Director |
Prof. Dr. Paul L.G. Vlek |
| Contact |
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| Department | ZEF C: Department of Ecology and Natural Resources Management | |
| Publications |
Vlek, P.L.G., A.M. Manschadi, and J.P.A. Lamers. 2011. Ökonomische und ökologische Umstrukturierung der Land- und Wassernutzung in der Region Khorezm (Usbekistan) – Ein Pilotprojekt in der Entwicklungsforschung. In: IWRM. Integriertes Wasserressourcen-Management: Von der Forschung zur Umsetzung. Leipzig, Magdeburg, 26-27. 2010. Assessment of Land Degradation, Its Possible Causes and Threat to Food Security in Sub-Saharan Africa. In: Lal, R. and B.A. Stewart (eds.): Advances in soil sciences food security and soil quality. P. 57,
Djumaeva, D., J.P.A. Lamers, C. Martius, A. Khamzina and P.L.G. Vlek.
2010.
Quantification of symbiotic nitrogen fixation by Elaeagnus angustifolia L. on salt-affected irrigated croplands using two 15N isotopic methods.
Nutr. Cycl. Agroecosyst.,
88:
329-339.
Djumaniyazova Y., R. Sommer, N. Ibragimov, J. Ruzimov, J. Lamers and P. Vlek. 2010. Simulating water use and N response of winter wheat in the irrigated floodplains. Field Crops Research, 116: 239-251.
Feitosa F., Q. B. Le and P. L. G. Vlek.
2010.
Multi-agent simulator for urban segregation (MASUS): A tool to explore alternatives for promoting inclusive cities computers, environment and urban systems.
Le, Q. B., S. J. Park and P. L.G. Vlek.
2010.
Land Use Dynamic Simulator (LUDAS): a multi-agent system model for simulating spatio-temporal dynamics of coupled human–landscape system. 2-. Scenario-based application for impact assessment of land-use policies.
Ecological Informatics,
5 (3):
203-221.
MacCarthy, D.S., Paul L.G. Vlek, A. Batiano, R. Tabo and M. Fosu.
2010.
Modeling nutrient and water productivity of sorghum in smallholder farming systems in a semi-arid region of Ghana.
Field Crops Res.,
Mondal, Md. A. H., M. Denich and P.L.G. Vlek.
2010.
The future choice of technologies and co-benefits of CO2 emission reduction in Bangladesh power sector.
Nyarko, B.K., D.K. Essumang, M.J. Eghan, B. Reichert, N. van de Giesen and P.L.G. Vlek. 2010. Use of isotopes to study floodplain and wetland and river flow interaction in the White River Volta Basin, Ghana. Isotopes in Environmental Health Studies, 46: 91-106.
Villamor, G.B. M. van Noordwijk, Q B Le, B. Lusiana, R. Matthews and P.L.G. Vlek.
2010.
Diversity deficits in modeled landscape.
1-10.
Vlek, P.L.G., Q. B. Le and L. Tamene. 2010. Assessment of land degradation, its possible causes and threat to food security in Sub-Saharan Africa. In: Rattan Lal and B.A. Stewart (eds.): Advances in Soil Science - Food Security and Soil Quality. CRC Press, Boca Raton, 57-86. Adwubi, A., B. K. Amegashie, W. A. Agyare, L. Tamene, S. Nii Odai, C. Quansah and P.L.G. Vlek. 2009. Assessing sediment inputs to small reservoirs in Upper East Region, Ghana. Lakes & Reservoirs, 14: 279-287. Djumaeva, D., N. Djanibekov, P.L.G. Vlek, C. Martius and J.P.A. Lamers. 2009. Options for optimizing dairy feed rations with foliage of trees grown in the irrigated drylands of Central Asia. Journal of Agricultural and Biological Sciences, 5(5): 698-708. Fatondji, D., C. Martius, C.L. Bielders, S. Koala, P.L.G. Vlek and R. Zougmore. 2009. Decomposition of organic amendment and nutrient release under the zai technique in the Sahel. Nutrient Cycling in Agroecosystems, 85(3): 225-239. Forkutsa, I., R. Sommer, Y.I. Shirokova, J.P.A. Lamers, K. Kienzler, B. Tischbein, C. Martius and P.L.G. Vlek. 2009. Modeling irrigated cotton with shallow groundwater in the Aral Sea Basin of Uzbekistan. II. Soil salinity dynamics Irrig Sci, 27 (4): 319-330. Forkutsa, I., R. Sommer, Y. I. Shirokova, J.P.A. Lamers, K. Kienzler, B. Tischbein, C. Martius and P.L.G. Vlek. 2009. Modeling irrigated cotton with shallow groundwater in the Aral Sea Basin of Uzbekistan: I. Water dynamics. Water dynamics Irrig Sci, 27 (4): 331-346. Khamzina, A, R. Sommer, J.P.A. Lamers and P.L.G. Vlek. 2009. Transpiration and early growth of tree plantations established on degraded cropland over shallow saline groundwater table in northwest Uzbekistan. Agricultural and Forest Meteorology, 11: 1865-1874. Khamzina, A., J.P.A. Lamers and P.L.G. Vlek. 2009. Nitrogen fixation by Eleagnus angustifolia L. in the reclamation of degraded croplands of Central Asia. Tree Physiology, 29: 799-808. MacCarthy, D.S., R. Sommer and P.L.G. Vlek. 2009. Modeling the impacts of contrasting nutrient and residue management practices on grain yield of sorghum (Sorghum bicolor (L.) Moench) in a semi-arid region of Ghana using APSIM. Field Crops Res., 113 (2): 105-115. Park, S. J., G. R. Rüecker, W. A. Agyare, A. Akramhanov, D. Kim, P. L. G. Vlek. 2009. Influence of grid cell size and flow routing algorithm on soil-landform modeling. Journal of the Korean Geographical Society, 44 (2): 122-145. Compaoré, H., J.M.H. Hendrickx, Sung-ho Hong, J. Friesen, N. van de Giesen, C. Rodgers, J. Szarzynski and P.L.G. Vlek. 2008. Evaporation mapping at two scales using optical imagery in the White Volta Basin, Upper East Ghana. Physics and Chemistry of the Earth, 33: 127-140. Khamzina, A., J.P.A. Lamers and P.L.G. Vlek. 2008. Tree establishment under deficit irrigation on degraded agricultural land in the lower Amu Darya river region, Aral Sea basin. Forest Ecology and Management, 255: 168-178. Vlek, P.L.G.. 2008. The incipient threat of land degradation. Journal of the Indian Society of Soil Science, 56 (1): 1-13. Vlek, P.L.G., D. Hillel and A.K. Braimoh. 