Agroforestry soil

1. THE ROLE OF
AGROFORESTRY IN
CONSERVING SOIL AND SOIL
MOISTURE IN NEPALESE
CONTEXT
Presenter:
Amit Chaudhary
Faculty of Forestry
Agriculture and Forestry University

2. OUTLINE
2
• Introduction
• Discussion
• Conclusion
Uthappa, et al. 2017

3. Source: Zhu et al., 2020
INTRODUCTION
Agroforestry: Integrating tree and agricultural crops in the same land
unit over temporal and spatial scales (Nair, 1993).
Addition of soil organic matter, moisture retention, soil binding
function, soil erosion mitigation, decreasing soil runoff velocity,
amelioration of soil microclimate, soil physical properties, and soil
fertility enhancement, soil toxicity reduction is achieved (Young,
1990).
From the interaction and sustainable management of different
components – Plants (different life forms- herbs, shrubs, trees),
livestock, fishery, etc. are arranged deliberately on a specific land unit.
It is imperative to sustain the livelihood of people dependent on it.
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4. LAND UNITS IN NEPAL
4
Source:
Juerg
Merz,
(2008)
Source: (Serchan, S.) in Khatri et al. 2021
Source: Cedamon, et al. 2019

5. Source: Cedamon, et al. 2019
 Soil Cover: Tree and cover crops are more effective in
 interception of rainfall;
 decreasing surface runoff;
 mulching by leaf litters;
 promotion of water infiltration, and
 formation of blocky erosion-resistant soil structure
(Uthappa et al., 2017).
 Application of legume (Flemengia sp.) mulch has been
recommended for optimal rice yield and soil health in
India (Lalremsang, et al. 2022).
SOIL COVER MAINTENANCE
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6. SOIL FERTILITY IMPROVEMENT
Agroforestry system promotes more closed nutrient cycling
than the agricultural systems by (Young, 1990):
Uptake and recycling: taking up of soil nutrients by tree
systems and recycling them as litter, including root residues.
Synchronization: helping to synchronize nutrient release
crop requirements by controlling the quality, timing, and
manner of addition of plant residues
Different components can best use their root system by
maximizing positive effects whilst reducing tree-crop
competition for moisture and nutrients.
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7. SOIL EROSION CONTROL
• Different land use types
studied were: stone dike
terraces—crops, earth banked
terraces—citrus, earth banked
terraces with hedgerows—
citrus, slope land with
hedgerows—crops, slope
with hedgerows—tea plants,
slope land with hedgerows—
citrus, slope land—crops,
land—tea plants, and slope
land—citrus.
• Figure: Runoff plots; Source:
Meng, et al. 2021
Meng, et al., (2021) studied the effect of land use and rainfall
pattern on soil loss of the hillslope in the Zhangjiachnong
watershed of China having a subtropical wet monsoon
climate. The study was done on a 25° slope.
The soil erosion was found to be the highest in the Earth-
banked terraces and lowest in the sloping land with
hedgerows. The hedgerow pattern was more effective in
controlling soil erosion under moderate and heavy rainfall
patterns compared to storm rainfall.
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8. SOIL PHYSICAL & CHEMICAL
PROPERTIES
Mixture of plant diversity increases the Soil Organic
Carbon and Soil nitrogen as indicated by research in tree-
shrub homesteads in subtropical countries like
Bangladesh, and Nepal (Jaman, et al. 2021).
Influence of the physical properties of tropical soils on
crop growth is evidently independent of other effects. One
of the important parameters is the water-holding capacity.
Some detrimental effects may be due to acidification by
trees which produce mor-type humus (Young, 1990). 8

9. NITROGEN FIXATION
Integrating Nitrogen fixing (leguminous) trees, shrubs –
Leucaena leucocephala, Gliricidia sepium, Indigofera sp.,
Flemengia spp., and Desmodium sp., into the farmland
unit enhances nitrogen in the soil.
Sesbania rostrata in wetland rice system can achieve by adding
500 kg N/ha/yr to soil. Leucaena has a comparable ability of N
fixation at a rate of 75-120 kg N/ha/yr while Acacia mearnsii
species can fix about 200 kg N/ha/yr (Nair, 1984;
Dommergues,1987).
Rosenstock et al. (2014) pointed out that Nitrogen fixing plants 9

