Effects of trees on soil

1. Agriculture and Forestry University
Faculty of Forestry
GRADUATE SEMINAR
Agroforestry System and Management (603 SFB)
12 september 2019 Hetauda
Carry out Some literature survey on
Effect of trees on soil
Presenter
Divesh Shrestha
Roll no : 6
M.Sc. Forestry

2. Introduction
• Agroforestry could be defined as a practice of raising
trees and agricultural crops in a given space and time
(Amatya, 2016).
• Agroforestry system as land use system that integrates
trees with agriculture crops, and or animals
simultaneously or sequentially to get higher productivity
more economic returns and better social and ecological
benefits on a sustainable yield basis than are obtainable
from mono-culture on the same unit of land, especially
under condition of low level of technological inputs on
marginal sites (ICRAF, 1982).

3. Introduction contd…
• Different tree species Albizia species, Dalbergia sissoo, Alnus nepalensis, Morus
alba, Ficus lacor, Bambusa species, Erythrina arborea, Salix species etc are
planted as agroforestry species (Amatya, 2016).
• Soil status is one of the important factors that determine how a crop will perform
on a certain site and trees growing with the crops will also have an impact on the
soil properties and moisture content of the soil (ICRAF, 1994).
• Direct effects of trees result from root growth, which supports the formation
of soil pores and soil aggregates (Angers and Caron, 1998), and from the
production of litter and root exudates, which greatly affects soil organic matter
content, chemistry, and soil structure (Brady and Weil, 2008)

4. Objectives
• To explore the effect of trees on soil.

5. Methodology
• Secondary data
- Different literatures, journals & thesis reports.
- Other related materials from different sources.

6. Finding and Discussion
Young, 1989
• Increasing inputs (organic matter,
nitrogen fixation, nutrient uptake).
• Reducing losses (organic matter,
nutrients) by promoting recycling
and checking erosion.
• Improving soil physical properties,
including water-holding capacity.
• Beneficial effects on soil biological
processes.
 Positive Effect

7. Finding and Discussion Contd…
Young,
1997
Processes which increase
additions to the soil
Processes which effect
soil physical conditions
Processes which
reduces losses from
the soil
Processes which
affect soil chemical
conditions
Soil Biological
processes and effects
Maintenance of soil
organic matter
Maintenance of soil
physical properties
Protection of
erosion
Reduction of acidity
or its rate
Production of high
quality leaf litter
Nitrogen fixation Modification of
extremes of soil
temperature
Nutrient retrieval
and recycling
Reduction of salinity
and sodicity.
Improved activity of
soil fauna
Nutrient uptake Reduction in the
rate of organic
matter
decomposition
Reduction of soil
toxicities
Improvement of
nitrogen
mineralization
Atmospheric inputs Reduction of water
loss from
evapotranspiration
Increased availability
of Phosphorus
Increased water
infiltration
Increased water
storage capacity
Root nodulation
Water retrieval Exudation of growth
promoting substances

8. Finding and Discussion Contd…
 It has been found that soils under trees compared with soil beyond the influence of
trees have higher C, N, P and K (Parthiban and Rai, 1994).
 Study conducted by Aggarwal (1993) with Prosopis cineraria in the arid part of
India also showed that C, N, P and K are higher.
Study carried out by Aggarwal and Dutta, 2002 shows
Organic carbon and total nitrogen concentrations were higher in the plantation stands.
The organic carbon content was maximum in the plots of Acacia auriculiformis.
Available nitrogen was highest in the plots of Eucalyptus hybrid.
Soil microbial biomass C, N and P were highest in the plots of Gravellia pteridifolia.
Ramamoorthy and Paliwal (1993) have found an interesting possibility is that
chemicals from Gliricidia sepium may contribute to the effect of mulch in reducing
weed growth and thereby increase crop yield.

9. Finding and Discussion Contd…
Negative Effect
 Trees also have a adverse effect on soil properties
• Loss of organic matter and nutrients in tree harvest
• Nutrient competition between trees and crops
• Moisture competition between trees and crops
• Production of substances which inhibit germination or growth. (Young, 1989)
 Mainly there are 3 types of effects of trees on soil
 Allelopathy: It is known as the release of substances by one plant which are toxic to
another.
 Acidification: Many plants produce organic acids. Where plant litter accumulates on or
is incorporated to the soil, these acids (including acetic acid, oxalic acid, and other
acids) are liberated.
 Removal of organic matter and nutrients: When trees are harvested considerable
amount of carbon and other nutrients of which trees accumulates in their biomass are
removed.

10. Finding and Discussion Contd…
In India, wheat and mustard yield reduction adjacent to rows of Eucalyptus
tereticornis were correlated with reductions in soil water (Malik and Sharma, 1990
quoted in Young 1997). Hauser (1993 b) reports that Flemingia congesta and
Gmelina arborea has small allelopathy effect.
The long-term impact of conifers on soil frequently involves nutrient loss and soil
acidification through litter and root inputs. These impacts are the result of slower
decomposition and litter build up on the forest floor (Berg and McClaugherty 2003;
Stendahl et al. 2010).
• Study carried out by Baber 2000, the organic matter content was low in the
Eucalyptus plantation area. Similarly in the teak and bombax plantation, soil pH
increased whereas organic carbon and exchange acidity declined with depth.

11. Finding and Discussion Contd…
THE EFFECT OF EUCALYPTUS ON CROP PRODUCTIVITY, AND SOIL
PROPERTIES IN THE KOGA WATERSHED, WESTERN AMHARA REGION,
ETHIOPIA
• Eucalyptus trees significantly affect available phosphorus,
exchangeable calcium, total nitrogen
• decreasing total nitrogen, avail. P and exch. Ca
• making soil unfertile
• Eucalyptus trees did not affect organic matter content in the soil
significantly.
• The available P content calculated was in the very low range.
Alemie, 2009

12. CONCLUSION
• .Trees plays an important role positively as well as negatively on soil
properties.
• Increasing organic matter, nitrogen fixation, reducing losses, benefit
effects on soil properties are the beneficial effects.
• Allelopathy, acidification and removal of organic matter and nutrients
are the negative effects.
• The benefits will only be obtained through a combination of the right
tree species with the right crops in the right spatial arrangements
and with the right management practices.

13. References
• Amatya, Swoyambhu Man, Shrestha, Kanhaiya Raj and Cedamon Edwin (2016). Nepal
Forestry Handbook. Kathmandu, Nepal.
• Raman kumar dutta & m. AGRAWAL, 2002, effect of tree plantations on the soil
characteristics and microbial activity of coal mine soil land, tropical ecology 43(2):
315-324.
• Tengnas B. 1994. Agroforestry extension manual for Kenya. Nairobi: International Centre
for Research in Agroforestry.
• Tilashwork Chanie Alemie, 2009, The effect of eucalyptus on crop productivity, and soil
properties in the koga watershed, western amhara region, ethiopia, Cornell
University.
• Young, T. 1989. Agroforestry for Soil Conservation. Wallingford, Oxford: CAB
International, 276 pp.

14. THANK YOU