Search

Nitrous oxide ([N.sub.2]O) is considered a major contributor to global climate change in addition to carbon dioxide and methane. A significant quantity of [N.sub.2]O emission originates from agriculture, largely from high rates of fertiliser application. We studied [N.sub.2]O emissions from wheat field to evaluate the effect of different forms of fertilisers and the potential for emission reduction. Field experiments were conducted for two consecutive seasons with four fertilisers, namely inorganic fertiliser (NPK), starch-coated urea (SCU), neem-coated urea (NCU), and urea alone (UA) in a tropical wheat ecosystem. Gas samples were collected from the field at weekly intervals using the static chamber technique and analysed with a gas Chromatograph. The cumulative [N.sub.2]O emissions were higher from the NPK. amended field (3.19 kg [N.sub.2]O-N [ha.sup.-1]) followed by UA (3.05 kg [N.sub.2]O-N [ha.sup.-1]). The SCU, NCU, and UA amendments decreased the total [N.sub.2]O emissions by 23%, 12%, and 4%, respectively (P Additional keywords: neem-coated urea, nitrous oxide emission, soil mineral N, soil organic carbon, starch-coated urea. Received 3 January 2016, accepted 7 July 2016, published online 26 September 2016, Introduction Nitrous oxide ([N.sub.2]O) is a long-lived powerful greenhouse gas in the atmosphere with a global warming potential ~298 times greater than C[O.sub.2] over a 100-year time horizon (Forster et [...]

Nitrous oxide is a greenhouse gas with high global warming potential emitted from agricultural sources. The effects of tillage practices and different levels of N fertiliser on seasonal fluxes of [N.sub.2]O were investigated in a field planted with the wheat variety Sonalika. The experiment was conducted during 2012-13 and 2013-14 under conventional tillage (CT) and reduced tillage (RT) farming systems in combination with four different levels of nitrogen fertiliser (i.e. zero nitrogen (FI), 60 kg N [ha.sup.-1] (F2), 80 kg N [ha.sup.-1] (F3) and 100 kg N [ha.sup.-1] (F4)). Both tillage practices and fertiliser significantly (P < 0.01) affected seasonal cumulative [N.sub.2]O emissions and wheat yield. However, there was no significant difference in [N.sub.2]O emissions between RTF1 and CTF1 (zero nitrogen). Compared with RT, [N.sub.2]O emission decreased under the CT practice by 2.49%, 10.11%, 7.9% and 27.46% in CTF1, CTF2, CTF3 and CTF4 respectively. Highest and lowest seasonal cumulative fluxes were recorded in RTF4 (N 100 kg ha 1) and CTF1 (N 0 kg [ha.sup.-1]) respectively. During the wheat-growing period, nitrogen use efficiency decreased with increasing nitrogen levels and treatment with 60 kg-N [ha.sup.-1] in the CT practice (CTF2) was found to be effective in increasing nitrogen use efficiency and decreasing yield- scaled [N.sub.2]O emissions. Additional keywords: agronomic nitrogen use efficiency, mineral nitrogen, soil organic carbon. Received 17 September 2015, accepted 7 December 2015, published online 4 July 2016, Introduction Changes in the concentration of greenhouse gases (GHG), mainly carbon dioxide (C[O.sub.2]), methane (C[H.sub.4]) and nitrous oxide ([N.sub.2]O), have occurred in past years and have been related to the [...]

Three rice (Oryza sativa L.) varieties viz. 'CR 683', 'Budumoni' "Budumoni", and 'Akisali' were grown in sand culture in a greenhouse with three levels of iron (Fe) in nutrient solutions viz., 0.045 (control), 5.34, and 7.12 mM Fe to study the effects of iron on physiology of rice seedling growth. Shoot length, root, and shoot dry weights were reduced significantly by higher levels of Fe in the medium. Results of leaf bronzing have revealed higher bronzing score in the seedlings grown at 7.12 mM Fe in the growth medium. Occurrence of bronzing was severe in varieties 'CR683' and 'Akisali'. Variety 'Budumoni'maintained higher leaf chlorophyll content, nitrate reductase activity and total soluble protein in the leaves at 5.34 and 7.12 mM Fe. Higher concentration of iron in the nutrient medium exerted an inhibiting effect on the concentration and content of almost all the macro and micronutrients in the root and shoot. Higher Fe and nitrogen (N) contents and lower phosphorus (P), potassium (K), manganese (Mn), copper (Cu), and zinc (Zn) were determined in roots and shoots in plants grown in medium supplied with 7.12 mM Fe. The variety 'Budumoni' "Budumoni" performed relatively better in comparison to other tested varieties at 7.12 mM Fe in the growth medium. 'Budumoni' "Budumoni" can be considered a suitable rice variety to use in the rice-breeding programme for Fe toxicity tolerance in acid soils of Assam. [ABSTRACT FROM AUTHOR]