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RESEARCH ARTICLE
Contents Vol 60(2)

Options for increasing the biological cycling of phosphorus in low-input and organic agricultural systems

C. N. Guppy A and M. J. McLaughlin B
+ Author Affiliations
- Author Affiliations

A School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia.

B CSIRO Land and Water and University of Adelaide, Glen Osmond, SA 5064, Australia.

C Corresponding author. Email: cguppy@une.edu.au

Crop and Pasture Science 60(2) 116-123 https://doi.org/10.1071/CP07157
Submitted: 28 May 2007  Accepted: 5 August 2008   Published: 27 February 2009

Abstract

In all systems, phosphorus (P), particularly phosphate, is inexorably drawn to sorption surfaces or precipitated, and is removed from the readily plant-available P pools. Mobilising this less-available P is a significant challenge in organic and low-input agro-ecosystems where readily available P sources may not be applied regularly. Although good-quality inputs, with low C : P ratio, and rotations may be effective in managing organic P cycles in pasture and forestry systems, extensive cropping systems will remain problematic. Two conceptual models are proposed to use organic matter additions to transfer this recalcitrant P into the biocycle, one involving highly labile organic matter and the other involving less-labile organic additions. Current literature provides some evidence for the efficacy of both models, but further work is necessary to clarify which is optimal for agro-ecosystems relying on either low inputs of P or forms of P that are allowed in organic agricultural systems, such as manures or rock phosphate. The microbial biomass is integral to P biocycling in organic systems, but further work is necessary to clarify the role of fungal and bacterial decomposers in decomposition processes. Identifying P-efficient cultivars with low translocation from roots to shoots to provide an ‘organic’ P source for following crops, essentially optimal rotation sequences for mobilising P using plants, is an avenue of promising research potential. Enzyme activation of recalcitrant organic P sources is unlikely to be effective if applied to bulk soils; however, further research on enzyme activities in the rhizosphere holds promise. We strongly recommend that further research be directed toward understanding and limiting reactions of inorganic P with soil colloids and minerals, either through chemical means (pH change, competitive sorption) or introduction and manipulation of organic materials. The research issues identified above overlap considerably with conventional agricultural concerns and benefits will accrue to both conventional and organic producers where further research is promoted.


Acknowledgements

CNG acknowledges support from the Australian Centre for International Agricultural Research, Rural Industries Research and Development Corporation, and Grains Research and Development Corporation for supporting research into P chemistry in soil. MJM acknowledges support for research on soil P availability from the Australian Research Council (LP0454086), the South Australian Grains Industry Trust, CSBP, the Fluid Fertilizer Foundation, and the Grains Research and Development Corporation.


References


Adams MA, Byrne LT (1989) 31P-NMR analysis of phosphorus compounds in extracts of surface soils from selected karri (Eucalyptus diversicolor F. Muell.) forests. Soil Biology & Biochemistry 21, 523–528.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Anderson G, Williams EG, Moir JO (1974) A comparison of the sorption of inorganic orthophosphate and inositol hexaphosphate by six acid soils. Journal of Soil Science 25, 51–62.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Barrow NJ (1975) Chemical form of inorganic phosphate in sheep faeces. Australian Journal of Soil Research 13, 63–67.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Borie F, Zunino H, Martinez L (1989) Macromolecule P associations and inositol phosphates in some Chilean volcanic soils of temperate regions. Communications in Soil Science and Plant Analysis 20, 1881–1894.
|  CAS | Crossref |
open url image1

