Assessment Of Nutrient Contribution And Cassava/Maize Yields In 3 and 4-Year Old Triplochiton scleroxylon (K. Schum.) Based Agroforestry Systems In Abia State, Nigeria
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ABSTRACT
Agroforestry tree species perform differently in terms of nutrient contributions, promotion of crops yields, carbon sequestration, biodiversity conservation and ecological services. Trials were conducted on quantity of leaf litter production, rate of leaf litter decomposition and nutrient content return of T. scleroxylon. Litter trays and litter bags methods harvested monthly were used to study leaf litter fall and leaf litter decomposition respectively in a single-factor Randomized Complete Block Design (RCBD) with three replications within the plantation. The coefficient of determination (R2) and decomposition constant (k) of T. scleroxylon leaf litter were determined using regression graphs. A 2x3x2 factorial experiment in a Randomized Complete Block Design (RCBD) was used to determine the effects of T. scleroxylon leaf litter nutrient contribution to soil fertility and cassava/maize yields in monocrop and intercrop systems in a 3/4 year old T. scleroxylon-based agroforestry in 2019 and 2020 respectively with a 7 year old bushfallow land as control at the Humid Forest Research Station, Forestry Research Institute of Nigeria (FRIN), Okwuta-Ibeku, Umuahia, Abia State, Nigeria. Results showed significant differences (P<0.05) in the monthly means of T. scleroxylon litter production of 2019 and 2020 respectively while no significant differences (P>0.05) occurred between the yearly means litter production of 2019 and 2020. The dry season months of November – March had litter production ranging from 174.07-724.53 kgha-1 in 2019 and 199.47-1485.10 kgha-1 in 2020 which were higher than the rainy season months of April – October at the ranges of 35.80 - 174.07 kgha-1 in 2019 and 85.45 - 220.00 kgha-1 in 2020. Total leaf litter decomposition (100%) of T. scleroxylon surface-placement method was observed at the 8th month (32 weeks) after commencement of the trials in 1st January 2019 and 2020 respectively. The coefficient of determination (R2), decomposition constant (k), C:N ratio, time to 50, 95 and 99% decay for leaf litter of T. scleroxylon in 2019 and 2020 were 0.76 and 0.80; 2.39 and 1.95; 2.:1 and 2:1; 0.29 and 0.36; 1.25 and 1.54; 1.92 and 2.36 respectively. The results of P, K, Ca and Mg content in the leaf litters between 2019 and 2020 were significantly different (P<0.05) while N, OC, OM and pH were not significantly different (P>0.05). The presence of T. scleroxylon litter in the T. scleroxylon agroforestry system increased cassava tuber yields over the yields in the bushfallow plot (control) in cassava monocropping and cassava/maize intercropping systems in the 2019/2020 cropping seasons. Irrespective of treatments, there were no significant differences (P>0.05) in the yearly mean yields of maize cobs and maize heights in the T. scleroxylon agroforestry system and bushfallow plot (control). T. scleroxylon being rich in organic matter, N, P, K, Mg and Ca minerals contributes remarkably in soil fertility improvement, and cassava and maize yields. In conclusion, farmers and stakeholders in agriculture should adopt and promote T. scleroxylon species respectively in their farming systems and plantation establishments.
