Claudio Hideo Martins da Costa

Produção, decomposição e ciclagem de nutrientes em resíduos de crotalária e milheto, cultivados solteiros e consorciados

The objective of this work was to evaluate the biomass production and the rates of decomposition and macronutrient and silicon release on crop residues of sunnhemp (Crotalaria juncea) and pearl millet (Pennisetum glaucum), in monocropped and intercropped systems. A randomized complete block design was used, with four replicates in a factorial arrangement consisting of three cover crops - pearl millet, sunnhemp, and these species intercropped - and six sampling times - 0, 18, 32, 46, 74, and 91 days after management (DAM). Pearl millet produces a greater amount of dry matter and accumulates more N, P, K, Mg, S, C, and Si, whereas sunnhemp accumulates more Ca. Pearl millet phytomass has the highest rates of decomposition and nutrient release. These rates are higher between 0 and 18 DAM. Over the time, the C/N, C/P and C/S ratios increase, and the C/Si ratio, as well as the decomposition rate, decreases. Potassium is the most rapidly released nutrient, and silicon has the lowest release rate.

Leaf application of silicic acid to white oat and wheat

Silicon (Si) is beneficial to plants in several aspects, but there are doubts about the effectiveness of leaf application. The purpose of this work was to evaluate the effects of Si, applied in a newly developed stabilized silicic acid form to the leaf, on nutrition and yield of irrigated white oat and wheat. Two experiments were performed (one per crop) in winter 2008, in Botucatu-SP, Brazil. A completely randomized block design with 14 replications was used. Treatments consisted of a control (without Si application) and Si leaf spraying, at a rate of 2.0 L ha-1 of the commercial product containing 0.8 % soluble Si. Silicon rate was divided in three parts, i.e. applications at tillering, floral differentiation and booting stages. Silicon leaf application increased N, P, K, and Si concentrations in white oat flag leaf, resulting in higher shoot dry matter, number of panicles per m2, number of grains per panicle and grain yield increase of 34 %. In wheat, Si leaf application increased K and Si concentrations, shoot dry matter and number of spikes per m2, resulting in a grain yield increase of 26.9 %.

Aplicação foliar de ácido silícico estabilizado na soja, feijão e amendoim

A aplicacao de silicio (Si) e benefica as plantas. Porem, existem duvidas sobre a eficiencia do seu fornecimento via foliar. Objetivou-se com este trabalho avaliar o efeito da aplicacao de Si via foliar, na forma de acido silicico estabilizado (fonte recem-desenvolvida), na nutricao e na produtividade das culturas da soja, feijao e amendoim. O delineamento experimental para cada cultura foi em blocos casualizados, com quatorze repeticoes. Os tratamentos foram: controle (sem aplicacao de Si) e aplicacao de Si via foliar, na dose de 2 L ha-1 do produto Silamol® (0,8% de Si soluvel como um concentrado estabilizado de acido silicico). A dose de Si foi parcelada em quatro aplicacoes. A aplicacao via foliar elevou os teores de Si, proporcionando aumento do numero de vagens e da produtividade de graos das tres culturas. O incremento foi da ordem de 14; 15 e 9,6%, respectivamente, para as culturas da soja, feijao e amendoim.

Consórcio de guandu-anão com milheto: persistência e liberação de macronutrientes e silício da fitomassa

Grasses and legumes intercropping can be an attractive alternative for phytomass supply to crop rotation systems; however, information about its decomposition and macronutrient release dynamics is scarce. Thus, the objective of this work was to evaluate the persistence of dry matter, nutrient, carbon and silicon release of pigeonpea and millet intercropping, with and without mechanical fragmentation of straw. The experiment was arranged as a 2x6 factorial in randomized block design, with four replications. First factor consisted of two straw managements (without and with fragmentation) and second consisted of six sampling times (0, 18, 32, 46, 74 and 91 days after management (DAM)). The fragmentation of straw did not alter decomposition and release of N, P, K, Ca, Mg and S, and the maximum daily release of these occurred between 0 and 18 DAM. At 91 DAM at least 80% of all macronutrients were released to the soil. Potassium was released faster, leaving only 1.4% of the total amount accumulated in the straw at 91 DAM, on average of the managements with and without mechanical fragmentation. Silicon was the most slowly released from the straw, still leaving 69% of the total amount accumulated in the straw at 91 DAM. The C/Si ratio is suggested as a tool to evaluate the degradation of straw.

