Addition of organic and inorganic P sources to soil – Effects on P pools and microorganisms

• Published in: Soil biology & biochemistry Vol. 49; pp. 106 - 113
• Main Authors: Malik, Muhammad Asghar, Marschner, Petra, Khan, Khalid Saifullah
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.06.2012; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Biochemistry and biology; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Compost; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Inorganic P; Microbial biomass; Microbiology; Organic P; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; P pools; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Residues; Soil science; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Organic P; Inorganic P; Compost; Residues; P pools; Microbial biomass; Inorganic compound; Organic phosphorus; Soils; Residue; Soil science; Microorganism; Organic compounds
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/j.soilbio.2012.02.013

Phosphorus deficiency is wide-spread due to the poor solubility of soil P and the rapid formation of poorly available P after P addition. Microbes play a key role in soil P dynamics by P uptake, solubilisation and mineralisation. Therefore a better understanding of the relationship between type of P amendment, microbial activity and changes in soil P pools is important for a better management of soil P. A P deficient soil was amended with two composts (low P or high P), two crop residues (low P or high P), and inorganic P (KH2PO4) at low and high P, and incubated for 56 days. Composts were added at 20gkg−1 resulting in a total P addition of 4.1mgkg−1 soil with the low P compost and 33.2mgkg−1 soil with the high P compost. The same amount of P was added with the other amendments (residues and inorganic P). All amendments increased cumulative respiration, but microbial biomass and the abundance of bacteria and fungi (assessed by phospholipid fatty acid analysis) increased significantly only in soils with organic amendments, with greater increases with residues. The concentration of the inorganic P pools NaHCO3-Pi, NaOH-Pi and HCl-P increased significantly within 5h after amendment, particularly with high P amendments. Over the following 56 days, labile inorganic P was converted mainly into non-labile inorganic P with inorganic P addition whereas labile and non-labile organic P was formed with organic amendments. It is concluded that organic P sources, particularly those with high P concentration can stimulate the formation of organic P forms in soils which may provide a long-term slow release P source for plants and soil organisms. ► Organic amendments (compost or residues) inorganic P were added at two P rates. ► Organic amendments induced strong increases in organic P pools. ► Inorganic P addition resulted in increases in inorganic P pools. ► Inorganic P was transformed to organic P pools particularly with organic amendments.