Crescimento radicular e nutrição mineral da soja em função da calagem e adubação fosfatada

Tanto o cálcio como o fósforo tem importante ação no crescimento de raízes. No presente trabalho foi estudado, em vasos, o efeito de tres níveis de Ca e quatro níveis de P no crescimento radicular, produção de matéria seca e nutrição de plantas de soja cv. IAC 17. Duas plantas foram cultivadas em cada vaso de 7 L, preenchidos com terra proveniente de um Latossolo Vermelho Escuro de textura média, por 35 dias. Foi efetuada calagem calculada para se atingir saturações do solo por bases de 45, 50 e 75 %. As doses de P foram 25, 50, 100 e 200 mg kg-1, utilizando-se de fonte de P isenta de Ca. O teor de 8,5 mmol(c) dm-3 de Ca no solo foi suficiente para o crescimento normal do sistema radicular da soja. A baixa disponibilidade de P, em saturação do solo por bases de 46%, induziu ao crescimento das raízes em comprimento e superfície, sem modificar a massa de matéria seca das raízes. Embora raízes finas e longas tenham geometria favorável à absorção de P, em parcelas com teores menores que 45 mg kg-1, este ajuste não é suficiente para manter a mesma absorção que é observada em parcelas com maior disponibilidade do nutriente.

Oxisol subsurface chemical attributes related to sugarcane productivity

Embora haja homogeneidade nas características morfológicas na classe dos Latossolos, existe grande diversidade química na subsuperfície. Trabalhos indicam que a produção agrícola apresenta correlação significativa com atributos químicos de subsuperfície, que são mais estáveis que na camada arável, sujeita a alterações decorrentes da exploração agrícola. Pelo exposto, o presente estudo avaliou os efeitos dos atributos químicos de subsuperfície de Latossolos da região Centro-Sul do Brasil na produtividade agrícola dos três primeiros cortes de clones de cana-de-açúcar e da variedade RB72454. Utilizaram-se os dados de produtividade agrícola correspondentes ao período de 1993 a 1998. Os solos foram caracterizados sob o ponto de vista granulométrico e químico na profundidade entre 0,8 e 1,0 m e foram feitos estudos de correlação entre tais atributos e as médias de produtividade agrícola diária durante o ciclo dos clones de cada ensaio e da variedade RB72454 e análise de regressão múltipla, com as variáveis selecionadas pelo procedimento stepwise em função do R². As características químicas de subsuperfície dos Latossolos influenciaram na produtividade agrícola da cana-de-açúcar, principalmente no 3º corte. Para as médias dos clones, o modelo de produtividade do 3º corte em função de saturação por bases e fósforo, mostra R² = 0,31, ou seja, que 31% da variação de TCH dia-1 pode ser explicada por esses dois atributos. No caso da variedade RB72454, essa mesma variação no 3º corte é explicada em 47% pelos atributos soma de bases e teores de cálcio e matéria orgânica. As variações de produtividade de 1º e 2º cortes foram melhor explicadas pelo pHágua.

Efeitos de fontes de fósforo e da calagem na produção de amendoim

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

ROOT-GROWTH AND MINERAL-NUTRITION OF CORN HYBRIDS AS AFFECTED BY PHOSPHORUS AND LIME

The effects of triple superphosphate (TS) and liming on macronutrient accumulation and root growth of Pioneer 3072 and Cargill 505 com hybrids were studied. Com plants were grown up to 30 days in pots with 7 L of a dark red Latosol sandy loam (Haplortox). Lime was applied to raise base saturation to 30, 50, and 70%, in two levels of phosphorus (P) fertilization with TS (0 and 200 ppm P). There was an increase in root surface due to lime only in pots without TS, with no effects on plant growth or nutrition. Both com hybrids responded to P fertilization, but Pioneer yielded more dry matter than Cargill. The roots of Cargill were thicker and, when in TS presence, were longer and had a larger surface than Pioneer. There was an increase in macronutrient uptake in the P fertilized pots. Pioneer required more nutrients and showed a higher efficiency in acquiring and utilizing the nutrients from the soil. A higher response of Pioneer in dry matter and nutrient acquisition was more related to the physiological efficiency than to root morphology.

