Paper Information

Journal:   JOURNAL OF AGROECOLOGY (كشاورزي بوم شناختي)   2017 , Volume 7 , Number 2 #G0056; Page(s) 107 To 118.
 
Paper: 

STUDY OF CARBON BUDGET AND CO2 EMISSIONS RATE FROM SOIL SURFACE IN NO TILLAGE SYSTEMS

 
 
Author(s):  ALIZADEH YASER*, KOOCHEKI ALIREZA, NASIRI MAHALLATI MAHDI
 
* DEPARTMENT OF AGRONOMY AND PLANT BREEDING SCIENCES, FACULTY OF AGRICULTURE, UNIVERSITY OF ILAM, ILAM, IRAN
 
Abstract: 

Introduction: Investigating whether agricultural ecosystems are performing as carbon source or sink due to either natural influences or management approaches plays a critical role in studies aimed at mitigating and adaptating to climatic variation. A sustained study of the application of agricultural ecosystems is the only achievable way to develop an accurate vision on gas exchange between the atmosphere and terrestrial ecosystems (Beziat et al., 2009). Estimating carbon budget in agricultural ecosystems is an effective way to find out whether a given ecosystem is a source or a sink of carbon dioxide (Twine and Kucharik, 2009). The goal of this investigation was to study the effects of maintaining crop residues on CO2 flux and carbon balance in an agricultural system.
Materials and methods: This study was conducted to investigate the effects of increased residue rate on the CO2 emission rate and determine the soil carbon budget in the presence or absence of residue in the soil surface. A randomized block design experiment including five treatments and three replications was carried out on a research farm of the University of Ferdowsi in 2011-12. Treatments include 0, 2, 4, 8 and 16 t ha-1 of wheat (Triticum aestivum L.) straw. The carbon budget was estimated in both years using a static closed chamber method according to analysis by gas chromatography (Shimizu et al., 2009).
Results and discussion: Results showed that in spring and summer, soil temperature was higher than air temperature. In winter and autumn, air temperature was usually higher than bare soil temperature. In both the experimental years, the temperature of residue-containing soil was lower than that of the air in spring. The treatment with the highest residue rate (16 ton ha-1) had the lowest temperature in all measurements, however, the difference between various residue treatments was slight and the difference between 8 and 16 tons ha-1 was not significant in any measurement. Duiker and Lal (2000) showed that soil temperature under application of residue was 14oc lower than bare soil. The daily CO2 emission rate ranged from 0.1 to 4.3 megagrams C ha-1year-1. The CO2 emission rate increased in line with increases in residue kept at the soil surface. The highest annual CO2 flux rate was obtained for 16 ton ha-1 residue as 3.7 in 2011 and 3.6 in 2012 and the lowest annual CO2 flux rate was gained in bare soil in the two experimental years as 0.7 and 0.9 tons ha-1. Based on this equation, annual CO2 flux was calculated. An exponential relationship between soil temperature and respiration has been also reported by other authors (Brar et al., 2013).
Conclusion: Residue application had a significant impact on soil temperature. The difference was large between unmulched and mulched treatments. Our results indicated a high correlation (> 85%) between soil temperature and CO2 flux which was positive and exponential. Although the total calculated CO2 flux from the bare soil treatment was lower than the other treatments, this treatment had a carbon budget more negative than the other treatments, which is an ecologically negative factor.

 
Keyword(s): GREENHOUSE GASES, SOIL TEMPERATURE, CLOSED CHAMBER METHOD, MULCH, CARBON DYNAMIC
 
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