Brannon CA, Sommers LE (1985a) Preparation and characterization of model humic polymers containing organic phosphorus. Soil Biology & Biochemistry 17, 213–219.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Brannon CA, Sommers LE (1985b) Stability and mineralisation of organic phosphorus incorporated into model humic polymers. Soil Biology & Biochemistry 17, 221–227.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Bromfield SM, Jones OL (1972) The initial leaching of hayed off pasture in relation to the recycling of phosphorus. Australian Journal of Agricultural Research 23, 811–824.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Bunemann EK, Bossio DA, Smithson PC, Frossard E, Oberson A (2004a) Microbial community composition and substrate use in a highly weathered soil as affected by crop rotation and P fertilisation. Soil Biology & Biochemistry 36, 889–901.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Bunemann EK, Heenan DP, Marschner P, McNeil AM (2006) Long-term effects of crop rotation, stubble management and tillage on soil phosphorus dynamics. Australian Journal of Soil Research 44, 611–618.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Bunemann EK, Marschner P, McNeill AM, McLaughlin MJ (2007) Measuring rates of gross and net mineralisation of organic phosphorus in soils. Soil Biology and Biochemistry 39, 900–913.
| Crossref |
open url image1

Bunemann EK, Smernik RJ, Doolette AL, Marschner P, Stonor R, Wakelin SA, McNeil AM (2008a) Forms of phosphorus in bacteria and fungi isolated from two Australian soils. Soil Biology & Biochemistry 40, 1908–1915.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Bunemann EK, Smernik RJ, Marschner P, McNeil AM (2008b) Microbial synthesis of organic and condensed forms of phosphorus in acid and calcareous soils. Soil Biology & Biochemistry 40, 932–946.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Bunemann EK, Steinebrunner F, Smithson PC, Frossard E, Oberson A (2004b) Phosphorus dynamics in a highly weathered soil as revealed by isotopic labeling techniques. Soil Science Society of America Journal 68, 1645–1655. open url image1

Chang SC (1939) The transformation of phosphorus during the decomposition of plant materials. Soil Science 4, 85–89. open url image1

Chauhan BS, Stewart JWB, Paul EA (1981) Effect of labile inorganic phosphate status and organic carbon additions on the microbial uptake of phosphorus in soils. Canadian Journal of Soil Science 61, 373–385.
|  CAS |
open url image1

Chen CR, Condron LM, Davis MR, Sherlock RR (2003) Seasonal changes in soil phosphorus and associated microbial properties under adjacent grassland and forest in New Zealand. Forest Ecology and Management 177, 539–557.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Condron LM, Goh KM, Newman RH (1985) Nature and distribution of soil phosphorus as revealed by a sequential extraction method followed by 31P nuclear magnetic resonance analysis. Journal of Soil Science 36, 199–207.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Condron LM , Tiessen H (2005) Interactions of organic phosphorus in terrestrial ecosystems. In ‘Organic phosphorus in the environment’. (Eds BL Turner, E Frossard, DS Baldwin) pp. 295–307. (CABI Publishing: Wallingford, UK)

Condron LM , Turner BL , Cade-Menun BJ (2005) Chemistry and dynamics of soil organic phosphorus. In ‘Phosphorus: agriculture and the environment’. pp. 87–121. (American Society of Agronomy, Crop Science Society of America, Soil Science Society of America: Madison, WI)

Cornish PS (2009) Phosphorus management on extensive organic and low-input farms. Crop & Pasture Science 60, 105–115. open url image1

Crews TE, Kitayama K, Fownes JH, Riley RH, Herbert DA, Mueller-Dombois D, Vitousek PM (1995) Changes in soil phosphorus fractions and ecosystem dynamics across a long chronosequence in Hawaii. Ecology 76, 1407–1424.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Cross AF, Schlesinger WH (1995) A literature review and evaluation of the Hedley fractionation: Applications to the biogeochemical cycle of soil phosphorus in natural ecosystems. Geoderma 64, 197–224.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Dalal RC (1979) Mineralisation of carbon and phosphorus from carbon-14 and phosphorus-32 labelled plant material added to soil. Soil Science Society of America Journal 43, 913–916.
|  CAS |
open url image1