2008. Soil degradation under irrigation.. In: A.K. Braimoh and P.L.G. Vlek (eds.): Land Use and Soil Resources. Springer Science 7 Business Media B.V. Dordrecht, 101-119. Anhar, A., Sommer, R., Becker, M. and P.L.G. Vlek. 2007. The isotope 15N enrichment technique to measure the biological nitrogen fixation in cacao agroforestry system in Central Sulawesi Indonesia. Agrista, 54-59. Rodgers, C., N. van de Giesen, W. Laube, P. L. G. Vlek and E. Youkhana. 2007. The GLOWA Volta Project: A framework for water resources decision-making and scientific capacity building in a transnational West African Basin. Water Resources Management, 21: 295-313. Chhabra, A., H. Geist, R.A. Houghton, H. Haberl, A.K. Braimoh, P.L.G. Vlek, J. Patz, J. Xu, N. Ramankutty, O. Coomes and E. F. Lambin. 2006. Multiple impacts of land-use/cover change. In: E.F. Lambim and H. Geist (eds.): Land-Use and Land-Cover Change. Local Processes and Global Impacts. Springer-Verlag, Berlin Heidelberg, Germany, Chapter 4: 71- 116. Giesen, N. van de, T. Berger, M. Iskanderani, S. Park and P.L.G. Vlek. 2006. Integrative Water Research: GLOWA Volta. In: E. Ehlers and T. Krafft (eds.): Earth System Science in the Anthropocene. Springer, Berlin/Heidelberg, Hendrickx, J.M.H., S.-h. Hong, J. Friesen, H. Compaore, N.C. van de Giesen, C. Rodgers, and P.L.G. Vlek. 2006. Mapping energy balance fluxes and root zone soil moisture in the White Volta Basin using optical imagery. Proc. International Society for Optical Engineering, SPIE, 6239: 238-249. Kaizzi, C.K., H. Ssali and P.L.G. Vlek. 2006. Differential use and benefits of Velvet bean (Mucuna pruriens var. utilis) and N fertilizers in maize production in contrasting agro-ecological zones of E. Uganda. Agric. Systems, 88: 44-60. Khamzina, A., J.P.A. Lamers, Chr. Martius, M. Worbes and P.L.G. Vlek. 2006. Potential of nine multipurpose tree species to reduce saline groundwater tables in the lower Amu Darya river region of Uzbekistan. Agroforestry Systems. Khamzina, A., J.P.A. Lamers, M. Worbes, E. Botman and P.L.G. Vlek. 2006. Assessing the potential of trees for afforestation of degraded landscapes in the Aral Sea Basin of Uzbekistan. Agroforestry Systems, 66 (2): 129-141. Tamene, L., S.J. Park, R. Dikau and P.L.G. Vlek. 2006. Analysis of factors determining sediment yield variability in the highlands of northern Ethiopia. Geomorphology, 76: 76-91. Tamene, L., S.J. Park, R. Dikau, and P.L.G. Vlek. 2006. Reservoir siltation in the semi-arid highlands of northern Ethiopia: sediment yield – catchment area relationship and a semi-quantitive approach for predicting sediment yield. Earth Surf. Process. Landforms, 31: 1364 – 1383. Vlek, P.L.G. and F.W. Gatzweiler.. 2006. Can we walk the "Middle Path" in coping with global environmental change?. Paper submitted for the conference on Ecology and Buddhism in the Knowledge-based Society, Dongguk University, Seoul, Korea, May 25-27, 2006. Braimoh, A.K. and Vlek, P.L.G. 2005. Land cover change trajectories in Northern Ghana. Environmental Management, 36 (3): 356-373. Braimoh, A.K., Stein, A. and Vlek, P.L.G. 2005. Identification and Mapping of Associations among Soil Variables. Soil Science, 170(2): 137-148. Codjoe, S.N.A., E. Ehlers and P.L.G. Vlek. 2005. Effects of change in population, household conditions and farming practices on agricultural land use in the Volta river basin of Ghana. Erdkunde, 59: 126-135. Denich, M., P.L.G. Vlek, T. de Abreu Sá, K. Viehauer and W. Lücke. 2005. A concept for the development of fire-free fallow management in the Eastern Amazon, Brazil. Agriculture, Ecosystems & Environment, 110 (1-2): 43-58. Gehring, C., M. Denich and P.L.G. Vlek. 2005. Resilience of secondary forest regrowth after Slash-and-Burn Agriculture in Central Amazonia. J. Trop. Ecology, 21: 1-9. Gehring, C., P.L.G. Vlek, L.A.G. de Souza and M. Denich. 2005. Biological nitrogen fixation in secondary and primary forests of Central Amazonia. Agric. Ecosyst. and Environm., 111: 237 – 252. Grote, U., E.T. Craswell and P.L.G. Vlek. 2005. Nutrient flows in international trade: Ecology and policy issues. Environmental Science & Policy, Vol. 8 (5): 439-451. Hendrickx, J.M.H., J.B.J. Harrison, R.L. Van Dam, B. Borchers, D.I. Norman, C.D. Dedzoe, B.O. Antwi, R.D. Asiamah, C. Rodgers, P. Vlek and J. Friesen. 2005. Magnetic soil properties in Ghana. Proc. International Society for Optical Engineering, SPIE 5794: in press. Hillel, D. and P. Vlek. 2005. The sustainability of irrigation. Advances in Agronomy 87. Le Phuong, T., M. Denich, P. L. G. Vlek and V. Balasubramanian. 2005. Suppressing weeds in direct-seeded lowland rice: effects of methods and rates of seeding. Journal of Agronomy and Crop Science, 191(3): 185-194. Mitra, S., R. Wassmann and P.L.G. Vlek. 2005. An appraisal of global wetland and its organic carbon stock. Current Science, 88 (1): 25-35. Park, S.J., N. van de Giesen and P.L.G. Vlek. 2005. Optimal spatial scale for land use change modelling: A case study in a savanna landscape in Northern Ghana. J. Korean Geogr. Soc., 40: 221-241. Ryan, J., P. Vlek and R. Paroda. 2005. Agriculture in Central Asia: Research for Development. ICARDA and ZEF, Senbeta, F., C. Schmitt, M. Denich, S. Demissew, P.L.G. Vlek. H. Preisinger, T. Woldemariam and D. Teketay. 