Fernando José Garbuio

Alterações químicas do solo e resposta do milho à calagem e aplicação de gesso

Root growth and crop yield can be affected by chemical modifications of the soil profile owing to lime and gypsum applications. A field trial was carried out on a dystrophic Clay Rhodic Hapludox in Ponta Grossa, Parana State, Brazil, aiming to evaluate the changes in the chemical soil properties and corn response to lime and gypsum applications at the installation of a no-tillage system. A randomized complete block design was used, with three replications, in a split-plot experiment. The main plots received dolomitic limestone treatments (no lime; 4.5 t ha-1 of lime applied on the surface supplying the total demand; 1/3 of the total demand applied on the surface during three years; total demand incorporated into the soil) and the subplots received gypsum rates (0, 3, 6, and 9 t ha-1). The treatments with lime were applied in July 1998 and the rates of gypsum in October 1998. Corn was evaluated in the agricultural year of 2001/02. The applied surface liming, at full or split rates, provided a more accentuated soil acidity correction in the superficial layer (0-0.05 m), and there was a stronger reaction in the 0.05-0.10 and 0.10-0.20 m layers, when lime was incorporated into the soil. Gypsum improved the subsoil, increasing the concentrations of Ca and S-SO42-, raised N, K, and Ca concentrations in the corn leaves, while it reduced the Mg concentration in soil and corn leaves. Liming and gypsum treatments did not affect the corn root growth. Liming (whether surface applied, at full or split rates, or incorporated into the soil) and gypsum increased the corn yield, due to an increase in the Ca soil saturation of the superficial layers. The application of gypsum associated to liming was an effective strategy to maximize grain yields.

Lime and gypsum application on the wheat crop

Root growth and crop yield can be affected by chemical modifications of the soil profile owing to lime and gypsum applications. A field trial was carried out on a dystrophic Clayey Rhodic Hapludox at Ponta Grossa, PR, Brazil, aiming to evaluate lime (without or with incorporation into the soil) and gypsum effects on root growth, mineral nutrition and grain yield of wheat (cv. OR 1). A randomized complete block design was used, with three replications, in a split-plot experiment. Treatments with dolomitic limestone (without lime and 4.5 t ha-1 of lime applied on the surface, in total rate and 1/3 of the requirement per year during 3 years, or incorporated into the soil) were applied in July 1998 (main plots) and the rates of gypsum (0, 3, 6 and 9 t ha-1) in October 1998 (subplots). Wheat was evaluated in the 2000 winter season. In conditions of water deficit absence, there was no limitation in root growth in depth, for exchangeable Ca of 6 mmolc dm-3. Lime incorporation of lime increased the Mg concentration in the leaves, but wheat yield was not influenced by the correction of soil acidity through liming treatments. Gypsum increased the concentrations of Ca and S in wheat leaves, with significant effects on grain yield. The critical level of S-SO42- in the 0-20 cm soil layer, extracted by ammonium acetate 0.5 mol L-1 in acetic acid 0.25 mol L-1, was 25.8 mg dm-3.

Surface application of lime ameliorates subsoil acidity and improves root growth and yield of wheat in an acid soil under no-till system

A calagem na superficie do solo em plantio direto ocasiona modificacoes quimicas no perfil que podem influenciar o crescimento do sistema radicular e a producao de graos das culturas. O crescimento de raizes e a producao de trigo (Triticum aestivum L. cv. CD 104, moderadamente sensivel ao Al), foram estudados cerca de 10 anos apos a aplicacao superficial de calcario (0, 2, 4 e 6 Mg ha-1) e tres anos da reaplicacao de calcario na superficie (0 e 3 Mg ha-1), em um Latossolo Vermelho distrofico textura media, manejado durante longo periodo no sistema plantio direto, em Ponta Grossa (PR). A acidez do solo limitou drasticamente o crescimento radicular e a producao de trigo, provavelmente por causa de prolongada falta de agua ocorrida durante a fase de desenvolvimento vegetativo da cultura. A calagem na superficie ocasionou aumento de ate 66% no crescimento radicular (0-60 cm) e de ate 140% na producao de trigo. A densidade de raizes e a producao de trigo correlacionaram-se positivamente com o pH e o teor de Ca2+ trocavel, e negativamente com o teor de Al3+ trocavel e a saturacao por Al3+, nas camadas superficiais e do subsolo.