TABLE OF CONTENTS
Cover page
Title page i
Declaration ii
Certification iii
Dedication iv
Acknowledgement v
Table of contents vi
Abstract xvii
CHAPTER 1: INTRODUCTION 1
1.1: Background information 1
1.2: Statement of the problem 3
1.3: Objectives of the study 5
1.4 :Justification of the study 5
1.5 :Scope of the study 7
CHAPTER 2: LITERATURE REVIEW 8
2.1: Agroforestry 8
2.1.1: Classification of agroforestry systems and practices 11
2.1.2: Roles of agroforestry in forest management 17
2.1.2.1: Carbon cycle 17
2.1.2.2: Biodiversity conservation 19
2.1.2.3: Healthy forest ecosystem 20
2.1.2.4: Socio-economic benefits 21
2.1.2.5: Wood and non-timber products 22
2.1.3: Plant species used in agroforestry ecosystem 23
2.2: Littterfall and litter production 26
2.2.1: Types and sources of leaf litter 28
2.2.2: Litter decomposition 29
2.2.3: Rate of litter decomposition 31
2.2.3.1: Some factors influencing litter decomposition rate 32
2.2.3.1.1: Climatic condition 32
2.2.3.1.2: Substrate quality 33
2.2.3.1.3: Microbial activities 36
2.2.4: Methods for estimating litter decomposition 37
2.2.4.1: Mass balance 38
2.2.4.2: Litterbags 38
2.2.4.3: Tethered Leaves Technique 39
2.2.4.4: Cohort layered screen 40
2.3: Litterfall as part of nutrient cycle 40
2.3.1: Nutrient accretion to soil through litterfall 41
2.4: Benefits of litter production and nutrient cycling 42
2.4.1: Degraded site restoration/erosion 43
2.4.2: Importance of litterfall on growth and yield of forest species 44
2.5: Application of fertilizers on arable crops production in agroforestry ecosystem 45
2.5.1: Effect of organic fertilizers on arable crop production in agroforestry ecosystem 46
2.5.2: Combination of inorganic fertilizers and organic fertilizers/manures 48
2.6: Crops yields in agroforestry 49
2.7: Soil fertility conditions in the tropics 50
2.7.1: Influence of trees on soil fertility 52
2.8: Agroforestry and climate change 55
2.9: Trees and soil biodiversity 57
2.10: Description of Triplochiton scleroxylon 58
2.10.1: Propagation of Triplochiton scleroxylon 59
2.10.2: Roles of Triplochiton scleroxylon 60
2.11: Origin of maize (Zea mays L.) 60
2.11.1: Ecology of maize 62
2.11.2: Utilization of maize 63
2.12: The Origin, domestication and distribution of Cassava (Manihot esculenta Crantz) 64
2.12.1: Classification of cassava 64
2.12.2: Flowering habit of cassava 65
2.12.3: Importance of cassava 67
CHAPTER 3: MATERIALS AND METHODS 69
3.1: Study location 69
3.2: Methodology 73
3.2.1: Stand structure of Triplochiton scleroxylon plantation at Okwuta-Ibeku, Umuahia,
Nigeria 73
3.2.2: Experiment 1: Leaf litter production of Triplochiton scleroxylon in 2019 and
2020 74
3.2.2.1: Determination of pH level of T. scleroxylon leaflitter 75
3.2.2.2: Determination of total Nitrogen (N) content of T. scleroxylon leaflitter 75
3.2.2.3: Determination of Organic Carbon (OC) and organic matter (OM) content of
T. scleroxylon leaflitter 76
3.2.2.4: Macro minerals (Ca, Mg, P and K) content of T. scleroxylon leaflitter 77
3.2.2.5: Nutrients returns of Triplochyton scleroxylon leaf litter 77
3.2.3: Experiment 2: Leaf litter decomposition studies 79
3.2.3.1: Regression equation of litter decomposition rates 81
3.2.4: Experiment 3: Determination of the contribution of T. scleroxylon to
soil fertility in cassava and maize production system in Okwuta-Ibeku, Umuahia, Abia State 81
3.2.4.1: Soil samples preparation 82
3.2.4.2: Determination of soil pH 82
3.2.4.3: Determination of soil Organic Carbon (OC) and organic matter (OM) 83
3.2.4.4: Determination of cation exchange capacity of Soil Sample 83
3.2.4.5: Determination of exchangeable base of sodium and potassium in
soil sample 84
3.2.4.6: Determination of exchangeable base of ca and mg in soil sample 85
3.2.4.7: Soil particle size determination 86
3.2.4.8: Heavy metal analysis: 87
3.2.4.9: Determination of total Nitrogen 87
3.2.5: Experiment 4: Establishment of cassava (var. TMS 05-1636) and maize (var.
