1 This study showed that, millet production grown with Neem and Heiglig trees recorded highest dry matter both straw and yield.
2 Trees vary in their capacity to induce changes in soil pH, OC, ECe and
effects on soil K, P and N were not substantial. In this respect, the Hashab tree was found to contribute much higher amounts of SOC to the soil. However, due to high initial content, Neem tree could be a good source for enriching soil with P.
3 Heiglig litter is a good source for K, due to the rapid loss of K during the incubation period of decomposition.
4 An important aspect, Phosphorus and N release patterns from all tree litters studies, did not show a period of immobilization indicated by a concentration that was higher than the initial content (100%). This result indicates that incorporation of such litters do not seem to cause P or N starvation to accompanied annual crops.
73
6.2: Recommendations:
1.If the main aim is to increase and sustain crops production in sandy soil, it is worth to utilize the capacity of trees in the improvement of soil fertility.
2.For long term fertility correction (ie. Build up of soil organic matter), combined mulch from Neem and Heiglig or application of litter from Hashab could improve content of soil organic carbon.
3.Judicious application of mixed Heiglig or Neem with Hashab will improve both short and long term soil fertility improvement.
4.Litter from Hashab decomposed slowly. This phenomenon increases chances of accumulation of soil organic matter; hence, this tree might be useful in moisture conservation in such soils. Consequently, it is expected that the soil under such tree will be of better resilience which is important in the reduction of soil erosion.
5. It is suggested that further studies should look into (1) biological effects (e.g. microbial biomass C and N, soil enzymes) and (2) soil stability
74
References
Adrien C. Finzi, Charles D. Canham and Nico van Breemen. (1998).
Canopy Tree-Soil Interactions within Temperate Forests: Species Effects on pH and Cations Ecological Applications, Vol. 8, No. 2: 447-454
Aerts, R., Verhoeven, J.T.A., and Whigham, D.F. (1999). Plantmediated
controls on nutrient cycling in temperate fens and bogs. Ecology, 80: 2170– 2181.
Ahlam, A.M. (2004). Assessment of rate of decomposition and nutrient
release from leaf residue of some tree species. M.Sc. Thesis desertification, U. of K.
Akbar G., Ahmed, M., Rafique, S., and K.N. Babar. (1990). Effect of trees
on the yiled of wheat crop. Agroforestry systems 11: 1-10.
Amelung, W. (2001). Methods using amino sugars as markers for microbial
residues in soil. In Assessment Methods for Soil Carbon. R. Lal, J.M. Kimble, R.F. Follett and B.A. Stewart (eds). CRC/Lewis Publishers,Boca Raton, FL, pp. 233 – 267.
Andrews. Fw(1950- 1956): The flowing plants of the anglo . Egyption
Sudan, published for the Sudan Government by T Bunkle and co. ltd, Arboath, UK.
Apdein Mohamed Abdalla (1990-91). Personal communications (Assistant
Manager. ELAin NFMP, Sudan).
ASB (Alternatives to Slash and Burn research consortium). Undated. Alternatives to slash and burn: A global initiative. Nairobi, ICRAF.
Balser, T.C. (2005) Humifi cation. In Encyclopedia of Soils in the
Environment. D. Hillel et al. (eds). Vol. 2. Elsevier, Oxford, UK, pp. 195 – 207.
75
bacterial biomass ratios as an indicator of ecosystem self-regulation in temperate meadow grasslands. Biol. Fertil. Soils 29 , 282 – 290.
Bardgett, R.D. and Walker, L.R. (2004) Impact of colonizer plant species
on the development of decomposer microbial communities following deglaciation. Soil Biol. Biochem. 36 , 555 – 559.
Barth, R.C. & Klemmedson, J.O. (1982). Amount and distribution of dry
matter, nitrogen and organic carbon in soil-plant systems of mesquite and palo verde. Journal of Range Management, 35: 412–418.
Basher, I.H. (2003). Producing and marketing Arabic in Dilling area partial
fuel fillment research for B. Sc. Dilling university, Dilling.
