Impacto do manejo da ��gua na toxidez por ferro no arroz irrigado por alagamento

A toxidez por ferro �� o dist��rbio nutricional de maior ocorr��ncia em arroz (Oryza sativa L.) cultivado em sistemas alagados, derivada da quantidade excessiva de ��ons ferrosos (Fe2+) gerados pela redu����o de ��xidos de ferro em solos alagados. Em experimento conduzido em casa de vegeta����o, foram avaliados os efeitos de manejos da ��gua de irriga����o na din��mica de redu����o de um Planossolo e na manifesta����o da toxidez por ferro em arroz. Os tratamentos dispostos em blocos completos ao acaso com quatro repeti����es constaram de cinco manejos da ��gua: T1- in��cio do alagamento no est��dio V2-V3 do arroz; T2- in��cio do alagamento no est��dio V6-V7; T3- T1 e drenagem no est��dio V10-V11; T4- T2 e drenagem no est��dio V10-V11; e T5- T1 e drenagens nos est��dios V7-V8 e V10-V11. O atraso do in��cio do alagamento para o est��dio V6-V7 do arroz manteve os valores do Eh da solu����o do solo mais elevados, promovendo menor disponibilidade de Fe2+ na solu����o do solo e deslocando a m��xima libera����o de Fe2+ na solu����o do solo para est��dios fenol��gicos mais avan��ados do arroz. A realiza����o de drenagens ao longo do ciclo vegetativo do arroz promoveu a reoxida����o do solo, que ocasionou o aumento dos valores de Eh e redu����o da concentra����o de Fe2+ na solu����o do solo. O uso de drenagens durante o per��odo vegetativo do arroz foi eficiente no controle da toxidez por excesso de ferro, em arroz cultivado em solo alagado.

Extra����o e exporta����o de nutrientes pelo feijoeiro adubado com nitrog��nio, em diferentes tempos de implanta����o do sistema plantio direto

O cultivo do feijoeiro em sistema plantio direto (SPD) tem aumentado de forma marcante no pa��s. Neste contexto, para aduba����es mais racionais, �� fundamental conhecer as exig��ncias nutricionais da cultura quando cultivada em SPD rec��m-implantado ou consolidado, j�� que o tempo de implanta����o do sistema pode alterar a disponibilidade de nutrientes e a resposta das culturas �� aduba����o nitrogenada. Objetivou-se avaliar a extra����o e exporta����o de nutrientes pelo feijoeiro em raz��o da aduba����o nitrogenada, em solo sob SPD rec��m-implantado ou consolidado. O experimento foi conduzido por dois anos agr��colas, em um Nitossolo Vermelho distr��fico, no munic��pio de Botucatu, SP. O delineamento experimental foi em blocos ao acaso, em esquema de parcelas subdivididas, com quatro repeti����es. As parcelas foram formadas por ��reas sob SPD com diferentes tempos de ado����o, e as subparcelas constitu��das por quatro formas de aplica����o do nitrog��nio (N) na cultura do feij��o (T0: controle, sem aplica����o de N; T1: 60 kg ha-1 na pr��-semeadura; T2: 60 kg ha-1 aplicado em cobertura no est��dio V4; e T3: 60 kg ha-1 na pr��-semeadura + 60 kg ha-1 em cobertura). Foram avaliados: mat��ria seca da parte a��rea, concentra����o e ac��mulo de nutrientes na parte a��rea, produtividade de gr��os e concentra����es e exporta����o de nutrientes nos gr��os. O tempo que a ��rea permaneceu sob SPD n��o influenciou a produtividade, a nutri����o e nem mesmo a resposta da cultura do feij��o �� aduba����o nitrogenada. A aplica����o de N, especialmente em pr��-semeadura, proporcionou maiores ac��mulos de mat��ria seca e nutrientes pela cultura do feij��o. As concentra����es de nutrientes nos gr��os foram pouco influenciadas pela aduba����o nitrogenada. As maiores produtividades de gr��os e exporta����es de nutrientes foram proporcionadas pela aplica����o de N em duas ��pocas (pr��-semeadura e em cobertura) ou apenas em cobertura.