Dang YP, Dalal RC, Routley R, Schwenke GD, Daniells I (2006) Subsoil constraints to grain production in the cropping soils of the north-east region of Australia: an overview. Australian Journal of Experimental Agriculture 46, 19–35.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Enwezor WO (1967) Significance of the C : organic P ratio in the mineralization of soil organic phosphorus. Soil Science 103, 62–67.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Enwezor WO (1976) The mineralisation of nitrogen and phosphorus in organic materials of varying C : N and C : P ratios. Plant and Soil 44, 237–240.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Floate MJS (1970a) Decomposition of organic materials from hill soils and pastures. 3. The effect of temperature on the mineralization of carbon, nitrogen and phosphorus from plant materials and sheep faeces. Soil Biology & Biochemistry 2, 187–196.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Floate MJS (1970b) Decomposition of organic materials from hill soils and pastures. 4. The effects of moisture content on the mineralization of carbon, nitrogen and phosphorus from plant materials and sheep faeces. Soil Biology & Biochemistry 2, 275–283.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Friesen DK, Blair GJ (1988) A dual radiotracer study of transformations of organic, inorganic and plant residue phosphorus in soil in the presence and absence of plants. Australian Journal of Soil Research 26, 355–366.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Friesen DK, Rao IM, Thomas RJ, Oberson A, Sanz JI (1997) Phosphorus acquisition and cycling in crop and pasture systems in low fertility tropical soils. Plant and Soil 196, 289–294.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Frossard E, Condron LM, Oberson A, Sinaj S, Fardeau JC (2000) Processes governing phosphorus availability in temperate soils. Journal of Environmental Quality 29, 15–23.
|  CAS |
open url image1

Fuller WH, Dean LA (1949) Utilization of phosphorus from green manures. Soil Science 68, 197–202.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Fuller WH, Nielsen DR, Miller RW (1956) Some factors influencing the utilization of phosphorus from crop residues. Soil Science Society of America Proceedings 20, 218–224.
|  CAS |
open url image1

Fuller WH, Rogers RN (1952) Utilization of phosphorus from barley residues. Soil Science 74, 373–382.
|  CAS |
open url image1

Grisi B, Grace C, Brookes PC, Benedetti A, Dell’abate MT (1998) Temperature effects on organic matter and microbial biomass dynamics in temperate and tropical soils. Soil Biology & Biochemistry 30, 1309–1315.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Harrison AF (1982a) 32Phosphorus method to compare rates of mineralization of labile organic phosphorus in woodland soils. Soil Biology & Biochemistry 14, 337–341.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Harrison AF (1982b) Labile organic phosphorus mineralization in relationship to soil properties. Soil Biology & Biochemistry 14, 343–351.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

He ZL, Wu J, O’Donnell AG, Syers JK (1997) Seasonal responses in microbial biomass carbon, phosphorus and sulphur in soils under pasture. Biology and Fertility of Soils 24, 421–428.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Hedley MJ , McLaughlin MJ (2005) Reactions of phosphate fertilizers and by-products in soils. In ‘Phosphorus: agriculture and the environment’. pp. 181–252. (American Society of Agronomy, Crop Science Society of America, Soil Science Society of America: Madison, WI)

Hedley MJ, Stewart JWB, Chauhan BS (1982) Changes in inorganic and organic soil phosphorus fractions induced by cultivation practices and by laboratory incubations. Soil Science Society of America Journal 46, 970–976.
|  CAS |
open url image1

Hong JK, Yamane I (1981) Distribution of inositol phosphate in the molecular size fractions of humic and fulvic acid fractions. Soil Science and Plant Nutrition 27, 295–303.
|  CAS |
open url image1

Hubel F, Beck E (1993) In-situ determination of the P relations around the primary root of maize with respect to inorganic and phytate-P. Plant and Soil 157, 1–9. open url image1

Iyamuremye F, Dick RP, Baham J (1996) Organic amendments and phosphorus dynamics: 2. Distribution of soil phosphorus fractions. Soil Science 161, 436–443.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Jenkinson DS, Ayanaba A (1977) Decomposition of carbon-14 labeled plant material under tropical conditions. Soil Science Society of America Journal 41, 912–915.
|  CAS |
open url image1