Yield and nitrogen uptake of peanuts as affected by lime, cobalt, and molybdenum

Peanut response to lime has been associated to calcium (Ca) nutrition, but a higher nitrogen (N) uptake has been observed in limed plots probably due to an increase in molybdenum (Mo) availability. A two-year experiment was conducted to study the effects of Mo, cobalt (Co), and liming on peanut yields and N nutrition. Peanut seeds were treated with Mo and/or Co and grown in soil with base saturation about 13, 41, 57, and 71%. There was no effect of seed treatment with Co on peanut yields or N nutrition. Liming and Mo application increased N contents in the leaves. Nitrogen uptake was increased by Mo and liming in cv. Tatu and only by liming in cv. Tupa. Manganese (Mn) contents in the leaves were decreased by liming. The higher yields were observed when the Ca/Mn ratio in the leaves was above 25. In acid soils, low availability of Mo and Mn toxicity can impair N acquisition by peanut plants and decrease grain yields.

Root growth and cotton nutrition as affected by liming and soil compaction

Soil columns were produced by filling PVC tubes with a Dark Red Latosol (Acrortox, 22% of clay). A compacted layer was established at the depth of 15 cm in the columns. In the compacted layer, soil was packed to 1.13, 1.32, 1.48, and 1.82 Mg kg(-1), resulting in cone resistances of 0.18, 0.43, 1.20, and 2.50 MPa. Cotton was cropped for 30 days. Lime was applied to raise base saturation to 40, 52, and 67%. The highest base saturation caused a decrease in phosphorus (P) and zinc (Zn) concentrations in the plants. A decrease in root dry matter, length and surface area was also observed. This could be a consequence of lime induced Zn deficiency. Root growth was decreased in the compacted layer, and complete inhibition was noticed at 2.50 MPa. Once the roots got through the compacted layer, there was a growth recovery in the bottom layer of the pots. The increase in base saturation up 52% was effective in preventing a decrease in cotton root length at soil resistances to 1.20 MPa. Where the roots were shorter, there was an increase in nutrient uptake per unit of root surface area, which kept the plants well nourished, except for P.

Manganês no solo, sua avaliação e toxidez de manganês em soja

Two experiments were carried out in pots with a Dusky Latossol showing a 15% base saturation. In the first experiment dolomitic limestone was applied to reach 45, 60, 75 and 90% of base saturation. In the second, MnSO4 was applied in rates of 30, 60, 90 and 120 ppm,and base saturation was raised to 70%.Soybean plants cv. IAC-9 were grown up to R6, when dry matter production and manganese accumulation were evaluated. Soybean responded to liming up to 60% base saturation, as Mn availability and evantualy Mn absorption were decreased to non-toxic levels. Mn applied to a reclamed soil up to 120 ppm was not enough to cause toxicity to soybean cv IAC-9. All of the chemical extractors (Ammonium Acetate, DTA, Mehlich and H2SO4) showed modification in Mn availabity in soil but were not definitely related to Mn absorption and dry matter production.

Soil compaction and soybean root growth

Soil compaction has a negative effect and Ca was shown to enhance root growth. The effects of soil subsurface compaction and liming on root growth and nutrient uptake by soybean were studied at the Department of Agriculture and Plant Breeding, São Paulo State University, Brazil. A Dark Red Latosol, sandy loam (Haplortox) was limed to raise base saturations to 40.1, 52.4 and 66.7%. The experimental pots were made of PVC tubes with 100 mm of diameter. Three rings with 150, 35 and 150 mm long were fixed one on the top of the other. In the central ring of 35 mm, the soil was compacted to bulk densities of 1.06, 1.25, 1.43 and 1.71 g.cm(-3). There was no effect of base saturation on soybean root and shoot growth and nutrition. Subsurface compaction led to an increase in root growth in the superficial layer of the pots with a correspondent quadratic decrease in the compacted layer. There was no effect of subsoil compaction on total root length and surface, soybean growth and nutrition. Soybean root growth was decreased by 10% and 50% when the soil penetrometer resistances were 0.52 MPa (bulk density of 1.45 g.cm(-1)) and 1.45 MPa (bulk density of 1.69 g.cm(-3)), respectively. In spite of the poor root growth in the compacted layer, once it nas overcome the root system showed an almost complete recovery.

