No abstract

RESUMOO uso de métodos de diagnoses para determinação de faixas normais de nutrientes é uma prática eficiente por ser desenvolvida em regiões específicas, não sendo extrapolada para as demais regiões. Este trabalho teve como objetivo a determinação de faixas normais de nutrientes para o algodoeiro, mediante a utilização dos métodos Chance Matemática (ChM), Sistema Integrado de Diagnose e Recomendação (DRIS) e Diagnose da Composição Nutricional (CND). Foi realizado em lavouras comerciais de algodão, no ano agrícola de 2004/2005, no município de São Desidério (BA). Utilizaram-se como base de dados os teores totais de nutrientes de 65 amostras de folha completa e a produtividade de algodão em caroço oriundo de talhões com média de 120 ha. Para ajuste do método, a população foi dividida em duas classes: uma com produtividade acima de 4.250 kg ha -1 e outra com produtividade abaixo desta . Os maiores valores de ChM para o N foram obtidos nas classes 3 e 5 (32,0 a 35,5 g kg -1 ). Esses valores concordam com os obtidos pelos métodos DRIS (32,7 a 35,4 g kg -1 ) e CND (32,8 a 35,4 g kg -1 ). Os maiores valores de ChM para obtenção de produtividades maiores que 4.250 kg ha -1 para o P foram observados na classe 3: entre 2,3 e 2,6 g kg -1 . Com relação ao K, as classes que apresentaram os maiores valores de Chance Matemática foram 14,6 a 21,2 g kg -1 . A utilização dos métodos DRIS, CND e ChM, em lavouras comerciais em geral, possibilitou a obtenção de menor amplitude da faixa normal dos nutrientes, em comparação com os valores obtidos pelos métodos convencionais, nível crítico e faixa de suficiência, encontrados na literatura. Termos de indexação: nutrição mineral, diagnose nutricional, Gossypium hirsutum. (1) Artigo extraído da Tese de Mestrado apresentada à Universidade Federal da Grande Dourados -UFGD. Trabalho financiado pelo CNPq. Recebido para publicação em março de 2009 e aprovado em outubro de 2009. (2) Doutorando em Produção Vegetal, Universidade Federal da Grande Dourados -UFGD. Rod. MS 270, km 12, Caixa Postal 533, CEP 79804-970 Dourados (MS).

RESUMO Com o desenvolvimento da soja resistente ao glifosato, Roundup Ready (RR), observa-se um aumento considerável no uso desse herbicida, com aplicações de três a quatro vezes durante o ciclo da cultura. Dessa forma, essas Mn (0, 20, 40, ) e cinco de glifosato (0; 0,648; 1,296; 1,944 Mn (0, 20, 40, ) and five of glyphosate drifts (0; 0,648; 1,296; 1,944

No abstract

SUMMARYThe physical quality of Amazonian soils is relatively unexplored, due to the unique characteristics of these soils. The index of soil physical quality is a widely accepted measure of the structural quality of soils and has been used to specify the structural quality of some tropical soils, as for example of the Cerrado ecoregion of Brazil. The research objective was to evaluate the physical quality index of an Amazonian dystrophic Oxisol under different management systems. Soils under five managements were sampled in Paragominas, State of Pará: 1) a 20-year-old second-growth forest (Forest); 2) Brachiaria sp pasture; 3) four years of no-tillage (NT4.); 4) eight years of no-tillage (NT8); and 5) two years of conventional tillage (CT2). The soil samples were evaluated for bulk density, macro and microporosity and for soil water retention. The physical quality index of the samples was calculated and the resulting value correlated with soil organic matter, bulk density and porosity. The surface layers of all systems were more compacted than those of the forest. The physical quality of the soil was best represented by the relations of the S index to bulk density and soil organic matter.Index terms: conventional tillage, no-tillage, S Index.(1) Part of the Master´s dissertation of the first author presented at the Universidade Federal Rural da Amazônia -UFRA.Received

The purpose of this research was to assess the crop rotation affects on agronomic traits of soybean in optimal (OCS) and dry cropping seasons (DCS). This research was carried out in 2010/2011 (OCS) and 2011/2012 (DCS) in a Rhodic Hapludox soil. The experimental design was set up in a randomized complete block and the treatments were arranged in a factorial 9 x 2, consisting of 9 crop rotations systems and two cropping seasons, with four replications. The soybean (Glycine max cv. BMX-Potência RR) was sowed on October 20 th 2010 and October 10 th 2011 (spring-summer season) 20 days after the fall-winter cover crops desiccation. It was assessed in the R8 reproductive stage (Full maturation) the plant height, the height of the first pod insertion, number of pod per plants, number of branches per plant, number of seed per pod, 1000-grain weight and grain yield. It was observed that in drought stress (DCS), the number of branches decreased, this reduction was 36% in relation to OCS. For the traits as plant height, first pod height, 1000-grain weight and yield, it was showed small values in DCS in contrast to OCS. It is feasible to introduce these cover crops in fall-winter season to make part of a crop rotation system. The number of pod per plant showed higher values under the crop rotation of corn/rapeseed/soybean, which showed highly associated with the soybean grain yield. This research brought options for cover crops system to be viable in no-till system with soybean in spring-summer season.