Jones OL, Bromfield SM (1969) Phosphorus changes during the leaching and decomposition of hayed off pasture plants. Australian Journal of Agricultural Research 20, 653–663.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Kouno K, Wu J, Brookes PC (2002) Turnover of biomass C and P in soil following incorporation of glucose or ryegrass. Soil Biology & Biochemistry 34, 617–622.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Kwabiah AB, Palm CA, Stoskopf NC, Voroney RP (2003a) Response of soil microbial biomass dynamics to quality of plant materials with emphasis on P availability. Soil Biology & Biochemistry 35, 207–216.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Kwabiah AB, Stoskopf NC, Palm CA, Voroney RP (2003b) Soil P availability as affected by the chemical composition of plant materials: implications for P-limiting agriculture in tropical Africa. Agriculture, Ecosystems & Environment 100, 53–61.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Kwabiah AB, Stoskopf NC, Voroney RP, Palm CA (2001) Nitrogen and phosphorus release from decomposing leaves under sub-humid tropical conditions. Biotropica 33, 229–240. open url image1

Lawrence D, Schlesinger WH (2001) Changes in soil phosphorus during 200 years of shifting cultivation in Indonesia. Ecology 82, 2769–2780. open url image1

Lehmann J, Cravo MS, Macedo JLV, Moreira A, Schroth G (2001a) Phosphorus management for perrenial crops in central Amazonian upland soils. Plant and Soil 237, 309–319.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Lehmann J, Gunther D, Socorro da Mota M, Pereira de Almeida M, Zech W, Kaiser K (2001b) Inorganic and organic soil phosphorus and sulfur pools in an Amazonian multistrata agroforestry system. Agroforestry Systems 53, 113–124.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Leiros MC, Trasar-Cepada C, Seoane S, Gil-Sotres F (1999) Dependance of mineralisation of soil organic matter on temperature and moisture. Soil Biology & Biochemistry 31, 327–335.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Lockett JL (1938) Nitrogen and phosphorus changes in the decomposition of rye and clover at different stages of growth. Soil Science 45, 13–24.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Lopez-Gutierrez JC, Toro M, Lopez-Hernandez D (2004) Seasonality of organic phosphorus mineralisation in the rhizosphere of the native savanna grass, Trachypogon plumosus. Soil Biology & Biochemistry 36, 1675–1684.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Lopez-Hernandez D, Brossard M, Frossard E (1998) P-isotopic exchange values in relation to Po mineralisation in soils with very low P-sorbing capacities. Soil Biology & Biochemistry 30, 1663–1670.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Magid J , Tiessen H , Condron LM (1996) Dynamics of organic phosphorus in soils under natural and agricultural ecosystems. In ‘Humic substances in terrestrial ecosystems’. (Ed. A Piccolo) pp. 171–223. (Elsevier: New York)

Maithani K, Tripathi RS, Arunachalam A, Pandey HN (1996) Seasonal dynamics of microbial biomass C, N and P during regrowth of a disturbed subtropical humid forest in north-east India. Applied Soil Ecology 4, 31–37.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Makarov MI, Haumaier L, Zech W, Marfenina OE, Lysak LV (2005) Can 31P NMR spectroscopy be used to indicate the origins of soil organic phosphates? Soil Biology & Biochemistry 37, 15–25.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Manguiat IJ, Singleton PW, Rocamora PM, Calo MU, Taleon EE (1997) Effectiveness of Sesbania rostrata and Phaseolus calcaratus as green manure for upland rice grown in acidic soil. Plant and Soil 192, 321–331.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Martin JK, Cunningham RB (1973) Factors controlling the release of phosphorus from decomposing wheat roots. Australian Journal of Biological Sciences 26, 715–727.
|  CAS |
open url image1

McGill WB, Cole CV (1981) Comparative aspects of cycling of organic C, N, S and P through soil organic matter. Geoderma 26, 267–286.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

McLaughlin MJ, Alston AM (1986) Measurement of phosphorus in the soil microbial biomass: a modified procedure for field soils. Soil Biology & Biochemistry 18, 437–443.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

McLaughlin MJ, Alston AM, Martin JK (1988a) Phosphorus cycling in wheat-pasture rotation. II. The role of the microbial biomass in phosphorus cycling. Australian Journal of Soil Research 26, 333–342.
| Crossref | GoogleScholarGoogle Scholar | open url image1