2005. The diversity and distribution of lianas in the Afromontane rain forests of Ethiopia. Diversity and Distrib., 11: 443-452. Youkhana, E., B. Arendt, H. Kunstmann, N. Martin, C. Rodgers, and P.L.G. Vlek. 2005. The GLOWA-Volta project: Studies on the sustainable use of water resources in the Volta river basin in West Africa. Hydrol. u. Wasserbewirtsch. (HW), 49 (4): 190-200. Braimoh, A.K. and P.L.G. Vlek. 2004. Land-cover change analyses in the Volta Basin of Ghana. Earth Interactions 8. Paper 21. Braimoh, A.K. and P.L.G. Vlek. 2004. Scale dependent relationships between land-use change and its determinants in the Volta Basin of Ghana. Earth Interactions, 8 (4): 1-23. Braimoh, A.K. and P.L.G. Vlek. 2004. The impact of land-cover change on soil properties in Nothern Ghana. Land Degrad. and Develop., 15: 65-74. Braimoh, A.K. and P.L.G. Vlek. 2004. Land-cover dynamics in an urban area of Ghana. Earth Interactions, 8 (1): 1- 15. Braimoh, A.K., P.L.G. Vlek and A. Stein. 2004. Land evaluation for maize based on fuzzy set and interpolation. Environm- Managem., 33: 226-238. Brunner, A.C., S. J. Park, G.R. Ruecker, R. Dikau and P.L.G. Vlek. 2004. Catenary soil development influencing erosion susceptability along a hilslope in Uganda. CATENA, 58: 1-22. de Macale, M.A.R. and P.L.G. Vlek. 2004. The role of Azolla cover in improving the nitrogen use efficiency of lowland rice. Plant Soil, 263: 307-317. Denich, M., K. Vielhauer, M.S. de A. Kato, A. Block, O.R. Kato, T.D. de Abreu SÃ, W. Lücke, P.L.G. Vlek. 2004. Mechanized land preparation in forest-based fallow systems: The experience from Eastern Amazonia. Agroforestry Systems, 61: 91-106. Fosu, M., R.F. Kühne and P.L.G. Vlek. 2004. Improving maize yield in the Guinea Savannah zone of Ghana with leguminous cover crops and PK fertilization. Journal of Agronomy, 3(2): 115-121. Gehring, Chr. and P.L.G. Vlek. 2004. Limitations of the 15N natural abundance method for estimating biological nitrogen fixation in Amazonian forest legumes. Basic and Applied Ecology, 5: 567 – 580. Ibrakhimov, M. S. Park and P.L.G. Vlek. 2004. Development of groundwater salinity in a region of the Lower Amudarya River, Khresm, Uzbekistan. In: J. Ryan, P.L.G. Vlek and R. Paroda (eds.): Agriculture in Central Asia: Research for Development. ICARDA, Aleppo, Syria, Kaizzi, C.K., H. Ssali and P.L.G. Vlek. 2004. The potential of Velvet bean (Mucuna pruriens) and N fertilizers in maize production on contrasting soils and agro-ecological zones of East Uganda. Nutr. Cycling in Agroecosyst, 68: 59-72. Kurzatkowski, D., Chr. Martius, H. Hüfer, M. Garcia, B. Fölster, L. Beck, P. Vlek. 2004. Litter decomposition, microbial biomass and activity of soil organisms in three agroforestry sites in central Amazonia. Nutr. Cycling Agroecosyst., 69: 257-268. Martius, C., J. Lamers, M. Ibrakhimov, P.L.G. Vlek. 2004. Towards a sustainable use of natural resources in the Aral Sea. In: H. Bogena, J-F. Hake, H. Vereecken (eds.): Water and Sustainable Development. Schriftendes Forschungzentrums Julich. Reihe Umwelt/Environment (48), 117-134. Martius, C., J. Lamers, P. Werheim, A. Schoeller-Schletter, R. Esxhanov, A. Tupitsa, A. Khamzina, A. Akramkhanov, P.L.G. Vlek. 2004. Developing sustainable land and water management for the Aral Sea Basin through an interdisciplinary approach. In: V. Water in Agriculture.Proceedings of a CARDI International Conference. Phnom Penh, Cambodia, 25-28 November 200. ACIAR Proceedings 116, 45-60. Martius, Chr. J. Lamers, P. Wehrheim, A. Schoeller-Schletter, R. Eschanov, A. Tupitsa, A. Khamzina, A. Akramkhanov and P.L.G. Vlek. 2004. Developing sustainable land and water management fort he Aral Sea Basin through an interdisciplinary approach. In: Vang Seng, Eric Craswell, Shu Fukai and Ken Fischer (eds.): Water in Agriculture. ACIAR Proceedings 116, Canberra, Australia, Oguntunde, P.G., N.C. van de Giesen, P.L.G. Vlek and H. Eggers. 2004. Water flux in a Cashew orchard during a wet-to dry transition period: Analysis of sap flow and eddy correlation measurements. Earth Interactions, 8 (15): 1-17. Vlek, P.L.G., G. Rodríguez-Kuhl and R. Sommer. 2004. Energy use and CO2 production in tropical agriculture amd means and strategies for reduction or mitigation. Environment, Development and Sustainability, 6 (1-2): 213-233. Wassmann R., and P.L.G. Vlek. 2004. Mitigating greenhouse gas emissions from tropical agriculture: Scope and Research Priorities. Environment, Development and Sustainability, 6(1-2): 1-9. Bationo, A., U. Mokwunye, P.L.G. Vlek, S. Koala and B.I. Shapiro. 2003. Soil fertility management for sustainable land use in the West African Sudano-Sahelian Zone. In: Gichuru, M. P., A. Bationo, M. A. Bekunda, H. C. Goma, P. L. Mafongonya, D. N. Mugendi, H. M. Murwira, S. M. Nandwa, P. Nyathi, P. and M.J. Swift (eds.): Soil fertilkity management in Africa: A regional perspective. Academic Science Publishers, African Academy of Sciences, Nairobi, Kenya, Cissé, M and P.L.G. Vlek. 2003. Influence of urea on biological N2 fixation and N transfer from Azolla intercropped with rice. Plant Soil, 250: 105 – 112. Cissé, M and P.L.G. Vlek. 2003. Conservation of urea-N by immobilization-remobilization in a rice-Azolla intercrop. Plan Soil, 250: 95 -104. Fosu, M., R.F. Kühne and P.L.G. Vlek. 2003. Recovery of cover-crop-N in the soil-plant system in the Guinea savannah zone of Ghana. Biol Fertil Soils, 39: 117 – 122. Gorfu, A., R.F. Kuehne, D.G. Tanner and P.L.G. Vlek. 2003. Recovery of 15N-labelled urea applied to wheat (Triticum aestivum L.) in th Ethiopian highlands as affected by P fertilization. J. Agronomy & Crop Science, 189: 30 – 38. Somado, E. A., M. Becker, R. Kühne, K. L. Sahrawat, P.L.G. Vlek. 2003. Rock-P effects on biomass and nitrogen accumulation by legumes in upland crop production systems of humid West Africa. Journal of Plant Nutrition and Soil Science (submitted), Somado, E. A., M. Becker, R. Kühne, K. L. Sahrawat, P.L.G. Vlek. 2003. Combined effects of legumes with phosphate rock on rice in West Africa. Agron. J., 95: 1172-1178. Sommer, R., H. Fölster, K. Vielhauer, E.J. Maklouf Carvalho and P.L.G. Vlek. 2003. Deep soil water dynamics and depletion by secondary vegetation in the Eastern Amazon. SSSAJ, 67 (6): 1672-1686. Vlek, P.L.G. and C. Martius. 