Temporal dynamic of P in different soil management systems in temperate and subtropical climate
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Data
2021-07-21Primeiro membro da banca
Pavinato, Paulo Sergio
Segundo membro da banca
Morel, Christian
Terceiro membro da banca
Chabbi, Abad
Quarto membro da banca
Winck, Bruna Raquel
Quinto membro da banca
Tiecher, Tales
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The prospect of world population increases requires that the production of food to be potentialized and better distributed around the world. One sustainable alternative to achieve high food production is an efficient use of the areas already cultivated. In this sense, appropriated management of nutritional inputs and soil management systems are fundamentals. Phosphorus (P) is an essential nutrient for plant production whose natural reserves are threatened with depletion in the coming decades. Thus, this work is placed in the scenario of increasing fertilizer efficiency, raising agricultural production, and maintaining the dynamic balance of nutrients aiming at the sustainability of agricultural systems, food security and reduction of climate change. Therefore, the main objective of this These was establishing a more effective strategy of P fertilization on increase forage production, maintenance of plant community and efficiency use of P. As well as, testing the effect of soil management systems on soil P availability and depletion and their stoichiometry with carbon and nitrogen. To achieve our objectives, we analyzed two long-term experiments. The first one was established in 1997 in a natural grassland of Pampa biome, Rio Grande do Sul, Brazil. The soil of this experiment is a phosphorus-poor soil with low total and available P stocks. In this site the effect different P sources were tested by analysing historical dry-matter production, P use efficiency and botanical changes, as well soil P availability and P pools dynamic. The second one was established in 2005 in an agricultural soil situated in l’ORE ACBB at l’INRAE - Lusignan, France. The experimental soil had high total and available P stocks due to an historic fertilization before experiment. The studies on this site were focused on the long term effect of two management systems (permanent cropland and permanent grassland) by field, P exportation, soil P, C and N total stocks depletion, P availability depletion and changes in soil C:N:P stoichiometry. The dynamic of P in soil microbial biomass and alteration of P, C and N coupling in soil aggregate sizes. We concluded that the use of soluble P sources (such as simple and triple superphosphate) associated with liming is a better strategy to improve dry matter production and P use efficiency in Pampa grassland. These fertilizers lead to a small change in species richness; however, there was higher species turnover, mainly in the tussock grass and forbs groups and in the legume contribution to forage production. To maintain dry matter yield, a regular phosphorus input with no more
than three years is necessary. Though, the use of natural phosphates (phosphate rocks) did not improve fertility conditions and dry matter production satisfactorily due to their long term non dissolution (more than six years). In soil with high P stock, permanent grassland provided a greater depletion of total and P-labile stocks. As well, permanent grassland supports a transformation from inorganic P to organic P in the most labile pool, accompanying the increase of C and N stocks in the soil. Additionally, we observed that the Pmic is an important bioavailable P pool in both management systems and accounted for up to 47% of the available P content (P Olsen) in a permanent cropland system. By 31P-NMR technique was observed that permanent grassland had a more significant effect in reducing α–glycerophosphate and increasing myo-IHP and adenosine monophosphate than permanent cropland.
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