Availability of phosphorus for maize in crop-livestock integration system

Abstract

-The objectives of this study were to assess the concentrations of available phosphorus (P) extracted using the Mehlich-1 (M1), ion exchange resin (IER) and modified Morgan (MM) methods after 36 months of experimentation with the application of phosphates in a crop-livestock integration system (CLIS). Moreover, this study aimed to assess which extraction method provides the best correlation of P concentrations with the maize crop attributes. The treatments consisted of applying annual doses of P 2 O 5 on the soil surface of the total area during the sowing of winter forage crops in the form of triple superphosphate (TSP), rock phosphate (RP) or magnesium thermophosphate (MTP). After 36 months of experimentation, soil samples were collected from the 0-5, 5-10, 10-15 and 15-20 cm layers to assess the concentrations of available P. The dry matter yield (DMY), the grain yield (GY), the accumulation of phosphorus in the dry matter (P-DM) and the export of phosphorus (P-Ex) were quantified in maize. The IER method extracted greater amounts of available P, followed by the M1 and MM extractions. The treatments that included the application of TSP and either the M1 or IER extractions had similar efficacies when correlated with the DMY, GY, P-DM and P-Ex attributes of maize. The P extracted by the IER was most correlated with P-DM and P-Ex for the water-insoluble P sources (RP and MTP). The MM solution was ineffective at predicting the availability of P for maize grown in a soil with that had received varying doses and sources of P applications in a CLIS. RESUMO -Os objetivos deste trabalho foram determinar as concentrações de P disponível extraído pelos métodos de Mehlich-1 (M1), Resina trocadora de íons (RTI) e Morgan Modificado (MM), após 36 meses de experimentação com aplicação de fosfatos em um sistema de integração lavoura-pecuária (SILP). Ainda, verificar qual método de extração proporciona melhor correlação com atributos da cultura do milho. O delineamento empregado foi em esquema fatorial incompleto, com quatro repetições. Foram aplicadas doses de P 2 O 5 , na superfície do solo, por ocasião da semeadura da forrageira de inverno, nas formas de superfosfato triplo (SFT), fosfato natural reativo (FNR) e termofosfato magnesiano (TFM). Após 36 meses, procederam-se coletas de solos das camadas de 0-5; 5-10; 10-15; 15-20 cm, visando determinar as concentrações de P disponível. Na cultura do milho foram quantificados o rendimento de massa seca (RMS), o rendimento de grãos (RG), o acúmulo de fósforo na massa seca (P-MS) e a exportação de fósforo (P-Ex). A RTI extraiu maiores quantidades de P disponível, seguida do extrator de M1 e do MM. Nos tratamentos que receberam aplicação de SFT, os extratores de M1 e RTI obtiveram eficiência semelhante quando correlacionados com os atributos de RMS, RG, P-MS e P-Ex do milho. Para as fontes insolúveis em água (FNR e TFM), o P extraído pela RTI melhor se correlacionou com o P-MS e o P-Ex. A solução de MM foi ineficiente para prever a biodisponibilidade de P para o milho, cul...

Phosphorus fractions and their relationships with soil chemical attributes in an integrated crop-livestock system under annual phosphates fertilization

“…However, in recent years, system fertilization has been used successfully (Galetto et al, 2014a,b;Guera et al, 2020). This system fertilization practice is more commonly practiced in South Brazil (Galetto et al, 2014a;Guera et al, 2020) by the anticipation of fertilization to the cover crop phase. System fertilization can be done using several approaches around the world and it is important to put this strategy in context to a broader audience.…”

“…Additionally, there is a tendency to apply phosphate fertilizer broadcast with or without incorporation instead of applying it in sowing furrow, to maximize the use of machines and seeding (Galetto et al, 2014a;Hansel et al, 2017;Guera et al, 2020). However, application of phosphates in ICLS under no-tillage can lead to increased P concentrations near the soil surface and P immobilization due to increased adsorption on soil colloids (Hansel et al, 2017).In this context, it is expected that there will be an increase in available P fractions, over time, combined to different low solubility sources of phosphate utilization, annually applied in broadcast without incorporation and with the maintenance of SOM and greater cycling of nutrients in ICLS.…”

Stocks and Distribution of Soil Carbon, Nitrogen, Phosphorus and Sulfur in an Integrated Crop-Livestock System Treated with Phosphates

“…Anticipated fertilization is a practice that provides for total or partial application of recommended doses of fertilizer to the summer crop at the time of sowing of the previous crop, in an incorporated form or at soil surface [12]. Thus the application of soil surface P to winter crops is an interesting practice in production systems such as ICLS, because it would improve P recycling, especially in the medium and/or long-term and ensure a better time and operational efficiency in sowing summer crop [13]. However, scientific information on practice of anticipated fertilization with different sources and doses of phosphates is still scarce, especially in the medium and/or long-term in ICLS.…”

Broadcast and in line application of phosphorus in soils with different densities

“…The most common method of P application in grain production is soil surface with or without incorporation, in row placement and in band placement (Galetto et al, 2014). Among the determining factors for the best P application method are soil physical and chemical proprieties, fertilizer type and crop type (Ceretta et al, 2007).…”