Bangladesh is a developing country where agriculture is the major economic activity. Farmers plant trees in the croplands for the increased production of timber, fodder, fuel wood, fruits, herbal medicines, raw material for small cottage industries, and short-term nontimber products and for environmental and ecological benefits [
Nutrients are uptaken by plants for their growth and development and a portion of these nutrients is accumulated in plant body [
Bangladesh is bordered by the Bay of Bengal on the south and India on all the other sides except for a small section of Myanmar. Southwestern Bangladesh is low (<10 m above mean sea level), flat, and located on a fertile deltaic plain which is predominated by calcareous to noncalcareous alluvium soils [
Yellowish senescent leaves of
Decomposition of leaf litter was determined using the litter bag technique [
Ten bags were collected for each species at every 10-day interval for the initial 30 days and subsequently at 60-, 90-, 120-, 150-, and 180-day interval for the remaining periods. The collected leaf litter samples were gently washed and all sediments and dirt particles were then removed by using a soft brush with running tap water followed by final rinsing in distilled water. Each sample was then oven-dried at 80°C to constant weight in the said laboratory.
The loss in dry mass of leaf samples was calculated from the initial converted oven-dry mass and remaining mass. The rate of decomposition was calculated from the percentage of mass loss divided by respective days of sample collection. Decay constants for leaf litter were calculated using the negative exponential decay model as follows:
The oven-dried leaf samples of individual species were ground and processed using acid digestion [
The rate of mass loss and nutrients concentration (N, P, and K) in leaf litter of different tree species at different collection time intervals and also with the tree species were compared by ANOVA analysis followed by Duncan multiple range test using SAS 6.12 statistical software. A
The mass loss due to microbial decomposition was significantly different (
Significant test of mass loss of leaf litter of the selected cropland agroforest horticultural tree species among dry and wet season.
Name of species | 00 days | 10 days | 20 days | 30 days | 60 days | 90 days | 120 days | 150 days | 180 days |
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0.11 |
7.24 |
11.55 |
9.47 |
8.66 |
6.16 |
7.18 |
2.53 |
1.78 |
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0.23 |
8.51 |
4.26 |
8.08 |
8.19 |
11.52 |
10.03 |
3.05 |
2.5 |
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0.16 |
14.07 |
16.14 |
19.96 |
16.84 |
15.47 |
22.21 |
7.60 |
4.69 |
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0.05 |
2.70 |
3.75 |
3.34 |
3.80 |
8.02 |
5.46 |
3.51 |
1.70 |
Average decay constant and half-life (
Name of species | Dry season | Wet season | ||
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Average decay constant (K) |
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Average decay constant (K) |
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2.14 | 118 | 2.34 | 108 |
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2.03 | 125 | 2.24 | 113 |
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1.44 | 176 | 1.61 | 157 |
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0.88 | 289 | 0.94 | 270 |
Relationship among rainfall and temperature with mass loss of leaf litter of selected cropland agroforest horticultural tree species (dry and wet season).
Name of species |
Rainfall versus mass loss relationship |
Temperature versus mass loss relationship |
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Dry season | Wet season | Dry season | Wet season | |
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Decomposition of leaf litter of four tree species used in agroforestry during the dry and wet seasons over 180-day periods.
Rate of decomposition of leaf litter of four tree species used in agroforestry during the dry and wet seasons over 180-day periods.
The nutrients concentration was found to decrease gradually at the end of the experiment (180 days) in dry season (Figures
Significant test of N concentration of leaf litter of the selected cropland agroforest horticultural tree species among dry and wet season.
