Spatial variability of leaf nutrient content and soybean yield grown for two years in a Rhodic Hapludox [Variabilidade espacial dos teores foliares de nutrientes e da produtividade da soja em dois anos de cultivo em um Latossolo Vermelho]
Vieira S.R.,Pesquisador Cientifico do Instituto Agronomico IAC |
Filho O.G.,University of Sao Paulo |
Chiba M.K.,Pesquisador Cientifico do Instituto Agronomico IAC |
Mellis E.V.,Pesquisador Cientifico do Instituto Agronomico IAC |
And 2 more authors.
Revista Brasileira de Ciencia do Solo | Year: 2010
The chemical analysis of plant tissue is an efficient method to assess the nutritional status. This study aimed to characterize the spatial variability of plant nutrients and soybean yield in an experimental area (120 x 160 m, totaling 1.92 ha) of a Rhodic Hapludox under no tillage for two years. Soybean leaf and grain yield were sampled at 63 points in a regular 20 m grid. Plant nutrient contents (N, P, K, Ca, Mg, Cu, Fe, Mn, and Zn) were determined analyzing the 3rd leaf from the top, collected from five plants randomly chosen near the sampling points. The crop yield was measured in 5 m2 subplots and expressed in kg ha-1. Data were analyzed using descriptive statistics to assess the measures of central tendency and dispersion. Spatial variability was analyzed using semivariogram parameters and contour maps based on interpolation by ordinary kriging. Spatial dependence was observed for some foliar nutrient contents and crop productivity in a homogeneously fertilized area of about 2 ha. Spatial dependence was not constant over time, which should be taken into account in studies with sequential crops. The spatial dependence of soybean yield increased in the two years studied. Among the nutrients applied annually by fertilization, the formation of a spatial pattern was observed in 1986 and 1988, especially for P.
Visual assessments as a soil quality index and its validation by soil physical and chemical analysis in a rhodic hapludox under different uses and managements [Avaliaçǒes visuais como índice de qualidade do solo e sua validaçǎo por análises físicas e quiacute;micas em um latossolo vermelho distroférrico com usos e manejos distintos]
Niero L.A.C.,Instituto Agronomico Area Of Concentracao Gestao Em Recursos |
Dechen S.C.F.,Pesquisador Cientifico do Instituto Agronomico IAC |
Coelho R.M.,Pesquisador Cientifico do Instituto Agronomico IAC |
de Maria I.C.,Pesquisador Cientifico do Instituto Agronomico IAC
Revista Brasileira de Ciencia do Solo | Year: 2010
Cropping systems modify soil attributes and can affect their quality. Traditionally evaluated by laboratory analytical methods, soil attributes have been used as indicators of its quality and are very accurate. However, many times, analytical methods are of difficult access by the producer and high cost. Visual Soil Assessment (VSA) has been developed to help land managers to assess soil condition easily, reliably and cheaply on a field scale. The objective of this study was to evaluate the performance of the VSA to assess soil quality, aiming to evaluate and monitor sustainable management practices. The experiments involved the following treatments: grain crop cultivated for twenty years and eight years under no-tillage system; grain crop with the use of sewage sludge in three application levels; cotton in conventional tillage; perennial crop and native forest. The experimental fields were located in an Oxisol within the Instituto Agronômico in Campinas, State of São Paulo, Brazil. The experimental design was completely randomized with eight treatments and four replications in plots 4 m wide and 25 m long. Soil samples were collected in July 2007 at the 0 - 0.20 m depth for physical analysis (aggregate stability, porosity, density, water holding capacity) and chemical analysis of soil fertility. Visual soil assessments were carried out in May 2008 with a single clod of 0 - 0.20 m side per plot for the following soil attributes: soil structure, soil color, soil porosity, number of earthworms, mottles, presence of tillage pan, and soil cover. For each indicator a visual score of zero (poor), 1 (moderate) and 2 (good) was given. Data were submitted to analysis of variance with the averages compared by Scott-Knott test at 5 % probability and to a multivariate analysis (principal component analysis). The results indicated that the intensive land use contributed to a reduction in its quality and that systems with low mobilization showed good physical quality expressed by soil aggregation, soil porosity and soil bulk density. The soil management treatments were classified in the decreasing order of soil quality, which was efficiently reproduced by the VSA index. The attributes showed correspondence between VSA and analytical soil results. The VSA method was an efficient tool to evaluate the soil quality and it showed to be sensitive to changes caused by soil management systems but its effectiveness must be confirmed for other soil types, uses and managements.