2003. Rettung für die Aralsee-Region?. e.velop, 13, 09/2003: Further Information: www.bundesregierung.de/Service/Online-Publikationen/E-Magazines-,9276.523747/e-magazine.htm?link=bpa_ezine. Andreini, M., P.L.G. Vlek and N. van de Giesen. 2002. Water sharing in the Volta basin. In: FRIEND 2002 – Regional Hydrology:Bridging the gap between research and practice. IAHS Publ. No 274, Giesen, N. van de, H. Kunstmann, G. Jung, J. Liebe, M. Andreini and P.L.G. Vlek. 2002. The GLOWA-Volta project: Integrated assessment of feedback mechanisms between climate, landuse, and hydrology. Advances in Global Change Research, 2002, Vol 10: 151-170. Gole., T.W., M. Denich, D. Teketay and P.L.G. Vlek. 2002. Human impact on the Coffea arabica genepool in Ethiopia and the need for its in situ conservation. In: Engels, Rao, Brown and Jackson (eds.): Managing plant genetic diversity. CAB International, Ch 23: 237- 247. Macale, M.A.R. de, and P.L.G. Vlek. 2002. The role of Azolla cover in improving the nitrogen use efficiency of lowland rice. In: Li Dajue (eds.): 2nd international conference on sustainable agriculture for food, energy and industry. Institute of Botany, Chinese Academy of Sciences, 921- 930. Manske, G.G.B. and P.L.G. Vlek. 2002. Root architecture – Wheat as a model plant. In: Y Waisel, A. Eshel, and U. Kafkafi (eds.): Plant roots, the hidden half. Marcel Dekker, Inc. New Yok-Basel, Manske, G.G.B., J.I. Ortiz-Monasterio and P.L.G. Vlek. 2002. Techniques for measuring genetic diversity in roots. In: M.P. Reynolds, J.I. Ortiz-Monasterio and A. McNab (eds.): Application of physiology in wheat breeding. Mexico D.F. Cimmyt, 208-218. Park, S.J. and P.L.G. Vlek. 2002. Soil-landscape analysis as a tool for sustainable land management. Geogr. J. Korea., 36: 31-49. Park, S.J. and P.L.G. Vlek. 2002. Environmental correlation of three-dimensional soil spatial variability: a comparison of three adaptive techniques. Geoderma, 109 (1-2): 117-140. Somado, E.A., R.F. Kuehne, M. Becker, K.L. Sahrawat and P.L.G. Vlek. 2002. Improving phosphate rock solubility and uptake and yield of lowland rice grown on an acidic soil amanded with legume green manure. In: Vanlauwe et al (eds.): Integrated plant nutrient management in Sub-saharan Africa: From concept to Practice. CABI Publishing, Wallingford, U.K, 251-263. Sommer, R., T.D. de Abreu Sá, K. Vielhauer, A. Carioca de Araújo, H. Foelster, and P.L.G. Vlek. 2002. Transpiration and canopy conductance of secondary vegetation in the Eastern Amazon. Agricult. And Forest Meteorology, 112: 103-121. Vlek, P.L.G., U. Eberhardt, U. and M-M. Aung. 2002. The role of Azolla in lowering the pH of simulated floodwater. Journal of Applied Biology, 76: 1-7. Wick, B. R.F. Kuehne, K. Vielhauer and P.L.G. Vlek. 2002. Temporal variability of selected soil microbiological and biochemical indicators under different soil quality conditions in south-western Nigeria. Biol. Fertil. Soils, 35: 155-167. Wick, B., R. Kuehne, K. Vielhauer and P.L.G. Vlek. 2002. Temporal variability of selected soil microbiological and biochemical indicators under different soil quality conditions in south-western Nigeria. Biology and Fertility of Soils, 35: 155-167. Manske G.G.B., J.I. Ortiz-Monasterio and P.L.G. Vlek. 2001. Techniques for measuring genetic diversity in roots. In: Reynolds et al. (eds.): Application of Physiology in Wheat Breeding. CIMMYT; Mexico, Ch. 18: 208-218. Manske. G.G.B., J.I. Ortiz-Monasterio, M. van Ginkel, R:M. González, R.A. Fischer, S. Rajaram and P.L.G. Vlek. 2001. Importance of P uptake efficiency versus P utilization for wheat in acid and calcareous soils in Mexico. European J. Agron, 14: 261 – 274. Martius. C., H. Tiessen, and P.L.G. Vlek. 2001. The management of organic matter in tropical soils: what are the priorities?. Nutrient Cycl. In Agroecosystems, 61: 1–6. Sommer. R., T.D.A. de Sá, K. Vielhauer, P.L.G. Vlek and H. Foelster. 2001. Water and nutrient balance under slash-and-burn agriculture in the Eastern Amazon, Brazil – The role of deep rooting fallow vegetation. In: Horst et al (eds.): Plant nutrition – Food security and sustainability of agr-ecosystems. Kluwer Sci. Publ. Dordrecht Netherlands, 1014-1015. Van de Giesen, N., M. Andreini, A. van Edig and P.L.G. Vlek. 2001. Competition for water resources of the Volta basin. Regional Water Managm. of Water Res. IAHS Publ no 268, Vlek, P.L.G., D. Hillel, J.C. Katyal and W. Seiler. 2001. Water deficiency and desertification. In: Ehlers and Krafft (eds.): Understanding the Earth System. Springer Berlin,Germany, 275 – 279. Vlek, Paul L.G., D. Hillel and S. Teimann. 2001. Land Degradation: Causes and Prevention. In: Virchow and Von Braun (eds.): Villages in the Future. Springer Verlag, Berlin, Ch. 25: 169-171. Bationo, A., S. P. Wani, C. L. Bielders, P. L. G. Vlek and A. U. Mokwunye. 