10. SOIL WATER AVAILABILITY
Agroforestry systems can reduce evaporation (by
temperature and wind reduction) (Lin, 2010), and improve
water and nutrient cycling and radiation protection.
Plants with deep roots can lift or redistribute water to the
upper layers potentially acting as ‘bioirrigators’ (Bayala
and Prieto, 2020)
Higher soil-water content increases diffusion rates and
thus inter-root competition. Thicker roots deplete the
nearb soil nutrient pools (Young, 1990).
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11. SOIL ORGANIC MATTER
Carbon sequestration (in the form of fallen wood, leaf, twigs, bark, and
fruits,)rates vary by tree species, soil type, climate, topography, and
management practices (Amatya, S. 2022).
Agroforestry systems increased the carbon stocks by 23.7 -35.6% in
relation to cropland in the top 1m soil. The 28-year-old agroforestry
systems had higher soil organic carbon stocks (65.3-71.6Mg/ha) than the
cropland (52.8±2.6 Mg/ha) (Yadav, et al., 2021).
Magar, L.K. et al. (2020) reported Soil Organic Carbon (SOC) in different
agroforestry systems of the Makwanpur district averaged to be 24.9
tons/ha. The SOC was found to be decreasing with soil depth and the
Silvopastoral system with more leaf litter had more organic matter than
the agrisilviculture.
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12. SOIL EROSION CONTROL AND
REHABILITATION
Source: Sthapit, 2006
Planting of tree seedlings and cuttings along with structural
measures: Species preferred: Michelia champaca, Melia
azedarach, Schima wallichii, Choerospondias axillaris,
Azadirachta indica, and Emblica officinnalis.
Grass species: Stylo, Gini grass, Moth Napier, Molasses,
Pumpa, Joint vetch, Signal etc.
More tree and fruit species could be added and grass species
multiplied to cover the barren land (Guedel, N. 2006).
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13. AGROFORESTRY PRACTICES
Agroforestry practices with
substantial positive effect on
soil fertility (Young, 1997):
Improved tree fallow
Trees on cropland
Plantation crop combination
Home gardens
Hedgerow intercropping
Trees on erosion-control
structures
Windbreaks and shelterbelts
Biomass transfer
Trees on rangeland or
pastures
Woodlots with multipurpose
management
Reclamation forestry with
multipurpose management
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14. CONCLUSION
Agroforestry utilizes temporal and spatial arrangement
and can be designed to provide vegetation cover and
hence the associated benefit of soil conservation.
With most of the hilly terrain, it is challenging to prevent
soil erosion within the different types of agroforestry
systems.
Soil conservation measures through agroforestry could
easily be adopted by the farmers benefitting from
increased productivity and also a healthy watershed.
More research on soil dynamics in these systems is
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15. THANK YOU
FOR YOUR ATTENTION!
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References
Bayala, J., & Prieto, I. (2020). Water acquisition, sharing and
redistribution by roots: applications to agroforestry systems. Plant and
Soil, 453(1), 17-28.
Lalremsang, P., Upadhyaya, K., Sahoo, U. K., & Singson, L. (2022).
Effect of legume leaf mulch and fertilizer on soil quality and rice yield
for small scale production. Acta Ecologica Sinica.
Meng, X., Zhu, Y., Yin, M. et al. The impact of land use and rainfall
patterns on the soil loss of the hillslope. Sci Rep 11, 16341 (2021).
https://doi.org/10.1038/s41598-021-95819-5
Kumari Magar, L., Kafle, G., & Aryal, P. (2020). Assessment of Soil
Organic Carbon in Tropical Agroforests in the Churiya Range of
Makawanpur, Nepal.
Young, A. 1990. Agroforestry for Soil conservation. CABI, UK.