Resumo -O objetivo deste trabalho foi determinar o efeito do consórcio de milho safrinha com Urochloa brizantha 'Marandu' e de fontes de nitrogênio nas frações granulométricas da matéria orgânica do solo em sistema plantio direto. Os tratamentos foram dispostos em arranjo fatorial 2x4 -dois tipos de cultivo de milho (com ou sem pasto) e quatro fontes de nitrogênio (sem nitrogênio, ureia, sulfato de amônio+ureia e sulfato de amônio) -, em blocos ao acaso, com quatro repetições. O experimento foi conduzido de 2005 a 2013. As coletas do solo foram realizadas em 2013, após a colheita do milho no outono/inverno, em quatro profundidades: 0-5, 5-10, 10-20 e 20-40 cm. Foram determinados os teores de carbono orgânico total (COT), lábil (CL), particulado (COP) e mineral (COM). O consórcio de milho com U. brizantha 'Marandu' resulta em maior teor de COT, CL e COP do que o cultivo de milho solteiro no outono/inverno. O sulfato de amônio+ureia aumenta os teores de COT na camada de 0-5 cm, mas os diminui na de 20-40 cm, além de incrementar os teores de COM em todas as profundidades. Os maiores teores de carbono orgânico total, lábil e particulado são verificados nas profundidades de 0-5 e 5-10 cm.Termos para indexação: Zea mays, fracionamento físico, matéria orgânica leve, plantio direto. Granulometric fractions of soil organic matter in intercropping of off-season corn with Marandu grass under nitrogen sourcesAbstract -The objective of this work was to determine the effect of off-season corn intercropped with Urochloa brizantha 'Marandu' and of nitrogen sources on the granulometric fractions of soil organic matter under a notillage system. The treatments were arranged in a 2x4 factorial arrangement -two types of corn cultivation (with or without pasture) and four nitrogen sources (without nitrogen, urea, ammonium sulfate+urea, and ammonium sulfate) -, in randomized complete blocks with four replicates. The experiment was carried out from 2005 to 2013. Soil sampling was performed in 2013, after corn harvest in fall/winter, at four depths: 0-5, [5][6][7][8][9][10][10][11][12][13][14][15][16][17][18][19][20], labile (LC), particulate (POC), and mineral-associated organic carbon (MOC) contents were determined. The intercropping of corn with U. brizantha 'Marandu' results in a higher concentration of TOC, LC, and POC than single corn cultivated in fall/winter. Ammonium sulfate+urea increases TOC contents at the 0-5-cm depth, but decreases them at the 20-40-cm depth, besides increasing the MOC contents at all depths. The highest total, labile, and particulate organic carbon contents are observed at the 0-5 and 5-10-cm depths.

The purpose of this research was to identify the soil organic matter (SOM) fractions changes in a crop rotation system under no-till system (NTS). This research was carried out from October 2010 to February 2014 in a Rhodic Hapludox. The experiment was set up in completely randomized blocks in a factorial design with eight cover crops and three soil depths (0-5, 5-10 and 10-20 cm) with four repetitions. Cover crops: fall-winter corn, intercropping fall-winter corn with Brachiaria ruziziensis, intercropping fall-winter corn with B. brizantha cv. Marandu, intercropping fall-winter corn with Crotalaria spectabilis, B. ruziziensis, B. brizantha cv. Marandu, Pennisetum glaucum L. and set-aside area. The results of SOM granulometric fractionation showed that 6.5% of the total organic carbon (TOC) stocks were in the particulate organic carbon (POC) fraction. The low values of POC observed in this research are associated with the weather condition of experimental site, which shows high temperature and moisture. In relation to the labile carbon (LC), the highest LC stock was observed in 0-5 cm depth, which differed from the 10-20 cm depth. The POC, LC and labile nitrogen (LN) were the SOM fractions that showed to be more sensitive to detect the changes promoted by the cover crops and soil depths in NTS, as well as the carbon management index (CMI). The intercropping fall-winter corn with B. brizantha cv. Marandu and B. ruziziensis were efficient in increasing the CMI in deeper depth (10-20 cm).