High levels of soil nitrogen (N) can interfere with N2 fixation of lentil (Lens culinaris) and have variable effects on growth, yield and maturity of this indeterminate crop in Saskatchewan. In a series of field and greenhouse experiments during 2006 to 2008, response of the above-ground biomass (DW), plant N, N2 fixation, yield and days to maturity (DTM) of lentil to different N sources, time of N availability, and also to two no tillage (NT) durations were studied. First, eight cultivars of lentil were grown under three fertility treatments of granular rhizobium inoculant, 50 kg N fertilizer ha-1 and a non-treated control in three environment-years at Saskatoon and Indian Head, SK. The fertility treatments, plant N status and N2 fixation did not alter lentil DTM, but weather did. On average, lentil matured 101 and 84 days after seeding with sufficient rain and with drought, respectively. Growth and yield of the lentil were identical in the inoculant and the N fertilizer treatments. The N fertilizer treatment occasionally restricted N2 fixation, but N shortage was compensated via more N uptake from soil. The greatest N accumulation of lentil occurred during podding to maturity and benefitted pod N content. By maturity, pod, stem and leaf had 60, 24 and 14% of total dry matter and 78, 9 and 13% of total plant N, respectively. Leaf N concentration, which closely resembled soil and plant N status, was reasonably predicted by SPAD chlorophyll meter observations after pod set. Yield of five lentil cultivars was tested for the effects of 25-years (LN) versus 5-years (SN) of no tillage in the Black Soil Zone at Indian Head, SK in 2006, 2007 and 2008. In the same location, CDC Sedley was grown with four N fertilizer rates at the both LN and SN. Under terminal drought in 2006, average DW, N content and yield of the lentil cultivars in SN were greater than in LN, likely because of inhibited N2 fixation by the amplified soil N in the LN. In this year, 60 kg N fertilizer ha-1 reduced the yield difference of CDC Sedley in SN and LN. Lentil yield was identical or tended to be greater in LN than in SN with more rain in 2007 and 2008 that prolonged N mineralization and N uptake. In the greenhouse study, applying N fertilizer from flowering until podding and until maturity increased DW, N content and yield, and delayed maturity of lentil compared to lentil relying on N2 fixation. Later flowering of one cultivar or greater N2 fixation in one soil medium diminished the variation of inoculated lentil with the post-flowering N treatments, suggesting N fixation could supply lentil N requirement. Large-seeded cultivars produced greater yield than the small-seeded cultivars across environments in the fertility treatment study. Cultivar CDC Milestone produced comparable yield to high-yielding cultivars CDC Plato and CDC Greenland, but matured earlier. This cultivar showed promising results under both cool-wet and drought conditions. In contrast, CDC Sedley had lower on N2 fixation and HI values across the experiments. In the Black Soil Zone, CDC Milestone and CDC Robin performance was improved by improved HI and N2 fixation. Overall, results of this thesis do not support the application of N fertilizer for inducing early maturity in lentil. Soil inoculation with commercial strains is suggested for Saskatchewan cropping systems. Applying N fertilizer is not required, unless soil test results suggest otherwise. In places like Indian Head, SK, cultivars with greater N2 fixation and higher HI can better fit the short growing season, cool temperature and high soil N content.

High levels of soil nitrogen (N) can interfere with N2 fixation of lentil (Lens culinaris) and have variable effects on growth, yield and maturity of this indeterminate crop in Saskatchewan. In a series of field and greenhouse experiments during 2006 to 2008, response of the above-ground biomass (DW), plant N, N2 fixation, yield and days to maturity (DTM) of lentil to different N sources, time of N availability, and also to two no tillage (NT) durations were studied. First, eight cultivars of lentil were grown under three fertility treatments of granular rhizobium inoculant, 50 kg N fertilizer ha-1 and a non-treated control in three environment-years at Saskatoon and Indian Head, SK. The fertility treatments, plant N status and N2 fixation did not alter lentil DTM, but weather did. On average, lentil matured 101 and 84 days after seeding with sufficient rain and with drought, respectively. Growth and yield of the lentil were identical in the inoculant and the N fertilizer treatments. The N fertilizer treatment occasionally restricted N2 fixation, but N shortage was compensated via more N uptake from soil. The greatest N accumulation of lentil occurred during podding to maturity and benefitted pod N content. By maturity, pod, stem and leaf had 60, 24 and 14% of total dry matter and 78, 9 and 13% of total plant N, respectively. Leaf N concentration, which closely resembled soil and plant N status, was reasonably predicted by SPAD chlorophyll meter observations after pod set. Yield of five lentil cultivars was tested for the effects of 25-years (LN) versus 5-years (SN) of no tillage in the Black Soil Zone at Indian Head, SK in 2006, 2007 and 2008. In the same location, CDC Sedley was grown with four N fertilizer rates at the both LN and SN. Under terminal drought in 2006, average DW, N content and yield of the lentil cultivars in SN were greater than in LN, likely because of inhibited N2 fixation by the amplified soil N in the LN. In this year, 60 kg N fertilizer ha-1 reduced the yield difference of CDC Sedley in SN and LN. Lentil yield was identical or tended to be greater in LN than in SN with more rain in 2007 and 2008 that prolonged N mineralization and N uptake. In the greenhouse study, applying N fertilizer from flowering until podding and until maturity increased DW, N content and yield, and delayed maturity of lentil compared to lentil relying on N2 fixation. Later flowering of one cultivar or greater N2 fixation in one soil medium diminished the variation of inoculated lentil with the post-flowering N treatments, suggesting N fixation could supply lentil N requirement. Large-seeded cultivars produced greater yield than the small-seeded cultivars across environments in the fertility treatment study. Cultivar CDC Milestone produced comparable yield to high-yielding cultivars CDC Plato and CDC Greenland, but matured earlier. This cultivar showed promising results under both cool-wet and drought conditions. In contrast, CDC Sedley had lower on N2 fixation and HI values across the experiments. In the Black Soil Zone, CDC Milestone and CDC Robin performance was improved by improved HI and N2 fixation. Overall, results of this thesis do not support the application of N fertilizer for inducing early maturity in lentil. Soil inoculation with commercial strains is suggested for Saskatchewan cropping systems. Applying N fertilizer is not required, unless soil test results suggest otherwise. In places like Indian Head, SK, cultivars with greater N2 fixation and higher HI can better fit the short growing season, cool temperature and high soil N content.

