Transcript of "Tree cropping system for reclamation of problem soil"
AGR606 – Plantation
Cik Solehah Binti Saedon
Faculty of Plantation & Agrotechnology
Agroforestry systems have the potential to
make use of marginal and degraded lands
through the soil improving effects of trees.
Underlying all aspects of the role of
agroforestry in maintenance of soil fertility
the fundamental proposition that trees
improve soils. It would be useful to have
guidelines on which properties of a tree or
shrub species make it desirable for the
of view of soil fertility.
How Do We Know That Trees
1. The soil that develops under natural forest and woodland is
fertile. It is well structured, has a good water-holding capacity
and has a store of nutrients bound up in the organic matter.
Farmers know they will get a good crop by planting on cleared
2. The cycles of carbon and nutrients under natural forest
ecosystems are relatively closed, with much recycling and low
inputs and outputs.
3. The practice of shifting cultivation demonstrated the power of
trees to restore fertility lost during cropping.
4. Experience of reclamation forestry has demonstrated the
power of trees to build up fertility on degraded land.
In Brazil there have apply the nitrogen-fixing legume tree species for
the reclamation of severely degraded lands (Chaer et. al, 2011).
The main challenges faced in the reclamation of severely degraded
lands are in the management of the systems and finding plant species
that will grow under the harsh conditions common in degraded soils.
This is especially important in extremely adverse situations found in
some substrates from mining activities or soils that have lost their
Under these conditions, recolonization of the area by native vegetation
through natural succession processes may be extremely limited. Once the
physical and chemical factors restrictive to plant growth are corrected or
attenuated, the introduction of leguminous trees able to form symbioses
nodulating N2-fixing bacteria and arbuscular mycorrhizal fungi constitutes
efficient strategy to accelerate soil reclamation and initiate natural
These symbioses give the legume species a
superior capacity to grow quickly in poor
substrates and to withstand the harsh
conditions presented in degraded soils. In the
article it was describe several successful
Brazil using N2-fixing legume tree species for
reclamation of areas degraded by soil erosion,
construction and mining activities, emphasizing
potential of the technique to recover soil
matter levels and restore ecosystem
Research on legume tree nodulation
the mid- 1960s (Döbereiner 1967) with
selection and field response of Mimosa
caesalpiniifolia, a native species from the
Brazilian Caatinga (dry forest biome). This
species is certainly one of the most
planted legume tree species in Brazil
Production of legume
seedlings for land reclamation
Production of legume tree seedlings
of several steps, which start with the
of seeds from selected mother plants.
Selection of mother plants is important to
ensure that seeds originate from healthy
containing superior phenotypic
and maximum genetic variability, so they
should be collected from a range of
According to a study by local watershed committees, this
form of erosion is the principal cause of the accelerated
silting up of the Paraíba do Sul River, which is the main
source of water to nine million people living in the
metropolitan area of the city of Rio de Janeiro. In this case
study we report the use of FGLTs to recover a gulley in a rural
site in Pinheiral, south of the State of Rio de Janeiro (Figure
1). The gulley had an area of ~1000 m2, 10 m depth and a
volume of approximately ~10,000 m3 (equivalent to 2000
truckloads of sediment). (Chaer et. al, 2011)
Figure 1. Location of case study areas. (A) Revegetation of
erosion gullies, Pinheiral, Rio de Janeiro State (22°31’27”S,
43°59’08”W, average height of 420 m asl). (B) Revegetation of
iron mining overburden, Mariana-Ouro Preto districts, Minas
Gerais State (20°15′28′′S, 43°30′35′′W, average height 1000 m
asl). (C) Revegetation of areas degraded by piçarra extraction,
Rio Grande do Norte State (average height 50 m asl). (D)
Carbon accumulation in soils reclaimed with legume trees,
Angra dos Reis, Rio de Janeiro State (23°02′30′′S, 44°11′30′′W,
100–200 m asl).
The intervention was started in 2000 with the
construction of terraces at the upper and lower ends of the
gulley, and walls of bamboo and tires were positioned in the
inner part to trap sediments. Seedlings of several legume
trees, inoculated with selected rhizobia and AMF, were
planted along the gulley into holes cut into the walls with 2 m
× 2 m spacing. The success of the intervention was
measured by the growth of the trees and by the amount of
sediments collected in sediment tanks.
The species A. mangium, Mimosa artemisiana, M.
caesalpiniifolia and Pseudosamanea guachapele showed the
best survival and development after 170 days. The species A.
auriculiformes, Acacia angustissima, Albizia
lebbek, Enterolobium contortisiliquum and Samanea saman
showed low indices of survival, sometimes because of their
lower resistance to drought, or their position in the gulley
where water was not retained, or because they suffered from
attack by leaf-cutting ants.
Land reclamation and the
process of plant succession
The primary objective of reclaiming severely degraded
areas is to promote fast plant colonization of the area in
order to protect the soil against erosion, and to input
new biomass/carbon to the system.
The planting of FGLTs inoculated with selected rhizobium
strains and AMF is a strategy that has proved to be very
efficient in achieving these objectives. These species can
large quantities of organic matter and N to the soil through
litterfall in a relatively short time, improving nutrient cycling
the rehabilitation process.
Increasing SOM is very important in degraded land rehabilitation
projects, since, according to Francis and Read (1994), it enhances the
capacity of the system to support a more complex community. Macedo
et al. (2008) also showed that the N increase derived from BNF was
directly related to C incorporation, as indicated by the strong
correlation of soil C and N in all areas in this study (r = 0.78, P <
0.0001, n = 50). Owing to their ability to fix nitrogen, legume species
have been used as an N source in several tropical agroecosystems,
including pastures (Fisher et al. 1994, Tarré et al. 2001), no-till fields
(Sisti et al. 2004, Boddey et al. 2010), tree plantations (Resh et al.
2002, Balieiro et al. 2008) and agroforestry (Handayanto et al. 1995).
In these diverse systems, soil N content and SOM stocks were
found to increase. Organic matter is very important in tropical soils
since it plays a crucial role in the formation and maintenance of soil
structure, fertility, and nutrient and water availability (Bayer et al. 2001,
Craswell and Lefroy 2001, Six et al. 2002). It seems that in pasture,
forest or arable systems under no-till, where soil is not regularly
disturbed by ploughing, etc., N2-fixing legumes can play a very
important role in increasing soil carbon (i.e., sequestering atmospheric
CO2), especially in degraded areas where C stocks start at a very low
level (Boddey et al. 2009).
In conclusion, the tree-cropping system for reclamation of
problem soil is the system that often practiced to keep maintains
the good condition of soil in the long term. It reclaiming severely
degraded areas and to promote fast plant colonization of the area
in order to protect the soil against erosion, and to input new
biomass to the system.
Since the nitrogen is one of the main sources for
fertilizer requirement, the leguminous crop as beneficial plant
which bacteria Rhizobium do nitrogen fixation in the plant are
required to help in establishment of tree-copping system to
reclaims the soil problem especially for the problem of soil
erosion that often occur when rainy season by colonization of the
leguminous crop on the problems area.
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