Specifics of soil temperature under winter wheat canopy

Abstract

The aim of this study was to evaluate the course of soil temperature under the winter wheat canopy and to determine relationships between soil temperature, air temperature and partly soil moisture. In addition, the aim was to describe the dependence by means of regression equations usable for phytopathological prediction models, crop development, and yield models. The measurement of soil temperatures was performed at the experimental field stationŽabčice (Europe, the Czech Republic, South Moravia). The soil in the first experimental plot is Gleyic Fluvisol with 49-58% of the content particles measuring < 0.01 mm, in the second experimental plot, the soil is Haplic Chernozem with 31-32% of the content particles measuring < 0.01 mm. The course of soil temperature and its specifics were determined under winter wheat canopy during the main growth season in the course of three years. Automatic soil temperature sensors were positioned at three depths (0.05, 0.10 and 0.20 m under soil surface), air temperature sensor in 0.05 m above soil surface. Results of the correlation analysis showed that the best interrelationships between these two variables were achieved after a 3-hour delay for the soil temperature at 0.05 m, 5-hour delay for 0.10 m, and 8-hour delay for 0.20 m. After the time correction, the determination coefficient reached values from 0.75 to 0.89 for the depth of 0.05 m, 0.61 to 0.82 for the depth of 0.10 m, and 0.33 to 0.70 for the depth of 0.20 m. When using multiple regression with quadratic spacing (modeling hourly soil temperature based on the hourly near surface air temperature and hourly soil moisture in the 0.10-0.40 m profile), the difference between the measured and the model soil temperatures at 0.05 m was −2.16 to 2.37 • C. The regression equation paired with alternative agrometeorological instruments enables relatively accurate modeling of soil temperatures (R 2 = 0.93).

Specifics of soil temperature under winter oilseed rape canopy

“…As it was found out by cross correlation analysis, the best interrelationships between these two variables were achieved in 2 hours delay for the soil temperature in 0.05 m, 4 hour delay for 0.10 m and 7 hour delay for 0.20 m for standard varieties (Sherpa and Petrol). For PX 104 this delay reached 6 hour for the soil temperature in 0.05 m, 7 hour delay for 0.10 m and 11 hour for 0.20 m. These delays were slightly different from those determined for wheat by Krčmářová et al (2013). Siebold and von Tiedemann (2012) also found high correlation between air temperatures measured in meteorological station and soil temperatures in depth 0.05 and 0.15 m, respectively, but they used Spearman rank correlation.…”

“…For example, important pathogen, Sclerotinia sclerotiorum, which causes Sclerotinia stem rot of rape, develops sexual ascospores in fruiting bodies apothecia which are formed on fungi mycelium firm bodies, called sclerocia. Carpogenic germination of sclerocia (apothecia formation) occurs from 10 to 25 • C with optimum 20 • C (Matheron and Porchas, 2005;Mila and Yang, 2008 As is broadly discussed in Krčmářová et al (2013), soil temperatures can be influenced by cover of plant canopy and its changes during the year, the spring vegetation period of winter oilseed rape was divided into four stages. Detailed course of soil temperatures and stratification was expressed as 2D nomograms.…”

“…The agrometeorological and pedological conditions of the locality are described by Krčmářová et al (2013).…”

“…The shape, dimensions and the geometrical structure of a specific plant species play important roles in the development of the canopy microclimate (Matejka and Huzulák, 1987). In our previous work (Krčmářová et al, 2013), we evaluated the course of soil temperatures under winter wheat canopy and we determined relationships between soil temperature, air temperature and partly soil moisture. The review of influence of shape, dimension and the geometrical structure of particular crop canopy and relationship between air and soil temperatures within the agroecosystem is given in this publication.…”