AGR606 – Plantation IntegrationPresented by

Cik Solehah Binti Saedon2011152061

Faculty of Plantation & AgrotechnologyUiTM Perlis

TREE-CROPPING SYSTEM FOR RECLAMATION OF PROBLEM

SOILS

INTRODUCTION

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 is 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 point of view of soil fertility.

How Do We Know That Trees Improve Soils

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 natural forest.

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.

Case StudiesIn 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

upper horizons.

Under these conditions, recolonization of the area by native vegetation

through natural succession processes may be extremely limited. Once the main

physical and chemical factors restrictive to plant growth are corrected or

attenuated, the introduction of leguminous trees able to form symbioses with

nodulating N2-fixing bacteria and arbuscular mycorrhizal fungi constitutes an

efficient strategy to accelerate soil reclamation and initiate natural succession.

Continue…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 results in Brazil using N2-fixing legume tree species for reclamation of areas degraded by soil erosion, construction and mining activities, emphasizing

the potential of the technique to recover soil organic matter levels and restore ecosystem biodiversity and other environmental functions.

Continue…Research on legume tree nodulation started in the mid- 1960s (Döbereiner 1967) with strain 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 frequently planted legume tree species in Brazil today, and has been widely used for live fencing, landscape stabilization and land reclamation.

Production of legume seedlings for land reclamationProduction of legume tree seedlings consists of several steps, which start with the harvest of seeds from selected mother plants. Selection of mother plants is important to ensure that seeds originate from healthy plants containing superior phenotypic characteristics, and maximum genetic variability, so they should be collected from a range of individual plants from a given region and not from a single plant.

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).

Continue…

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

add large quantities of organic matter and N to the soil through litterfall in a relatively short time, improving nutrient

cycling and 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).

Conclusion

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.

REFERENCES Döbereiner, J. 1967. Efeito da inoculação de sementeiras de sabiá (Mimosa caesalpiniifolia) no

estabelecimento e desenvovimento das mudas no campo. Pesqui. Agropecu. Bras. 2:301–305. Francis, R. and Read, D.J. 1994. The contributions of mycorrhizal fungi to the determination of plant

community structure. Plant Soil 159:11–25. Macedo, M.O., Resende A.S., Garcia, P.C. Boddey, R.M. Jantalia, C.P. Urquiaga, S. Campello E.F.C. and

Franco, A.A.. 2008. Changes in soil C and N stocks and nutrient dynamics 13 years after recovery of degraded land using leguminous nitrogen-fixing trees. For. Ecol. Manage. 255:1516–1524.

Fisher, M.J., Rao, I.M. Ayarza, M.A. Lascano, C.E. Sanz, J.I. Thomas R.J. and Vera, R.R. 1994. Carbon storage by introduced deep-rooted grasses in the South American savannas. Nature 371:236–238.

Tarré, R.M., Macedo, R. Cantarutti, R.B. Resende, C.P. Pereira, J.M. Ferreira, E. Alves, B.J.R.Urquiaga S. and Boddey, R.M. 2001. The effect of the presence of a forage legume on nitrogen and carbon levels in soils under Brachiaria pastures in the Atlantic Forest region of the South of Bahia, Brazil. Plant Soil 234:15–26.

Sisti, C.P.J., Santos, H.P. Kohhann, R.A. Alves, B.J.R. Urquiaga S. and Boddey, R.M. 2004. Change in carbon and nitrogen stocks in soil under 13 years of conventional or zero tillage in southern Brazil. Soil Till. Res. 76:39–58.

Resh, S.C., Binkley D. and Parrotta, J.A. 2002. Greater soil carbon sequestration under nitrogen-fixing trees compared with Eucalyptus species. Ecosystems 5:217–231.

Handayanto, E., Cadisch, G. and Giller, K.E. 1995. Manipulation of quality and mineralization of tropical legume tree prunings by varying nitrogen supply. Plant Soil 176:149–160.

Bayer, C., Martin-Neto, L. Mielniczuk, J. Pillon C.N. and Sangoi. L. 2001. Changes in soil organic matter fractions under subtropical no-till cropping systems. Soil Sci. Soc. Am. J. 65:1473–1478.

Boddey, R.M., Alves, B.J.R. Soares, L.H.D.B. Jantalia C. and Urquiaga, S. 2009. Biological nitrogen fixation and the mitigation of greenhouse gas emissions. In Nitrogen Fixation in Crop Production. Eds. D.W. merich and H.B. Krishnan. ASA-CSSA-SSSA, Madison, WI, pp 387 413.

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