Perfusion and diffusion MRI of glioblastoma progression in a four-year prospective temozolomide clinical trial

RESUME BUT Cette ��tude a ��t�� men��e sur le suivi de patients trait��s pour un glioblastome nouvellement diagnostiqu��. Son objectif a ��t�� de d��terminer l'impact des s��quences de perfusion et de diffusion en imagerie par r��sonance magn��tique (IRM). Un int��r��t particulier a ��t�� port�� au potentiel de ces nouvelles techniques d'imagerie dans l'anticipation de la progression de la maladie. En effet, l'intervalle de temps libre de progression est une mesure alternative de pronostic fr��quemment utilis��e. MATERIEL ET METHODE L'��tude a port�� sur 41 patients participant �� un essai clinique de phase II de traitement par temozolomide. Leur suivi radiologique a comport�� un examen IRM dans les 21 �� 28 jours apr��s radiochimioth��rapie et tous les 2 mois par la suite. L'��valuation des images s'est faite sur la base de l'��valuation de l'effet de masse ainsi que de la mesure de la taille de la l��sion sur les images suivantes : T1 avec produit de contraste, T2, diffusion, perfusion. Afin de d��terminer la date de progression de la maladie, les crit��res classiques de variation de taille adjoints aux crit��res cliniques habituels ont ��t�� utilis��s. RESULAT 311 examens IRM ont ��t�� revus. Au moment de la progression (32 patients), une r��gression multivari��e selon Cox a permis de d��terminer deux param��tres de survie : diam��tre maximal en T1 (p>0.02) et variation de taille en T2 (p<0.05). L'impact de la perfusion et de la diffusion n'a pas ��t�� d��montr�� de mani��re statistiquement significative. CONCLUSION Les techniques de perfusion et de diffusion ne peuvent pas ��tre utilis��es pour anticiper la progression tumorale. Alors que la prise de d��cision au niveau th��rapeutique est critique au moment de la progression de la maladie, l'IRM classique en T1 et en T2 reste la m��thode d'imagerie de choix. De mani��re plus sp��cifique, une prise de contraste en T1 sup��rieure �� 3 cm dans son plus grand diam��tre associ��e �� un hypersignal T2 en augmentation forment un marqueur de mauvais pronostic.

Perennial grasses for recovery of the aggregation capacity of a reconstructed soil in a coal mining area in southern Brazil

The construction of a soil after surface coal mining involves heavy machinery traffic during the topographic regeneration of the area, resulting in compaction of the relocated soil layers. This leads to problems with water infiltration and redistribution along the new profile, causing water erosion and consequently hampering the revegetation of the reconstructed soil. The planting of species useful in the process of soil decompaction is a promising strategy for the recovery of the soil structural quality. This study investigated the influence of different perennial grasses on the recovery of reconstructed soil aggregation in a coal mining area of the Companhia Riograndense de Minera����o, located in Candiota-RS, which were planted in September/October 2007. The treatments consisted of planting: T1- Cynodon dactylon cv vaquero; T2 - Urochloa brizantha; T3 - Panicum maximun; T4 - Urochloa humidicola; T5 - Hemarthria altissima; T6 - Cynodon dactylon cv tifton 85. Bare reconstructed soil, adjacent to the experimental area, was used as control treatment (T7) and natural soil adjacent to the mining area covered with native vegetation was used as reference area (T8). Disturbed and undisturbed soil samples were collected in October/2009 (layers 0.00-0.05 and 0.10-0.15 m) to determine the percentage of macro- and microaggregates, mean weight diameter (MWD) of aggregates, organic matter content, bulk density, and macro- and microporosity. The lower values of macroaggregates and MWD in the surface than in the subsurface layer of the reconstructed soil resulted from the high degree of compaction caused by the traffic of heavy machinery on the clay material. After 24 months, all experimental grass treatments showed improvements in soil aggregation compared to the bare reconstructed soil (control), mainly in the 0.00-0.05 m layer, particularly in the two Urochloa treatments (T2 and T4) and Hemarthria altissima (T5). However, the great differences between the treatments with grasses and natural soil (reference) indicate that the recovery of the pre-mining soil structure could take decades.

