Strategies to improve phosphorus availability and reduce environmental impact in rice agrosystems

Résumé

Phosphorus (P) is a limiting element in the dynamics of legume-grass succession, because it fulfills different roles that imply functionality in the absorption efficiency with other elements such as Nitrogen and Iron (Fe), the latter especially in tropical soils. Rice has shaped the diet, economy, and culture of millions of people around the world. It is considered the third most produced crop after corn and wheat on the planet. China is the largest producer and consumer of rice in the world with an area of 30 million hectares with a total amount of 145 million tons, while Italy is the main producer of rice in Europe. with an area of 234,133 ha there is a rice production of more than 1.5 million tons. Rice production faces agronomic and environmental challenges, such as the reduction of nutrient losses that can cause contamination of ecosystems, the increase of efficiency in fertilizer applications using alternative sources such as struvite, the use of friendly practices with the sustainable development of cover crops during the fallow period to improve soil fertility. Therefore, this thesis aimed to evaluate the role of P on biological N fixation (BNF) efficiency in legumes and the role of these cover crops on nutrient dynamics in temperate rice agrosystems (Northern Italy). Another objective of this thesis was developed under tropical conditions and aimed to evaluate P forms in acid soils under different water management and fertilized with conventional and alternative phosphate fertilizers.