Utilization and fate of phosphorus of different sources applied to cohesive soil of Amazonian periphery

Abstract

In the Amazonian region, P is often a primary factor limiting sustainable agrosystems. We compared the efficiencies of local aluminous phosphate (ALP) and single superphosphate (SSP) under a cover of leguminous residues to determine the fate of P sources in an Amazonian soil with hardsetting characteristics. The experiment followed a randomized block design with four replications and the following treatments: ALPU, i.e. ALP plus urea (U); ALPL, i.e., ALP plus leucaena (L); SSPU, i.e., SSP plus urea; SSPL, i.e., SSP plus leucaena; and BS, i.e., bare soil (without residues). To assess the residual values of the P sources, we used a sequence of crops consisting of maize, cowpea and cassava. Both ALP and SSP exhibited low P efficiency in BS. The greatest amounts of P and N uptake in the plots where P sources and leucaena residues were added, as in those covered with leucaena residue, resulted in higher productivity levels.These differences are important for the adoption of beneficial soil management practices and the use of P sources to enhance efficiency in tropical soils. The use of residues increased the P use efficiency of both P sources, as it enhanced the uptake of both N and soluble P. The replacement of SSP with ALP may be advantageous in the second year of planting with high-demand crops, but the P of the SSP retained in the minus soluble fractions may be available if the SSP is used in P-depleting crops combined with no-tillage underneath a mulch of residues.

Solubility and Efficiency of Rock Phosphate Fertilizers Partially Acidulated with Zeolite and Pillared Clay as Additives

“…For better comprehension of the P dynamics and its accumulation in soils, sequential extraction with distinct strength solutions has become a fundamental tool [47][48][49][50]. The "P fractionation" procedure According to the acidulation level and additives incorporated in each source evaluated herein, distinct amounts of P were detected in the leachate through the soil columns over the 60 days' incubation period (T1-T12) (Figure 5a).…”

“…For better comprehension of the P dynamics and its accumulation in soils, sequential extraction with distinct strength solutions has become a fundamental tool [47][48][49][50]. The "P fractionation" procedure allows for evaluating the forms and distribution of this nutrient in the soil according to the fractions extracted, as well as the fate of P applied via fertilizers, in order to identify changes in soil nutrient dynamics.…”

Incorporação de argilas pilarizadas, zeólitas e substâncias húmicas em fertilizantes fosfatados para controle da solubilidade no solo

“…As análises estatísticas dos dados foram realizadas por meio do pacote estatístico ExpDes As reações que ocorrem dentro do próprio grânulo do fertilizante ou na região bem próxima a ele justificam, em parte, a limitada difusão do P no solo. Silva (2013) THIECHER et al, 2012;COELHO et al, 2017). O "fracionamento de P", como é conhecida essa técnica, permite avaliar, além do P disponível quantificado por métodos de rotina, as formas e distribuição deste nutriente no solo, bem como destino do P aplicado via fertilizantes, de modo a identificar possíveis mudanças na dinâmica do nutriente no solo.…”

“…Dentre as várias metodologias existentes, a de Hedley, Stewart e Chauhan (1982) com modificações propostas por Condron, Goh e Newman (1985) foi a empregada nesse estudo porque, além de ser o método mais utilizado em trabalhos brasileiros COELHO, et al 2017;TELES et al, 2017), permite estimar a labilidade das frações de P extraídas, uma vez que a remoção do P ocorre de maneira sequencial das formas mais disponíveis até as mais estáveis, englobando tanto o P inorgânico quanto o P orgânico. Al (GATIBONI et al, 2007;TIECHER et al, 2012;TELES et al, 2017).…”