Understanding nitrous oxide (N 2 O) emissions from agricultural soils in semi-arid regions is required to better understand global terrestrial N 2 O losses. Nitrous oxide emissions were measured from a rain-fed, cropped soil in a semi-arid region of southwestern Australia for one year on a sub-daily basis. The site included N-fertilized (100 kg N ha À1 yr À1 ) and nonfertilized plots. Emissions were measured using soil chambers connected to a fully automated system that measured N 2 O using gas chromatography. Daily N 2 O emissions were low (À1.8 to 7.3 g N 2 O-N ha À1 day À1 ) and culminated in an annual loss of 0.11 kg N 2 O-N ha À1 from N-fertilized soil and 0.09 kg N 2 O-N ha À1 from nonfertilized soil. Over half (55%) the annual N 2 O emission occurred from both N treatments when the soil was fallow, following a series of summer rainfall events. At this time of the year, conditions were conducive for soil microbial N 2 O production: elevated soil water content, available N, soil temperatures generally 425 1C and no active plant growth. The proportion of N fertilizer emitted as N 2 O in 1 year, after correction for the 'background' emission (no N fertilizer applied), was 0.02%. The emission factor reported in this study was 60 times lower than the IPCC default value for the application of synthetic fertilizers to land (1.25%), suggesting that the default may not be suitable for cropped soils in semi-arid regions. Applying N fertilizer did not significantly increase the annual N 2 O emission, demonstrating that a proportion of N 2 O emitted from agricultural soils may not be directly derived from the application of N fertilizer. 'Background' emissions, resulting from other agricultural practices, need to be accounted for if we are to fully assess the impact of agriculture in semi-arid regions on global terrestrial N 2 O emissions.

Chickpea (Cicer arietinum) developed as a post-rainy season, spring-sown crop early in its evolution and spread into warm subtropical regions, in contrast to its wild relatives that have remained as winter annuals in West and Central Asia. To test whether these different life cycles selected for different phenological strategies in wild and cultivated Cicer, germplasm from a wide range of habitats was subjected to different cold treatments (vernalisation, control) at germination, and phenology evaluated at warm and cool field sites (14.8–15.1°C and 13.1°C, respectively). All wild Cicer species, except for C. yamashitae, responded positively to vernalisation and accelerated the dates of flowering, podding, and maturity. There was no vernalisation response in cultivated chickpea, whereas C. arietinum/C. echinospermum and C. arietinum/C. reticulatum interspecific hybrids were intermediate, flowering 6–16 days earlier after vernalisation. Relative podding dates differed between sites. Chickpea podded earlier than most vernalised wild species under warm conditions, but not at the cool site. Regression against post-anthesis temperature showed that the delay in podding was consistent with a lack of cold tolerance in the cultigen. The interspecific hybrids were significantly more cold tolerant than chickpea, and the wild species were almost insensitive to the temperature range recorded at the cool site. Vernalisation responsiveness and a greater tolerance of low temperatures during the reproductive phase demonstrate that the annual wild Cicer species harbour important traits that can be used to widen adaptation in the cultigen, and may help to improve the performance of chickpea as a Mediterranean cool-season crop.

The effects of N fertiliser regimes on N leaching and turfgrass quality during the establishment and maintenance of Kikuyu turfgrass (Pennisetum clandestinum (Holst. Ex Chiov)) were evaluated in a 24 month field study. Treatments included two turfgrass ages (established from 20 week or 20 year old turfgrass, the later included a 50 mm 'mat' layer), three N application rates (50, 100 or 150 kg N ha −1 yr −1 ) and three application frequencies (every 4 weeks, 4 applications per year, 2 applications per year); and included turfgrass plots that received no N fertiliser. Nitrogen leaching, measured using soil lysimeters, ranged from 35 to 69 kg N ha −1 by the end of 24 months, and varied with turfgrass age, but not N fertiliser regime. Greatest N losses occurred during turfgrass establishment, with up to 50% of all N leached in the organic form. We recommend measuring both total N and mineral N when assessing N leaching from turfgrass. The quality of the older turfgrass was maintained using less N fertiliser than the younger turfgrass, while increasing N application frequency improved the consistency of turfgrass growth and colour.

Th e eff ect of N fertilizer rate on Kikuyu turfgrass [Pennisetum clandestinum (Hochst. ex Chiov)] evapotranspiration was evaluated during two summers. Evapotranspiration was measured using weighing lysimeters (205 mm in diameter by 625 mm in length) inserted in turfgrass fi eld plots (10 m 2 ). Th e experiment was a randomized plot design with three replicates. Treatments included two turfgrass ages (established from 20 wk or 20-yr-old turfgrass) and three N application rates (0, 50, or 150 kg N ha -1 yr -1 ). Evapotranspiration ranged from 2.8 to 7.5 mm d -1 (or 56-81% of evaporative demand), and varied with daily evaporative demand, turfgrass age, and N fertilizer rate. Th e older turfgrass used more water than the younger turfgrass during both summers; while increasing the N application rate also increased evapotranspiration for both turfgrass types (younger turfgrass only in the second summer). Evapotranspiration was positively correlated with turfgrass growth (r 2 = 0.74-0.80) and transpiring leaf area (r 2 = 0.78). Older turfgrass at all N treatments, and the younger turfgrass receiving 150 kg N ha -1 yr -1 , had adequate growth, color, and leaf N concentrations. Optimizing fertilizer applications such that the minimum N required to maintain turfgrass quality is applied, is an approach for decreasing water consumption by turfgrass.