Document Type : Research Article
Authors
1
Department of Water Engineering, Faculty of Agricultural Engineering, Sari Agricultural Sciences and Natural Resources University, Mazandaran, Iran
2
Department of Irrigation and Drainage, Faculty of Agricultural Engineering, Sari Agricultural Sciences and Natural Resources University, Mazandaran, Iran
3
Sari Agricultural Sciences and Natural Recourses University, Genetics and Agricultural Biotechnology Institute of Tabarestan, Sari, Iran
Abstract
Introduction
The challenges of climate change and increasing greenhouse gas emissions have led to consequences such as global warming and successive droughts. Additionally, the rise in agricultural activities has significantly increased the pressure on available water resources. Consequently, it has become essential to consider wastewater resources. To make appropriate management decisions and find solutions to reduce CO2 emissions in the agricultural sector, it is crucial to understand how soil moisture and sources of irrigation affect greenhouse gas (GHG) emissions, particularly CO2. Therefore, the aim of this research was to evaluate the effects of water stress and irrigation management on soil CO2 emissions, water productivity, and soybean yield and yield components.
Materials and Methods
This research was carried out at Sari University of Agricultural Sciences and Natural Resources with latitude (36° 33′ N) and longitude (53° 00׳ E), elevation (14 m, above sea level), average temperature (17.9°C) and total of precipitation (650 mm), during the growing season (2022-2023). The experiment was carried out in the form of a split plot based on a randomized complete block design in three replications in growth season 1402-1403, Sari. Experimental treatments include; the main factor was water stress in three levels ((non-stress, FC100), FC75 and FC50) and the sub factor was irrigation management in two levels (Urban Wastewater (UWW) and Well Water (WW).
Results and Discussion
Based on the findings, the highest amount of CO2 emission in the middle and end stages of sampling in 60, 75, 90 and 105 day after sowing in non-stress conditions-FC100 was observed with 535.9, 534.5, 543.6 and 444.5 ppm.min-1, respectively. In addition, its lowest amount was related to water stress-FC50 with 505.3, 499.8, 506.5 and 409.8 ppm.min-1, respectively. The results showed that the highest amount of Co2 emission was assigned to irrigation with urban wastewater with 536.5, 540.1, 538 and 516.9, respectively. Due to the increase in the plant growth rate and approaching the grain maturity, the amount of CO2 emission increased with the increase in temperature, root system development, plant roots respiration and the soil microorganism’s activities. The highest amount of water productivity was observed in the non-stress condition FC100 with a 0.62 kg.m-3. Which compared to water stress conditions-FC75 and FC50 increased by 43.5% and 51.6%, respectively. Also, the results showed that in the non-stress condition-FC100 and irrigation with urban wastewater, the highest pod number (304.8), grain number of per pod (665.1), 100-grain weight (18.7 g), grain yield (1060.4 kg.ha-1) and total dry matter (743.3 kg.ha-1) were obtained. In the condition of irrigation with urban wastewater, the highest number of pods, grain number of per pod, 100-grain weight, grain yield and total dry matter was observed with 234.5, 495.8, 18.5 g, 679.4 kg.ha-1 and 645.7 kg.ha-1, respectively. While their lowest amount was assigned to water stress conditions-FC50 with 218.6, 483.3, 17.7 g, 555.1 kg.ha-1 and 625.5 kg.ha-1, respectively. Optimum soil moisture conditions under non-stress conditions-FC100 and water stress conditions-FC75, especially when irrigating with urban wastewater, increased the yield and yield components by providing nutrients needed by the plant.
Conclusion
The results showed that in the early stages of soil sampling, irrigation management (source of irrigation) did not significantly affect the amount of CO2 emission. However, in the middle and final stages of sampling, the growth and development of plant organs and increased soil respiration due to the development of the root system caused the release of CO2. This effect was more pronounced during irrigation with wastewater than with well water. Based on the findings, considering the water scarcity crisis and the challenge of water stress during the soybean growth season, it appears that accurate management and efficient use of wastewater resources is both inevitable and a suitable solution.
Acknowledgement
Sari Agricultural sciences and Natural Resources University (SANRU) financially supported this research under contract number: 02-1397-05.
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