Low‐input production of barley on the predominantly calcareous soils in most countries of West Asia and North Africa is affected by drought and a low availability of P and Zn. Especially during the early growth stages, P and Zn deficiencies retard seedling growth, rendering the young plantlets particularly sensitive to the frequently encountered dry spells. Seed priming (soaking in water and drying back to storage moisture until use) has been shown to improve crop establishment and, in some instances, to increase crop yields. While increased seedling vigor will improve barley establishment, possible benefits are likely to be limited when P and Zn are deficient. A promising variation of the priming concept is the seed treatment with solutions containing the limiting nutrient. A series of experiments was conducted in a phytotron in 2003 to develop a nutrient‐priming approach to foster the establishment of barley under marginal growing conditions. Seeds of the traditional barley cultivar Arabi aswad were soaked for 0–48 hours in water and for 12 hours in solutions containing 5–500 mM P, Zn, and P+Zn, and dried back to 12% moisture until further use. Seeds were incubated at 10°C, and germination was evaluated over a 6‐ to 8‐day period. Additionally, growth and nutrient uptake of 4‐week‐old seedlings, grown at 25% and 100% field capacity in a typical Xerosol from Syria were evaluated. Water priming for 12 hours with subsequent seed storage of up to 9 weeks increased germination rate from 65% to 95%, and advanced germination by up to 3 days compared to unprimed seeds. Addition of 10 mM Zn and 50 mM P to the priming solution increased the P and Zn content of the seeds without affecting germination. It furthermore significantly stimulated growth and P and Zn uptake by 4‐week‐old seedlings and improved the water use efficiency of drought‐stressed plants by 44% above that of unprimed seeds.

Soil N2O emissions vary with N source. A study was undertaken on a clay soil in the Red River Valley, Manitoba, Canada, to determine the effect of granular N fertilizers and dairy manure on N2O emissions from a field cropped to rapeseed (Brassica napus L.) in 2009 and spring wheat (Triticum aestivum L.) in 2010. Treatments included an unamended control, granular urea, controlled‐release urea (ESN), stabilized urea (SuperU), and solid dairy manure added at rates to achieve a total of 140 kg available N ha−1 (product plus soil N test). The N fertilizers were broadcast and shallowly incorporated each spring before planting; the manure was broadcast incorporated the previous fall. Nitrous oxide emissions were monitored from planting to freeze in fall and during spring thaw in 2011 using static‐vented chambers. In both years, N2O emissions occurred within 4 to 5 wk of planting but not in fall after manure application. Area‐scale cumulative N2O emissions (∑N2O, kg N ha−1) from planting to freeze were control < ESN = manure < urea = SuperU. Nitrous oxide emission factors were 0.017 kg N2O‐N kg−1 available N added for urea and SuperU and 0.007 kg N2O‐N kg−1 available N for ESN. Seventy‐eight percent of the variation in ∑N2O could be explained by NO3− intensity, an integration of soil NO3− concentrations during the study periods. Greater ∑N2O were also associated with higher yields. These findings suggest that N release rates, as indicated by NO3− intensity and yield, determined N2O emissions. The results highlight the challenge of meeting crop demand yet reducing N2O emissions by selection of an N source.

e e ects of band placement of enhanced e ciency fertilizers (EEF) on nitrous oxide (N 2 O) emissions are uncertain. Placement and EEF on N 2 O emissions from spring wheat (Triticum aestivum L.) at two locations in Manitoba, in 2011 and 2012 were examined. Treatments were a no N control and 80 kg N ha -1 at planting of ve combinations of placement and granular N source: broadcast-incorporated urea (Urea I ) and, subsurface side-banded urea (Urea S ; each row side-banded), midrow-banded urea (Urea M ; placement between every other set of rows), midrow-banded environmentally smart nitrogen (ESN, Agrium, Inc.) (ESN M ), and midrow-banded SuperU (Koch Industries Inc.) (SuperU M ). Planting in 2011 was delayed 40 d compared to 2012. Planting coincided with higher soil temperature and moisture resulting in three-to sevenfold more growing season N 2 O emissions (SN 2 O) in 2011 than 2012. In 2011, SuperU M and ESN M reduced SN 2 O, emission factor (EF) scaled by N-applied EF, and yield-scaled N 2 O emission intensity (EI) by 47, 67, and 55%, respectively, compared with Urea I . In 2011, increasing placement concentration of N in order broadcast-incorporation, side-banding, and midrow-banding tended to decrease SN 2 O, EF, and EI of granular urea, but not statistically signi cant. e SN 2 O and nitrate exposure (NE), were signi cantly correlated over the siteyears, indicating N availability from treatments in part determined emissions. Grain yield and crop N uptake were una ected by sources and placement. ese results suggest for early season wet and warm conditions, EEF N sources can reduce emissions compared with granular urea. Further studies are required to clarify placement e ects on N 2 O emissions.

International audienc

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