4 research outputs found
Extraction methods and availability of micronutrients for wheat under a no-till system with a surface application of lime
Effects of 59Fe, 65Zn and of three soil types on dry matter yield, chemical composition and nitrogen fixation in Phaseolus vulgaris L. cv. carioca
The aim of this work was to study in greenhouse conditions the effects of two levels of iron and zinc on yield and chemical composition of common bean (Phaseolus vulgaris L.) and on atmospheric nitrogen fixation, in three soils, classified as Terra Roxa Estruturada (TRE), Latossol Vermelho Escuro (LVE), and Podzolico Vermelho Amarelo (PVA). The coefficient of utilization of these micronutrients by this crop and its distribution in above-ground parts and roots were also assessed. The rates for iron were 1.5 and 3.0 ppm, and for zinc, 2.5 and 5.0 ppm. It was applied 7.5 µCi of 59Fe/kg of soil with the lower rate of the stable iron, and 5.0 and 10.0 µCi of Zn/kg of soil in the pots corresponding to the lower and higher rate of the stable zinc, respectively. The plants were harveste at the age of 60 days and nitrogen, phosphorus, potassium, iron and zinc contents were determined. Immediately after harvest, symbiotic nitrogen fixation was assessed, using the acetylene reduction method. The detection of 59Fe and 65zn radioactivity were carried out on nitric percloric extract, by gamma ray spectrometry. The behavior of common bean presented high variation among the three soils, for all the variables. There was no influence of treatments of iron and zinc on dry matter of above ground part and root and also on the weight and number of nodules. The rate of 3.0 ppm of iron decreased the capacity of nodules to fix atmospheric nitrogen in relation to rate of 1.5 ppm, while the rate of 5.0 ppm of zinc increased this capacity, in relation to the rate of 2.5 ppm. There was significative effect of treatments on nitrogen, potassium and zinc contents in above ground part and on nitrogen and zinc contents in the root. The absorption of zinc from the fertilizer and the percentagem of zinc in the plant derived from fertilizer were diretly influenced by rate of zinc The higher coefficient of utilization of zinc from the fertilizer was 4.0%.No presente trabalho, conduzido em casa de vegetação, procuramos estudar os efeitos dos micronutrientes ferro e zinco na produção de materia seca, composição química do feijoeiro (Phaseolus vulgaris L.) e na fixação do nitrogênio atmosférico, em três solos, classificados como Terra Roxa Estruturada (TRE), Latossol Vermelho Escuro (LVE) e Podzólico Vermelho Amarelo (PVA). Procuramos também determinar os índices de aproveitamento destes micronutrientes pelo feijoeiro e sua distribuição na parte aérea e na raiz. O delineamento experimental foi um fatorial 3x7, sendo três solos e sete tratamentos por solo, com três repetições. Nos tratamentos, foram utilizados duas doses de ferro e duas doses de zinco em separado ou combinando as doses menores e maiores destes micronutrientes (Fe1Zn1, Fe2Zn2). As doses de ferro foram 1,5 e 3,0 ppm e as de zinco foram 2,5 e 5,0 ppm. Foram aplicados 7,5 µCi de 59Fe/kg de solo nos vasos correspondentes à dose menor de ferro e 5,0 e 10,0 µCi de 65Zn/kg de solo nos vasos correspondentes respectivamente à dose menor e maior de zinco. Todos os tratamentos receberam uma adubação básica. O comportamento do feijoeiro apresentou grande variação entre os três tipos de solos, para todas as variáveis. Não houve influência dos tratamentos de ferro e zinco na produção de parte aérea e raiz e nem no peso e numero dos nodulos. A dose de 3,0 ppm de ferro diminuiu a capacidade dos nódulos de fixarem nitrogênio atmosférico em relação à dose de 1,5 ppm enquanto que a dose de 5,0 ppm de zinco aumentou esta capacidade, em relação à dose de 2,5 ppm. Houve um efeito significativo dos tratamentos na concentração de nitrogênio, potássio, ferro e zinco na parte aérea e na concentração de nitrogênio, e zinco na raiz. A absorção de zinco dos fertilizantes e a percentagem do zinco na planta proveniente do adubo foram influenciadas diretamente pelas doses de zinco. O maior coeficiente de aproveitamento do zinco do adubo foi de 4,0%
Fertility characterization of soils at six research sites in NW Cameroon
Fertility capability of surface (0–20 cm) soils was evaluated at six sites in the North-West Cameroon highlands. Two main soil groups, designated as Classes A and B, were identified based on elevation. The Class A soils from low elevations (600–1178 m) had higher Ca, Mg, K, pH, sorbed less P and were lower in organic carbon and sesquioxides than the highland (> 1200 m) soils. Soil acidity (Al saturation > 30%) and high P sorption appeared to be the most limiting factors to crop production especially on the Class B soils where the Standard P Requirement exceeded 500 mg kg−1. Phosphorus sorption data were best described by the Freundlich equation. Amorphous aluminium was the most important determinant of solution P concentration (r = 0.85,p < 0.001) followed by soil organic carbon, (r = 0.80,p < 0.001) at high P rates. Nitrogen deficiency symptoms of maize were pronounced on the Class B soils. Consequently, crop growth and yield were lower on Class B than on Class A soils despite the high organic carbon in B. We hypothesize that the supply of high quality organic material (high in N and low in lignin and polyphenols) at site B through agroforestry and related cropping systems, would improve the fertility of the soil and crop yield