Oba super 6) monocrop and intercrop plots under T. scleroxylon plantation in 88
Okwuta-Ibeku, Umuahia, Abia State
3.2.5.1: Cultural practices 88
3.2.5.2: Treatment combinations of factors at the T. scleroxylon agroforestry 89
3.2.5.3: Treatment combinations of factors at the bush fallow land 89
3.2.6: Yield parameters of cassava and maize in T. scleroxylon agroforestry system
in Okwuta-Ibeku, Umuahia, Abia State 90
3.3: Statistical analysis 94
CHAPTER 4: RESULTS AND DISCUSSION 95
4.1: Results 95
4.1.1: Leaf litterfall of Triplochiton scleroxylon 95
4.1.2: Leaf litter decomposition rates of Triplochiton scleroxylon 97
4.1.2.1: Cumulative leaf litter decomposition rates in 2019 and 2020 97
4.1.2.2: Coefficient of determination (R2), decomposition constants (k), C: N ratio time to
50, 95, and 99% decay for leaf litter of Triplochiton scleroxylon in 2019 and
2020 in Umuahia 100
4.1.3: Nutrient composition of leaf litter Of Triplochiton scleroxylon stand in
Okwuta- Ibeku Umuahia, Nigeria 101
4.1.3.1: Nitrogen (N) (g/kg) contents of the leaf litter of Triplochiton scleroxylon 101
4.1.3.2: Phosphorus (P) (g/kg) contents of the leaf litter of Triplochiton
Scleroxylon 103
4.1.3.3: Potassium (K) (g/kg) contents of the leaf litter of Triplochiton scleroxylon 105
4.1.3.4: Calcium (Ca) (g/kg) contents of leaf litter of Triplochiton scleroxylon 107
4.1.3.5: Magnesium (Mg) (g/kg) contents of the leaf litter of T. scleroxylon 109
4.1.3.6: Organic Carbon (OC) (%) contents of the leaf litter of T. scleroxylon 111
4.1.3.7: Organic Matter (OM) (%) contents of the leaf litter of T. scleroxylon 113
4.1.3.8: pH levels of the leaf litter of Triplochiton scleroxylon 115
4.1.4: Pre- and post harvest soil physico-chemical properties in Triplochiton
scleroxylon agroforestry and Bushfallow Plots at Umuahia 117
4.1.4.1:Pre-planting physico-chemical properties of soil in Triplochiton scleroxylon
Agroforestry and bushfallow plots at Umuahia 117
4.1.4.2:Post-harvest physico-chemical properties of soil in Triplochiton scleroxylon
agroforestry and bushfallow plots at Umuahia 119
4.1.4.2.1: Post-harvest pH levels of soils 119
4.1.4.2.2 Post-harvest cation exchange capacity (CEC) of the soils 123
4.1.4.2.3: Post-harvest Organic Carbon (OC) (%) contents of soils 127
4.1.4.2.4: Post-harvest Organic Matter (OM) (%) contents of soils 131
4.1.4.2.5: Post-harvest total Nitrogen (TN) (mg/kg) contents of soils 135
4.1.4.2.6: Post-harvest Phosphorus (P) (mg/kg) contents of soils 139
4.1.4.2.7: Post-harvest exchangeable Calcium (Ca2+)(meq/100 g soil) contents of soils 143
4.1.4.2.8: Post-harvest exchangeable Magnesium (Mg2+) (meq/100 g soil) contents of
soils 147
4.1.4.2.9: Post-harvest exchangeable Potassium (K+) (meq/100 g soil) contents of soils 151
4.1.4.2.10: Post-harvest exchangeable Sodium (Na+) ((meq/100 g soil)) contents of
soils 155
4.1.4.2.11: Post-harvest Iron (Fe) (mg/kg) contents of soils 159
4.1.4.2.1 2: Post-harvest Copper (Cu) (mg/kg) contents of soils 163
4.1.4.2.1 3: Post-harvest Manganese (Mn) (mg/kg) contents of the soils 167
4.1.4.2.14: Post-harvest Zinc (Zn) (mg/kg) contents of soils 171
4.1.5: Cassava tuber yield in the Triplochiton scleroxylon agroforestry and bushfallow
plots in 2019 and 2020 cropping seasons in Umuahia 175
4.1.6: Maize cob yields in the Triplochiton scleroxylon agroforestry and bushfallow
plots in 2019 and 2020 in Umuahia 179
4.1.7: Maize stalk drymatter in the Triplochiton scleroxylon agroforestry and bushfallow
plots in 2019 and 2020 in Umuahia 182
4.1.8: Maize plants heights (cm) in 2019 and 2020 cropping season in the
Triplochiton scleroxylon agroforestry and bushfallow plots in Umuahia 186
4.2: Discussion 190
4.2.1: Leaf litter production of Triplochiton scleroxylon 190