Plantas de cobertura, manejo da palhada e produtividade da mamoneira no sistema plantio direto

Cover crops that have high phytomass production and nutrient cycling are essential to maximize the crop yields in succession under no-tillage system. This study aimed to evaluate dry matter production and nutrients accumulation by pigeonpea (Cajanus cajan) and pearl millet (Pennisetum glaucum), in sole crop and intercropped, and the effect of straw mulch mechanical management on out-of-season castor bean performance, in no-tillage system establishment. The experiment was carried out on a Rhodic Nitisol, in Botucatu, SP, Brazil. A randomized blocks design, in a split-plot scheme, with four replications, was used. Plots were composed by cover crops (pigeonpea, pearl millet, and pigeonpea-pearl millet intercropping). Subplots were composed by absence or presence of straw mulch mechanical management, by horizontal crusher use, 20 days after chemical management. Pearl millet sole crop produced greater amounts of dry matter (14,040 kg ha-1) and showed higher K and Mg concentrations, accumulated greater amounts of nutrients in aboveground. Castor bean grain yield was higher in succession to pigeonpea-pearl millet intercropping. Castor bean grain yield was higher in the absence of straw mulch mechanical management.Cover crops that have high phytomass production and nutrient cycling are essential to maximize the crop yields in succession under no-tillage system. This study aimed to evaluate dry matter production and nutrients accumulation by pigeonpea (Cajanus cajan) and pearl millet (Pennisetum glaucum), in sole crop and intercropped, and the effect of straw mulch mechanical management on out-of-season castor bean performance, in no-tillage system establishment. The experiment was carried out on a Rhodic Nitisol, in Botucatu, SP, Brazil. A randomized blocks design, in a split-plot scheme, with four replications, was used. Plots were composed by cover crops (pigeonpea, pearl millet, and pigeonpea-pearl millet intercropping). Subplots were composed by absence or presence of straw mulch mechanical management, by horizontal crusher use, 20 days after chemical management. Pearl millet sole crop produced greater amounts of dry matter (14,040 kg ha-1) and showed higher K and Mg concentrations, accumulated greater amounts of nutrients in aboveground. Castor bean grain yield was higher in succession to pigeonpea-pearl millet intercropping. Castor bean grain yield was higher in the absence of straw mulch mechanical management.

Cycling of nutrients and silicon in pigeonpea and pearl millet monoculture and intercropping

In a no-tillage system, cover crops must be used that combine shoot dry matter production and nutrient recycling. The aim of this study was to evaluate shoot dry matter production, decomposition rate and macronutrient and silicon release from pigeonpea and pearl millet in monoculture and intercropping systems. A randomized block design was used with a 3 x 6 factorial arrangement, with four replications. The first factor consisted of three cover crops (pigeonpea, pearl millet and intercropping of these cover crops) and the second consisted of six sampling times [0, 18, 32, 46, 74 and 91 days after desiccation (DAD)]. Pearl millet produced greater amounts of shoot dry matter and content of N, P, K, Ca, Mg, S, C and Si and had a higher decomposition rate and macronutrient and Si release than the other cover crops. The rates of decomposition and daily nutrient release from shoot dry matter were highest in the first period of evaluation (0-18 DAD). Over time, the C/N, C/P and C/S ratios increased, while C/Si and the decomposition rate decreased. Potassium was the nutrient most quickly released to the soil, especially from pearl millet residue. Silicon had the lowest release rate, with 62, 82 and 74 % of the total content in the shoot dry matter remaining in the last evaluation of pearl millet, pigeonpea and in the intercrop system, respectively. The shoot dry matter from the intercrop system had a different decomposition rate than that from the pearl millet monoculture and pigeonpea. Plants with greater shoot dry matter production and lower C/Si ratio are more effective in a no-tillage system for providing a more complete and persistent soil cover.