Efeito de semeadora com haste sulcadora para a����o profunda em solo manejado com plantio direto

A ado����o do plantio direto na regi��o subtropical ��mida do Brasil, fundamentada apenas em dois preceitos da agricultura conservacionista - mobiliza����o de solo restrita �� linha de semeadura e manuten����o de res��duos culturais na superf��cie do solo -, tem induzido �� estratifica����o de atributos qu��micos do solo na camada de 0-20 cm profundidade e degrada����o f��sica da camada subsuperficial (entre aproximadamente 5-20 cm de profundidade), que podem contribuir para frustra����es de safras agr��colas, quando da ocorr��ncia de estiagens. O objetivo deste trabalho foi avaliar o efeito residual de uma semeadora/adubadora, equipada com elemento rompedor de solo tipo haste sulcadora, atuando em quatro profundidades para a semeadura de milho (Zea mays L.), na mitiga����o de problemas de ordem f��sica e qu��mica, em um Latossolo Vermelho distr��fico h��mico, manejado em plantio direto h�� mais de 10 anos. Os tratamentos avaliados foram: T1 = hastes sulcadoras atuando at�� 5 cm de profundidade; T2 = hastes sulcadoras atuando at�� 10 cm de profundidade; T3 = hastes sulcadoras atuando at�� 15 cm de profundidade; e T4 = hastes sulcadoras atuando at�� 17 cm de profundidade. O efeito desses tratamentos sobre os atributos f��sicos do solo foi avaliado pela t��cnica do perfil cultural associada �� determina����o da densidade, porosidade total, macroporosidade e resist��ncia do solo �� penetra����o, aos oito e 12 meses, ap��s a semeadura da cultura de milho. Sobre os atributos qu��micos, esses efeitos foram avaliados pela determina����o de pH em H2O, P e K dispon��veis, Ca, Mg e Al troc��veis, acidez potencial e mat��ria org��nica, em amostras de solo coletadas em camadas de 2,5 cm de espessura, de 0-22,5 cm de profundidade. A utiliza����o da semeadora/adubadora, equipada com elemento rompedor de solo tipo haste sulcadora, evidenciou-se eficaz em mitigar os problemas f��sicos e qu��micos do solo, tanto aos oito como aos 12 meses ap��s a opera����o de semeadura.

Nutri����o e produtividade da nogueira-macad��mia em raz��o do parcelamento da aduba����o mineral

A disponibilidade de nutrientes durante o ano pode influenciar o desempenho da nogueira-macad��mia (Macadamia integrifolia). Contudo, n��o existem informa����es sobre a resposta dessa cultura ao parcelamento da aduba����o nas condi����es brasileiras. O objetivo deste trabalho foi avaliar a influ��ncia do parcelamento da aduba����o mineral na nutri����o, produtividade e qualidade de frutos da nogueira-macad��mia. O experimento foi conduzido, durante tr��s anos agr��colas, num Latossolo Vermelho, em Jaboticabal, SP. O delineamento experimental foi de blocos casualizados, com cinco repeti����es. O experimento foi constitu��do por quatro formas de parcelamento da aduba����o NPK (T1 - uma ��nica aplica����o, em outubro; T2 - duas aplica����es, em outubro e dezembro; T3 - tr��s aplica����es, em outubro, dezembro e fevereiro; e T4 - quatro aplica����es, em outubro, dezembro, fevereiro e abril). O parcelamento da aduba����o NPK proporcionou maiores teores de N nas folhas que a aplica����o em dose ��nica, mas n��o interferiu nos teores dos demais nutrientes. A produtividade da nogueira-macad��mia foi incrementada de forma similar com o parcelamento da aduba����o NPK em duas, tr��s ou quatro vezes, entre outubro e abril, em compara����o �� aplica����o ��nica em outubro. A taxa de recupera����o de am��ndoas n��o foi interferida pelo parcelamento da aduba����o NPK.