2000. Crop Residue and Fertilizer Management to Improve Soil Organic Carbon Content, Soil Quality and Productivity in the Desert. In: R. Lal, H. Eswaran, J. M. Kimble and B. A. Stewart (eds.): Global climate change and tropical ecosystems. Lewis Publishers CRC pressBoca Raton, Fl.USA, Denich, M., M. Kanashiro and P.L.G. Vlek. 2000. 2000. The potential and dynamics of carbon sequestration in traditional and modified fallow systems of the eastern Amazon region, Brazil. In: R. Lal, H. Eswaran, J.M. Kimble and B. A. Stewart (eds.): Global climate change and tropical ecosystems. Lewis Publishers CRC pressBoca Raton, Fl. USA, Gorfu, A., R.F. Kuehne, D.G. Tanner and P.L.G. Vlek. 2000. Biological nitrogen fixation in Faba bean (Vicia faba L.) in the Ethiopian highlands as affected by P fertilization and inoculation. Biol. Fert. Soil, 32: 1-7. Lange-Ness, R. and P.L.G. Vlek. 2000. Mechanism of calcium and phosphate release from Hydroxy-Apatite by mycorrhizal hyphae. SSSAJ, 64: 949-955. Manske, G.G.B., J.I. Ortiz-Monasterio, M. van Ginkel, R.M. González, S. Rajaram, E. Molina and P.L.G. Vlek. 2000. Traits associated with improved P-uptake efficiency in CYMMIT’s semidwarf spring bread wheat grown on an acid Andisol in Mexico. Plant Soil, 221(2): 189-204. Sommer, R., M. Denich and P.L.G. Vlek. 2000. Carbon storage and root penetration in deep soils under small-farmer land-use systems in the Eastern Amazon region, Brazil. Plant Soil, 219: 231-241. Egle, K., G. Manske, W. Roemer and P.L.G. Vlek. 1999. Improved phosphorus efficiency of three new wheat genotypes from CIMMYT in comparison with an older Mexican variety. J. Plant Nutr. Soil Sci., 162: 353-358. Gehring, Chr., M. Denich, M. Kaneshiro and P.L.G. Vlek. 1999. Response of secondary vegetation in Eastern Amazonia to relaxed nutrient availability constraints. Biogeochemistry, 45: 223-241. Kato, M.S.A ., O.R. Kato, M. Denich and P.L.G. Vlek. 1999. Fire-free alternatives to slash-and-burn for shifting cultivation in the eastern Amazon region: the role of fertilizers. Field Crops Research, 62: 225-237. Kühne, R.F., P. Vlek and H. Tiessen. 1999. Maintaining soil quality in tropical cropping systems. Mitt.Ges.Pflanzenbauwiss., 12: 11-16. Kühne, R.F., P.L.G. Vlek and H. Tiessen. 1999. Maintaining soil quality in tropical cropping systems. Mitteilungen der Gesellschaft für Pflanzenbauwissenschaften, Band 12, 1999: 11-16. Mandal, B., P.L.G. Vlek and L.N. Mandal. 1999. Beneficial effects of blue-green algae and Azolla, excluding supplying nitrogen, on wetland rice fields: a review. Biology & Fert. of Soils, 28: 329-342. Schultz, C., G. Ginting, A.M. Moawad and P.L.G. Vlek. 1999. The role of (vesicular-) arbuscular mycorrhiza in the weaning stage of micropropagated oil palms. Mitteilungen aus der Biologischen Bundesanstalt für Land- und Forstwirtschaft Berlin-Dahlem, Heft 363, 1999: 74-82. Bationo, A., and P.L.G. Vlek. 1998. The Role of Nitrogen Fertilizers Applied to Food Crops in the Sudano-Sahelian Zone of West Africa. In: Renard, G., Neef, A., Becker, K. and von Oppen, M. (eds.): Soil Fertility Management in West African Land Use Systems. Proc. Regional Workshop Univ. Hohenheim, ICRISAT Sahelian Centre and INRAN 4-8 March 1997, Niamey, Niger. Margraf, Weikersheim, 41-51. Sanetra, C.M., O. Ito, S.M. Virmani, and P.L.G. Vlek. 1998. Remobilization of nitrogen from senescing leaves of pigeonpea (Cajanus cajan (L.) Millsp.): genotypic differences across maturity groups. J. Exp. Bot., 49 (322): 853-862. Wick, B., R.F. Kühne, and P.L.G. Vlek. 1998. Soil microbiological parameters as indicators of soil quality under improved fallow management systems in south-western Nigeria. Plant and Soil, 202, 1998: 97-107. Vlek, P.L.G., R.F. Kühne, and M. Denich. 1997. Nutrient resources for crop procution in the tropics. Phil. Trans. R. Soc. Lond., B 352: 975-985. Wiesenmüller, J., M. Denich, and P.L.G. Vlek. 1997. Bedeutung des Wurzelsystems für die Regeneration der Brachevegetation in Nordost-Brasilien. (Significance of the root system for the regeneration of the fallow vegetation on N. E. Brazil). In: W. Merbach (eds.): Rhizosphärenforschung, Umweltstreß und Ökosystemstabilität. B.G. Teubner Verlagsges. Stuttgart, 84-89. Edi Premono, M., A.M. Moawad, and P.L.G. Vlek. 1996. "Effect of phosphate-solubilizing Pseudomonas putida on the growth of maize and its survival in the rhizosphere". Indones. J. Crop Sci., 11 (1): 13-23. Vlek, P.L.G., A.B. Lüttger, and G.G.B. Manske. 1996. The Potential Contribution of Arbuscular Mycorrhiza to the Development of Nutrient and Water Efficient Wheat. In: Tanner, D.G., Payne, T.S., and Abdalla, O.S. 1996 (eds.): The Ninth Regional Wheat Workshop for Eastern, Central and Southern Africa. Addis Ababa, Ethiopia: CIMMYT, 28-46. Diekmann, U., M. Denich, and P.L.G. Vlek. 1995. Characterization of Soil Microbiological Processes in Different Phases of the Cultivation System (Slash-and-Burn) in the Bragantina Zone of the State of Pará, Brazil. In: J.A. Parrotta, and M. Kanashiro (eds.): Management and Rehabilitation of Degraded Lands and Secondary Forests in Amazonia. Proc. Intern. Symposium/Workshop Santarém, Pará, Brazil 18-22.4.1993. Intern. Inst. Trop. Forestry (IITF), USDA-Forest Service, Río Piedras, Puerto Rico, USA, 40-43. Thielen-Klinge, A., A. Wanisch, M. Denich, M.M.L.S. Santos, and P.L.G. Vlek. 1995. Natural Abundance of 15N in Fallow Vegetation of Northeast Pará State, Brazil - Preliminary Results. In: J.A. Parrotta, and M. Kanashiro (eds.): Management and Rehabilitation of Degraded Lands and Secondary Forests in Amazonia. Proc. Intern. Symposium/Workshop Santarém, Pará, Brazil 18-22.4.1993. Intern. Inst. Trop. Forestry (IITF), USDA-Forest Service, Río Piedras, Puerto Rico, USA, 108-1. Vlek, P.L.G. 1995. The soil and its artisans in sub-Saharan African agriculture. Geoderma, 67: 165-170. Vlek, P.L.G., M.Y. Diakite, and H. Mueller. 