Mônica Sartori de Camargo

Silicon sources for rice crop

Although silicon is not an essential nutrient, its application is beneficial for plant growth and development. To evaluate silicon sources in relation to agronomic efficiency and economic viability in rice crops (Oryza sativa L.), a greenhouse experiment was conducted, Quartzipsamment soil, in a completely randomized experimental design (n = 4). Treatments were 12 silicon sources and a control. Silicon was applied at the rate of 125 kg Si ha-1. Data were compared to a standard response curve for Si using the standard source Wollastonite at rates of 0, 125, 250, 375, and 500 kg Si ha-1. All treatments received CaCO3 and MgCO3 to balance pH, Ca and Mg. One hundred and fifty days after sowing, evaluations on dry matter yield in the above-ground part of plants, grain yield, and Si contents in the soil and plant tissues were performed. Wollastonite had linear response, increasing silicon in the soil and plants with increasing application rates. Differences between silicon sources in relation to Si uptake were observed. Phosphate slag provided the highest Si uptake, followed by Wollastonite and electric furnace silicates which however, did not show differed among themselves. The highest Si accumulation in grain was observed for stainless steel, which significantly differed from the control, silicate clay, Wollastonite, and AF2 (blast furnace of the company 2) slag. Silicate clay showed the lowest Si accumulation in grain and did not differ from the control, AF2 slag, AF1 slag, schist ash, schist, and LD4 (furnace steel type LD of the company 4) slag.

Reatividade de corretivos da acidez e condicionadores de solo em colunas de lixiviação

A acidez do solo e um dos principais fatores limitantes na producao agricola. O calcario e o corretivo mais utilizado, porem tem lenta mobilidade no perfil do solo, sendo lenta a correcao alem da camada de incorporacao. Por isso, outros produtos tem sido testados para a correcao da acidez, como os silicatos, ou para a amenizacao de seus efeitos em camadas de solo mais profundas, como o gesso. Este trabalho teve como objetivo comparar o efeito do calcario, gesso e silicatos quanto a sua capacidade de fornecer Ca, Mg, Si e corrigir o pH do solo em profundidade. Foram utilizadas amostras de um Neossolo Quartzarenico Ortico tipico coletado sob mata natural com baixos teores de Ca e Mg trocaveis e acidez elevada. Foram montados lisimetros, divididos em 12xa0aneis de 5xa0cm, que foram preenchidos pelo solo amostrado, incorporando-se, no primeiro anel (0-5xa0cm), o equivalente a 500 e 1.000xa0kgxa0ha-1 de Ca, na forma de silicato de calcio (Wollastonita), silicato de Ca e Mg, termofosfato, calcario comercial (calcitico) e gesso agricola, num delineamento em blocos casualizados com quatro repeticoes. As colunas de solo foram incubadas por quarenta dias, aplicando-se o equivalente a 2.000xa0mm de agua destilada (cinco vezes/semana) durante os quarenta dias de incubacao. Determinaram-se o pH CaCl2, Ca e Mg trocaveis e Si disponivel. O gesso aumentou os teores de Ca em todo o perfil do solo, mas nao corrigiu a acidez. Os silicatos corrigiram a acidez do solo e aumentaram os teores de Ca trocavel com maior eficiencia que o calcario. A aplicacao de silicato de Ca e Mg e de termofosfato aumentou a concentracao de Mg no solo ate a profundidade de 25xa0cm. O Si foi carreado ate as camadas mais profundas dos lisimetros (55xa0cm), independentemente da fonte de Si utilizada.

Phosphate fertilizers and heavy metals in an Oxisol cultivated with rice

The contribuition of phosphate fertilizers to the pool of heavy metals in the soil and their transfer to plants and animals is a subject of concern specially among envirommentalists. The objective of this study was to assess the accumulation of heavy metals contained in phosphate fertilizers in the rice plant using a simple sequential method of extraction which could provide information about the availability of heavy metals in the soil. Greenhouse and laboratory experiments used a Xantic Ferralsol previously cultivated with Centrosema pubescens and Brachiaria decubens. The forages received triple superphosphate, termophosphate and North Caroline and Arad rock phosphates at the rates of 50, 100 and 200 mg dm-3 P. There was no increase in heavy metals (Cu, Mn, Cd, Ni, Zn) in the soil or in plants due to the rates of phosphate fertilizers applied. As expected, 6 mol L-1 HCl extracted higher amounts of heavy metals than Mehlich 1 and water extractant.

Competição das cultivares de alface Vera e Verônica em dois espaçamentos

An experiment was carried out from March 25th to April 30th, 2002, in Ribeirao Preto, Sao Paulo State, Brazil, to compare the performance of lettuce cultivars Vera and Veronica in two different planting space systems. The experimental design was a randomized complete block design in a 2 x 2 factorial scheme with four replications. The treatments were the combination of two lettuce cultivars and two planting spacing (20 x 20 cm and 20 x 30 cm). We evaluated the aerial part dry matter weight, aerial part fresh matter weight and yield. The cultivar Vera presented the greatest aerial part fresh matter weight and yield in the planting spacing 20 x 20 cm. Cultivar Vera presented higher aerial part dry matter weight than cultivar Veronica, independent of planting space.