Bauhus, J., Paré, D. and Côté, L. (1998). Effects of tree species, stand age
and soil type on soil microbial biomass and its activity in a southern boreal forest. Soil Biol. Biochem. 30 , 1077 – 1089
Belsky, A.J., Mwonga, S.M., Amundson, R.G., Duxbury, J.M. & Ali, A.R. - (1993). Comparative effects of isolated trees on their under canopy
environments in high- and low-rainfall savannas. Journal of Applied Ecology, 30: 143–155.
Belyea, L.R. (1996). Separating the effects of litter quality and
microenvironment on decomposition rates in a patterned peatland. Oikos, 77: 529–539.
Berg, B. (1984). Decomposition of root litter and some factors regulating
the process: Long-term root litter decomposition in Scots pine forest. Soil Biology and Biochemistry 16: 609-617.
Berg, B. and Staaf, H. (1981). Leaching accumulation and release of
nitrogen in decomposing forest litter. Ecol. Bull.33:163-178.
Berg, B. and Wessen, B. (1984). Changes in organic chemical components
76
compared to pine needles. Pedobiological 26: 285-298.
Blair, G.J.; Blair, N.; Lefroy, R.D.B.; Conteh, A. and Daniel, H. (1997).
Relationships between KMnO2 oxidizable C and soil aggregate stability and
the derivation of carbon management index. In: The role of humic substances in the ecosystems and environmental protection (Eds J. Drozd, SS Gonet. N Sensi. J Weber) pp. 227-232.
Blume , H., P. (1965). Die Charakterisierung von Humuskorpern durch
Streu-und Humns – Stoffgrup – penanalysen unter Berucksichtigung ihrer morphologischen Eigenschaften . Z. PflanzenernaehrDueng . Bodenkd . 111 : 95 – 114.
Branney.P (1989). "propagation of tree species for afforestation in Northern
Sudan". Find report for ODA.
Bravard, S. Righi, D., (1991). Characterization of fulvic and humic acids
from an Oxisol-Spodosol toposequence of Amazonia, Brazil. Geoderma 48, 151-162.
Brethelin, J., and F. Toutain. (1982). Soil Biology . In Constituents and
Prosperities of soil . M . Bonneau and B . Souchier (eds) . Academic Press, London , pp. 140 – 183.
Bridgham, S.D., Updegraff, K., and Pastor, J. (1998). Carbon, nitrogen
and phosphorus mineralization in northern wetlands. Ecology, 79: 1545– 1561.
Brookes P.C. (1995). The use of microbial parameters in monitoring soil
pollution by heavy metals. Biology and Fertility of Soils 19, 269–279.
Bunnell, F.L. and Tait, D.E. (1974). Mathematical simulation models of
decomposition in Tundra, A.J. Holding, O.W. Heal, S.F. Maclean and P.W. Flanagan (Eds), pp. 207-226. Swedish IBP Committee, Stockholm.
77
M.N., and Bayley, S.E. (2000). Net primary production and standing
standing biomass in northern continental wetlands. Can. For. Serv. Inf. Rep. NOR-X-369.
Cannell, M.G.R., van Noordwijk, M., Ong, C.K., (1996). The central
agroforestry hypothesis: the tree must acquire resources that the crop would not otherwise acquire . Agrofor. Syst.34, 27-31.
Champan, H.D and part, P.F. (1961). Methods of analysis of soil, plant
waters University of California USA.
Chantigny, M.H., Angers, D.A., Prévost, D., Vézina, L.P. and Chalifour, F.-P. (1997). Soil aggregation and fungal and bacterial biomass under
annual and perennial cropping systems. Soil Sci.Soc. Am. J.61,262– 267.
Clymo, R.S. (1965). Experiments on the breakdown of Sphagnum in two
bogs. J. Ecol. 53: 747–757.
Cobo, J.G.; Barrios, Kass, D.C.L. and Thomas, R.J. (2002).