1995. "The Role of Azolla in Curbing Ammonia Volatilization from Flooded Rice Systems". Fertilizer Research, 42: 165-174. Wiesenmüller, J., M. Denich, and P.L.G. Vlek. 1995. "Vegetative Fallow Regeneration in the Eastern Amazon Region, Brazil". In: J.A. Parrotta, and M. Kanashiro (eds.): Management and Rehabilitation of Degraded Lands and Secondary Forests in Amazonia. Proc. Intern. Symposium/Workshop Santarém, Pará, Brazil 18-22.4.1993. Intern. Inst. Trop. Forestry (IITF), USDA-Forest Service, Río Piedras, Puerto Rico, USA, 111-114. Lüttger, A.B., G.G.B. Manske, R.K. Behl, and P.L.G. Vlek. 1994. Felduntersuchungen in Nordindien zur Charakterisierung von. Ökophysiologie des Wurzelraumes, Nr. 5: 104-107. Manske, G.G.B., and P.L.G. Vlek. 1994. The Prospects of Developing Nutrient Efficient Varieties (NEV) for Wheat Based on Symbiosis with VA Mycorrhizal Fungi. In: R.K. Behl (eds.): Crop Tolerance to Abiotic Stresses. Proc. Nat. Conf. Plant Res. Develop., Feb. 26-28, 1990. CCS Haryana Agric. Univ. Press, Hisar., 171-188. Vlek, P.L.G., and K. Vielhauer. 1994. Nutrient Management Strategies in Stressed Environments". In: S.M. Virmani, J.C. Katyal, H. Eswaran and I.P. Abrol (eds.): Stressed Ecosystems and Sustainable Agriculture. S.M. Virmani. Oxford & IBH Publishing Co., New Delhi, India, 203-229. Lüttger, A.B., G.G.B. Manske, R.K. Behl and P.L.G. Vlek. 1993. Nährstoff-aneignung von Weizensorten in Abhängigkeit von VA-Mykorrhiza und Gesamt¬wurzellänge: Felduntersuchungen in Nordindien. (Nutrient uptake by wheat varieties as a function of VA mycorrhiza and root length: Field studies in north India). In: Ökophysiologie des Wurzelraumes Nr. 4. Zentrum für Agrarlandschafts- und Landnutzungsforschung (ZALF), Müncheberg, Deutschland, 49-52. Vlek, P.L.G. 1993. "Strategies for Sustaining Agriculture in sub-Saharan Africa: The Fertilizer Technology Issue". In: Ragland, J. and R. Lal (eds.): Technologies for Sustainable Agriculture in the Tropics. ASA Special Publication No 56. , Madison, WI, USA, 265-278. Fresco, L.O., and P.L.G. Vlek. 1992. "Temperate" and "Tropical" Agronomy: A Case for Symbiosis. Proc. 2nd European Society for Agronomy Congress, Warwick Univ. U.K., August 1992, Hong, C.W., J.C. Katyal and P.L.G. Vlek. 1992. "Losses and Utilization of Nitrogen by Sorghum as Affected by the Depth of a Swelling Clay Soil". J. Agronomy and Crop Science, 168: 263-271. Vlek, P.L.G. and H. Koch. 1992. "The Soil Resource Base and Food Production in the Developing World: Special Focus on Africa". Göttinger Beiträge zur Land- und Forstwirtschaft in den Tropen und Subtropen, 71: 139-160. Vlek, P.L.G., W. Fugger and U. Biker. 1992. The fate of fertilizer N under Azolla in wetland rice. Proc. 2nd ESA Congress, Warwick Univ., UK., August 1992, Christianson, C.B., and P.L.G. Vlek. 1991. Alleviating soil fertility constraints to food production in West Africa: Efficiency of nitrogen fertilizers applied to food crops. Fertilizer Research, 29: 21-33. Manske, G.G.B. and P.L.G. Vlek. 1991. Eine Strategie für die Entwicklung von nährstoffeffizienten Pflanzensorten unter Einbezug der VA-Mykorrhiza. (A strategy for developing nutrient efficient varieties (NEV's) with special reference to VA mycorrhiza). Ökophysiologie des Wurzelraumes , Forschungszentrum für Bodenfruchtbarkeit Müncheberg, Deutschland, Nr. 2: 84-89. Stumpe, J.M., and P.L.G. Vlek. 1991. Acidification induced by different nitrogen sources in columns of selected tropical soils. Soil Sci. Soc. Am. J., 55: Jan/Feb: Buresh, R.J., P.L.G. Vlek, and K. Harmsen. 1990. "Fate of fertilizer nitrogen applied to wheat under simulated Mediterranean environmental conditions". Fertilizer Research, 23: 25-36. Christianson, C.B., A. Bationo, J. Henao, and P.L.G. Vlek. 1990. Fate and efficiency of N fertilizers applied to pearl millet in Niger. Plant and Soil, 125: 221-231. Mughogbo, S.K., C.B. Christianson, J.M. Stumpe, and P.L.G. Vlek. 1990. "Nitrogen Efficiency at three sites in Nigeria as affected by N Source and Management". Trop. Agric (Trinidad), Vol.67: 127-132 April. Vlek, P.L.G. 1990. "The role of fertilizers in sustaining agriculture in sub-Saharan Africa". Fertilizer Research, 26: 327-339. Stumpe, J.M., P.L.G. Vlek, S.K. Mughogho, and F.Ganry. 1989. Microplot Size Requirements for Measuring Balances of Fertilizer 15N Applied to Maize. Soil Sci. Soc. Am. J., 53: 797-800. Vlek, P.L.G., and A. Uzo Mokwunye. 