José Ramon Barros Cantalice

Compressibilidade, resistência a penetração e intervalo hídrico ótimo de um Argissolo Amarelo cultivado com cana-de-açúcar nos Tabuleiros Costeiros de Alagoas

The intensive traffic of agricultural machinery of cultivation and harvesting operations of sugarcane can promote soil compaction and affect crop yield and longevity. One of the ways to evaluate soil degradation due to compaction is by analyses of soil compressibility and least limiting water range. The objective of this study was to evaluate the effect of sugarcane cultivation on pre-compaction pressure (sp), laboratory-determined soil penetration resistance (LPS) and on the least limiting water range (LLWR) of a cohesive Yellow Ultisol of the coastal tablelands of Alagoas. The study was conducted on the Fazenda Progresso, of the Usina Coruripe, where five sugarcane areas were selected, representing different use periods and crop systems: four years under winter cropping (4 year W), 14 years under winter cropping (14 year W), 14 years under summer cropping (14 year S), thirty years under winter cropping (30 year W), and 30 years under summer cropping (30 year S). A native subperennial forest fragment (Forest) was also included in this study as a reference area. To determine the effect of sugarcane cultivation on soil compaction, sp, LPS and LLWR were determined in soil samples from the layers 00,20 m, 0,200,40 m and 0,400,60 m, corresponding to the horizons A (Forest) or Ap (agricultural areas), AB and Bt. Sugarcane cultivation increased the σp and LPS of the Ap, AB and Bt horizons of the Yellow Ultisol, however, in the Ap horizon of the soil of the agricultural areas the LPS did not reach the value considered critical for root development, and the LLWR was higher than in the surface horizon of native forest. The mechanized operations for sugarcane cultivation increased LPS to critical levels for root development, even at moisture contents near field capacity, which decreased LLWR of AB and Bt horizons in the agricultural areas. Pre-compaction pressure can be used as an indicator of load support capacity in the strategic planning of machinery operations in sugarcane fields, in order to avoid further soil compaction in the subsurface horizons of cohesive Yellow Ultisol.

Escoamento superficial e desagregação do solo em entressulcos em solo franco-argilo-arenoso com resíduos vegetais

Soil surface cover with crop residue modifies surface flow characteristics, generated by excess rainfall, and soil detachment and sediment transport resulting from the erosion process. The objective of this study was to evaluate the hydraulic conditions, detachment and flow resistance on interrill erosion on soil covered with residue. The experiment was conducted in the laboratory, on a Hapludult soil at a slope of 0.10 m m -1 , under simulated rainfall and soil surface covered with soybean residue at the rates of 0, 0.05, 0.1, 0.2, 0.4, and 0.8 kg m -2 . The increase in soil surface cover (SC) with residue, caused an increase in water flow depth and hydraulic roughness, and a decrease in the mean flow velocity, due to an increase in the viscous forces from the physical interference of residue on runoff, thus contributing to a reduction in interrill soil detachment rate (Di). The Di was 5.35x10 -4 kg m -2 s -1 for bare soil and was reduced to 1.50x10 -5 kg m -2 s -1 for soil with 100% of surface cover. The Laflens and the potential models were adequate to estimate the coefficient of soil coverage by residue in direct contact with soil as a function of the soil surface cover.

Estabilidade de agregados de um latossolo amarelo distrocoeso de tabuleiro costeiro sob diferentes aportes de resíduos orgânicos da cana-de-açúcar

