Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-27T13:30:37Z No. of bitstreams: 5 66.pdf: 633982 bytes, checksum: fdad2ae3be9096fae7ea678fc3d85800 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-27T19:48:45Z (GMT) No. of bitstreams: 5 66.pdf: 633982 bytes, checksum: fdad2ae3be9096fae7ea678fc3d85800 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Made available in DSpace on 2015-02-27T19:48:45Z (GMT). No. of bitstreams: 5 66.pdf: 633982 bytes, checksum: fdad2ae3be9096fae7ea678fc3d85800 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) Previous issue date: 2012 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (Capes) / Melhorar a efici?ncia da absor??o de P no solo pelas culturas, por meio de manejos diferenciados da aduba??o fosfatada, diz respeito a um melhor aproveitamento do nutriente adicionado via fertiliza??o, que significa ganhos em produtividade. Em solos onde predominam argilas de baixa atividade e ?xidos em sua fra??o mineral, a fixa??o de P por meio dos processos de adsor??o e precipita??o torna a nutri??o fosfatada um fator limitante para produ??o da maioria das esp?cies cultiv?veis. O ?nion citrato, derivado da dissocia??o do ?cido c?trico no solo, possui elevado poder complexante de metais. Al?m disso, sua carga negativa garante afinidade com as cargas positivas dos ?xidos no solo, competindo com o fosfato pelos mesmos s?tios de liga??o. Com objetivo de verificar o potencial do ?cido c?trico em aumentar a biodisponibilidade ao milho e modificar as formas de P inorg?nico no solo, testou-se a combina??o das doses 0; 45; 90 e 180 mg dm-3 de P num Neossolo Quartzar?nico e 0; 100; 200 e 400 mg dm-3 de P num Latossolo Vermelho Amarelo, com doses equivalentes a 0; 1; 2 e 4 kg ha-1 de ?cido c?trico, em experimentos em vasos, em condi??es de casa de vegeta??o. No Neossolo Quartzar?nico, 119 mg dm-3 de P e equivalente a 0,8 kg ha-1 de ?cido c?trico proporcionaram m?ximo crescimento das plantas de milho. J? no Latossolo Vermelho Amarelo, a estimativa das doses foi de 96 mg dm-3 de P e equivalente a 2,0 kg ha-1 de ?cido c?trico. A resposta das plantas ? aplica??o do ?cido c?trico deveu-se ? solubiliza??o de formas menos l?beis aumentando as formas mais l?beis de P inorg?nico no solo. Os teores de P na planta e aqueles extra?dos por Mehlich-1e Resina de Troca Ani?nica n?o se correlacionaram quanto ? adi??o de ?cido c?trico no Latossolo Vermelho Amarelo. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2012. / ABSTRACT To improve the efficiency of absorption, by crops, of P in soil, through differentiated maneuvers of phosphorus fertilization, relates to a better utilization of nutrients added through fertilization, which means productivity gains. In soils with a predominance of low activity clays and oxides in their mineral fraction, the P fixation through the processes of adsorption and precipitation makes phosphorus nutrition a limiting factor for production of most cultivable species. The anion citrate derived from citric acid dissociation of the soil has high metal complexing power. Furthermore, its negative charge ensures an affinity with the positive charges of the oxides in the soil, competing with phosphate for the same binding sites. In order to verify the potential of citric acid to increase the bioavailability for maize and to modify the forms of inorganic P in the soil, there had been tested the combination doses of 0, 45, 90 and 180 mg dm-3 of P in a Typic Quartzipsamment soil and 0; 100, 200 and 400 mg dm-3 of P in a Typic Hapludox soil, with doses of 0, 1, 2 and 4 kg ha-1 of citric acid in experiments conducted in pots under greenhouse conditions. In Typic Quartzipsamment soil, 119 mg dm-3 of P and an equivalent to 0.8 kg ha-1 of citric acid gave maximum growth of maize crops. In the Typic Hapludox soil, the estimated dose was 96 mg dm-3 of P and equivalent to 2.0 kg ha-1 of citric acid. The plant response to the application of citric acid was due to solubilization of less labile forms increasing the more labile forms of inorganic P in soil. The phosphorus content in the plant and those extracted by Mehlich-1 and Anion Exchange Resin were not correlated to the addition of citric acid in the Typic Hapludox soil.