Showing papers by "Eduardo Fávero Caires published in 2000"

Calagem na superfície em sistema plantio direto

Abstract: Existem informacoes conflitantes a respeito da eficiencia da aplicacao superficial de calcario em sistema plantio direto, particularmente na correcao da acidez do subsolo, e de criterios de recomendacao de calagem para tal sistema de cultivo. Com o objetivo de avaliar a correcao da acidez do solo e a producao de graos de culturas em rotacao no sistema plantio direto, considerando a aplicacao de calcario na superficie, foi realizado um experimento em um Latossolo Vermelho-Escuro distrofico textura media, em Ponta Grossa (PR), no periodo de 1993 a 1998. Os tratamentos, dispostos em blocos completos ao acaso com tres repeticoes, constaram de quatro doses de calcario dolomitico: 0, 2, 4 e 6 t ha-1, calculadas para elevar a saturacao por bases do solo a 50, 70 e 90%. O calcario foi aplicado em julho de 1993, a lanco, na superficie do solo. Foram cultivados, na sequencia, soja (1993/94), milho (1994/95), soja (1995/96), trigo (1996), soja (1996/97), triticale (1997) e soja (1997/98). A aplicacao de calcario na superficie aumentou significativamente o pH, os teores de Ca + Mg trocaveis e a saturacao por bases e reduziu significativamente os teores de H + Al do solo, ate a profundidade de 60 cm. Estimou-se que a maxima eficiencia tecnica (MET) e a economica (MEE) ocorreriam, respectivamente, com as doses de 3,8 e 3,3 t ha-1 de calcario. A dose de calcario para MEE foi a indicada pelo metodo da elevacao da saturacao por bases do solo a 65%, para amostra coletada na profundidade de 0-20 cm, mostrando ser este criterio adequado para recomendacao de calagem na superficie em sistema plantio direto. Todavia, a calagem na superficie deve ser recomendada somente para solo com pH (CaCl2) inferior a 5,6 ou saturacao por bases inferior a 65%, na camada de 0-5 cm.

Absorção de nutrientes pela soja cultivada no sistema de plantio direto em função da calagem na superfície

Abstract: Liming surface application effects on plant chemical traits, under no-tillage systems, are not well defined yet. A field trial has been carried out on a dystrophic dark red latosol (Haplortox) at Ponta Grossa, State of Parana, Brazil, aiming at evaluate liming surface application effects, under a no-tillage scheme, on soybean nutrient uptake and its reflexes on grain yielding performances. A randomized complete block design has been used, in which four dolomitic limestone rates have been studied (0, 2, 4 and 6 t.ha-1), with twelve replications. Those rates have been set up to increase soil base saturation, in the 0-20 cm soil layer, to 50%, 70% and 90%, respectively. Surface liming application has increased P and Mg plant levels and decreased Zn and Mn ones, as expected by the presence of higher soil pH’s in surface layers, with no significant effects on grain yields. So, high soybean grain yields, reported in highly acidic soils under no-tillage systems, might be related to proper water and nutrient uptakes due to higher soil moisture avaiability.

Correção da acidez do solo em função de modos de incorporação de calcário

Abstract: The solubilization of lime in soil, without which the acidity neutralization does not occur, demands time and requires incorporation for increasing the contact between lime and soil coloides. In order to study the correction of soil acidity in function of lime incorporation manners, a field experiment was carried out, in Ponta Grossa, State of Parana, Brazil, in a dystrophic Dark Red Latosol, in native field. A randomized complete block design was used, with three replications, in a split-plot experiment. The treatments consisted of five incorporation methods: disk plowing plus two spring disk harrowing, off-set harrowing plus two spring disk harrowing, rotary tilling, chisel plowing plus two spring disk harrowing and lime distribution on the surface without incorporation (main plots), and four rates of dolomitic limestone: 0, 2.8, 6.6 and 10.3 t ha-1, in order to raise base saturation of soil to 30, 60 and 90% (subplots). The cultivated plant was maize. The results showed that the lime incorporation manner in the soil affects its efficiency in relation to the depth in the profile in which there is neutralization of the acidity. There was elevation in base saturation of the soil to the layer of 20cm, 15cm and 10cm, respectively, for the following incorporation manners: rotary tilling, disk plowing or off-set harrowing and chisel plowing or lime distribution on the surface without incorporation. The saturation values for wanted bases were not reached, three months after liming, independent in the incorporation manner of lime.

Nodulação e absorção de nitrogênio pelo amendoim em resposta à calagem, cobalto e molibdênio

Abstract: The response of the peanut plant to lime has been associated with calcium nutrition, but a higher nitrogen uptake has been observed in limed plots. A greenhouse experiment was conducted using a Red Latosol (Rhodic Hapludox) to study the effects of molybdenum, cobalt and liming on the nodulation and N uptake by peanut. A randomized block design was used, with four replicaties, in a factorial 4x3 scheme. Seed treatments (0.16 g kg-1 of Co, 0.58 g kg-1 of Mo, 0.16 g kg-1 of Co + 0.58 g kg-1 of Mo and no treatment) were applied to the peanut, cv. "Tatu", grown receiving three rates of lime (0, 4 and 6 t ha-1). There was no effect of seed treatment with Co on the nodulation and N uptake of peanut. Liming increased N uptake due to the formation of a larger number of nodules in the plant. The dry matter of peanut nodules was increased by Mo, but N uptake was not affected, showing that the decrease in Mn toxicity due to liming was more important than the increase in Mo availability for nodule formation and symbiotic N2 fixation.

Correção da acidez do solo em função de modos de incorporação de calcário correction of soil acidity in function of lime incorporation manners

Abstract: Engenheiro Agronomo formado pela Universidade Estadual de Ponta Grossa.RESUMOA solubilizacao do calcario no solo, sem o que naoocorre neutralizacao da acidez, demanda tempo e exige incorpo-racao para aumentar o contato entre o corretivo e os coloides dosolo. Com o objetivo de avaliar a correcao da acidez do solo emfuncao de diferentes modos de incorporacao de calcario, foiconduzido um experimento, no ano agricola 1993/94, em umLatossolo vermelho-escuro, distrofico, de campo nativo, domunicipio de Ponta Grossa (PR). O delineamento experimentalempregado foi o de blocos ao acaso, em parcelas subdivididas,com tres repeticoes. Os tratamentos foram constituidos por cincomodos de incorporacao: arado de discos mais duas gradagens,grade aradora mais duas gradagens, enxada rotativa, aradoescarificador mais duas gradagens e distribuicao na superficiesem incorporacao, e por quatro doses de calcario dolomitico: 0,2,8, 6,6 e 10,3 t ha