The potential yield of sugarcane depends on factors related to climate, soil and the plant variety. Management systems that provide the addition of organic waste to the soil can cause changes in physical attributes of the soil, enhancing the growth of the root system and sugarcane yield. The objective of this study was to evaluate the effects of different management systems at several levels of organic residue addition on the distribution and indices of aggregate stability of dystrophic cohesive Yellow Latosol of coastal plains, in the State of Alagoas. Plots were selected in the following sugarcane-growing areas: area under irrigation management system, area fertigated with vinasse, and an area under application of vinasse + filter cake. These management systems were compared to each other and to a control (native forest). To evaluate the distribution and stability indices of soil aggregates, soil samples were randomly collected in the different areas, at the depths 0-0.20; 0.20-0.40 and 0.40-0.60 m, at points between two neighboring sugarcane rows. The results were subjected to analysis of variance and the mean compared by the Tukey test at 5 % significance. Simple correlation analysis was performed between some measured variables. Results showed that the different management systems induced changes in the aggregate distribution and that the stabilization of soil aggregates in the surface layer dependeds on the organic matter content and the action of successive cycles of soil wetting and drying. The studies of simple correlations showed that total organic C and aggregate stability indices were significantly and positively correlated.

Relationship between bedload and suspended sediment in the sand-bed Exu River, in the semi-arid region of Brazil

Abstract Suspended sediment and bedload discharges in sand-bed rivers shape semi-arid landscapes and impact sediment delivery from these landscapes, but are still incompletely understood. Suspended sediment and bedload fluxes of the intermittent Exu River, Brazil, were sampled by direct measurements. The highest suspended sediment concentration observed was 4847.4 mg L-1 and this value was possibly associated with the entrainment of sediment that was deposited in the preceding year. The bedload flux was well related to the stream power and the river efficiently transported all available bedload with a mean rate of 0.0047 kg m-1 s-1, and the percentage of bedload to suspended sediment varied between 4 and 12.72. The bed sediment of Exu River was prone to entrainment and showed a proclivity for transport. Thus, sand-bed and gravel-bed rivers of arid environments seem to exhibit the same mobility in the absence of armour layer. Editor D. Koutsoyiannis; Associate editor B. Touaibia Citation Cantalice, J.R.B., Cunha Filho, M., Stosic, B.D., Piscoya, V.C., Guerra, S.M.S., and Singh, V.P., 2013. Relationship between bedload and suspended sediment in the sand-bed Exu River, in the semi-arid region of Brazil. Hydrological Sciences Journal, 58 (8), 1789–1802.

Quantificação da erosão em pastagem com diferentes declives na microbacia do Ribeirão Salomea

A erosao hidrica e uma das principais formas de degradacao do solo e, dentre os diversos fatores que exercem influencia sobre ela, dois se destacam: a cobertura do solo e a declividade do terreno. Com este trabalho, objetivou-se quantificar as perdas de solo por erosao hidrica sob chuva simulada em cobertura de pastagem comparando-as com solo descoberto em diferentes classes de declividade e avaliar a erodibilidade do solo estudado, visando avaliar a capacidade dessa cobertura vegetal em proteger o solo da erosao, bem como a influencia da declividade da area nas perdas de solo, para as condicoes da microbacia do Ribeirao Salomea, sul da Bahia. Os tratamentos com quatro repeticoes foram: com e sem cobertura de pastagem em quatro classes de declive: < 9, 10-15, 25-30 e 35-40%. Aplicaram-se 32 chuvas simuladas em parcelas delimitadas por chapas metalicas cravadas no solo, com uma calha coletora para a amostragem da enxurrada. Os resultados mostraram que a cobertura do solo influenciou as perdas, dentro de cada classe de declive. Ocorreu aumento das perdas com o aumento de declividade do terreno, as quais foram maiores no tratamento sem cobertura que naquele com cobertura. Para o Chernossolo Argiluvico ortico tipico estudado, o valor da erodibilidade foi de 1,48 x 105 kg s m-4.