Artificial zinc finger fusions targeting Sp1-binding sites and the trans-activator-responsive element potently repress transcription and replication of HIV-1.

Tat activates transcription by interacting with Sp1, NF-kappaB, positive transcription elongation factor b, and trans-activator-responsive element (TAR). Tat and Sp1 play major roles in transcription by protein-protein interactions at human immunodeficiency virus, type 1 (HIV-1) long terminal repeat. Sp1 activates transcription by interacting with cyclin T1 in the absence of Tat. To disrupt the transcription activation by Tat and Sp1, we fused Sp1-inhibiting polypeptides, zinc finger polypeptide, and the TAR-binding mutant Tat (TatdMt) together. A designed or natural zinc finger and Tat mutant fusion was used to target the fusion to the key regulatory sites (GC box and TAR) on the long terminal repeat and nascent short transcripts to disrupt the molecular interaction that normally result in robust transcription. The designed zinc finger and TatdMt fusions were targeted to the TAR, and they potently repressed both transcription and replication of HIV-1. The Sp1-inhibiting POZ domain, TatdMt, and zinc fingers are key functional domains important in repression of transcription and replication. The designed artificial zinc fingers were targeted to the high affinity Sp1-binding site, and by being fused with TatdMt and POZ domain, they strongly block both Sp1-cyclin T1-dependent transcription and Tat-dependent transcription, even in the presence of excess expressed Tat.

Soil water erosion under different cultivation systems and different fertilization rates and forms over 10 years

The action of rain and surface runoff together are the active agents of water erosion, and further influences are the soil type, terrain, soil cover, soil management, and conservation practices. Soil water erosion is low in the no-tillage management system, being influenced by the amount and form of lime and fertilizer application to the soil, among other factors. The aim was to evaluate the effect of the form of liming, the quantity and management of fertilizer application on the soil and water losses by erosion under natural rainfall. The study was carried out between 2003 and 2013 on a Humic Dystrupept soil, with the following treatments: T1 - cultivation with liming and corrective fertilizer incorporated into the soil in the first year, and with 100 % annual maintenance fertilization of P and K; T2 - surface liming and corrective fertilization distributed over five years, and with 75 % annual maintenance fertilization of P and K; T3 - surface liming and corrective fertilization distributed over three years, and with 50 % annual maintenance fertilization of P and K; T4 - surface liming and corrective fertilization distributed over two years, and with 25 % annual maintenance fertilization of P and K; T5 - fallow soil, without liming or fertilization. In the rotation the crops black oat (Avena strigosa ), soybean (Glycine max ), common vetch (Vicia sativa ), maize (Zea mays ), fodder radish (Raphanus sativus ), and black beans (Phaseolus vulgaris ). The split application of lime and mineral fertilizer to the soil surface in a no-tillage system over three and five years, results in better control of soil losses than when split in two years. The increase in the amount of fertilizer applied to the soil surface under no-tillage cultivation increases phytomass production and reduces soil loss by water erosion. Water losses in treatments under no-tillage cultivation were low in all crop cycles, with a similar behavior as soil losses.

INTERVALO H��DRICO ��TIMO EM SOLO CONSTRU��DO AP��S MINERA����O DE CARV��O EM DIFERENTES LIMITES CR��TICOS DE RESIST��NCIA �� PENETRA����O E UMIDADE

