The role of nitrogen and in-crop lucerne suppression for increasing cereal performance in companion cropping systems

Abstract Five field experiments located at four sites (Burraja, Grogan, North Boorhaman and Roseworthy) across south eastern Australia compared cereal grain yields in the presence of lucerne (companion cropping) and absence of lucerne (cereal monoculture). Top-dressed nitrogen (N) was applied to subplots at Burraja, Grogan and North Boorhaman, while in-crop lucerne suppression was applied to plots at Burraja and two separate, but adjacent experiments at Roseworthy, to determine if these management strategies could improve cereal performance in the presence of lucerne. In addition annual lucerne and cereal biomass was measured at North Boorhaman from a companion crop and compared with both a lucerne and cereal monoculture. Over the three years and four sites, cereals growing with lucerne yielded between 19% and 57% less (P<0.05) grain than cereals growing alone. There was no main treatment by top-dressed N interaction at all sites, indicating that applying N to cereals irrespective of whether they were growing with or without lucerne, resulted in same yield responses. Top-dressing N at North Boorhaman in 2003 and 2005 resulted in a 14% and 40% respectively, increase (P<0.05) in grain yield across all cereal crops. The absence of a response at Burraja and Grogan was probably due to sub-optimal growing season rainfall. In-crop lucerne suppression did not increase grain yields at either Burraja or Roseworthy, but in some seasons reduced (P<0.05) cereal grain contamination by lucerne pods and flowers. Companion cropping increased (P<0.05) total (cereal and lucerne) annual biomass production by 20-41%, compared with the lucerne monoculture, and 16% more (P<0.05) than the cereal monoculture. Demonstrating that while grain yield reductions reduce the attractiveness of companion cropping, this practice does offer other advantages in terms of improved yearly water use and quality out-of-season feed supply that cereal monocultures can not deliver. Key words Inter-cropping, companion cropping, grain yield reduction, in-crop lucerne suppression, top-dressed nitrogen, lucerne, wheat, barley. Introduction Lucerne companion cropping (also known as inter-cropping or over-cropping) involves sowing an annual crop directly into an existing lucerne stand. In comparison with conventional cropping systems, companion cropping promotes greater utilisation of rainfall by maintaining a perennial plant throughout the year, and therefore reducing the risk of excess rainfall leaking below the root zone and contributing to the harmful effects of dryland salinity

The role of nitrogen and in-crop lucerne suppression for increasing cereal performance in companion cropping systems

Five field experiments located at four sites (Burraja, Grogan, North Boorhaman and Roseworthy) across south eastern Australia compared cereal grain yields in the presence of lucerne (companion cropping) and absence of lucerne (cereal monoculture). Top-dressed nitrogen (N) was applied to subplots at Burraja, Grogan and North Boorhaman, while in-crop lucerne suppression was applied to plots at Burraja and two separate, but adjacent experiments at Roseworthy, to determine if these management strategies could improve cereal performance in the presence of lucerne. In addition annual lucerne and cereal biomass was measured at North Boorhaman from a companion crop and compared with both a lucerne and cereal monoculture. Over the three years and four sites, cereals growing with lucerne yielded between 19% and 57% less (P<0.05) grain than cereals growing alone. There was no main treatment by top-dressed N interaction at all sites, indicating that applying N to cereals irrespective of whether they were growing with or without lucerne, resulted in same yield responses. Top-dressing N at North Boorhaman in 2003 and 2005 resulted in a 14% and 40% respectively, increase (P<0.05) in grain yield across all cereal crops. The absence of a response at Burraja and Grogan was probably due to sub-optimal growing season rainfall. In-crop lucerne suppression did not increase grain yields at either Burraja or Roseworthy, but in some seasons reduced (P<0.05) cereal grain contamination by lucerne pods and flowers. Companion cropping increased (P<0.05) total (cereal and lucerne) annual biomass production by 20-41%, compared with the lucerne monoculture, and 16% more (P<0.05) than the cereal monoculture. Demonstrating that while grain yield reductions reduce the attractiveness of companion cropping, this practice does offer other advantages in terms of improved yearly water use and quality out-of-season feed supply that cereal monocultures can not deliver.Rob Harris, Tim Clune, Mark Peoples, Antony Swan, William Bellotti and Wen Che

The importance of in-crop lucerne suppression and nitrogen for cereal companion crops in south-eastern Australia

