Changes of Soil Phosphorus Fractionation According to pH in Red Soils of China: An Incubation Experiment

• Published in: Communications in Soil Science and Plant Analysis Vol. 49; no. 7; pp. 791 - 802
• Main Authors: Xiaoyang, Zhou, Minggang, Xu, Boren, Wang, Zejiang, Cai, Gilles, Colinet
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 12.04.2018; Taylor & Francis Ltd
• Subjects: Acidity; Availability; Biological fertilization; calcium; China; Crop growth; DIP; ferralic cambisols; Fertilization; fertilizer application; Fractionation; Incubation; Incubation period; inorganic P fractions; inorganic phosphorus; Olsen-P; pH effects; Phosphorus; phosphorus fertilizers; Phosphorus pentoxide; Redundancy; Soil; soil acidity; Soil chemistry; Soil management; Soil pH; Soils; China
• DOI: 10.1080/00103624.2018.1435676
• ISSN: 0010-3624; 1532-2416

Phosphorus (P) deficiency is one of the main problems limiting crop growth in red soils of southern China. The primary objective of this study was to examine P availability as a function of soil acidity. Soils were sampled from a long-term fertilization experiment and are referred as low-P (No P fertilization) and high-P (120 kg P 2 O 5 ha -1 ). Both low-P and high-P treatments were incubated adjusting soil pH to seven levels from 3.0 to 6.5 for 10, 20, 30 and 45 days. The pH, DIP, and Olsen-P were determined after each incubation period, and inorganic P fractions were measured at the end of incubation. For both low-P and high-P treatments, DIP decreased with rising pH value and increased with decreasing soil pH. Olsen-P, Ca-P (Ca 2 -P, Ca 8 -P, and Ca 10 -P) and Al-P increased significantly with soil pH in low-P treatment. In high-P, Olsen-P increased with pH between 3.4 and 5.0 and was stable at higher pH. Moreover, Ca-P and Al-P increased significantly but Fe-P decreased with soil pH increase. The redundancy analysis showed that Ca-P, Al-P, and pH had positive effects on Olsen-P, but Occluded-P showed a negative correlation with Olsen-P in both soils. Our results confirmed that soil P availability was influenced by pH and that the changes in DIP and Olsen-P were linked to changes of inorganic fractions from occluded to Ca- and Al-bound forms. Managing soil acidity is a key issue regarding the availability of P in red soils of China and our results suggest that at least a pH of 5.0 should be targeted.