No description available.

Two field grazing experiments were conducted in New Zealand (NZ) in spring (Experiment 1; November 2008) and autumn (Experiment 2; April 2009) to evaluate the effects of feeding a high sugar perennial ryegrass (HSG; cv. AberDart; derived in the United Kingdom; UK) versus a NZ- derived control grass (cv. Impact) on milk production and estimated nitrogen (N) partitioning within the cow. Areas of both ryegrasses were replicated and sown with or without white clover (cl) (HSG+cl, control+cl, HSG and control). A cross-over design with four 10-day periods was used in each experiment, using 15 Friesian cows per treatment per period in Experiment 1 and 5 cows per treatment per period in Experiment 2. Treatment effects upon pasture botanical and chemical composition, cows’ milk yield and composition, and estimated N partitioning were studied. Nitrogen partitioning was calculated using indirect methods. Herbage concentrations of water soluble carbohydrates (WSC) were lower in autumn than in spring whilst crude protein (CP) concentrations were higher in autumn. Organic matter digestibility (OMD) and metabolisable energy (ME) concentration was similar in both seasons. There were no differences in the concentration of CP, WSC and dry matter (DM) among treatments in Experiment 1. The HSG+cl treatment had the lowest concentrations of neutral detergent fibre (NDF, 417 g/kg DM) and the highest content of ME (12.6 MJ/kg DM) and tended to have the lowest sward dead matter content compared with the other three treatments. In Experiment 2 both HSG treatments showed higher concentrations of WSC (15 g/kg DM) compared with the control, both with and without clover; the concentrations of NDF and acid detergent fibre (ADF) were the lowest for both HSG treatments. In Experiment 1, cows grazing treatments with white clover produced more milk (1.6 kg/day) and more milk solids (MS; 0.16 kg/day) than cows grazing pure ryegrass swards ( P< 0.01), with highest milk yields being from cows grazing the HSG+cl treatment (ryegrass cultivar x white clover interaction P<0.05). No differences in milk production were found in Experiment 2. Estimated urinary N excretion (g/day) was similar for all treatments in both seasons, although N intake differed among treatments. The proportion of N intake excreted in urine or secreted in milk was similar for all treatments in both experiments. Nitrogen output (g/day) in milk was the highest for the HSG+cl treatment in Experiment 1 but no differences were found in Experiment 2. Data were combined from both experiments to study the effects of the herbage CP:WSC ratio upon estimated N partitioning between milk and urine. Mean ratios were 0.72 for spring herbage and 2.27 for autumn herbage. As the amount of WSC increased in the diet relative to the amount of CP (thus a lower CP:WSC ratio) there was a significant increase in the amount of milk N secreted per unit of N intake in spring but not in autumn. The breakpoint in the relationship between the herbage CP:WSC ratio and the nitrogen utilisation efficiency for milk production (NUEm) was 1.32, and the NUEm for that breakpoint was 14 g milk N per 100 g N intake. Ratios below this point were associated with improved efficiency of converting pasture N to milk N; ratios above this point were not correlated with changes in N conversion efficiency. It is concluded that the CP:WSC ratio in perennial ryegrass may be important in the partition of absorbed N into milk or urine. A NZ-selected HSG with a lower CP:WSC ratio is likely to have major benefits for pastoral farming in NZ. In order to be effective, a NZ-derived HSG should substantially increase WSC concentration in autumn pasture (from approximately 100 to 200 g/kg DM) whilst reducing CP content simultaneously (from 240 to 190 g/kg DM). The lower structural fibre and higher milk production for the HSG+cl treatment in both experiments suggest that under NZ conditions, best productive responses to HSG may be obtained in management systems that include white clover.

No description available.