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20152
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Subject: Soil Science × End date: 2015 × Start date: 2015 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Soil water dynamics and water productivity of ricewheat system under different establishment methods
    (PAU, 2015) Bhatt, Rajan; Kukal, S.S.
    The prevalent wheat-rice cropping system in Punjab has been taking a toll on the natural resources in the region. The wheat and rice grown with conservation technologies need to be studied for the cropping system as a whole. Field experiments were carried out during 2012- 14 in a sandy loam soil to assess the role of zero tillage and crop establishment method on crop performance, soil water dynamics, soil physical environment and water productivity of the wheat-rice cropping system. The treatments consisted of zero- (ZTW) and conventionaltillage (CTW) as main, establishment methods viz. direct seeded (DSR) and mechanical transplanted rice (MTR) as sub and tillage in rice viz. puddle (P), conventional (CT) and zero till (ZT) as sub-sub treatments. Zero tillage in wheat and rice did not affect the wheat yield during both the years. The grain yield of DSR was similar to MTR during 2013 but was significantly higher during 2014. The land productivity of wheat-rice cropping system was 15.8 and 11.3 per cent higher in CTW than in ZTW plots during 2012-13 and 2013-14, respectively. It was highest in CTW-DSR-P and lowest in ZTW-MT-ZT. The irrigation water productivity of the system (WPI) was highest in CTW-MT-P and lowest in ZTW-DSR-ZT. The WPI of wheat-rice cropping system was significantly higher (16-19.5 per cent) in CTW than in ZTW plots. The WPI of the cropping system was higher in MTR (0.81-0.88 g kg-1) than DSR (0.60-0.77 g kg-1). The WPI of wheat-rice cropping system, though similar in CT (0.76 g kg-1) and ZT (0.71 g kg-1) plots of rice during 2012-13, was 11.2 per cent lower in ZT plots during 2013-14. The evapo-transpiration (ET) losses of the wheat-rice cropping system were higher during 2013-14 (971-1057 mm) than in 2012-13 (908-922 mm). The ET losses of wheat-rice cropping system including the intervening period were not affected by tillage in wheat or rice.
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    ThesisItemOpen Access
    Effect of long-term application of fertilizers and manures on green house gas emission
    (PAU, 2015) Dhadli, Harmanjit Singh; Brar, B.S.
    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.