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Organic and inorganic phosphorus forms of soils ammended with organic wastes and relationships with availability

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Author(s):
Lucas Boscov Braos
Total Authors: 1
Document type: Doctoral Thesis
Press: Jaboticabal. 2018-01-08.
Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
Defense date:
Advisor: Mara Cristina Pessôa da Cruz
Abstract

Evaluating the forms and transformations of phosphorus (P) applied via organic and mineral fertilizers is important to improve the management and optimize the use of P. The objectives of the present study were to evaluate organic and inorganic forms of P in two soil types, fertilized with dairy manure, filter cake and triple superphosphate, as a function of the incubation time, and to establish relationships between soil P forms and P available, plant uptake P and growth. The organic (Po) and inorganic (P) forms of P were determined on samples of typic Hapludox clayey and arenic Hapludult sand, fertilized or not with 100 mg dm-3 of P as dairy manure, filter cake and triple superphosphate, and incubated for 15, 45, 90 and 180 days. Pi was fractionated into soluble and weakly bound P, Al or Fe bound P, occluded P and Ca bound P. The organic Po was fractionated into labile Po, microbial Po, moderately labile Po, fulvic acids associate Po, humic acids associate Po and residual Po. In the soil samples, an experiment with maize plants was also carried out to determine the plant dry matter production and the absorption of P. It was observed higher levels of occluded Pi and residual Po in the Hapludox. The fertilization also increased the contents of these fractions indicating that P is incorporated to the less available fractions. Therefore, the available P contents were smaller in this soil. In the Hapludult, Fe bound Pi and humic acids associated Po were the predominant P forms. The added P was incorporated into the Al and Fe bound P forms, which contributed to higher P availability in this soil. The more stable fractions of both Pi and Po did not correlate with available P, and the less stable fractions correlated with accumulated dry matter and P uptook by plants, indicating that even having a higher P content, the more stable fractions contribute in a more limited way to the P uptake by plants. In the Hapludox, the increase of Al, Fe bound P in the triple superphosphate treatment was crucial for greater availability. In the Hapludult, the increase of Al, Fe bound P, with lower occlusion of P in cattle manure treatment, resulted in higher availability. The interaction between the soil and fertilizer type defined the fate of the applied P, as well as the availability (AU)

FAPESP's process: 14/11466-3 - Organics and inorganics phosphorus forms in soils treated with organic wastes and its relations with availability
Grantee:Lucas Boscov Braos
Support Opportunities: Scholarships in Brazil - Doctorate