Persistência e liberação de elementos da fitomassa do consórcio crotalária com milheto sob fragmentação

Objetivou-se, com esse trabalho, avaliar a taxa de decomposicao e a velocidade de liberacao de macronutrientes e Si da fitomassa do consorcio crotalaria mais milheto, em funcao do tempo apos manejo, sem e com fragmentacao. O experimento foi conduzido em condicoes de campo, em Botucatu-SP. O delineamento experimental foi de blocos casualizados, com quatro repeticoes, em esquema fatorial constituido por dois manejos da fitomassa da parte aerea (sem e com fragmentacao mecânica) e seis epocas de coleta [0; 18; 32; 46; 74 e 91 dias apos manejo (DAM)]. Foram determinadas a massa de materia seca, teor de macronutrientes e Si e quantidade dos nutrientes remanescentes. Os dados foram submetidos a analise de variância, as medias dos tratamentos do fator manejo comparadas pelo teste de t (LSD) a 5% e do fator epocas de coletas ajustados a equacoes matematicas. A fragmentacao da fitomassa aumenta a taxa de decomposicao e a liberacao de N, P, Ca e S. O K e rapidamente disponibilizado, restando 91 DAM, em media, 1,5% da quantidade total acumulada. Aos 91 DAM pelo menos 80% de todos os macronutrientes ja haviam sido liberados ao solo. A maxima liberacao diaria dos macronutrientes ocorre entre 0 a 18 DAM. A taxa de liberacao de Si e constante e ocorre aumento do teor do elemento na fitomassa com o tempo devido a acentuada liberacao de C. O Si e o elemento liberado mais lentamente ao solo, restando ainda 91 DAM, em media, 85% da quantidade total acumulada na fitomassa.

Intensive annual crop production and root development in a tropical acid soil under long-term no-till and soil-amendment management

In tropical conservation agricultural systems, crop yield is limited by soil acidity and root-growth inhibition, especially under intensive crop rotation. This study evaluated the effect of surface applications of lime and phosphogypsum in improving soil fertility and crop yield in a tropical region. Four treatments were evaluated: control (without soil amendment); and application phosphogypsum (2.1 + 2.1 + 2.1 Mg ha–1), lime (2.7 + 2.0 + 2.0 Mg ha–1), and a combination of lime and phosphogypsum at the given rates, applied in 2002, 2004 and 2010, respectively. We evaluated the soil chemical properties, root development, plant nutrition, yield components and grain yield of 10 crops over 4 years using five species: maize (Zea mays), crambe (Crambe abyssinica), cowpea (Vigna unguiculata), wheat (Triticum aestivum) and common bean (Phaseolus vulgaris). Our long-term results demonstrate the benefits of surface liming in alleviating subsoil acidity, reducing Al3+ toxicity, improving availability of Ca2+ and Mg2+, and increasing accumulation of soil organic matter in all soil profiles at depths up to 0.60 m. For maize and crambe, adding phosphogypsum increased development of plants and reproductive structures, which increased grain yield. Phosphogypsum exhibited synergistic effects in association with lime for maize and common bean. Phosphogypsum did not have an effect on cowpea and wheat, whereas surface liming was essential to improve plant nutrition, grain yield and wheat grain quality. The combination of both soil amendments is an important tool to reduce the soil acidification process, resulting in the highest levels of Ca2+ and Mg2+ and the highest base-saturation values in the topsoil layers (0–0.20 m) over time. Our long-term results showed the viability of surface liming plus phosphogypsum for improving tropical soil fertility, which can reflect an increase in grain yield and contribute to the sustainability of agricultural systems under intensive land use in highly weathered areas.