Corn cob dry

Moisture

Temp.

10 ºC

20 ºC

30 ºC

Average
15%

DM Loss

0.01 (Aa)

0.07 (Ba)

0.17 (Ca)

0.08
25%

DM Loss

0.24(Ab)

0.62 (Bb)

1.66 (Cb)

0.84
35%

DM Loss

1.09 (Ac)

2.40 (Bc)

2.75 (Cc)

2.08

Average

0.45

1.03

1.53

Note: Tukey’s standardized range is symbolized with capital letters for temperature difference (between rows) and lower case letters for difference between moisture contents (within columns). Significantly different means was tested with α<0.05.

A T test (LSD) was performed with alpha 0.05 for the treatments identifying differences

among moistures and another test performed for the differences in temperatures. The least

significant difference among temperature means was found to be 0.22% DM, whereas the least

significant difference among moisture was 0.34% DM loss. The greatest deterioration was

achieved with 35% moisture significantly different from the 25 and 15%. Likewise, lower

temperature of 10C was statistically different 20 and 30C. As a whole, every moisture and

temperature was statistically different from each other. The resulting combination of both

factors high temperature and moisture resulted in 2.73 % ±0.40% of dry matter loss, whereas

negligible dry matter loss was observed with 10C and 15% moisture. On average, for every

increase of one percent of moisture, the dry matter loss increased 0.1 percentage point versus

0.05 percentage point for every Celsius degree over 21 days. Thus moisture content should be

carefully kept in mind while storing this kind of biomass.

41

The interaction makes the analysis and interpretation more complicated, in the sense that

not only moisture and temperature had additive effects on the deterioration model but also an

interaction effect which was highly significant. Therefore, it is not appropriate to just consider

each variable separately; both have to be considered for calculation of the resulting dry matter

loss.

The deterioration trend lines (Figure 3) are intended to predict what would happen to

materials with different moisture content after being stored for 21 days. Although the experiment

was performed in vitro, it was intended to be useful in some extent for commercial cobs piles.

Knowing the moisture content and tracking the temperature within the pile, equations 1 would

give a useful approximate to predict deterioration rate after 21 days.