Na quantificação do intervalo hídrico ótimo (IHO), são utilizados diferentes limites críticos de resistência à penetração (RP) e umidade na capacidade de campo (θCC). Para solos agrícolas, esses valores estão sendo documentados na literatura. Entretanto, para solos construídos após mineração de carvão, constata-se grande lacuna de informações. O objetivo deste trabalho foi quantificar a faixa de variação do intervalo hídrico ótimo de um solo construído sob diferentes plantas de cobertura na área de mineração de carvão de Candiota, sul do Brasil, considerando diferentes limites críticos de umidade do solo na capacidade de campo e de resistência à penetração. Foram avaliadas no experimento, em blocos casualizados com quatro repetições, as seguintes plantas de cobertura: Hemártria (Hemarthria altissima (Poir.) Stapf & C. E. Hubbard), tratamento 1 (T1); Pensacola (Paspalum notatum Flüggé), tratamento 2 (T2); Grama Tifton (Cynodon dactilon (L.) Pers.), tratamento 3 (T3); Controle (Urochloa brizantha (Hochst.) Stapf), tratamento 4 (T4); e sem plantas de cobertura, tratamento 5 (T5). Para determinar o IHO, foram utilizados diferentes valores críticos de θCC referentes às tensões de 0,006; 0,01; e 0,033 MPa e RP de 1,5; 2,0; 2,5; e 3,0 MPa, mantendo-se sempre constante a umidade do solo no ponto de murcha permanente (θPMP) como sendo igual ao valor retido na tensão de 1,5 MPa e a umidade do solo em que a porosidade de aeração (PA) é de 10 %. A faixa de variação do IHO foi maior no solo construído cultivado com Urochloa brizantha; e a menor com Pensacola, independentemente dos limites críticos de θCC e de RP. Os limites críticos de θCC e de RP utilizados na definição do IHO originaram diferentes valores de densidade critica (Dsc) para o solo construído sob diferentes plantas de cobertura. Os menores e maiores valores de Dsc foram obtidos quando utilizados como limites críticos na definição do IHO, o θCC = 0,033 MPa e a RP = 3 MPa. O solo construído cultivado com Urochloa brizantha e Hemártria apresentou valor de Ds muito próximo ao de Dsc.

Squamous cell carcinoma of the larynx with subglottic extension: is larynx preservation possible?. Plattenepithelkarzinom des Larynx mit subglottischer Ausdehnung: ist ein Larynxerhalt m��glich ?

PURPOSE: Squamous cell carcinoma of larynx with subglottic extension (sSCC) is a rare location described to carry a poor prognosis. The aim of this study was to analyze outcomes and feasibility of larynx preservation in sSCC patients. PATIENTS AND METHODS: Between 1996 and 2012, 197��patients with sSCC were treated at our institution and included in the analysis. Stage III-IV tumors accounted for 76 %. Patients received surgery (62 %), radiotherapy (RT) (18 %), or induction chemotherapy (CT) (20 %) as front-line therapy. RESULTS: The 5-year actuarial overall survival (OS), locoregional control (LRC), and distant control rate were 59 % (95 % CI 51-68), 83 % (95 % CI 77-89), and 88 % (95 % CI 83-93), respectively, with a median follow-up of 54.4 months. There was no difference in OS and LRC according to front-line treatments or between primary subglottic cancer and glottosupraglottic cancers with subglottic extension. In the multivariate analysis, age > 60 years and positive N stage were the only predictors for OS (HR 2, 95 % CI 1.2-3.6; HR1.9, 95 % CI 1-3.5, respectively). A lower LRC was observed for T3 patients receiving a larynx preservation protocol as compared with those receiving a front-line surgery (HR 14.1, 95 % CI 2.5-136.7; p = 0.02); however, no difference of ultimate LRC was observed according to the first therapy when including T3 patients who underwent salvage laryngectomy (p = 0.6). In patients receiving a larynx preservation protocol, the 5-year larynx-preservation rate was 55 % (95 % CI 43-68), with 36 % in T3 patients. The 5-year larynx preservation rate was 81 % (95 % CI 65-96) and 35 % (95 % CI 20-51) for patients who received RT or induction CT as a front-line treatment, respectively. CONCLUSION: Outcomes of sSCC are comparable with other laryngeal cancers when managed with modern therapeutic options. Larynx-preservation protocols could be a suitable option in T1-T2 (RT or chemo-RT) and selected T3 sSCC patients (induction CT).

