Determining the effects of conservation tillage methods on post-tillage and long-term CO2 emissions within climate change and agriculture interaction

Aim: The research aimed to determine the effects of different tillage methods on CO2 emissions, monitor and investigate the effects of cultural applications (fertilization, irrigation, pest management, hoeing) on CO2 emissions throughout the entire vegetation period of the plants, examine the periodic changes of CO2 emissions due to tillage and seasonal changes and determine the time period of highest and lowest CO2 emissions within the day. Material and Method: The research was carried out at the International Agricultural Research and Training Center, in a designated area where conservation tillage studies have been carried out for many years, using traditional tillage and sowing, reduced tillage, and no-till practices in four different subjects in accordance with the rotation system of 1st year wheat + silage corn, 2nd year cotton for 2 years in a field strip cropping, randomized block experimental design, with 3 fixed replications. Findings: The CO2 emission values measured in this study conducted between 2020 and 2022 showed that; different soil cultivation methods, the choice of tools and equipment used in soil cultivation, and the number of repetitions have a direct impact on the amount of CO2 released from the soil. Measurements were repeated immediately after agricultural practices during cultivation and their effects on CO2 emissions were investigated. Accordingly, it was determined that the amount of emissions increased on the days of inter-row tillage applications. However, in irrigation an entirely different situation has emerged. A sudden increase in CO2 emission amounts was recorded after some irrigation applications, whereas, a sudden decrease was observed in the measurement made immediately after some irrigation applications. According to the results of the LSD test performed on all CO2 emission values measured since the beginning of the experiment, reduced tillage subjects were in group A B. While traditional tillage was in group A and direct drilling was in group B. According to the results, on a subject basis, the highest average CO2 emission was recorded as 5,5266 µmol.m-2.s-1 in the traditional tillage method, while the lowest average CO2 emission was obtained in the direct drilling method with 4.2000 µmol.m-2.s-1. Evaluating measurements made at different times of the day, it was seen that the lowest emission values occurred in the hours after sunset. This is thought to be related to the slowing down of microorganismic activities in the soil. As a result of the data obtained from the study, it was concluded that the CO2 emission values, which increase immediately after tillage, vary according to months. While this change stabilized in less than 24 hours in the winter months, it stabilized after the third day in the relatively warmer summer months. In the light of the data acquired from CO2 measurements made throughout the year, we can say that the highest CO2 emissions in the conditions of Izmir Menemen region occur in June, July and August. It has been detected that the CO2 emission amounts, measured higher in TT(traditional tillage) immediately after tillage activities, increased proportionally less in the measurements in the spring months, but the emission increase in other subjects was higher, and in total, the TT subject had the highest emission volume. Conclusion: It has been concluded that if direct drilling is preferred instead of traditional tillage in order to reduce the amount of emissions, it can be achieved to reduce 15 - 25%. In light of the data acquired from all studies in which similar results were obtained, it seems possible to reduce the amount of CO2 emissions from agriculture by choosing conservation tillage methods. According to the results, carrying out tillage activities at sunset or early in the morning may result in lower CO2 emissions. Since these hours will be more advantageous in terms of greenhouse gas emissions, this timetable can be preferred for tillage or can be recommended to farmers.