4.2.2: Leaf litter decomposition rates of Triplochiton scleroxylon 192
4.2.3: Nutrient composition of leaf litter of Triplochiton scleroxylon in
the Humid Forest Research Station, Umuahia, Nigeria 195
4.2.3.1: Nitrogen (N), Phosphorus (P) and Potassium (K) contents of the leaf litter of
Triplochiton scleroxylon 195
4.2.3.2: Calcium (Ca) and Magnesium (Mg) contents of the leaf litter of Triplochiton
Scleroxylon 198
4.2.3.3: Organic carbon (OC), organic matter (OM) and pH levels of the leaf litter of
Triplochiton scleroxylon 199
4.2.4.1:Pre-planting physico-chemical properties of soil in Triplochiton scleroxylon
agroforestry and bushfallow plots in Umuahia 200
4.2.4.2: Effect of cassava/maize cropping systems on soil chemical parameters during
and over 2019 and 2020 cropping seasons in Triplochiton scleroxylon
agroforestry and bushfallow plots at Umuahia 202
4.2.5:Cassava tuber yield in the Triplochiton scleroxylon agroforestry and
bush fallow farm ecosystems in 2019 and 2020 at Umuahia 207
4.2.6: Maize cobs mass, stovers and height yields in the Triplochiton scleroxylon
agroforestry and Bush fallow farm ecosycstems in 2019 and 2020 at Umuahia 208
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS 210
5.1: Conclusion 210
5.2: Recommendations 211
References 212
LIST OF TABLES
2.1: Preferred Agroforestry species in Nigeria 25
3.1: Monthly climatic variables in 2019 and 2020 at the study site in
the Humid Forest Research Station, Forestry Research Institute of Nigeria (FRIN),
Umuahia, Nigeria 71
4.1: Monthly mean leaf litter production of Triplochiton scleroxylon plantation
in 2019 and 2020 at Umuahia 96
4.2: Leaf litter decomposition percentages of Triplochiton scleroxylon leaf litter
at the Triplochiton scleroxylon plantation in 2019 and 2020 at Umuahia 98
4.3: Coefficient of determination (R2), Decomposition constants (k), C:N ratio
time to 50, 95, and 99% decay for leaf litter of Triplochiton scleroxylon in 2019
and 2020 in Umuahia 100
4.4: Nitrogen (N) (g/kg) contents of the leaf litter of Triplochiton scleroxylon 102
4.5: Phosphorus (P) (g/kg) contents of the leaf litter of T. scleroxylon 104
4.6: Potassium (K) (gkg-1) contents of the leaf litter of Triplochiton scleroxylon 106
4.7: Calcium (Ca) (g/kg) contents of the leaf litter of Triplochiton scleroxylon 108
4.8: Magnesium (Mg) (g/kg) contents of the leaf litter of T. scleroxylon 110
4.9: Organic carbon (OC) (%) contents of the leaf litter of Triplochiton
scleroxylon 112
4.10: Organic matter (OM)(%) contents of the leaf litter of Triplochiton
Scleroxylon 114
4.11: pH levels of the leaf litter of Triplochiton scleroxylon in 2019 and 2020 at
Umuahia 116
4.12: Pre-planting physico-chemical properties of soil in Triplochiton scleroxylon
agroforestry and bushfallow plots at Umuahia 118
4.13: Post-harvest pH levels of soil in Triplochiton scleroxylon agroforestry and
bushfallow plot s at Umuahia 122
4.14: Post-harvest cation exchange capacity (CEC) of the soils in Triplochiton
scleroxylon agroforestry and bushfallow plots at Umuahia 126
4.15: Post-harvest organic carbon (OC) (%) contents of soils in Triplochiton
scleroxylon agroforestry and bushfallow plots at Umuahia 130
4.16: Post-harvest organic matter (OM) (%) contents of soils in Triplochiton
scleroxylon agroforestry and bushfallow plots in Umuahia 134
4.17: Post-harvest Total Nitrogen (N) (mg/kg) contents of soils in Triplochiton
scleroxylon agroforestry and bushfallow plots at Umuahia 138
4.18: Post-harvest Phosphorus (P) (mg/kg) contents of soils in Triplochiton
scleroxylon agroforestry and bushfallow plots at Umuahia 142
4.19: Post-harvest Exchangeable Calcium (Ca2+) (meq/100 g soil) contents of soils in
Triplochiton scleroxylon agroforestry and bushfallow plots at Umuahia 146