Organic Matter Fractions and Quality of the Surface Layer of a Constructed and Vegetated Soil After Coal Mining. I - Humic Substances and Chemical Characterization

After open coal mining, soils are “constructed”, which usually contain low levels and quality of organic matter (OM). Therefore, the use of plant species for revegetation and reclamation of degraded areas is essential. This study evaluated the distribution of carbon (C) in the chemical fractions as well as the chemical characteristics and humification degree of OM in a soil constructed after coal mining under cultivation of perennial grasses. The experiment was established in 2003 with the following treatments: Hemarthria altissima (T1), Paspalum notatum (T2), Cynodon dactilon (T3), Urochloa brizantha (T4), bare constructed soil (T5), and natural soil (T6). In 2009, soil samples were collected from the 0.00-0.03 m layer and the total organic carbon stock (TOC) and C stock in the chemical fractions: acid extract (CHCl), fulvic acid (CFA), humic acid (CHA), and humin (CHU) were determined. The humic acid (HA) fraction was characterized by infrared spectroscopy and the laser-induced fluorescence index (ILIF) of OM was also calculated. After six years, differences were only observed in the CHA stocks, which were highest in T1 (0.89 Mg ha-1) and T4 (1.06 Mg ha-1). The infrared spectra of HA in T1, T2 and T4 were similar to T6, with greater contribution of aliphatic organic compounds than in the other treatments. In this way, ILIF decreased in the sequence T5>T3>T4>T1>T2>T6, indicating higher OM humification in T3 and T5 and more labile OM in the other treatments. Consequently, the potential of OM quality recovery in the constructed soil was greatest in treatments T1 and T4.

Organic Matter Fractions and Quality of the Surface Layer of a Constructed and Vegetated Soil After Coal Mining. II - Physical Compartments and Carbon Management Index

Soils constructed after mining often have low carbon (C) stocks and low quality of organic matter (OM). Cover crops are decisive for the recovery process of these stocks, improving the quality of constructed soils. Therefore, the goal of this study was to evaluate the effect of cover crops on total organic C (TOC) stocks, C distribution in physical fractions of OM and the C management index (CMI) of a soil constructed after coal mining. The experiment was initiated in 2003 with six treatments: Hemarthria altissima (T1), Paspalum notatum (T2), Cynodon dactylon (T3), Urochloa brizantha (T4), bare constructed soil (T5), and natural soil (T6). Soil samples were collected in 2009 from the 0.00-0.03 m layer, and the TOC and C stocks in the physical particle size fractions (carbon in the coarse fraction - CCF, and mineral-associated carbon - MAC) and density fractions (free light fraction - FLF; occluded light fraction - OLF, and heavy fraction - HF) of OM were determined. The CMI components: carbon pool index (CPI), lability (L) and lability index (LI) were estimated by both fractionation methods. No differences were observed between TOC, CCF and MAC stocks. The lowest C stocks in FLF and OLF fractions were presented by T2, 0.86 and 0.61 Mg ha-1, respectively. The values of TOC stock, C stock in physical fractions and CMI were intermediate, greater than T5 and lower than T6 in all treatments, indicating the partial recovery of soil quality. As a result of the better adaptation of the species Hemarthria and Brizantha, resulting in greater accumulation of labile organic material, the CPI, L, LI and CMI values were higher in these treatments, suggesting a greater potential of these species for recovery of constructed soils.

Chemical and Biochemical Properties of Oxisols after Sewage Sludge Application for 16 Years