Efeito da calagem sobre a produção de matéria seca de três gramíneas forrageiras

A greenhouse investigation was carried out to study the effects of liming on the dry matter (DM) production of the grasses Brachiaria brizantha (Hoscht.) Stapf. cv. Marandu, Andropogon gayanus Kunth cv. Planaltina and Panicum maximum Jacq cv. Aruana, cultivated on a Dark-Red Latosol, medium texture. The liming levels were obtained through the addition of carbonates in a Ca:Mg ratio of 4:1, necessary to increase the degree of base saturation (V%) to the following values; 4% (control), 20%, 36%, 52%, 68% and 84%. During the experimental period (180 days), four cuts were done to determine the DM production. The results indicated that the DM production was increased (P<0,05) with the liming-levels increased to the three grasses. Panicum maximum cv. Aruana yielded the lower DM quantity, but it presented a better response to liming. The inverse was observed in relation to A. gayanus. The data allowed to conclude that the DM production increased by liming and when the V% level was lower than 50%, it will be increased to 70% for establishment.

Crescimento radicular e aéreo de cultivares de arroz de terras altas em função da calagem

This work aimed to evaluate root growth, shoot development and nutrient absorption efficiency by rice cultivars Caiapo and Maravilha as affected by lime application. The experiment was carried out in a greenhouse, with treatments set up by Caiapo and Maravilha cultivars in combination with the base saturation (V%) of 10%, 40% and 70%. The experiment was in a randomized complete block design, with four replications. The number of tillers, root length, root dry matter, leaves and stems, leaf content and macronutrients absorption efficiency were evaluated. Comparing cultivars, Maravilha cultivar presented higher root dry weight, root length, number of stems, dry matter of stems and shoot than Caiapo cultivar, as well as accumulated more nutrients in the shoots. on the other hand, nutrient contents were higher in the cultivar Caiapo compared to Maravilha. Maravilha cultivar shows greater root and shoot growth while Caiapo shows higher nutrient absorption efficiency from the soil. The base saturation of 40% is the most effective for both cultivars.

Spatial variability of soil attributes and sugarcane yield in relation to topographic location

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Características químicas de solo cultivado com soja e irrigado com água residuária da suinocultura

In this work the distribution was evaluated "in situ" of phosphorus (P), organic matter (MO), potassium (K), calcium (Ca), magnesium (Mg), cation exchange capacity (CEC), aluminum (Al), sum of bases (S), base saturation (V) and pH of a soil cultivated with soybean and irrigated with swine wastewater in the 0, 25, 50 and 75% levels. The factorial scheme was constituted by the 20, 40 and 60 cm soil depths and four wastewater levels with five repetitions. The results showed that significant difference occurred only for P, K and CEC in the soil profile. However, in all parameters, the 60 cm soil depth showed that the concentrations levels are similar to before the aplication of treatments.

Atividade da enzima redutase do nitrato e teores de prolina livre em raízes de cana-de-açúcar sob os estresses hídrico e ácido no solo

The aim of this work was evaluate the physiological indicators of association between water deficiency and soil acidity, by determining the nitrate reductase activity, the levels of free proline and initial growth of the root system of seedlings of sugarcane cv. IAC91-5155. After 30 days, the seedlings were transferred to plastic pots with 12 dm3 of dystrophic alic Red Latosol (Oxisol) and submitted to association of three treatments of water availability: no stress (70%), moderate stress (55%) and severe stress (40%), in according with field capacity and three acidity treatments: no stress (55%), moderate stress (33%) and severe stress (23%), considering the base saturation. The experimental design was that of random blocks under factorial scheme of 3x3, with four replicates. After 60 days under the stress association, the levels of free proline, the nitrate reductase activity and the growth of the sugarcane roots system were evaluated in seedlings of sugarcane. The nitrate reductase enzyme activity can be considered a physiological indicator of the effect of the association of acid and water stress in moderate conditions in soil, while the free proline can be considered physiological indicator to both stress in severe conditions. Water deficiency increasing reduced growth of sugarcane roots.

Characterization, feasibility and optimization of Agaricus subrufescens growth based on chemical elements on casing layer

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caracteristicas gerais e classificacao de solos basalticos da regiao Central do Estado de Sao Paulo.

Giving a special emphasis on soil classification relative to their positions in the landscape, five soil profiles in the Barra Bonita-Jau area were characterized through morphological, granulometric and chemical routine soil analysis. It was observed that the soil structure gradually changes from strong blocks with cutans (lowlands and smooth parts - Jau). In this direction, the silt/clay ratio and the base saturation is reduced, and the aluminium saturation increases. -from English summary