McLaughlin MJ, Alston AM, Martin JK (1988b) Phosphorus cycling in wheat-pasture rotations. III. Organic phosphorus turnover and phosphorus cycling. Australian Journal of Soil Research 26, 343–353.
| Crossref | GoogleScholarGoogle Scholar | open url image1

McLaughlin MJ, Champion L (1987) Sewage sludge as a phosphorus amendment for sesquioxic soils. Soil Science 143, 113–119.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Nuruzzaman M, Lambers H, Bolland MDA, Veneklaas EJ (2005) Phosphorus benefits of different legume crops to subsequent wheat grown in different soils of Western Australia. Plant and Soil 271, 175–187.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Nziguheba G , Bunemann EK (2005) Organic phosphorus dynamics in tropical agroecosystems. In ‘Organic phosphorus in the environment’. (Eds BL Turner, E Frossard, DS Baldwin) pp. 243–268. (CABI Publishing: Wallingford, UK)

Nziguheba G, Palm CA, Buresh RJ, Smithson PC (1998) Soil phosphorus fractions and adsorption as affected by organic and inorganic sources. Plant and Soil 198, 159–168.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Oberson A, Besson JM, Maire N, Sticher H (1996) Microbiological processes in soil organic phosphorus transformations in conventional and biological cropping systems. Biology and Fertility of Soils 21, 138–148.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Oberson A, Friesen DK, Rao IM, Buhler S, Frossard E (2001) Phosphorus transformations in an Oxisol under contrasting land use systems: The role of the soil microbial biomass. Plant and Soil 237, 197–210.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Oberson A, Friesen DK, Tiessen H, Morel C, Stahel W (1999) Phosphorus status and cycling in native savanna and improved pastures on an acid low-P Colombian Oxisol. Nutrient Cycling in Agroecosystems 55, 77–88.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Oberson A , Joner EJ (2005) Microbial turnover of phosphorus in soil. In ‘Organic phosphorus in the environment’. (Eds BL Turner, E Frossard, DS Baldwin) pp. 133–164. (CABI Publishing: Wallingford, UK)

Ofori-Frimpong K, Rowell DL (1999) The decomposition of cocoa leaves and their effect on phosphorus dynamics in tropical soil. European Journal of Soil Science 50, 165–172.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Paniagua A, Mazzarino MJ, Kass D, Szott L, Fernandez C (1995) Soil phosphorus fractions under five tropical agroecosystems on a volcanic soil. Australian Journal of Soil Research 33, 311–320.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Pierzynski GM , McDowell RW , Sims JT (2005) Chemistry, cycling, and potential movement of inorganic phosphorus in soils. In ‘Phosphorus: agriculture and the environment’. pp. 53–86. (American Society of Agronomy, Crop Science Society of America, Soil Science Society of America: Madison, WI)

Quiquampoix H , Mousain D (2005) Enzymatic hydrolysis of organic phosphorus. In ‘Organic phosphorus in the environment’. (Eds BL Turner, E Frossard, DS Baldwin) pp. 89–112. (CABI Publishing: Wallingford, UK)

Randhawa PS, Condron LM, Di HJ, Sinaj S, McLenaghen RD (2005) Effect of green manure addition on soil organic phosphorus mineralisation. Nutrient Cycling in Agroecosystems 73, 181–189.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Richardson AE, Hocking PJ, Simpson RJ, George TS (2009) Plant mechanisms to optimise access to soil phosphorus. Crop & Pasture Science 60, 124–143. open url image1

Salas AM, Elliott ET, Westfall DG, Cole CV, Six J (2003) The role of particulate organic matter in phosphorus cycling. Soil Science Society of America Journal 67, 181–189.
|  CAS |
open url image1

