Resistência do solo à penetração em sistemas de preparo e velocidades de deslocamento do trator

Abstract

The continuous use of tillage equipment without variation of the work depth can lead to soil compression problems. This study aimed to evaluate the spatial variability of soil resistance to penetration (RP) in a yellow ultisol profile in different tillage systems and tractor-equipment speeds. The experiment was carried out at the Agricultural Sciences Campus – UNIVASF, Petrolina- PE, Brazil, in randomized blocks with split plot with four repetitions. The treatments consisted of five tillage systems applied to the plots: without the first soil preparation, tandem grid and moldboard plow, 0.56 m off-set grid discs, 0.61 m off-set grid disc plus tandem grid and chisel plow. For the subplots, the speeds of the tractor-equipment used were: 2.45 km h‑1 (L1), 3.88 km h-1 (L2), 5.72 km h-1 (L3) and 6.50 km h-1 (H1). For the soil data collection and the RP determination, an electronic penetrometer was used, determining the sample profile moisture. Data analysis was carried out based on geostatistics and isoline maps. It can be verified the operationarea of the active organs of the equipment, the zoning of compacted areas (RP) and the RP levels of the studied profile. The lower RP was obtained when the tandem grid plus the chisel plow was used.

Spatial Variability of Soil Resistance to Penetration in No Tillage System

“…From the semivariogram analysis for RP (Table 4) we observed the adjustment of the spherical model for the evaluated layers and for the analysis of the maximum resistances and the occurrence depths of maximum resistances throughout the evaluated area, agreeing with Cortez et al (2014) when analyzing RP in Yellow Argisol under different intensities of tractor traffic. Similarly, Marasca et al (2011), Oliveira Filho et al, (2015 and Nagahama et al (2016) when evaluating spatial variability of RP verified a greater adjustment of the spherical model for soil physical attributes. It is observed that the nugget effect presented zero value for all the attributes in the studied layers.…”

“…It is observed that the nugget effect presented zero value for all the attributes in the studied layers. Values of nugget effect close to zero were found by Bottega et al (2013) and Nagahama et al (2016) who pointed out that the occurrence of such values increases the accuracy of estimates through kriging. This is because the lower the proportion of the nugget effect in relation to the variogram baseline, the greater the continuity of the phenomenon and the variance of the estimate, and the greater the confidence that can be had in the estimation (Bottega et al, 2013).…”

“…The semivariograms were adjusted by the GS + program from which the models were selected based on the best coefficient of determination (r 2 ) and the smallest sum of squared residual being tested the spherical, exponential, Gaussian, linear models and linear without baseline and pure nugget effect. In the adjusted semivariograms the following parameters were defined: nugget effect (C0); baseline (C0 + C1) and range (A) (Marasca et al, 2011;Coelho et al, 2012;Bottega et al, 2013;Oliveira Filho et al, 2015;Nagahama et al, 2016).…”

Variabilidade espacial da resistência do solo à penetração em um sistema de semeadura direta

“…Os semivariogramas foram ajustados e a partir deles foram selecionados modelos com base no melhor coeficiente de determinação (r 2 ) e na menor soma de quadrados do resíduo, sendo testados os modelos esférico, exponencial, gaussiano, linear, linear sem patamar e efeito pepita puro. Nos semivariogramas ajustados, foram definidos os seguintes parâmetros: efeito pepita (C0); patamar (C0 + C1) e alcance (A) (Marasca et al, 2011;Bottega et al, 2011;Bottega et al, 2013;Nagahama et al, 2016).…”

Atributos Físicos De Solos Em Áreas Sob Diferentes Usos No Semiárido Baiano

“…Houve diferença entre as áreas para Pt e Ds na camada de 0,20--0,40 m de solo de Casa Nova e nas camadas superficiais do solo de Sento Sé, em ambas com ocorrência de redução de Ds e aumento de Pt no solo com uso agrícola em relação à com caatinga, o que demonstra relação estreita e inversa entre os atributos (Cortez et al, 2011). Contudo, esses resultados aparentemente não têm relação com o manejo do solo utilizado nas áreas, visto que tais atributos em solos arenosos do semiárido parecem não ser afetados pela ação das ferramentas de preparo e tráfego de máquinas agrícola (Cortez et al, 2011;Nagahama et al, 2016), mas sim pelas características dos solos da região (Arcoverde et al, 2015).…”