ABSTRACT The large production of sewage sludge (SS), especially in large urban centers, has led to the suggestion of using this waste as fertilizer in agriculture. The economic viability of this action is great and contributes to improve the environment by cycling the nutrients present in this waste, including high contents of organic matter and plant nutrients. This study evaluated the chemical and biochemical properties of Dystrophic and EutroferricLatossolos Vermelhos (Oxisols) under corn and after SS application at different rates for 16 years. The field experiment was carried out in Jaboticabal, S��o Paulo State, Brazil, using a randomized block design with four treatments and five replications. Treatments consisted of control - T1 (mineral fertilization, without SS application), 5 Mg ha-1 SS - T2, 10 Mg ha-1 SS - T3, and 20 Mg ha-1 SS - T4 (dry weight base). The data were submitted to variance analysis and means were compared by the Duncan test at 5 %. Sewage sludge increased P extracted by resin in both theLatossolos Vermelhos, Dystrophic and Eutroferric, and the organic matter content in the Dystrophic Latossolo Vermelho. The waste at the rate 20 Mg ha-1 on a dry weight basis promoted increases in acid phosphatase activity in Eutroferric Latossolo Vermelho, basal respiration and metabolic quotient in DystrophicLatossolo Vermelho. The rate 20 Mg ha-1 sewage sludge on a dry weight basis did not alter the soil microbial biomass in both the Latossolos Vermelhos; in addition, it improved corn yields without inducing any symptoms of phytotoxicity or nutrient deficiency in the plants.

Least Limiting Water Range and Load Bearing Capacity of Soil under Types of Tractor-Trailers for Mechanical Harvesting of Green Sugarcane

ABSTRACT The expansion of the sugarcane industry in Brazil has intensified the mechanization of agriculture and caused effects on the soil physical quality. The purpose of this study was to evaluate the limiting water range and soil bearing capacity of a Latossolo Vermelho distrof��rrico t��pico (Rhodic Hapludox) under the influence of different tractor-trailers used in mechanical sugarcane harvesting. The experiment was arranged in a randomized block design with five replications. The treatments consisted of green sugarcane harvesting with: harvester without trailer (T1); harvester with two trailers with a capacity of 10 Mg each (T2); harvester with trailer with a capacity of 20 Mg (T3) and harvester and truck with trailer with a capacity of 20 Mg (10 Mg per compartment) (T4). The least limiting water range and soil bearing capacity were evaluated. The transport equipment to remove the harvested sugarcane from the field (trailer) at harvest decreased the least limiting water range, reducing the structural soil quality. The truck trailer caused the greatest impact on the soil physical properties studied. The soil load bearing capacity was unaffected by the treatments, since the pressure of the harvester (T1) exceeded the pre-consolidation pressure of the soil.

SWEET SORGHUM PERFORMANCE AFFECTED BY SOIL COMPACTION AND SOWING TIME AS A SECOND CROP IN THE BRAZILIAN CERRADO

ABSTRACT Increasing attention has recently been given to sweet sorghum as a renewable raw material for ethanol production, mainly because its cultivation can be fully mechanized. However, the intensive use of agricultural machinery causes soil structural degradation, especially when performed under inadequate conditions of soil moisture. The aims of this study were to evaluate the physical quality of aLatossolo Vermelho Distrof��rrico (Oxisol) under compaction and its components on sweet sorghum yield forsecond cropsowing in the Brazilian Cerrado (Brazilian tropical savanna). The experiment was conducted in a randomized block design, in a split plot arrangement, with four replications. Five levels of soil compaction were tested from the passing of a tractor at the following traffic intensities: 0 (absence of additional compaction), 1, 2, 7, and 15 passes over the same spot. The subplots consisted of three different sowing times of sweet sorghum during the off-season of 2013 (20/01, 17/02, and 16/03). Soil physical quality was measured through the least limiting water range (LLWR) and soil water limitation; crop yield and technological parameters were also measured. Monitoring of soil water contents indicated a reduction in the frequency of water content in the soil within the limits of the LLWR (Fwithin) as agricultural traffic increased (T0 = T1 = T2>T7>T15), and crop yield is directly associated with soil water content. The crop sown in January had higher industrial quality; however, there was stalk yield reduction when bulk density was greater than 1.26 Mg m-3, with a maximum yield of 50 Mg ha-1 in this sowing time. Cultivation of sweet sorghum as a second crop is a promising alternative, but care should be taken in cultivation under conditions of pronounced climatic risks, due to low stalk yield.