Plant and Soil

, 211:19 | Cite as

Mobilization of soil and fertilizer phosphate by cover crops

  • Mahmoud Kamh
  • Walter J. Horst
  • Fathi Amer
  • Hamida Mostafa
  • Peter Maier


Incorporation of cover crops into cropping systems may contribute to a more efficient utilization of soil and fertilizer P by less P-efficient crops through exudation of P-mobilizing compounds by the roots of P-efficient plant species. The main objective of the present work was to test this hypothesis. First a method has been developed which allows the quantification of organic anion exudation from individual cluster roots formed by P-deficient white lupin (Lupinus albus L.). Lupin plants were grown in nutrient solution at 1 μM P and in a low P loess in small rhizotrons. Organic anions exuded from intact plants grown in nutrient solution were collected from individual cluster roots and root tips sealed in small compartments by an anion-exchange resin placed in nylon bags (resin-bags). Succinate was the dominant organic anion exuded followed by citrate and malate. The mean of citrate exudation-rate was 0.06 pmol mm−1 s−1 with exudation highly dependent on the citrate concentration and on the age of the cluster roots. Exudates from cluster roots and root tips grown at the soil surface (rhizotron-grown plants) were collected using overlayered resin–agar (resin mixed with agar). Citrate exudation from cluster roots was 10 times higher than that from root tips. Fractionation of P in the cluster root rhizosphere-soil indicates that white lupin can mobilize P not only from the available and acid-soluble P, but also from the stable residual soil P fractions. In pot experiments with an acid luvisol derived from loess low in available P, growth of wheat was significantly improved when mixed-cropped with white lupin due to improved P uptake. Both in mixed culture and in rotation wheat could benefit from the P mobilization capacity of white lupin, supporting the hypothesis above. Nine tropical leguminous cover crops and maize were grown in a pot experiment using a luvisol from Northern Nigeria low in available P. All plant species derived most of their P from the resin and bicarbonate-extractable inorganic P. Organic P (Po) accumulated particularly in the rhizosphere of all plant species. There was a significant negative correlation between the species-specific rhizosphere acid phosphatase activity and Po accumulation. Growth and P uptake of maize grown in rotation after legumes were enhanced indicating that improved P nutrition was a contributing factor.

