results will be discussed by plant species with each interaction addressed separately.

Squash Stalk Lengths
Significant interactions were detected between the planting media and the experiments for squash stalk length; therefore, the squash stem length data will be discussed by experiment (Table 1).In experiment 1, 75% SBA produced longer stalk lengths than the 100% SBA, and was not different from any other SBA percentage (Table 1).In experiment 2, squash stalk lengths were the greatest for the 100% SBA with a consistent decreasing trend to the 0% SBA (Table 1).In both experiments, the 75% SBA had one of the longest squash stalk lengths for the soilless growth media (Table 1).Note. z Percentage of sugarcane bagasse ash (SBA) in the growth medium based on volume.
y Means in a column followed by the same lower case letter are not significantly different at P ≤ 0.05, ANOVA.

Squash Fresh and Dry Plant Weights
No significant interactions were detected between the experiments and the growth media, therefore the squash plant fresh and dry weights will be discussed averaged across experiments (Tables 2 and 3).The squash seedling fresh weights for the leaves, seedling tops (stalks + leaves), and seedling total fresh weight (stalks + leaves + roots] increased from the 0% SBA to 75% SBA (Table 2).The squash root fresh weights were not consistent, but did peak at the 100% SBA, whereas the stalk fresh weights were not different across the SBA percentages (Table 2).Squash dry weights varied considerably depending on the plant components involved (Table 3).The squash stalks (0.42 g), leaves (0.94 g), and tops (stalks +leaves) (1.35 g) peaked at the 50% SBA, while the root dry weights and total plant weights peaked at the 100% SBA (Table 3).
Table 2. Impact of sugarcane bagasse ash percentage of growth medium on squash seedling fresh plant weights (g) averaged across two experiments, four replications per experiment, and five seedlings per replication   y Means in a column followed by the same lower case letter are not significantly different at P ≤ 0.05, ANOVA.

Squash Data Summary
The squash seedling lengths, fresh and dry weights indicate that although there does not seem to be a clear and unequivocal advantage of adding the sugarcane bagasse ash to the squash seedling growth media, there is also not a disadvantage, as far as squash seedling growth, to adding 50% to 75% sugarcane bagasse ash to the growth media.Adding at least the 25% amount consistently shows a positive response, although not always of statistical significance.

Cantaloupe Seedling Analysis
Significant interactions were detected between the planting media and experiments for cantaloupe leaves, fresh (P ≤ 0.0499) and dry (P ≤ 0.0481) weights (Table 4), therefore the leaf data will be discussed by experiments (Table 4).Due to the absence of interaction by experiments, the cantaloupe stalk lengths and other seedling fresh and dry weights will be discussed averaged across experiments (Tables 5 and 6).

Cantaloupe Fresh and Dry Leaf Weights
In both experiments, the cantaloupe leaf fresh weights were the greatest for the 25% and 50% SBA media, decreasing with either a lower or greater percentage of SBA (Table 4).The leaf fresh weight interaction between experiments was due to a greater decrease between the 75% and 100% SBA in experiment 2 (2.24 g vs. 1.52 g) compared to experiment 1 (2.07 g vs. 1.62 g) (Table 4).Cantaloupe leaf dry weights followed a similar trend, where the 25% and 50% SBA media produced greater plant weights with lesser yields observed at the 75% and 100% SBA levels (Table 4).Unlike the leaf fresh weights, the interaction between experiments 1 and 2 for the leaf dry weights occurred when comparing the differences between the 25% SBA media and the 0% SBA media (Table 4).Whereas, in experiment 1, there was a significant decrease between the 25% and the 0% SBA media, there was no difference between the 25% and 0% SBA media in experiment 2 (Table 4).The cantaloupe seedling stalk lengths and other fresh weights (stalks, seedling tops, roots, and total seedling) followed a similar trend as the leaf fresh and dry weights, typically peaking at the 25% or 50% SBA media (Table 5), but never producing higher values at either the 75% or 100% SBA levels compared to the 25% and 50% media.The cantaloupe seedling dry weights also peaked in the 25% and 50% SBA range, with the stalk dry weights not differening among soil media contents (Table 6).
Table 5. Impact of sugarcane bagasse ash percentage of growth medium on cantaloupe seedling stalk lengths and plant fresh weights (g) averaged across two experiments, four replications per experiment, and five seedlings per replication Note.z Percentage of sugarcane bagasse ash (SBA) in the growth medium based on volume.
y Means in a column followed by the same lower case letter are not significantly different at P ≤ 0.05, ANOVA.

Cantaloupe Seedling Summary
The 25% SBA consistently produced the greatest cantaloupe seedling growth across the various plant parameters measured, although the 50% SBA media was often not significantly different from the 25% SBFA results (Tables 5 and 6).This data suggests that 25% SBA was certainly a suitable soilless media combination for cantaloupe seedling production.

Conclusions
The research indicates that the addition of sugarcane bagasse ash can enhance squash and cantaloupe seedling growth depending on the percentage of the ash added to the growth media.Squash plant stalk lengths and plant fresh weights (stalk, leaves, tops, roots, and total plant) overall responded best at the 75% SBA and the 25% to 100% SBA squash dry weights were consistently greater than the 0% SBA.The 25% and 50% SBA media produced the greatest cantaloupe leaf fresh weights.Cantaloupe leaf dry weights followed a similar trend, where the 25% and 50% SBA media produced greater plant weights with lesser yields observed at the 75% and 100% SBA levels.This data suggests that the 75% SBA and 25% SBA were certainly suitable potting media combinations for the squash and cantaloupe seedling production, respectively.Further research should investigate the impact of adding starter fertilizers to the bagasse amended media to further enhance the growth of the squash and cantaloupe seedlings.Also additional plant species should also be evaluated in their response to bagasse ash amended growth media.

Table 1 .
Impact of sugarcane bagasse ash percentage of growth medium on squash seedling stalk length (mm) averaged across two experiments, four replications per experiment, and five seedlings per replication

Table 3 .
Impact of sugarcane bagasse ash percentage of growth medium on squash seedling oven dried plant weights (g) averaged across two experiments, four replications per experiment, and five seedlings per replication Note. z Percentage of sugarcane bagasse ash (SBA) in the growth medium based on volume.

Table 4 .
Impact of sugarcane bagasse fly ash percentage of growth medium on cantaloupe fresh and dry leaf weights (g) averaged across two experiments, four replications per experiment, and five seedlings per replication.Note.zPercentage of sugarcane bagasse ash (SBA) in the growth medium based on volume.Means in a column followed by the same lower case letter are not significantly different at P ≤ 0.05,ANOVA.3.3.3Cantaloupe Stalk, Plant Tops, Roots, and Total Plant Fresh and Dry Weights y

Table 6 .
Note. z Percentage of sugarcane bagasse ash (SBA) in the growth medium based on volume.Impact of sugarcane bagasse ash percentage of growth medium on cantaloupe seedling oven dried weights (g) averaged across two experiments, four replications per experiment, and five seedlings per replication y Means in a column followed by the same lower case letter are not significantly different at P ≤ 0.05, ANOVA.