Crescimento e absorção de nutrientes pelo Lisianthus (Eustoma grandiflorum) cultivado em solo

Lisianthus is a cut flower crop that has been intensively studied around the world. However, there is not enough information about its nutrition under tropical conditions. In this work the growth and nutrient absorption of lisianthus (var. Echo) cultivated in soil was evaluated. Seedlings were transplanted 60 days after sowing in October 99. Plant samples were taken at 8; 22; 36; 50; 64; 78; 92; 106 and 120 days after transplanting. Plant growth and dry matter production were slow in the beginning but plants reached 90.5 cm in height and 28.4 of dry weight at the end of cycle. Nutrient uptake (kg ha-1) at 120 days was: 238.8 of N, 157.1 of K, 33.9 of S, 17.5 of Mg, 14.9 of P, 10.6 of Ca and micronutrients (g ha-1): 1281.3 of Fe, 294.4 of B, 127.1 of Mn, 121.1 of Zn and 35.8 of Cu.

EFEITO RESIDUAL DE FERTILIZANTES FOSFATADOS PARA O ARROZ: AVALIAÇÃO DO FÓSFORO NA PLANTA E NO SOLO POR DIFERENTES EXTRATORES

The objective of this study was to evaluate residual effects of phosphate fertilizers (triple superphosphate, Yoorin thermophosphate, North Caroline rock phosphate and Arad rock phosphate) and the efficiency of chemical phosphorus extractants. The fertilizers were applied to pots using a Xantic Ferralsol and three levels of phosphorus (50, 100 e 200 mg dm-3). Pots were planted with rice. Phosphorus rates increased both dry matter and phosphorus accumulation; triple superphosphate had the highest values of dry matter; Mehlich 1 was the best extractant to evaluate rock phosphates while the resin method was for soluble fertilizers. Soil phosphorus values estimated using Mehlich 1 and 3 and resin extraction were well correlated among themselves and gave similar results. The E value was correlated with dry matter to North Caroline phosphate, Arad phosphate and Yoorin termophosphate. All extractants were efficient and similar.

Crescimento e absorção de nutrientes pelo Aster ericoides cultivado em solo sob estufa

Aster ericoides is a cut flower crop with great market and production potential that was only recently introduced into Brazil. Thus, little information is available regarding fertilization and nutrition under tropical conditions. The growth, dry matter production and nutrient absorption of Aster ericoides (cv. White Master) cultivated in an UDOX soil under greenhouse conditions was evaluated. Seedlings were transplanted 30 days after sowing date, in October 99. Plant samples were taken at 15; 30; 45; 60; 75; 90 and 96 days after transplanting. Plant growth and dry matter production were slow in the beginning but at 60 days (before flowering) 69% of the height, 27% of the top and 50% of the roots dry matter was reached. Plants reached 137 cm in height and 24.21 g of dry weight at the end of cycle. Flowering began after 75 to 90 days after transplanting date. Macronutrients uptake (kg ha-1) at 96 days was 316,32 of K > 230,52 N > 35,30 P > 18,39 S > 16,12 Mg > 8,57 Ca and micronutrients uptake (g ha-1) was 3464,89 Mn > 1603,23 Fe > 1104 Zn > 308 B > 61 Cu.

Silicate fertilization of tropical soils: silicon availability and recovery index of sugarcane

Sugarcane is considered a Si-accumulating plant, but in Brazil, where several soil types are used for cultivation, there is little information about silicon (Si) fertilization. The objectives of this study were to evaluate the silicon availability, uptake and recovery index of Si from the applied silicate on tropical soils with and without silicate fertilization, in three crops. The experiments in pots (100 L) were performed with specific Si rates (0, 185, 370 and 555 kg ha-1 Si), three soils (Quartzipsamment-Q, 6 % clay; Rhodic Hapludox-RH, 22 % clay; and Rhodic Acrudox-RA, 68 % clay), with four replications. The silicon source was Ca-Mg silicate. The same Ca and Mg quantities were applied to all pots, with lime and/or MgCl2, when necessary. Sugarcane was harvested in the plant cane and first- and second-ratoon crops. The silicon rates increased soil Si availability and Si uptake by sugarcane and had a strong residual effect. The contents of soluble Si were reduced by harvesting and increased with silicate application in the following decreasing order: Q>RH>RA. The silicate rates promoted an increase in soluble Si-acetic acid at harvest for all crops and in all soils, except RA. The amounts of Si-CaCl2 were not influenced by silicate in the ratoon crops. The plant Si uptake increased according to the Si rates and was highest in RA at all harvests. The recovery index of applied Si (RI) of sugarcane increased over time, and was highest in RA.