1989. Soil Fertility Problems in the Semiarid Tropics of Africa. In: C.B. Christianson (eds.): Soil Technology and Fertilizer Management in Semi-Arid Tropical India. IFDC Special Publication - 11 Muscle Shoals, Al. 35662, USA, Abdelmonem, M.A.S., K. Harmsen, W.L. Lindsay and P.L.G. Vlek. 1988. Fate of nitrogen-tagged urea applied to wheat in the arid Mediterranean region. In: Matar, A., P.N. Soltanpour and A. Chouinard (eds.): Soil test calibration in West Asia and North Africa. Proceedings of the second regional workshop, Ankara, Turkey, 1-6 September 1987. ICARDA-120 En. ICARDA, Aleppo, Syria, 103-110. Cori, C.E. de, L.S. Holt, and P.L.G. Vlek. 1988. Destino del Nitrógeno Ureico Aplicado a un Tropaquept Arcilloso, bajo Condiciones Similadas de Arroz en Siembra Directa ("Fate of urea nitrogen applied to a clayey Tropaquept, under simulated conditions in direct seeded rice". Turrialba, 38 (4): 294-299. Katyal, J.C., Bijay Singh, and P.L.G. Vlek. 1988. Effect of Granule Size and the Placement Geometry on the Efficiency of Urea Supergranules for Wetland Rice Grown on a Permeable Soil. Fert. Res., 15: 193-201. Katyal, J.C., M.F. Carter, and P.L.G. Vlek. 1988. Nitrification Activity in Submerged Soils and Its Relation to Denitrification Loss. Biology and Fertility of Soils, 7: 16-22. Katyal, J.C., Bijay Singh, P.L.G. Vlek, and R.J. Buresh. 1987. Efficient N Use as Affected by Urea Application and Irrigation Sequence. Soil Sci. Soc. Am. J., 51: 366-370. Katyal, J.C., C.W. Hong, and P.L.G. Vlek. 1987. Fertilizer Management in Vertisols. In: Proceedings Seminar on Management of Vertisols under Semi-Arid Conditions. IBSRAM Nairobi, Kenya, Katyal, J.C., D.K. Friesen, and P.L.G. Vlek. 1987. Deficiencies of Micronutrients and Sulfur in Wheat. In: Proceedings Conference on Wheat Production Constraints in Tropical Environments. CIMMYT, Chiang Mai, Thailand, Ashby, J.A., and P.L.G. Vlek. 1986. Farming Systems Research of the International Fertilizer Development Center. IARC Workshop on Farming Systems Research. ICRISAT, Feb.: 17-21. Carter M.F., P.L.G. Vlek, and J.T. Touchton. 1986. Agronomic Evaluation of New Ureaforms for Flooded Rice. Soil Sci. Soc. Am. J., 50: 1055-1060. Fillery, I.R.P., and P.L.G. Vlek. 1986. Reappraisal of the Significance of Ammonia Volatilization as an N loss Mechanism in Flooded Rice Fields. In: S.K. DeDatta and W.H. Patrick (eds.): Nitrogen Economy in Flooded Rice Soils. Martinus Nijhoff Publishers, Dordrecht, The Netherlands, 79-99. Mughogho, S.K., A. Bationo, B. Christianson and P.L.G. Vlek. 1986. Management of Nitrogen Fertilizers for Tropical African Soils. In: Mokwunye, A.U., and P.L.G. Vlek (eds.): "Management of Nitrogen and Phosphorus Fertilizers in Sub-Saharan Africa". Martinus Nijhoff Publishers. The Hague, The Netherlands, 117-172. Sillanpaa, M., and P.L.G. Vlek. 1986. Micronutrients and the Agro-Ecology of Tropical and Mediterranean Regions. Fertilizer Research, 7: 131-150. Singh, B., J.C. Katyal, P.K. Malhotra, and P.L.G. Vlek. 1986. Path Coefficient Analysis of N Nutrition on Yield and Yield Components for Rice in a Highly Percolating Soil. Commun. in Soil Sci. Plant Anal, 17: 853-867. Vlek, P.L.G., and B.H. Byrnes. 1986. The Efficacy and Loss of Fertilizer N in Lowland Rice. In: S.K. DeDatta and W.H.Patrick, Jr. (eds.): Nitrogen Economy in Flooded Rice Soils. Martinus Nijhoff Publishers, Dordrecht, The Netherlands, 131-148. Craswell, E.T., S.K. De Datta, C.S. Weeraratne, and P.L.G. Vlek. 1985. Fate and Efficiency of Nitrogen Fertilizers Applied to Wetland Rice. I. The Philippines. Fertilizer Research, 6 (1): 49-63. Godwin, D.C., and P.L.G. Vlek. 1985. Simulation of Nitrogen Dynamics in Wheat Cropping Systems. In: W. Day (eds.): Wheat Growth and Modeling. NATO Advanced Research Series, 311-332. Harmsen, K. and P.L.G. Vlek. 1985. "The Chemistry of Micronutrients in Soil". Fertilizer Research, 7: 1-42. Katyal, J.C., and P.L.G. Vlek. 1985. "Micronutrient Problems in Tropical Asia". Fertilizer Research, 7: 69-94. Katyal, J.C., Bijay Singh, P.L.G. Vlek, and E.T. Craswell. 1985. Fate and Efficiency of Nitrogen Fertilizers Applied to Wetland Rice. II. Punjab, India. Fertilizer Research, 6 (3): 279-290. Leon, L.A., A.S. Lopez, and P.L.G. Vlek. 1985. "Micronutrient Problems in Tropical Latin America". Fertilizer Research, 7: 95-130. Mokwunye, A.U., and P.L.G. Vlek. 1985. Feeding the African People or Feeding Crops that Feed the People:Food for Thought. Agribusiness Worldwide, 8: 6-8. Van der Heide, J., A.C.B.M. van der Kruijs, B.T. Kang, and P.L.G. Vlek. 1985. Nitrogen Management in Multiple Cropping Systems. In: B.T. Kang and J. van der Heide (eds.): Nitrogen Management in Farming Systems in Humid and Subhumid Tropics. Symposium Proceedings, Ibadan, Nigeria, 291-306. Vlek, P.L.G (Editor). 1985. Micronutrients in Tropical Foodcrop Production. Martinus Nijhoff/Dr. W. Junk Publishers, The Hague, the Netherlands, 260. Special Issue of Fertilizer Research. Bouwmeester, R.J.B., P.L.G. Vlek, and J.M. Stumpe. 1984. Effect of Environmental Factors on NH3 Volatilization from a Urea-Fertilized Soil. Soil Sci. Soc. Am. J., 49 (2): 376-381. Buresh, R.J., P.L.G. Vlek, and J.M. Stumpe. 1984. Labelled Nitrogen Fertilizer Research with urea in the Semi Tropics: I. Greenhouse Studies. Plant and Soil, 80: 3-19. Moraghan, J.T., T.J. Rego, R.J. Buresh, P.L.G. Vlek, J.R. Burford, S. Singh and K.L. Sahrawat. 1984. Labelled Nitrogen Fertilizer Research with Urea in the Semi-Arid Tropics:II.Field Studies on a Vertisol. Plant and Soil, 80: 21-33. Stumpe, J.M., P.L.G. Vlek, and W.L. Lindsay. 1984. Ammonia Volatilization from Urea and Urea Phosphates in Calcareous Soils. Soil Sci. Soc. Am. J., 48 (4): 921-927. Vlek, P.L.G., and I.R.P. Fillery. 1984. Improving Nitrogen Efficiency in Wetland Rice Soils. The Fertilizer Society Proceedings, No. 230: Craswell, E.T. and P.L.G. Vlek. 1983. Fate of Fertilizer Nitrogen in Flooded Systems. In: J. Simpson and J.R.Freney (eds.): Gaseous Losses of Nitrogen from Plant Soil Systems. Martinus Nijhoff Publishers. The Hague, The Netherlands, Godwin, D.C., C.A. Jones, J.T. Ritchie, P.L.G. Vlek, and L.J. Youngdahl. 