Calagem superficial e cobertura de aveia preta antecedendo os cultivos de milho e soja em sistema plantio direto

Cover crop residues mobilize cations and benefit the action of lime applied on the soil surface owing to the release of low molecular weight organic acids from the soluble fraction of residues. However, these effects in no-till system are yet to be confirmed in field studies. A five-year trial was carried out on a no-till dystrophic Rhodic Hapludox in Ponta Grossa, State of Parana, Brazil, with the aim of evaluating changes in chemical soil attributes, as well as the corn and soybean response to surface application of dolomitic lime (0, 2.5, 5.0 and 7.5 t ha-1), with and without black oat cover. Lime rates were applied onto the main plots in November 2000 and the treatments on the subplots consisted of the presence or absence of black oat in 2001 and 2002, preceding corn and soybean crops. Surface-applied lime did not influence the dry matter yield of black oat, which was approximately 4 t ha-1 in both 2001 and 2002 years. Liming did not affect the H+ ions neutralizing capacity (482 mmolc dm-3), the sum of soluble cations (29.5 mmolc L-1) or electric conductivity (1,230 µS cm-1) of the black oat extract either. Liming applied on the soil surface decreased exchangeable Al3+ and increased pH, exchangeable Ca2+ and exchangeable Mg2+ down to a 10 cm depth. Black oat residue on the soil surface under no-till did not benefit the mobility of surface-applied lime to alleviate subsoil acidity. Surface application of lime did not affect corn mineral nutrition or corn and soybean yields, but decreased Zn and Mn concentrations in soybean leaves. Cover black oat residue raised the P, Ca, and Mg concentrations in the corn and N and P in the soybean leaves and caused a decrease of Mn concentration in the soybean leaves. The black oat cover on the soil surface increased corn yield, but did not affect soybean yield, grown under no-till after corn.

Surface application of gypsum in low acidic Oxisol under no-till cropping system

Nao estao claras as condicoes em que se podem esperar efeitos favoraveis da aplicacao de gesso na producao das culturas. Em um experimento de campo avaliaram-se, durante tres anos, os efeitos da aplicacao de gesso nos atributos quimicos de um Latossolo Vermelho argiloso de alta fertilidade e baixa acidez sob plantio direto e na nutricao e producao de milho (Zea mays L.) e soja (Glycine max L. Merrill), em Guarapuava (PR). Os tratamentos, dispostos em blocos completos ao acaso com quatro repeticoes, constaram da aplicacao superficial de gesso nas doses 4, 8 e 12 Mg ha-1. A aplicacao de gesso aumentou a concentracao de P na camada mais superficial (0.0 - 0,1 m), bem como os teores de Ca trocavel e de S-SO42- e a relacao Ca/Mg no perfil do solo (0.0 - 0,6 m). A adicao de gesso tambem ocasionou movimentacao de Mg e K trocaveis no solo. A concentracao de Ca nas folhas de milho e as concentracoes de P e S nas folhas de milho e soja foram aumentadas com a aplicacao de gesso. Houve aumento na producao de milho apos aplicacao de gesso, mas as culturas de soja subsequentes nao responderam ao gesso. A aplicacao de gesso foi eficiente para maximizar a producao de graos de milho no sistema plantio direto.

Soybean yield and quality a function oflime and gypsum applications

Effects of lime and gypsum applications on the quality of soybeans grown under no-till (NT) are not well defined yet. A field trial established in 1998 on a dystrophic clayey Rhodic Hapludox, at Ponta Grossa, State of Parana, Brazil, evaluated grain yield and soybean quality based on oil, protein and nutrient content, after lime and gypsum applications under NT, in a randomized complete block design (n = 3), split-plot experiment. In the main plots, the treatments with dolomitic lime were: control (no lime), split application of lime on the surface (three yearly applications of 1.5 Mg ha1), surface lime (4.5 Mg ha1), and incorporated lime (4.5 Mg ha1). Subplots received four different rates of gypsum: 0, 3, 6, and 9 Mg ha-1. The soybean crop was evaluated in the agricultural years of 20022003 and 20032004. After 58 months, the correction of acidity through surface liming, with full or split rates, was more pronounced in the top layer (00.05 m) and there was greater reaction at the depths of 0.050.10 and 0.100.20 m when lime was incorporated. Surface or incorporated liming had no effect on grain yield, soybean oil and protein content. Gypsum improved chemical subsoil conditions, raising pH (0.01 mol L-1 CaCl2) as well as Ca2+ and S-SO42- contents; it also caused exchangeable Mg2+ leaching in the soil profile. The application of gypsum did not affect grain yield, yet it improved soybean quality through an increase in protein and S contents, in 20032004, and in grain P, K and Ca, in the two cropping years. The use of gypsum in NT soybeans can be especially important for fields of seeds production.

Hillslope curvature, clay mineralogy, and phosphorus adsorption in an Alfisol cultivated with sugarcane

Hillslope curvatures are associated with specific environments that correlate to chemical and mineralogical attributes of soil, so determining specific management zones. Phosphorus is one of the main limiting factors to the development and longevity of sugarcane. The type and the mineralogical constitution of the clay fraction play an important role in the phosphorus (P) adsorption of soil. High proportion of gibbsite (Gb) in soil may be the major responsible for P adsorption. The relationships among spatial variability as a function of hillslope curvature, the proportion of kaolinite (Kt) and Gb, and phosphorus adsorption were evaluated in an Alfisol cultivated with sugarcane. Two plots of 1 ha of a concave and a convex hillslope area were selected and 121 samples were collected in each area. The maximum P adsorption was determined in six samples taken randomly in each area. Data were submitted to descriptive statistical and geostatistical analysis. The lowest average values of available phosphorus were found in the convex area. In this area, the proportion of gibbsite, expressed by the values of the ratio [Gb/(Gb + Ct)] and the values of maximum adsorption capacity of phosphorus were higher than in the concave area.