Qualidade física de Latossolo Amarelo de tabuleiros costeiros em diferentes sistemas de manejo da cana-de-açúcar

The physical attributes are important indicators to evaluate management systems. The objective of this research was to study alterations in the soil properties of the distrophic cohesive yellow Oxisol of a coastal plain in Alagoas state, Brazil, cultivated with sugarcane. Plots were selected in the following sugarcane-growing areas: area under irrigation management system (IMS), area fertigated with vinasse (FV), and area under application of vinasse + filter cake (V + FC). These management systems were compared to each other and to a control (native forest). The bulk soil density, total porosity, weighted mean diameter of the aggregates, hydraulic conductivity, total organic carbon and compaction degree were evaluated in 0-0.20; 0.20-0.40 e 0.40-0.60 m depths. The results showed that management system that receives residues of the sugarcane presents alterations in the physical properties of soil more adequate for development of sugarcane. Among the evaluated systems, little physical degradation was observed in area with application of vinasse + filter cake followed by area with application of vinasse.

Compressibilidade de um Latossolo Amarelo distrocoeso não saturado sob diferentes sistemas de manejo da cana-de-açúcar

The application of sugarcane residues to the soil may induce changes in soil compressibility parameters. The objective of this study was to investigate the compressibility behavior of a dystrophic cohesive Yellow Latosol in the coastal tablelands of the state of Alagoas, in three different management systems with sugarcane, with different levels of organic residue application. The experiment was conducted in an area of sugarcane production (Usina Santa Clotilde), Alagoas. Three plots were chosen in sugarcane fields: sugarcane under irrigation (SMI), under fertigation with vinasse (SMV) and with application of vinasse + filter cake (SMVT). These management systems were compared to each other and to a control plot, represented by native forest (NF). The three sugar cane management systems had been established four years before soil sampling. Undisturbed soil were collected (layers 0-0.20 m and 0.20-0.40 m), using a metal sampler. The samples were first tested by uniaxial compression (gravimetric moisture levels of 0.10; 0.14; 0.18; and 0.22 kg kg-1). For the compression test, loads were applied with vertical tensions of 12.5; 25; 50; 100; 200; 400; 800 and 1600 kPa and readings taken every 30 sec. Thereafter, the samples were oven-dried for gravimetric moisture determination. The results were subjected to variance and multiple regression analysis of the pre-compaction tension, according to the following independent variables: bulk density (Ds), gravimetric moisture (Ug), mean weight diameter of water-stable aggregates (DMPu) and dissipated energy (Ed). The load carrying capacity of native forest soil was lower in both layers than in the three sugarcane managements; the management systems under sugar cane with organic residue application (SMV and SMVT) have lower tension levels; the limit curves (suction increase and loading collapse) can be used in the planning of mechanical operations and pre-compaction stress can be predicted from the physical properties.

Erosão em entressulcos sob caatinga e culturas agrícolas

Dentre as formas de erosao hidrica do solo, a erosao em entressulcos e uma das que causam maiores danos no processo produtivo dos solos utilizados na agricultura, por provocar perdas de solo, agua e nutrientes. Frente a isso, o presente trabalho visou avaliar a protecao ambiental promovida pela cobertura vegetal da caatinga, do feijao-guandu (Cajanus cajan) e da batata-doce (Ipomoea batatas Lam) em relacao ao solo descoberto, bem como o efeito das praticas de cultivos dessas culturas, por meio das taxas da erosao em entressulcos e das caracteristicas hidraulicas do escoamento superficial vinculado a erosao em entressulcos, em um Luvissolo. Para isso, foi implementada uma serie de 20 chuvas simuladas em Serra Talhada, municipio do semi-arido do Estado de Pernambuco, sob os seguintes tratamentos: (1) solo descoberto; (2) solo coberto pela cultura do feijao-guandu (Cajanus cajan); (3) solo coberto pela cultura da batata-doce (Ipomoea batatas Lam.); (4) solo coberto por Caatinga semi-arbustiva. Todos os regimes de escoamento superficial obtidos foram laminar lento. As coberturas vegetais proporcionadas pela Caatinga e pelo guandu, que deram origem aos maiores valores de cobertura do solo, responderam pelas menores taxas de concentracao de sedimentos e desagregacao do solo na erosao em entressulcos, em decorrencia da maior rugosidade hidraulica da superficie do solo promovida por essas vegetacoes. As taxas de concentracao de sedimentos no cultivo da batata-doce foram iguais as do solo descoberto, por conta do revolvimento do solo na preparacao das leiras de plantio, e determinou as maiores taxas de desagregacao do solo entre as coberturas vegetais; em contrapartida, as leiras permitiram retencao do escoamento superficial. As coberturas vegetais Caatinga, guandu e batata-doce e as respectivas rugosidades hidraulicas impostas ao escoamento superficial determinaram reducoes exponenciais das perdas de solo. A cobertura vegetal da Caatinga semi-arbustiva proporcionou o menor coeficiente de escoamento superficial (C = 0,32), em decorrencia de sua maior cobertura do solo, da maior resistencia hidraulica e do nao-revolvimento do solo.

