Effects of goat manure and inorganic phosphate addition on soil inorganic and microbial biomass phosphorus fractions under laboratory incubation conditions

• Published in: Soil science and plant nutrition (Tokyo) Vol. 55; no. 6; pp. 764 - 771
• Main Authors: Gichangi, E.M., University of Fort Hare, Alice (South Africa), Mnkeni, P.N.S, Brookes, P.C
• Format: Journal Article
• Language: English
• Published: Oxford, UK Taylor & Francis Group 01.12.2009; Blackwell Publishing Ltd
• Subjects: ABONOS FOSFATADOS; AFRIQUE DU SUD; CAPRIN; CAPRINOS; ENGRAIS PHOSPHATE; EXCREMENTS; EXCRETA; EXPERIMENTACION EN LABORATORIO; EXPERIMENTATION EN LABORATOIRE; FERRALSOL; FERRALSOLES; FERRALSOLS; FOSFORO; goat manure; GOATS; http://www.fao.org/aos/agrovoc#c_15989; http://www.fao.org/aos/agrovoc#c_2749; http://www.fao.org/aos/agrovoc#c_2858; http://www.fao.org/aos/agrovoc#c_3324; http://www.fao.org/aos/agrovoc#c_5800; http://www.fao.org/aos/agrovoc#c_5804; http://www.fao.org/aos/agrovoc#c_7252; LABORATORY EXPERIMENTATION; microbial biomass phosphorus; NaHCO; NaHCO3 Pi; PHOSPHATE FERTILIZERS; PHOSPHORE; PHOSPHORUS; phosphorus fractionation; resin P; SOUTH AFRICA; SUDAFRICA
• ISSN: 0038-0768; 1747-0765
• DOI: 10.1111/j.1747-0765.2009.00415.x

Changes in inorganic phosphorus (P) and soil microbial biomass P following the addition of goat manure and different amounts of inorganic P to an Umbric Ferralsol were assessed over 12 weeks under laboratory incubation conditions using a sequential fractionation procedure. Triple superphosphate was added at rates equivalent to 0, 45, 90, 135 and 180 mg P kg −1 , with or without goat manure at a rate of 10 g kg −1 soil on a dry-weight basis and incubated moist. Resin P, 0.5 mol L −1 NaHCO 3 extractable inorganic P (NaHCO 3 -P i ), 0.1 mol L −1 NaOH extractable inorganic P (NaOH P i ) and soil microbial biomass P concentrations were determined on days 7, 14, 28, 56 and 84. The magnitudes of the inorganic P fractions extracted were: NaOH P i  > Resin P > NaHCO 3 P i . Thus, NaOH P i was the major sink for the applied P. The dynamics of the three labile P fractions (resin P, NaHCO 3 P i and microbial biomass P) varied considerably during the incubation period. The resin P fraction consistently declined with time in all treatments, whereas the NaHCO 3 P i fraction changed little with time in the control and goat manure amended soil, but increased rapidly with time when inorganic P was applied alone or in combination with goat manure. Microbial biomass P increased with time in all treatments, peaking on day 28 and declining thereafter. The co-application of inorganic P with goat manure produced up to twofold more microbial biomass P than either inorganic P or goat manure applied alone. Therefore, the combined application of manure with low rates of P fertilizers may be a cost effective strategy for increasing the efficiency of fertilizer P use through enhanced biological cycling of P in small-holder farms in South Africa.