1983. The Water and Nitrogen Components of the CERES Models. In: Minimum Data Sets for Agrotechnology Transfer. IBSNAT/ICRISAT Symposium, Hyderabad, India, March 1983, Osiname, O., H. van Gijn, and P.L.G. Vlek. 1983. The Effect of Nitrification Inhibitors on the Fate and Efficiency of Nitrogenous Fertilizers Under Simulated Humid Tropical Conditions. Tropical Agriculture, 60: 211-217. Vlek, P.L.G., and M.F. Carter. 1983. The Effect of Soil Environment and Fertilizer Modification on the Kinetics of Hydrolysis of Applied Urea. Soil Science, 136: 56-63. Craswell, E.T., and P.L.G. Vlek. 1982. Nitrogen Management for Submerged Rice Soils. In: Vertisols and Rice Soils of the Tropics, Symposia Papers II. 12th International Congress of Soil Science, New Delhi, India. El-Zahaby, E.M., S.H. Chien, N.K.Savant, P.L.G. Vlek, and A.U. Mokwunye. 1982. Effect of Pyrophosphate on Phosphate Sorption and Ammonia Volatilization by Calcareous Soils Treated with Ammonium Phosphates. Soil Sci. Soc. Am. J., 46: 733-740. Fillery, I.R.P., and P.L.G. Vlek. 1982. The Significance of Denitrification of Applied Nitrogen in Fallow and Cropped Rice Soils Under Different Flooding Regimes. Plant and Soil, 65: 153-169. Moeller, M.B., and P.L.G. Vlek. 1982. The Chemical Dynamics of Ammonia Volatilization from Aqueous Solution. Atmospheric Environment, 16: 709-7l8. Vlek, P.L.G., and E.T. Craswell. 1982. Ammonia Volatilization from Flooded Soils. Fertilizer Research, 2: 227-245. Youngdahl, L.J., R. Pacheco, J.J. Street, and P.L.G. Vlek. 1982. The Kinetics of Ammonium and Nitrate Uptake by Young Rice Plants. Plant and Soil, 69: 225-232. Bouwmeester, R.J.B., and P.L.G. Vlek. 1981. Wind-Tunnel Simulation and Assessment of Ammonia Volatilization from Ponded Water. Agronomy Journal, 73: 546-552. Bouwmeester, R.J.B., and P.L.G. Vlek. 1981. Rate Control of Ammonia Volatilization from Rice Paddies. Atmospheric Environment, 15: 131-140. Vlek, P.L.G., I.R.P. Fillery, and J.R. Burford. 1981. Accession, Transformation and Loss of Nitrogen in Soils of the Arid Region. Plant and Soil, 58: 133-175. Craswell, E.T., and P.L.G. Vlek. 1980. Research to Reduce Losses of Fertilizer Nitrogen from Wetland Rice Soils. In: Fertilizers in India in the Eighties, FAI Annual Seminar, December 4-6, 1980, New Delhi, India. Tejeda, H.R., C.W. Hong, and P.L.G. Vlek. 1980. Comparison of Modified Urea Fertilizers and Estimation of their availability Coefficient Using Quadratic Models. Soil Sci. Soc. Am. J., 44: 1256-1262. Vlek, P.L.G., B.H. Byrnes, and E.T. Craswell. 1980. Effect of Urea Placement on Leaching Losses of Nitrogen from Flooded Rice Soils. Plant and Soil, 54: 441-449. Vlek, P.L.G., J.M. Stumpe, and B.H. Byrnes. 1980. Urease Activity and Inhibition in Flooded Soil Systems. Fertilizer Research, 1: 191-202. Byrnes, B.H., P.L.G. Vlek, and E.T. Craswell. 1979. The Promise and Problem of Super Granules for Rice Fertilization. In: S. Ahmed et al. (eds.): Adoptive Production Systems. Vlek, P.L.G., C.W. Hong, and L.J. Youngdahl. 1979. An Analysis of N Nutrition on Yield and Yield Components for the Improvement of Rice Fertilization in Korea. Agronomy Journal, 71: 829-833. Craswell, E.T., and P.L.G. Vlek. 1978. Fate of Fertilizer Nitrogen Applied to Wetland Rice. In: Nitrogen and Rice, Symposium proceedings. International Rice Research Institute, Manila, Philippines, l75-l93. Vlek, P.L.G., and E.T. Craswell. 1978. Effect of Nitrogen Source and Management on Ammonia Volatilization Losses from Flooded Rice Soil Systems. Soil Sci. Soc. Am. Proc., 43: 352-358. Vlek, P.L.G., and J.M. Stumpe. 1978. Effects of Solution Chemistry and Environmental Conditions on Ammonia Volatilization Losses from Aqueous Systems. Soil Sci. Soc. Am. J., 42: 4l6-421. Vlek, P.L.G., and W.L. Lindsay. 1978. Potential Use of Finely Disintegrated Iron Pyrite in Sodic and Iron-Deficient Soils. Journal of Environmental Quality, 7: 111-114. Lindsay, W.L., and P.L.G. Vlek. 1977. Phosphate Minerals. In: J.B. Dixon and B.S. Weed (eds.): Minerals in Soil Environments. Soil Sci. Soc. Am., Inc., Madison, Wisconsin, 639-670. Vlek, P.L.G., and W.L. Lindsay. 1977. Thermodynamic Stability and Solubility of Molybdenum Minerals in Soils. Soil Sci. Soc. Am. J., 41: 42-46. Vlek, P.L.G., and W.L. Lindsay. 1977. Molybdenum Contamination in Colorado Pasture Soils. In: W.K. Chappell and K. Kellogg Petersen (eds.): Molybdenum in the Environment, Vol. II. Marcel Dekker, Inc., New York, 6l9-650. Vlek, P.L.G., Th.J.M. Blom, J. Beek, and W.L. Lindsay. 1974. Determination of the Solubility Product of Various Iron Hydroxides and Jarosite by the Chelation Method. Soil Science Society of America Proceedings, 38 (3): 429-432. Vlek, P.L.G. 1971. Some Morphological, Physical and Chemical Aspects of Acid Sulphate Soils in Thailand. Soil Survey Report No. 84, Department of Land Development, Bangkok, Thailand,
Djumaeva, D., J.P.A.Lamers, C. Martius, A. Khamzina and P.L.G. Vlek.
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Quantification of symbiotic nitrogen fixation by Elaeagnus angustifolia L. on salt-affected irrigated croplands using two 15N isotopic methods.
Nutrient Cycling Agroecosystems,
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Vlek, P.L.G.. 0. Ayayi A numerical model for simulating Hortonian overland flow on tropical hillslopes with vegetation elements. |
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