Correção da acidez do solo, crescimento radicular e nutrição do milho de acordo com a calagem na superfície em sistema plantio direto

Os efeitos das alteracoes quimicas do solo, decorrentes da calagem na superficie, em sistema plantio direto, no crescimento radicular e na nutricao do milho nao sao muito conhecidos. Com o objetivo de estudar a correcao da acidez do solo, o crescimento de raizes de milho (hibrido AG 9090), a nutricao da planta e seus reflexos sobre a producao de graos, considerando a aplicacao superficial de calcario no sistema plantio direto, foi realizado um experimento em um Latossolo Vermelho distrofico textura media, em Ponta Grossa (PR). O delineamento experimental empregado foi o de blocos ao acaso em parcelas subdivididas, com tres repeticoes. As parcelas receberam quatro doses de calcario dolomitico na superficie (0, 2, 4 e 6 t ha-1), em julho de 1993, e, nas subparcelas, foram reaplicadas duas doses de calcario dolomitico na superficie (0 e 3 t ha-1), em junho de 2000. A calagem, apos 92 meses, aumentou o pH, o Ca trocavel e a saturacao por bases e reduziu o Al trocavel do solo, ate a profundidade de 0,60 m. A reaplicacao de calcario, apos nove meses, proporcionou aumento no pH, Ca trocavel e saturacao por bases e reducao no Al trocavel do solo, ate a profundidade de 0,20 m. A reacao do calcario reaplicado na superficie foi mais rapida em condicoes de maior acidez do solo. Nao houve limitacao do crescimento radicular e da producao de milho para concentracao de 10 mmolc dm-3 de Al trocavel, na ausencia de deficit hidrico em solo com alto teor de materia orgânica, mas a calagem na superficie melhorou a distribuicao relativa de raizes na presenca de solo compactado. O calcario dolomitico aplicado na superficie em plantio direto proporcionou reducao no teor de K no tecido foliar do milho, sem alterar a producao de graos.

Soil acidity, liming and soybean performance under no-till

Os efeitos das alteracoes quimicas do solo ocasionadas pela aplicacao superficial de calcario no crescimento radicular, na nutricao mineral e na producao de graos de soja cultivada em sistema plantio direto sao pouco conhecidos e foram estudados no presente trabalho. O experimento foi realizado em um Latossolo Vermelho distrofico textura media, em Ponta Grossa (PR). O delineamento experimental empregado foi o de blocos completos ao acaso em parcelas subdivididas, com tres repeticoes. As parcelas receberam quatro doses de calcario dolomitico na superficie (0, 2, 4 e 6 Mg ha-1), em julho de 1993, e, nas subparcelas, foram reaplicadas duas doses de calcario dolomitico na superficie (0 e 3 Mg ha-1), em junho de 2000. A calagem, apos nove anos, aumentou o pH e o Ca2+ trocavel e reduziu o Al3+ trocavel e a saturacao por aluminio do solo, ate a profundidade de 60 cm. A reaplicacao de calcario, apos dois anos, tambem proporcionou melhoria nas condicoes de acidez do solo ate a profundidade de 60 cm. O comprimento total de raizes de soja por unidade de area superficial de solo (0-60 cm) foi reduzido com a calagem na superficie em plantio direto. A reducao de Al3+ trocavel no solo com a calagem nao alterou as concentracoes de Al nas raizes e nas folhas de soja. O calcario dolomitico aplicado na superficie em plantio direto aumentou as concentracoes de Ca e Mg e reduziu o teor de Mn nas raizes e nas folhas de soja. A producao de graos de soja nao foi influenciada pela calagem na superficie por causa da baixa toxicidade do Al e ainda porque o crescimento radicular foi estimulado por condicoes de stress de acidez do solo no sistema plantio direto.

Adsorção de metais pesados após calagem superficial em um Latossolo Vermelho sob sistema de plantio direto

There are few researches about control of soil acidy and adsorption of heavy metals in no-till system (NTS). The aim of this study was evaluate the cadmium (Cd), nickel (Ni), copper (Cu) and zinc (Zn) adsorption in a Rhodic Hapludox, clayey, without and with surface liming (4.5 t ha-1) under NTS. The experiment was established in Ponta Grossa, PR, in 1998. After 10 years, soil samples were collected to adsorption study. Doses of 0 to 180 mg L-1 of Cd and Ni, and of 0 to 180 mg L-1 of Cu and Zn were added, in competitive systems. After the equilibrium, the quantity of heavy metals was measured. Surface liming increased soil pH in all studied layers, resulting in improve of Cu, Zn, Cd and Ni adsorptions, mostly in the superficial layer. Moreover, surface liming changed dynamics of heavy metals in soil, being an efficient strategy to minimize environmental problems associate with Cd, Ni, Cu and Zn in NTS.