Some physics and hydraulics properties of three soils in the Apodi Tableland, RN, cultivated with musk melon

Este trabalho teve o objetivo de caracterizar os principais solos explorados com a cultura do melão na Chapada do Apodi - RN, no qual se refere aos aspectos físicos, visando fornecer subsídios para adequado manejo da cultura e do solo. Foram estudados, em setembro de 2003, três solos: Cambissolo Háplico Ta eutrófico típico - CXve (Typic Haplocambids), Latossolo Vermelho-Amarelo eutrófico típico - LVAe (Typic Eutrotorrox) e Argissolo Vermelho distrófico arênico - PVd (Arenic Kandiustults). Uma análise geral dos atributos físicos revelou que os perfis apresentam densidade acima dos valores normais para solos afins, com maiores agravantes para os perfis 2 (LVAe) e 3 (PVd), que se refletem na porosidade total e no desbalanço da proporção macro:microporosidade; o manejo da irrigação dos três solos deve ser diferenciado, obedecendo às relações macro:microporo-sidade; a estabilidade de agregados em água é relativamente boa em todos os perfis; a capacidade de água disponível para a profundidade de 30 cm (profundidade efetiva para as raízes do meloeiro) é decrescente do perfil 1 (CXve) para o perfil 3 (PVd); o uso e manejo do solo diminuiu o grau de floculação dos horizontes superficiais dos perfis 1 (CXve) e 2 (LVAe); e, considerando o índice de plasticidade, o risco de degradação pelo uso de máquinas e implementos é acentuado no perfil 1 (CXve) e baixo nos perfis 2 (LVAe) e 3 (PVd).This study had the objective of characterizing the main soil types cultivated with melon, based on physical features, in the Apodi Tableland, state of Rio Grande do Norte, to provide basic information for an adequate soil and crop management. Three soil types were studied, in September 2003: Cambissolo Háplico Ta eutrófico típico - CXve (Typic Haplocambids), Latossolo Vermelho-Amarelo eutrófico típico - LVAe (Typic Eutrotorrox) e Argissolo Vermelho distrófico arênico - PVd (Arenic Kandiustults). A general analysis of the soil physical attributes in the profiles revealed bulk density values above the normal values for such soils, while higher values were found for the profiles 2 (LVAe) and 3 (PVd), expressed in the total porosity and the imbalance of the ratio of macro:microporosity. The irrigation management of the three soils must be differentiated, according to the ratio of macro: microporosity. The soil aggregate stability in water was satisfactory in all profiles studied; the capacity of available water at a depth of 30 cm (real depth for musk melon roots) decreased from profile 1 (CXve) to profile 3 (PVd). The soil use and management decreased the flocculation degree of the surface horizons of the profiles 1 (CXve) and 2 (LVAe) and, considering the plasticity index, the degradation risk for the use of machines and implements is accentuated in profile 1 (CXve) and low in the profiles 2 (LVAe) and 3 (PVd)

Potentialities and limitations of Planosols with distinct depths of diagnostic horizon

There is a variation in the depth of subsurface horizon of Planosols in semi-arid region, which may influence the agricultural potential and affect food production. The general aim of this study was to identify potentialities and limitations of two Planosols as a function of subsurface horizon depth. The adjacent profiles P1 and P2 were studied in Pentecoste (Ceará, Brazil). Morphological, physical, and chemical analyses were done aiming at soil characterization. Soil bulk density (BD), porosity, and penetration resistance (PR) were analyzed in a completely randomized split-plot design with four replicates to compare P1 and P2 and the horizons Ap and Btf. Btf was found at 62cm depth in P1 and at 18 cm depth in P2. Indicatives of water saturation were more evident in P2. The profile P1 showed lower hardness and higher friability, as well as higher acidity in subsurface (pHH2O from 4.4 to 4.7) and higher aluminum content (1.2cmolc kg-1). Both profiles were eutrophic and showed low contents of organic carbon (1.5 to 8.5g kg-1) and phosphorus (0.9 to 3.9mg kg-1). The sodium percentage in CEC was 9.1% in P1 and 5.5% in P2. Water retention increases in Btf compared with Ap was 7.3% in P2 and 2.7% in P1. Both profiles showed increase in BD in Btf, reaching 1.7g cm-3, while PR was higher in P2 (1.5 MPa). There are potentialities and limitations common to both soil profiles, but P1 has more physical potentialities and more chemical limitations than P2