Name of species | 00 days | 10 days | 20 days | 30 days | 60 days | 90 days | 120 days | 150 days | 180 days |
---|---|---|---|---|---|---|---|---|---|
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0.34 |
1.55 |
1.47 |
4.19 |
3.81 |
1.63 |
2.20 |
4.64 |
4.11 |
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0.59 |
4.19 |
5.44 |
6.97 |
9.78 |
14.91 |
15.28 |
9.27 |
8.98 |
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0.24 |
3.04 |
2.83 |
6.15 |
2.61 |
7.52 |
16.21 |
14.51 |
8.37 |
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0.76 |
4.53 |
3.37 |
5.03 |
5.05 |
5.32 |
3.89 |
2.61 |
0.54 |
Significant test of P concentration of leaf litter of the selected cropland agroforest horticultural tree species among dry and wet season.
Name of species | 00 days | 10 days | 20 days | 30 days | 60 days | 90 days | 120 days | 150 days | 180 days |
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1.56 |
0.57 |
2.005 |
0.300 |
0.30 |
3.17 |
0.80 |
0.184 |
2.145 |
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0.70 |
5.83 |
0.84 |
3.002 |
0.64 |
0.70 |
5.50 |
7.84 |
3.69 |
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0.36 |
3.73 |
1.49 |
0.40 |
0.54 |
0.60 |
1.02 |
0.55 |
1.92 |
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0.45 |
1.56 |
0.09 |
0.60 |
0.82 |
3.04 |
2.43 |
0.83 |
5.04 |
Significant test of K concentration of leaf litter of the selected cropland agroforest horticultural tree species among dry and wet season.
Name of species | 00 days | 10 days | 20 days | 30 days | 60 days | 90 days | 120 days | 150 days | 180 days |
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0.67 |
12.97 |
10.02 |
52.22 |
17.37 |
1.86 |
4.98 |
14.89 |
11.58 |
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0.35 |
37.41 |
4.89 |
7.49 |
0.155 |
5.73 |
6.52 |
4.83 |
19.76 |
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0.77 |
18.11 |
16.01 |
8.55 |
57.33 |
3.73 |
0.89 |
10.72 |
17.78 |
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0.64 |
2.04 |
11.38 |
10.03 |
5.21 |
3.03 |
2.73 |
0.44 |
6.12 |
Nutrients added through microbial decomposition of leaf litter of cropland agroforest horticultural tree species in dry and wet season.
Species | N concentration (mg/g) | P concentration (mg/g) | K concentration (mg/g) | |||
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Dry season | Wet season | Dry season | Wet season | Dry season | Wet season | |
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9.06 | 13.93 | 3.74 | 1.00 | 27.82 | 25.42 |
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17.22 | 8.22 | 11.47 | 18.95 | 48.39 | 45.63 |
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12.20 | 8.48 | 3.16 | 3.50 | 36.96 | 31.26 |
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21.81 | 25.11 | 14.31 | 15.54 | 53.95 | 55.34 |
N concentration (mg/g) of leaf litter of four tree species used in agroforestry during the dry and wet seasons over 180-day periods due to microbial decomposition.
P concentration (mg/g) of leaf litter of four tree species used in agroforestry during the dry and wet seasons over 180-day periods due to microbial decomposition.
K concentration (mg/g) of leaf litter of four tree species used in agroforestry during the dry and wet seasons over 180-day periods due to microbial decomposition.
The mass loss pattern and rate of decomposition showed significant (
The variation in nutrients (N, P, and K) concentration in the leaf litter of the studied species at the initial stages of decomposition was found (Figures
A considerable amount of organic matter and nutrients added to the soil through the process of leaf litter decomposition and a portion of these organic matter and nutrients would be reused by the plants. More organic matter and nutrients can be added to the soil through the process of leaf litter decomposition during wet season because of higher rate of decomposition in wet season than dry season. The added nutrients may contribute to the sustainability of soil fertility, which is becoming an important phenomenon for agroforestry practices. Among the considered tree species,
The authors declare that there is no conflict of interests regarding the publication of this paper.
The authors wish to thank Bangladesh Academy of Sciences (BAS) for the financial support through BAS-USDA Programme in Agricultural and Life Science Innovative Research Fund. The authors are also thankful to Forestry and Wood Technology Discipline of Khulna University, Bangladesh, for the logistic supports throughout the study period.