Abstract
Aim of study: To evaluate the effects of conventional tillage (CT) and no tillage (NT) systems on the soil organic carbon (SOC) changes, CO2 emissions and their relation with soil temperature and grain yield in a monoculture of irrigated maize during six years.Area of study: In Zamadueñas experimental field in the Spanish province of Valladolid, from 2011 to 2017.Material and methods: The SOC content was determined by collecting soil samples up to 30 cm in November at two years interval. Short-term CO2 emissions were measured simultaneously with soil temperature using a respiration chamber and a hand-held probe immediately before, after every tillage operation and during the maize cycle.Main results: The SOC stock of the top 30 cm soil layers was 13% greater under NT than CT. Short-term CO2 emissions were significantly higher under CT ranging from 0.8 to 3.4 g CO2 m-2 h-1 immediately after tillage while under NT system, soil CO2 fluxes were low and stable during this study period. During the first 48 h following tillage, cumulative CO2 emissions ranged from 0.6 to 2.4 Mg CO2 ha-1 and from 0.2 to 0.3 Mg CO2 ha-1 under CT and NT systems, respectively. Soil temperature did not show significant correlation with CO2 emissions; however, it depended mostly on the time of measurement.Research highlights: No tillage increased the SOC accumulation in the topsoil layer, reduced CO2 emissions without decreasing maize grain yield and minimized the impact on climate change compared to CT system.
Highlights
Maize crop (Zea mays L.) is one of the most important crops worldwide and its production is mainly assured by conventional methods as the frequent ploughing of the soil
No-tillage system recorded low temperature during all different studied seasons, suggesting that crop residues in NT plots diminished the effect of high air temperatures and the solar radiation (Fig.1)
From December to March 2015, the increase of soil temperature under NT could be explained by the fact that the mean air temperature during these months was generally lower than the reported ones during the same months of the other years (Table 2)
Summary
Maize crop (Zea mays L.) is one of the most important crops worldwide and its production is mainly assured by conventional methods as the frequent ploughing of the soil. Appropriate management can enable agricultural soils to provide a net sink for sequestering atmospheric CO2 and other GHGs (Paustian et al, 1997a; West & Post, 2002) Agricultural operations such CT promotes the rapid oxidation processes and the release of a large CO2 amount into the atmosphere, decreasing the levels of organic matter (OM) and contributing to the global warming. Conservation agriculture such as NT practices improves the soil structure, water retention and helps the nutrients preservation. No-tillage system could play an important role by increasing SOC and improving the environmental quality in the production systems (Reicosky et al, 1997) and would be a viable alternative to stabilize CO2 concentrations in the atmosphere and a way to counteract climate change
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