engleski

Differential responses of soil carbon dioxide emissions to fertilization during soybean vegetation

Carbon dioxide (CO2) emissions from terrestrial ecosystems represent one of the most important contributors to climate change. It is considered that most of the carbon released to the atmosphere is originated through agricultural activities that mainly increased since the industrial revolution where irresponsible land management often leads to soil carbon loss and increased carbon dioxide emissions to the atmosphere. Likewise, agricultural management practices that include changing the soil environment affect soil CO2 flux. The objective of this study was to determine the influence of different fertilization in soybean agro ecosystem on CO2 respiration. The field experiment with four different fertilization treatments was set up in central part of Croatia (N 45° 33' 21.42'', E 16° 31' 44.62'') on deep, distric pseudogley (Stagnosol). It contains four different fertilization treatments as follows: (I) control treatment – no fertilization, (II) organic fertilization – 40 t ha−1 of solid farmyard mixed manure + P + K, (III) mineral fertilization – 300 kg ha−1 N + P + K and (IV) black fallow – no vegetation. The cover crop at the experimental field in the investigated year (2018) was soybean (Glycine max L.– Tena variety) which was sown on 27th April 2018 and harvested on 26th September 2018. The experimental plot is characterized by continental climate. In the studied year (2018) mean amount of precipitation was 824.5 mm with mean temperature of 12.7 °C. The measurements of soil CO2 concentrations and soil properties were conducted eight times during the vegetation year (January, March, April, May, June, July, August and September) in three repetitions on each treatment. The soil CO2 concentrations were measured by a closed static chamber method with incubation time of 30 minutes. After 30 minutes, the soil CO2 concentrations were measured with portable infrared CO2 detector (GasAlerMicro5 IR, 2011). The soil carbon dioxide flux was expressed as kg C-CO2 per ha per day. At the beginning and the end of each measurement, air temperature and relative air humidity were measured with Testo 610 (2011) and air pressure with Testo 511 (2011). Soil properties (temperature and moisture) were measured with IMKO HD2 – probe Trime, Pico64, 2011 at 10 cm depth in the vicinity of the chambers in three replications. Depending on fertilization treatment, mean annual C-CO2 flux ranged from 7.7 kg ha-1 day-1 on black fallow to 16.7 kg ha-1 day-1 on treatment with mineral fertilization and were significantly different (SAS 9.1 p<0.05). Thus, through biological activity stimulated by N fertilization, CO2 flux consequently increases. The highest soil temperature was recorded in May (31.4 °C) while the highest soil moisture was recorded in January (30.0 %). Increased knowledge about the impacts of the different land uses and soil management on soil GHG emissions can potentially be used in the creation of more sustainable agricultural practices.

soil C-CO2 flux ; fertilization ; soybean

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