4.20: Post-harvest Exchangeable Magnesium (Mg2+) (meq/100 g soil) contents of
soils in Triplochiton scleroxylon agroforestry and bushfallow plot at
Umuahia 150
4.21: Post-harvest Exchangeable Potassium (K+) (meq/100 g soil) contents of soils in
Triplochiton scleroxylon agroforestry and bushfallow plots at Umuahia 154
4.22: Post-harvest Exchangeable Sodium (Na+) (meq/100 g soil) contents of soils in
Triplochiton scleroxylon agroforestry and bushfallow plots at Umuahia 158
4.23: Post-harvest Iron (Fe) (mg/kg) contents of soils in Triplochiton scleroxylon
agroforestry and bushfallow plots at Umuahia 162
4.24: Post-harvest Copper (Cu) (mg/kg) contents of soils in T. scleroxylon
agroforestry and bushfallow plots in Umuahia 166
4.25: Post-harvest Manganese (Mn) (mg/kg) contents of soils in Triplochiton
scleroxylon agroforestry and bushfallow plots in Umuahia 170
4.26 :Post-harvest Zinc (Zn) (mg/kg) contents of soils in T. scleroxylon agroforestry
and bushfallow plots in Umuahia 174
4.27: Cassava tuber yield in the Triplochiton scleroxylon agroforestry and bush
fallow plots in 2019 and 2020 in Umuahia 177
4.28: Maize cob yield in the Triplochiton scleroxylon agroforestry and Bush
fallow plots in 2019 and 2020 at Umuahia 180
4.29: Maize stalk dry matter (DM) (stover) yield at the Triplochiton scleroxylon
agroforestry and bushfallow plots in 2019 and 2020 in Umuahia 184
4.30: Maize plants heights (cm) in 2019 and 2020 cropping season in the
Triplochiton scleroxylon agroforestry and bushfallow plots in Umuahia 188
LIST OF FIGURES
3.1: Location map of the study area in Umuahia, Abia State, Nigeria 72
4.1: Biomass remaining in the litter bags at various time (Month) intervals for
Triplochiton scleroxylon leaf litter decomposition experiments in 2019 and
2020 99
4.10: Cassava tuber yield in the Triplochiton scleroxylon agroforestry and
bushfallow plots in 2019 and 2020 in Umuahia 178
4.11: Maize cob yield in the Triplochiton scleroxylon agroforestry and Bush fallow
plots in 2019 and 2020 at Umuahia 181
4.12: Maize stalk dry matter yield in the Triplochiton scleroxylon agroforestry
and Bush Fallow plots in 2019 and 2020 in Umuahia 185
4.13: Maize plants heights (cm) in 2019 and 2020 cropping season in the T.
scleroxylon agroforestry and bushfallow plots in Umuahia 189
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APA
ONYENSO, & IKECHUKWU, A. (2023). Assessment Of Nutrient Contribution And Cassava/Maize Yields In 3 and 4-Year Old Triplochiton scleroxylon (K. Schum.) Based Agroforestry Systems In Abia State, Nigeria. Michael Okpara University of Agriculture. Retrieved June 7, 2026, from http://repository.mouau.edu.ng/works/assessment-of-nutrient-contribution-and-cassavamaize-yields-in-3-and-4-year-old-triplochiton-scleroxylon-k-schum-based-agroforestry-systems-in-abia-state-nigeria-7-2
MLA
ONYENSO, and ANTHONY IKECHUKWU. "Assessment Of Nutrient Contribution And Cassava/Maize Yields In 3 and 4-Year Old Triplochiton scleroxylon (K. Schum.) Based Agroforestry Systems In Abia State, Nigeria." Michael Okpara University of Agriculture, 19 Jul. 2023, http://repository.mouau.edu.ng/works/assessment-of-nutrient-contribution-and-cassavamaize-yields-in-3-and-4-year-old-triplochiton-scleroxylon-k-schum-based-agroforestry-systems-in-abia-state-nigeria-7-2. Accessed June 7, 2026.
Chicago
ONYENSO, and ANTHONY IKECHUKWU. "Assessment Of Nutrient Contribution And Cassava/Maize Yields In 3 and 4-Year Old Triplochiton scleroxylon (K. Schum.) Based Agroforestry Systems In Abia State, Nigeria." Michael Okpara University of Agriculture (2023). Accessed June 7, 2026. http://repository.mouau.edu.ng/works/assessment-of-nutrient-contribution-and-cassavamaize-yields-in-3-and-4-year-old-triplochiton-scleroxylon-k-schum-based-agroforestry-systems-in-abia-state-nigeria-7-2