Phosphorus application and liming effects on forage production, floristic composition and soil chemical properties in the Campos biome, southern Brazil

Abstract

Studies of responses of native and introduced grassland species to lime and phosphorus (P) applications could contribute to improved understanding of the potential production of South American natural grasslands. To determine the effect of applying lime and different P sources on forage production, diversity and floristic composition, and on soil chemical properties, a small‐plot experiment was conducted over 12 years in natural grassland oversown with Lolium multiflorum and Trifolium vesiculosum in the Campos of southern Brazil. In treatments with soluble phosphate application, dry‐matter (DM) yield in November 2008, after 164 d of winter and early spring growth, increased from 2·3 to 3·2 t ha−1. Differences in DM yield in March 2009, after 111 d of growth during late spring and early summer, were not significant. The DM yield in April 2010, after 419 d of growth, increased from 7·7 to 9·2 t ha−1 in the treatments with P, regardless of the P source. Increased forage yield during the slow growth period in winter was only possible with the introduction of winter‐growing species (L. multiflorum and T. vesiculosum) and soluble phosphate application. Assessment of annual forage yield showed that the effectiveness of Gafsa rock phosphate was equivalent to that of soluble phosphates in the long term. Soluble phosphates and liming modified the botanical composition of natural Campos grassland in the long term, but floristic diversity was not altered.

Formas de fósforo no solo sob pastagens naturais submetidas à adição de fosfatos

“…Dessa forma, as espécies nativas, componentes das pastagens naturais, podem tornarem-se menos dependentes da mineralização das frações orgânicas de P para a produção de forragem (Tiecher et al, 2013).…”

“…Altas produções de forragem são possíveis porque em ambientes naturais equilibrados a biociclagem do P orgânico do solo, do P contido nos tecidos vegetais e na biomassa microbiana do solo (BMS) atende às necessidades das plantas (Oliveira et al, 2011). Todavia, há possibilidades de aumentar a produtividade das áreas de pastagens naturais, evitando a sua substituição por culturas anuais, florestas ou pastagens cultivadas (Tiecher et al, 2013). Nesse sentido, a aplicação de fertilizantes fosfatados sobre as pastagens tem evidenciado-se rentável economicamente e com impactos ambientais desprezíveis (Gatiboni et al, 2003).…”

“…Entretanto, em solos ácidos (pH < 5,2) e com baixos teores de Ca, a eficiência agronômica dos FN em longo prazo pode ser suficientemente elevada para obterem-se rendimentos compatíveis à aplicação dos fosfatos solúveis (Gatiboni et al, 2003;Chien et al, 2011), apresentando-se adequados para o uso em culturas perenes (Szilas et al, 2007). Nesse sentido, Tiecher et al (2013) demonstraram que após 154 meses o teor de P disponível no solo e a produção anual de forragem foram equivalentes com a aplicação de hiperfosfato de Gafsa e fosfatos solúveis. Contudo, o aumento de produção de forragem no inverno, período de baixo crescimento das pastagens naturais no sul do Brasil, só foi possível com a introdução de espécies exóticas de inverno e aplicação de fertilizantes fosfatados solúveis, que promoveram aumento rápido de P disponível no solo, fornecendo assim as condições necessárias para o estabelecimento do trevo vesiculoso (Trifolium vesiculosum) e do azevém (Lolium multiflorum).…”

Phosphorus Availability in Low-P and Acidic Soils as Affected by Liming and P Addition

“…The second way (i.e., more generous P applications) addresses the symptoms (low P availability) rather than the root of the problem (acidic soil activity) but is the usual agricultural practice. While the problem of low P availability and dynamics has been recognized and addressed in the past years, and consequently a lot of research has been conducted in highly weathered soils (e.g., Ultisols, Tiecher et al 2013;Oxisols, Guedes et al 2012), P dynamics in recently developed Mediterranean acidic, low-P status soils has been overlooked. However, even in such recent soils of acidic reaction, low P availability may be as much a restraining factor for plant growth as in well-developed soils.…”

Liming and application of micronutrients in the establishment of Tifton pasture

“…The proposed increase in the soil pH to be reached by the practice of liming is conditioned, among others, to the need of the plant, with plants more or less responsive to liming (Tiecher et al, 2013), and to the buffer power (Gatiboni et al, 2000;CQFS-RS/SC, 2004). However, few studies address the response of pastures with micronutrients (Volpe et al, 2008) and the interaction of these with liming, since in some situations micronutrient deficiency may occur in plants (Impa & Johnson -Beebout, 2012).…”