Shand CA, Cheshire MV, Bedrock CN, Chapman PJ, Fraser AR, Chudek JA (1999) Solid-phase 31P NMR spectra of peat and mineral soils, humic acids and soil solution components: Influence of iron and manganese. Plant and Soil 214, 153–163.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Shand CA, Macklon AES, Edwards AC, Smith S (1994) Inorganic and organic P in soil solutions from three upland soils. I. Effect of soil solution extraction conditions, soil type and season. Plant and Soil 159, 255–264.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Shang C, Caldwell DE, Stewart JWB, Tiessen H, Huang PM (1996) Bioavailability of organic and inorganic phosphates adsorbed on short-range ordered aluminium precipitate. Microbial Ecology 31, 29–39.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Smeck NE (1985) Phosphorus dynamics in soil and landscapes. Geoderma 36, 185–199.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Smeck NE, Torrent J, Barron V (1994) Genesis and native phosphorus distribution in some Palexeralfs of southern Spain. Soil Science Society of America Journal 58, 1718–1723.
|  CAS |
open url image1

Smernik RJ, Dougherty WJ (2007) Identification of phytate in phosphorus-31 nuclear magnetic resonance spectra: The need for spiking. Soil Science Society of America Journal 71, 1045–1050.
|  CAS |
open url image1

Solomon D, Lehmann J, Mamo T, Fritzsche F, Zech W (2002) Phosphorus forms and dynamics as influenced by land use changes in the sub-humid Ethiopian highlands. Geoderma 105, 21–48.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Soon YK, Arshad MA (2002) Comparison of the decomposition and N and P mineralization of canola, pea and wheat residues. Biology and Fertility of Soils 36, 10–17.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Srivastava SC (1992) Microbial C, N, and P in dry tropical soils: seasonal changes and influence of soil moisture. Soil Biology & Biochemistry 24, 711–714.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Stewart JWB, Tiessen H (1987) Dynamics of soil organic phosphorus. Biogeochemistry 4, 41–60.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Szott LT, Melendez G (2001) Phosphorus availability under annual cropping, alley cropping, and multistrata agroforestry systems. Agroforestry Systems 53, 125–132.
| Crossref |
open url image1

Tate KR (1984) The biological transformation of P in soil. Plant and Soil 76, 245–256.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Tate KR, Newman RH (1982) Phosphorus fractions of a climosequence of soils in New Zealand tussock grassland. Soil Biology & Biochemistry 14, 191–196.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Tian G, Brusaard L, Kang BT (1995) An index for assessing the quality of plant residues and evaluating their effects on soil and crops in the (sub) humid tropics. Applied Soil Ecology 2, 25–32.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Turner BL (2008) Resource partitioning for soil phosphorus: a hypothesis. Journal of Ecology 96, 698–702.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Turner BL, Paphazy MJ, Haygarth PM, Mckelvie ID (2002) Inositol phosphates in the environment. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 357, 449–469.
| Crossref | GoogleScholarGoogle Scholar | CAS | PubMed | open url image1

Van Gestel M, Merckx R, Vlasak K (1993) Soil drying and rewetting and the turnover of 14C-labelled plant residues: first order decay rates of biomass and non-biomass 14C. Soil Biology & Biochemistry 25, 125–134.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Ventura W, Ladha JK (1997) Sesbania phosphorus requirements when used as biofertilser for long-term rice cultivation. Soil Science Society of America Journal 61, 1240–1244.
|  CAS |
open url image1

Walker TW, Syers JK (1976) The fate of phosphorus during pedogenesis. Geoderma 15, 1–19.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Weil RR, Benedetto PW, Sikora LJ, Bandel VA (1988) Influence of tillage practices on phosphorus distribution and forms in three Ultisols. Agronomy Journal 80, 503–509. open url image1

White RE, Ayoub AT (1983) Decomposition of plant residues of variable C/P ratio and the effect on soil phosphate availability. Plant and Soil 74, 163–173.
| Crossref | GoogleScholarGoogle Scholar | CAS | open url image1

Zhang H, Turner NC, Poole ML, Simpson N (2006) Crop production in the high rainfall zones of southern Australia – potential, constraints and opportunities. Australian Journal of Experimental Agriculture 46, 1035–1049.
| Crossref | GoogleScholarGoogle Scholar | open url image1