The influence of forest regrowth on soil hydraulic properties and erosion in a semiarid region of Brazil

Department of Ecosystem Science and Management, Texas A&M University, College Station, TX 77843, USA Universidade Federal Rural de Pernambuco, Serra Talhada, Pernambuco, Brazil Department of Soil Science, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil Correspondence Pedro A. M. Leite, Research Associate, Department of Ecosystem Science and Management, Texas A&M University, College Station, TX 77843, USA. Email: pedro.leite@tamu.edu

Compactabilidade de um Latossolo Amarelo distrocoeso dos tabuleiros costeiros de Alagoas sob diferentes sistemas de manejo da cana-de-açúcar

A compactacao do solo agricola e um fenomeno de grande interesse para a Ciencia do Solo. O estudo investigativo de diferentes sistemas de manejo visando encontrar aquele que degrade menos o solo e o objetivo maior da pesquisa sobre o comportamento mecânico do solo. De maneira geral, para um mesmo nivel de energia de compactacao, quanto maior o teor de materia orgânica, menor a densidade maxima do solo e maior a umidade critica de compactacao; consequentemente, o risco de degradacao fisica do solo se reduz. O objetivo deste trabalho experimental foi estudar a compactabilidade de um Latossolo Amarelo distrocoeso dos Tabuleiros Costeiros de Alagoas. Foram selecionadas tres areas em talhoes sob cultivo da cana-de-acucar, representativos de tres sistemas de manejo adotados pela Usina Santa Clotilde. Os tres sistemas de manejo investigados foram: uma area cultivada sob sistema de manejo irrigado (SMI), uma area sob sistema de manejo de fertirrigacao com vinhaca (SMV) e uma area com aplicacao de vinhaca + torta de filtro (SMVT). Os tres sistemas de manejo foram implantados na safra 2003/2004, e a coleta de amostras do solo, realizada em fevereiro de 2007. Esses sistemas foram comparados entre si e em relacao a uma testemunha-padrao, representada por uma mata nativa (MN). A densidade maxima do solo e a umidade critica de compactacao foram avaliadas nas profundidades de 0-0,20, 0,20-0,40 e 0,40-0,60 m. Para avaliar a capacidade dos residuos da cana-de-acucar em dissipar parte da energia compactante, foram realizados ensaios de Proctor, utilizando quatro niveis de energia de compactacao. A avaliacao da energia dissipada pelos residuos foi feita em amostras deformadas apenas da profundidade de 0-0,20 m. O sistema de manejo irrigado (SMI), que nao recebeu adicao de residuo da cana-de-acucar, foi o que apresentou maior densidade maxima do solo e menor umidade critica de compactacao. Entre os diferentes sistemas de manejo cultivados com cana-de-acucar, o mais eficiente na dissipacao da energia compactante foi a area sob aplicacao de vinhaca + torta de filtro, seguida da area sob sistema de manejo de fertirrigacao com vinhaca, respectivamente com os valores de 54 e 41 % de dissipacao para o nivel mais alto de energia de compactacao. Verificou-se tambem que a dissipacao da energia de compactacao foi maior para os niveis de energia mais altos.