Five field experiments located at four sites across south-eastern Australia found cereal grain yields were less in the presence of lucerne (companion cropping) than in the absence of lucerne (cereal monoculture). Top-dressed nitrogen (N) and in-crop lucerne suppression, generally did not enhance cereal crop yields in the presence of lucerne compared with cereals growing in monoculture. Grain yield reductions from cereals growing with lucerne were found at four of the five sites, with reductions ranging from 16 to 26% compared with cereals growing in monoculture. In regard to cereal production, there was no main treatment by top-dressed N interaction at all sites, indicating that applying N to cereals irrespective of whether they were growing with or without lucerne, resulted in the same yield responses. With favourable growing seasons (decile > 6) and low available soil N levels, top-dressing N resulted in a 31% and a 0.8 unit increase in grain yield and grain protein, respectively, across all cereal crops and years. However, the absence of a grain yield response to top-dressed N at one site was due to excessive cereal biomass production from N application, causing extensive crop lodging in 2003, and decile 2 growing season rainfall in 2004. At another site, high available soil N levels and low growing season rainfall (decile 3) resulted in a 12% decline in grain yield across all cereal crops and years in response to top-dressing N. We therefore conclude that N application to cereals growing with lucerne can increase cereal grain yields, but only when accompanied by favourable growing season rainfall and low available soil N levels. In-crop lucerne suppression was effective at reducing cereal grain contamination by lucerne pods and flowers in companion crops, but was less effective under dry seasonal conditions, demonstrating that soil moisture will affect herbicide efficacy and the effectiveness of this practice. Economic analyses of companion cropping based on grain yields alone, will not be adequate without an assessment of summer lucerne production, until such data exists across a range of environments, it would be premature to conclude whether and or where this practice has commercial merit

The role of nitrogen and in-crop lucerne suppression for increasing cereal performance in companion cropping systems

Five field experiments located at four sites (Burraja, Grogan, North Boorhaman and Roseworthy) across south eastern Australia compared cereal grain yields in the presence of lucerne (companion cropping) and absence of lucerne (cereal monoculture). Top-dressed nitrogen (N) was applied to subplots at Burraja, Grogan and North Boorhaman, while in-crop lucerne suppression was applied to plots at Burraja and two separate, but adjacent experiments at Roseworthy, to determine if these management strategies could improve cereal performance in the presence of lucerne. In addition annual lucerne and cereal biomass was measured at North Boorhaman from a companion crop and compared with both a lucerne and cereal monoculture. Over the three years and four sites, cereals growing with lucerne yielded between 19% and 57% less (P<0.05) grain than cereals growing alone. There was no main treatment by top-dressed N interaction at all sites, indicating that applying N to cereals irrespective of whether they were growing with or without lucerne, resulted in same yield responses. Top-dressing N at North Boorhaman in 2003 and 2005 resulted in a 14% and 40% respectively, increase (P<0.05) in grain yield across all cereal crops. The absence of a response at Burraja and Grogan was probably due to sub-optimal growing season rainfall. In-crop lucerne suppression did not increase grain yields at either Burraja or Roseworthy, but in some seasons reduced (P<0.05) cereal grain contamination by lucerne pods and flowers. Companion cropping increased (P<0.05) total (cereal and lucerne) annual biomass production by 20-41%, compared with the lucerne monoculture, and 16% more (P<0.05) than the cereal monoculture. Demonstrating that while grain yield reductions reduce the attractiveness of companion cropping, this practice does offer other advantages in terms of improved yearly water use and quality out-of-season feed supply that cereal monocultures can not deliver

Baseline Predictors of A1C Reduction in Adults Using Sensor-Augmented Pump Therapy or Multiple Daily Injection Therapy: The STAR 3 Experience

Background: Baseline characteristics from the adult cohort of a randomized controlled trial comparing sensoraugmented pump (SAP) and multiple daily injection (MDI) therapy were analyzed for significant relationships with -0.5% A1C change at 1 year of therapy without incidence of severe hypoglycemia (defined as A1C benefit). Methods: Baseline characteristics were compared with A1C benefit. Statistically significant predictors were analyzed further to determine appropriate cutpoints of relative A1C benefit. Results: Baseline A1C ≥ 9.1%, age at randomization ≥ 36 years, and age at diabetes diagnosis of ≥ 17 years were associated with a greater SAP benefit relative to MDI than other cutpoints. Conclusions: People with type 1 diabetes who had a high A1C and who were older at diagnosis and older at randomization experienced the most benefit from SAP therapy