Davut Akbolat

Quantifying soil respiration in response to short-term tillage practices: a case study in southern Turkey

Abstract The study aimed at quantifying the rates of soil CO2 efflux under the influence of common tillage systems of moldboard plow (PT), chisel plow (CT), rotary tiller (RT), heavy disc harrow (DT), and no-tillage (NT) for 46 days in October and November in a field left fallow after wheat harvest located in southern Turkey. The NT and DT plots produced the lowest soil CO2 effluxes of 0.3 and 0.7 g m−2 h−1, respectively, relative to the other plots (P < 0.001). Following the highest rainfall amount of 87 mm on the tenth day after the tillage, soil CO2 efflux rates of all the plots peaked on the 12th day, with less influence on soil CO2 efflux in the NT plot than in the conventional tillage plots. Soil evaporation in NT (64 mmol m−2 s−1) was significantly lower than in the PT (85 mmol m−2 s−1) and RT (89 mmol m−2 s−1) tillage treatments (P < 0.01). The best multiple-regression model selected explained 46% of variation in soil respiration rates as a function of the tillage treatments, soil temperature, and soil evaporation (P < 0.001). The tillage systems of RT, PT, and CT led, on average, to 0.23, 0.22, and 0.18 g m−2 h−1 more soil CO2 efflux than the baseline of NT, respectively (P≤0.001).

Rotary tiller velocity effects on the distribution of wheat (Triticum aestivum) residue in the soil profile

Abstract Effect of velocity ratios of a forward rotational‐rotary tiller on the distribution of wheat (Triticum aestivum) stubbles incorporated into soil layers was investigated. A 2‐year experiment was conducted in a field with silt loam soil on an experimental site at Süleyman Demirel University located near Isparta, Turkey. Velocity ratios of the rotary tiller were maintained at 6.01, 7.51, 9.39, and 11.77. The soil depths studied were 0–5, 5–10, and 10–15 cm. Results showed that there were no significant differences among velocity ratios, and soil depths by velocity ratio interaction means in terms of stubble mass. However, there were significant differences among soil depths means in terms of stubble mass (P < 0.01). This indicates that there is no advantage of increasing velocity ratios of rotary tiller to bury more stubble mass into the soil since fuel consumption of the tractor and the power requirement of the rotary tiller increase with increased velocity ratios of the rotary tiller. There were significant differences among the soil depths means in terms of distribution of stubble length at the soil depths (P < 0.01). Longer stubbles accumulated at a soil depth of 0–5 cm whereas shorter stubbles were buried in a 5–15 cm soil layer regardless of velocity ratio.