Effect of long-term application of fertilizers and manures on green house gas emission
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Date
2015
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Publisher
PAU
Abstract
The effect of long-term application of fertilizers and manures on green house gas emissions in maizewheat and rice-wheat cropping systems was studied in two field experiments in progress since 1972
and 1999, respectively, at Research Farm, Punjab Agricultural University, Ludhiana, India. Fluxes of
CH4, N2O and CO2 were measured by closed chambers and gas chromatographer. Due to the longterm
application of inorganic fertilizers and organic amendments, soil pH decreased while soil organic carbon along with available P and K status improved. Significant variability in various soil C and N forms was observed under various long-term treatments of the two cropping systems. In the maizewheat
cropping system, N2O emissions from 100% NPK, 150% NPK, 100%N and FYM treatments in
the maize crop season were higher by 130-150 % and in the wheat crop season by 40-60%over the
control. Total CO2 emissions in different treatments in the maize season were higher by 55-90% and
in the wheat crop season by 44-85% over the control. In the rice-wheat cropping system, CH4
emissions in the rice season were the highest from straw treatment (146 Kg CH4 ha-1), followed by
control, FYM, 150% NPK, 100%NPK, GM and 100%N treatments and in the wheat crop season
CH4emission was not observed. N2O emissions in various long-term inorganic fertilizers and organic
amendment treatments were higher by >100% and >60% over the control in rice and wheat seasons,
while CO2 emissions were higher by 40-100% in rice and 30-70% in wheat over the control. Daily
N2O fluxes were found significantly controlled by soil NO3⁻-N and total-N along with water input or
rainfall. Temporal variations in CO2 fluxes were controlled by soil temperature and soil OC while,
CH4 fluxes were controlled by water depth along with water soluble C and total N in soil. Methane
fluxes were dependent on dissolved organic C in soil, which increased with the growth of rice plants
and increase was comparatively more in the root zone of rice plants grown in soils of the long-term
control treatment followed by 100%N treatment. Rate of C and N mineralization was relatively higher
in soils of FYM treatment followed by NPK and control of maize-wheat cropping system. Carbon and
N mineralization increased significantly with addition of wheat straw or green manure or FYM.
Apparently it can be concluded that with the application of fertilizers and manures, GHG emissions
increase, but yield scaled global warming potential (GWP) was much higher for control treatments in
both the cropping systems, except straw treatment in rice-wheat cropping system, which suggested
that to achieve the food security, integrated nutrient management may be adopted.
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Keywords
inorganic compounds, crops, seasons, fertilizers, wheats, cropping systems, rice, maize, irrigation, organic fertilizers