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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

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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.

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).

ResumoA deposição de resíduos orgânicos através da colheita mecanizada da cana-de-açúcar é uma prática crescente no sistema de produção canavieiro. A manutenção desses resíduos na superfície do solo depende principalmente das condições ambientais. A adubação nitrogenada sobre os resíduos secos tendem a retardar a decomposição desses, proporcionando benefícios como o aumento da MOS. Diante disto, o objetivo da pesquisa foi avaliar o efeito da aplicação de diferentes doses de nitrogênio sobre os resíduos culturais de cana-de-açúcar, quanto a sua decomposição e contribuição para o sequestro de carbono no solo. O experimento foi realizado em Dourados-MS e consistiu de um delineamento experimental em blocos casualizados. Os resíduos secos foram colocados em litter bags e os tratamentos foram arranjados em parcelas subdivididas, sendo as quatro doses de nitrogênio (0,50, 100 e 150 kg ha -1 N) as parcelas, e as sete épocas de coleta (0, 30, 60, 90, 120, 150 e 180 dias) as subparcelas. Foram analisados a taxa de decomposição dos resíduos, carbono orgânico total e carbono lábil no solo. A aplicação de doses crescente de N proporcionou aumento nas suas taxas de decomposição. Apesar disso, destaca-se a aplicação de N-mineral como uma estratégia de manejo para obter maiores teores de carbono lábil no solo. Palavras-chave: Adubação nitrogenada, manutenção de palhada, carbono orgânico total, carbono lábil AbstractThe deposition of organic residues through mechanical harvesting of cane sugar is a growing practice in sugarcane production system. The maintenance of these residues on the soil surface depends mainly on environmental conditions. Nitrogen fertilization on dry residues tend to retard decomposition of these, providing benefits such as increased SOM. Thus, the object of this research was to evaluate the effect of different doses of nitrogen on sugar cane crop residues, as its decomposition and contribution to carbon sequestration in soil. The experiment was conducted in Dourados-MS and consisted of a randomized complete block design. Dried residues were placed in litter bags and the treatments were arranged in a split plot, being the four nitrogen rates (0, 50, 100 and 150 kg ha -1 N) the plots, and the seven sampling times (0, 30, 60, 90, 120, 150 and 180) the spit plots. Decomposition rates of residues, total organic carbon and labile carbon on soil were analysed. The application of increasing N doses resulted in an increase in their decomposition rates. Despite this, note also the mineral N application as a strategy to get higher levels of labile carbon in soil.