How to cite: Gubiani PI, Müller EA, Somavilla A, Zwirtes AL, Mulazzani RP, Marchesan E. Transpiration reduction factor and soybean yield in low land soil with ridge and chiseling. Rev Bras Cienc Solo. 2018;42:e0170282.

Stony soils have been increasingly used for agriculture production; however, little is known about their hydraulic properties due to problems, such as sample deformation and hydraulic continuity between samples and suction devices when the sampling and measurements are accomplished with traditional techniques. In this study, the traditional ring sampling technique was replaced by the sampling of undisturbed soil blocks coated with paraffin wax to preserve their structure. A saturated paste of fine-grained mineral particles was used to ensure contact and hydraulic continuity between samples and suction devices (sand table and ceramic plates). This allowed us to determine 30 water retention curves for three stony soils with coarse particle contents (> 2 mm) ranging from zero to 69 %. The van Genuchten model was fitted to the measured retention data and the root mean square errors were between 0.0034 and 0.0331 m 3 m -3 , with no outliers or odd behavior in the retention curves. These results showed that consistent water retention curves for stony soils can be determined with the technique proposed.Fine-grained minerals sandwiched between the surface of suctions sources and sampled blocks improve hydraulic continuity between them. These techniques can be applied to determine water retention properties in structured soil samples with coarse particles where it is unfeasible to collect structured soil samples with metal sampling rings.

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-The objective of this work was to evaluate the effect of different amounts of black oat (Avena strigosa) straw covering soil surface on soil temperature at different depths. The treatments consisted of 0, 3, 6, and 9 Mg ha -1 straw. Soil temperature was measured hourly by a thermocouple inserted at different depths (0, 5, 15, 30, and 50 cm) and was used to adjust an equation correlating the temperature of covered soil with that of bare soil. With the correlations, it was possible to observe a point value of temperature (inversion temperature of straw effect), below which the presence of straw acts positively on the maintenance of soil temperature and above which the presence of straw acts negatively on soil heating.Index terms: Avena strigosa, inversion temperature, mulch effect, no-tillage, plant residue, soil thermal regime. Alterações da temperatura em solo coberto de palha de aveia-pretaResumo -O objetivo deste trabalho foi avaliar o efeito de diferentes quantidades de palha de aveia-preta (Avena strigosa) em cobertura do solo sobre a temperatura do solo em diferentes profundidades. Os tratamentos consistiram de 0, 3, 6 e 9 Mg ha -1 de palha. A temperatura do solo foi medida a cada hora por meio de termopares inseridos em diferentes profundidades (0, 5, 15, 30 e 50 cm) e usada para ajustar uma equação que correlaciona a temperatura do solo coberto com a do solo descoberto. A partir dessas correlações, foi possível observar um valor pontual de temperatura (temperatura de inversão do efeito da palha), abaixo do qual a presença de palha atua positivamente na manutenção da temperatura do solo e acima do qual a presença de palha atua negativamente no aquecimento do solo.Termos para indexação: Avena strigosa, temperatura de inversão, efeito da palha, plantio direto, resíduo vegetal, regime térmico do solo.

The sensitivity of infiltration predictions by Hydrus‐1D and Green‐Ampt models to rainfall discretisation was investigated by assessing the accuracy of infiltration predictions with rainfall rate profiles at step sizes D between 2 and 1440 min. Five peak rainfall profiles and one sine‐wave rainfall profile, all with a cumulative rainfall amount of 28.8 cm and a duration of 24 h were used. Discrete rainfall profiles were generated based on the peak rainfall profiles for several step sizes. The rainfall profiles were evaluated in a sandy loam with a high saturated hydraulic conductivity and a silt loam with a low saturated hydraulic conductivity for two initial pressure heads. For both models, insensitivity was found below a critical step size Dcrit, whereas high sensitivity was observed above it, Dcrit depending on soil hydraulic conductivity and rainfall peak intensity, regardless of initial pressure head. In the sandy loam, Dcrit was 20–30 (high‐intensity peak) and 70 min (low‐intensity peak); in the silt loam, values were 100 and 200–300 min, respectively. Therefore, rainfall data from common weather station data at D = 60 min allow accurate estimates of infiltration only in low‐conductivity soils or for low‐intensity rainfall. The disaggregation of daily cumulative rainfall into sine‐wave profiles improved predictions in more conductive soils. Results indicate that higher saturated hydraulic conductivity and intensity peak rainfall rate require smaller values of D for the accurate modelling of infiltration with Hydrus‐1D and Green‐Ampt models. Highlights Temporal resolution of rainfall data is important in infiltration modelling. Temporal resolution of rainfall data affects Green‐Ampt and Hydrus‐1D predicted infiltration Green‐Ampt and Hydrus‐1D cumulative infiltration predictions are insensitive for rainfall resolution ≤20 min Predictions are more sensitive to rainfall resolution >20 min in soils with higher hydraulic conductivity.