cover crops legumes Lupinus albus phosphorus efficiency root exudates rotation 


  1. Ae N, A J, Okada K, Yoshihara T and Johansen C 1990Phosphorus uptake by pigeon pea and its role in cropping systems of the Indian subcontinent. Science 248, 477–480.PubMedGoogle Scholar
  2. Dinkelaker B, Hengeler Ch and Marschner H 1995Distribution and function of proteoid roots and other root clusters. Bot. Acta. 108, 183–200.Google Scholar
  3. Dinkelaker B, Römheld V and Marschner H 1989Citric acid excretion and precipitation of calcium citrate in the rhizosphere of white lupin (Lupinus albus L.). Plant Cell Environ. 12, 285–292.CrossRefGoogle Scholar
  4. Evans J, Fettel N A, Conventry D R, O'Conner G E, Walsgott D N, Mahoney J and Armstrong E L 1991Wheat response after temperate crop legumes in south-eastern Aust. J. Agric. Res. 42, 31–43.CrossRefGoogle Scholar
  5. Gardner W K and Boundy K 1983The acquisition of phosphorus by Lupinus albus L. IV. The effect of interplanting wheat and white lupin on the growth and mineral composition of the two species. Plant Soil 70, 391–402.CrossRefGoogle Scholar
  6. Gardner W K, Parbery K G, and Barber D A 1981Proteoid root morphology and function in Lupinus albus. Plant Soil 60, 143–147.CrossRefGoogle Scholar
  7. Gardner W K, Barber D A and Parbery K G 1983The acquisition of phosphorus by Lupinus albus L. III. The probable mechanism by which phosphorus movement in the soil/root interface is enhanced. Plant Soil 70, 107–124.CrossRefGoogle Scholar
  8. Gerke J 1992Phosphate, iron, and aluminium in the soil solution of three different soils in relation to varying concentrations of citric acid. Z. Pflanzenernähr. Bodenk. 155, 339–343.Google Scholar
  9. Gerke J 1993Solubilization of Fe (III) from humic–Fe complexes, humic/Fe oxide mixtures and from poorly ordered Fe-oxide by organic acids-consequences for P adsorption. Z. Pflanzenernähr. Bodenk. 156, 253–257.Google Scholar
  10. Gerke J, Römer W and Jungk A 1994The excretion of citric and malic acids by proteoid roots of Lupinus albus L., effect on soil solution concentrations of phosphate, iron, and aluminium in the proteoid rhizosphere in samples of an oxisol and a luvisol. Z. Planzenernähr. Bodenk. 157, 289–294.Google Scholar
  11. Grierson R F 1992Organic acids in the rhizosphere of Banksia integrifolia L. Plant Soil 144, 259–265.CrossRefGoogle Scholar
  12. Häussling M and Marschner H 1989Organic and inorganic soil phosphates and acid phosphatase actvity in the rhizosphere of 80-year-old Norway spruce. Biol. Fertil. Soils 8, 128–133.CrossRefGoogle Scholar
  13. Hedley M J, White R E and Nye P H 1982Plant-induced changes in the rhizosphere of rape (Brassica napus var. Emerald) seedlings. III Changes in L value, soil phosphate fractions and phosphatase activity. New Phytol. 91, 45–56.CrossRefGoogle Scholar
  14. Hoffland E, Findenegg G R and Nelemans J A 1989Solubilization of rock phosphate by rape. II. Local root exudation of organic acids as a response to P starvation. Plant Soil 113, 161–165.CrossRefGoogle Scholar
  15. Hoffland E, Van den Boogaard R, Nelemans J A and Findenegg G R 1992Biosynthesis and root exudation of citric and malic acids in phosphate-starved rape plants. New Phytol. 122, 675–680.Google Scholar
  16. Horst W J and Härdter R 1994Rotation of maize and cowpea improves yield and nutrient use of maize compared to maize monocropping in an alfisol in the northern Guinea Savanna of Ghana. Plant Soil 160, 171–183.CrossRefGoogle Scholar
  17. Horst W J and Waschkies C 1987Phosphorus nutrition of spring wheat in mixed culture with white lupin. Z. Pflanzenernähr. Bodenk. 150, 1–8.Google Scholar
  18. Johnson J F, Allan D L and Vance C P 1994Phosphorus stressinduced proteoid roots show altered metabolism in Lupinus albus. Plant Physiol. 104, 657–665.PubMedGoogle Scholar
  19. Johnson J F, Allan D L, Vance C P and Weiblen G 1996Root carbon dioxide fixation by phosphorus-deficient Lupinus albus. Contribution to organic acid exudation by proteoid roots. Plant Physiol. 112, 19–30.PubMedCrossRefGoogle Scholar
  20. Keerthisinghe G, Hocking P J, Ryan P R and Delhaize E 1998Effect of phosphorus supply on the formation and function of proteoid roots of white lupin (Lupinus albus L.). Plant Cell Environ. 21, 467–478.CrossRefGoogle Scholar
  21. Lattif M A, Mehuys G R, Mackenzie A F, Ali I and Faris M A 1992 Effect of legumes on soil physical quality in a maize crop. Plant Soil 140, 15–23.CrossRefGoogle Scholar
  22. Li M, Shinano T and Tadano T 1997Distribution of exudates of lupin roots in the rhizosphere under phosphorus deficient conditions. Soil Sci. Plant Nutr. 43, 237–245.Google Scholar
  23. Lipton D G, Blanchar R W and Blevins D G 1987Citrate, malate, succinate in exudates from P sufficient and P stressed Medicago sativa L. seedlings. Plant Physiol. 85, 315–317.PubMedCrossRefGoogle Scholar
  24. Marschner H, Römheld V, Horst W J and Martin P 1986Root induced changes in the rhizosphere: Importance for the mineral nutrition of plants. Z. Pflanzenernähr. Bodenk. 149, 441–456.Google Scholar
  25. Marschner H, Römheld V and Cakmak I 1987Root-induced changes of nutrient availability in the rhizosphere. J. Plant Nutrition 10, 9–16.CrossRefGoogle Scholar
  26. Nguluu S, Probert M, Myers R and Waring S 1996Effect of tissue phosphorus concentration on the mineralization of nitrogen from stylo and cowpea residues. Plant Soil 191, 139–146.CrossRefGoogle Scholar
  27. Norman M, Rearsonand C and Searle P 1995The Ecology of Tropical Food Crops. Cambridge University Press, Cambridge.Google Scholar
  28. Olsen S R, Cole C V, Watanabe F S and Dean L A 1954Estimation of available phosphorus in soils by extraction with sodium bicarbonate. USDA Circ. 939, 1–29.Google Scholar
  29. Page A L, Miller R H and Keeney D R 1982Methods of Soil Analysis. Part 2, Chemical and Microbiological Properties (2 Ed.). Madison, WI. USA.Google Scholar
  30. Peoples M B, Herridge D F and Land J K 1995Biological nitrogen fixation: an efficient source of nitrogen for sustainable agriculture production. Plant Soil 174, 3–28.CrossRefGoogle Scholar
  31. Schüller H 1969Die CAL-Methode, Eine neue Methode zur Bestimmung des pflanzenverfügbaren Phosphates in Böden. Z. Pflanzenernähr. Bodenkd. 123, 48–63.Google Scholar
  32. Tabatabai M and Bremner J 1969Use of p-nitrophenyl phosphate for assay of soil phosphatase activity. Soil Biol. Biochem. 1, 301–307.CrossRefGoogle Scholar
  33. Tarafdar J C and Jungk A 1987Phosphatase activity in the rhizosphere and its relation to the depletion of soil organic phosphorus. Biol. Fertil. Soils 3, 199–481.CrossRefGoogle Scholar
  34. Tennant D 1975A test of a modified line intersect method of estimating root length. J. Ecol. 63, 995–1001.CrossRefGoogle Scholar
  35. Zhang F S, Ma J and Cao Y P 1997Phosphorus deficiency enhances root exudation of low-molecular weight organic acids and utilization of sparingly soluble inorganic phosphates by radish (Raphanus sativus L.) and rape (Brassica napus L.) plants. Plant Soil 196, 261–264.CrossRefGoogle Scholar

Copyright information

© Kluwer Academic Publishers 1999

Authors and Affiliations

  • Mahmoud Kamh
    • 2
  • Walter J. Horst
    • 1
  • Fathi Amer
    • 2
  • Hamida Mostafa
    • 2
  • Peter Maier
    • 1
  1. 1.Soil and Water Science Department, Faculty of AgricultureUniversity of Alexandria, El-ShatbyAlexandriaEgypt
  2. 2.Institute of Plant NutritionUniversity of HannoverHannoverGermany fax

Personalised recommendations