Avaliação do fosfato natural de Gafsa para recuperação de pastagem degradada em latossolo vermelho-escuro

Abstract

e THOMAZ ADOLPHO REIN 2 RESUMO -Este experimento de campo, instalado em janeiro de 1994, teve os objetivos: 1) avaliar a eficiência do fosfato natural de Gafsa farelado (FGF) na recuperação de pastagem de Brachiaria decumbens cv. Basilisk num Latossolo Vermelho-Escuro textura argilosa do Distrito Federal, e 2) verificar efeitos de interações entre fontes de P (fosfato natural de Gafsa e superfosfato triplo (SFT) e incorporação do fosfato com grade e adubação complementar (N, Ca, Mg, K, S e micronutrientes), sobre a disponibilidade de forragem. Os fosfatos foram aplicados na dose de 100 kg ha -1 de P 2 O 5 . O delineamento foi o de blocos casualizados, com parcelas subdivididas, com o tratamento incorporação nas parcelas e o fatorial, fontes de P vs. adubação complementar, nas subparcelas, perfazendo 12 tratamentos com quatro repetições. A resposta à aplicação dos fosfatos só foi efetivada com aplicação simultânea de adubação complementar; a incorporação com grade foi essencial para aumentar a eficiência do FGF; ao ser incorporado com grade, o FGF teve desempenho tão bom quanto o SFT; sem incorporação, o FGF proporcionou produção de matéria seca inferior à proporcionada pelo SFT (p<0,05).Termos para indexação: fosfato de rocha reativo, cerrados, Brachiaria decumbens, adubação de pastagem. EVALUATION OF A COARSE-GROUND GAFSA ROCK PHOSPHATE IN THE RECUPERATION OF A DEGRADED PASTURE ON A CLAYEY DARK-RED LATOSOLABSTRACT -A field experiment was conducted on a Dark-Red Latossol (Haplustox) of the Cerrado of the Federal District, Brazil, to evaluate a coarse-ground Gafsa rock phosphate (CGRP) in the recuperation of a Brachiaria decumbens cv. Basilisk pasture. CGRP was compared with triple superphosphate (TSP) at a P 2 O 5 rate of 100 kg ha -1 both applied by broadcasting. A control treatment without P was included together with two other variables: 1) incorporation of the phosphate with a harrow (with and without) and 2) supplementary fertilization (SF) with Ca, Mg, N, K, S and micronutrients (presence and absence). The response to application of phosphates was only observed with the simultaneous application of SF; incorporation was essential for increasing the efficiency of CGRP; with incorporation, the efficiency of CGRP was equal to that of TSP; without incorporation, TSP was significantly superior to CGRP (p< 0.05).

Production, nutritional status and chemical properties of soils with addition of cattle manure, reactive natural phosphate and biotite schist in Massai cultivar

“…Similar increases in dry matter yield with the addition of phosphorous on Urochloa decumbens were obtained by Yost et al (1982) and Soares et al (2000) by incorporating 150 kg ha -1 of natural rock phosphate from North Carolina (30% of P 2 O 5 ) and 100 kg ha -1 of reactive natural rock phosphate from Gafsa (28% of P 2 O 5 ), respectively. Similar quantities of triple superphosphate (soluble source -40% of P 2 O 5 ) were also obtained with the use of RNRP (Arad and North Carolina) by Moreira & Malavolta (2001) with alfalfa (Medicago sativa) and Brazilian butterfly peas (Centrosema pubescens Benth).…”

Influence of organic-mineral fertilization of an oxisol on soil chemical properties and Bracharia brizantha production

“…More than half of an estimated total of 48 million hectares in the region are Brachiaria decumbens pastures (Soares et al, 2000). However, approximately 80 % of the pastures in the Cerrado are partially degraded, as indicated by the low productivity and low support capacity (Lima et al, 2000).…”

Phosphorus in Forage Production

“…The most P-sources used in forage grasses are soluble P-sources (Table 1), and less is relate to reactive natural phosphate (RNP), even with such researches showing the incorporation of RNP can result in approximated efficiency than soluble sources as triple phosphate [72]. Even with low solubility, maybe in sand soil, it is possible to improve the uptake of forage through the use of RNP in pasture because of minor adsorption site than in clay soil.…”

“…Massai [73]. In the case of Brachiaria decumbens, application of RNF promoted 30% of dry matter production with RNF was applied [72]. Therefore, it is important to remember that acidity in rhizosphere is higher than surround soil [15], which can contribute to improve RNF solubility and plant uptake.…”