Decomposition and nutrient release by green manures in a tropical hillside agroecosystem. Plant and soil 240: 331342.
Day, F.P. (1983). Effects of flooding on leaf litter decomposition in
microcosms. Oecologia, 56: 180–184.
Deans et al. (2003). Forest ecology and management. Vol 176: 253-264. Deans, J. D., Lindley, D.K., Munro, R., C., (1995). Deep Beneath Trees in
Senegal. Annual report 1993, Institute of Terrestrial Ecology, Bush Estate, penicuik, Scotland, UK, 1994, pp. 12-14.
Doran J.W. & Parkin T.B. (1994). Defining and assessing soil quality. In:
Defining soil quality for a sustainable environment, ed JW Doran, SSSA Special Publication no. 35. SSSA ASA Madison WI pp 3–21.
Dubois, O. (2003). Forest-Based Poverty Reduction: A Brief Review of
Facts, Figures, Challenges and Possible Ways Forward. Pp. 65-83. In: Oksanen, Pajari, Tuomasjukka (eds.) Forests in Poverty Reduction
78
Strategies: Capturing the Potential. EFI Proceedings No. 47. European Forest Institute. 206 p.
Duchafour , P. (1976). Dynamics of Organic matter in Soils of temperature
regions : Its action on pedogenesis . Geoderma 15:31 – 40 .
Edmunds, W.M., (1991). Ground-water Recharge in the West African
Sahel. Natural Environmental Research Council News No.17,pp.8-10.
Frolking, S., Roulet, N.T., Moore, T.R., Richard, P.J.H., Lavoie, M., and Muller, S.D. (2001). Modelling northern peatland decomposition and peat
accumulation. Ecosystems, 4: 479–498.
G.B. (1982). Seasonal dynamics of nitrogen cycling for a Prosopis
woodland in the Sonoran Loftis, S.G. & Kurtz, E.B. (1980). Field studies of inorganic nitrogen added to semi - arid soils by rainfall and blue-green algae. Soil Science, 129: 150–155.
Garcia-Moya, E., & McKell, C.M. (1970). Contribution of shrubs to the
nitrogen economy of a desert wash plant community. Ecology, 51: 81–88.
Gholz, I.I.L.; Perry, C.S.; Cropper, W.P. and Hendry, L.C. (1985).
Litterfall, decomposition, and nitrogen and phosphorus dynamics in a chronoseuence of slash pine (Pinus elliottii) plantation. For Sci. 31: 463- 478.
Glaser, B., Turriَn, M.-B. and Alef, K. (2004) Amino sugars and muramic
acid – biomarkers for soil microbial community structure analysis. Soil Biol. Biochem. 36 , 399 – 407.
Glover, E.K. 2005. Tropical dryland rehabilitation Case study on participatory forest management in Gedaref, Sudan. Doctoral thesis. University of Helsinki, Dept. of Forest Ecology, Viikki Tropical Resources Institute (VITRI). 183 p.
79
floors under four tree species in coastal British Columbia. Soil Biol. Biochem. 37 , 1157 – 1167.
Grayston, S.J., Griffi th, G.S., Mawdsley, J.L., Campbell, C.D. and Bardgett, R.D. (2001) Accounting for variability in soil microbial
communities of temperate upland grassland ecosystems. Soil Biol. Biochem. 33 , 533 – 551.
Guggenberger, G., Frey, S.D., Six, J., Paustian, K. and Elliott, E.T. (1999). Bacterial and fungal cell-wall residues in conventional and no-
tillage agroecosystems. Soil Sci. Soc. Am. J. 63 , 1188 – 1198.
Hackl, E., Pfeffer, M., Donat, C., Bachmann, G. and Zechmeister- Boltenstern, S. (2005). Composition of the microbial communities in the
mineral soil under different types of natural forest. Soil Biol. Biochem. 37, 661 – 671.
Hamza Mohamed ELAmin (1990). Trees and shrubs of the Sudan, Ithaca
press, Exeter, UK.