Sowing Date Affects Dry Matter Yield of Fodder Beet (\u3ci\u3eBeta vulgaris\u3c/i\u3e L.) Crops and Farm Profitability

Fodder beet (Beta vulgaris L.) is a high yielding and high energy supplementary ruminant feed. Including the crop in a pasture system means loss in production and additional costs during crop establishment, but economic benefits may be recovered with increased seasonal productivity and feed quality. In this study, the Agricultural Production Systems sIMulator was used to estimate herbage production of a typical dairy farm in the Canterbury region of New Zealand based on using a ryegrass (Lolium perenne L.)-clover (Trifolium repens L.) pasture (“Pasture only”) or pasture in combination with fodder beet as winter feed (“Pasture+Fodder beet (FB)”). Mean yields of pasture were used to estimate the potential pasture yield lost from spraying out paddocks 1 month before establishing fodder beet. Fodder beet (‘Rivage’) yields from a 2014 sowing date trial: 19 September (Sep-FB), 17 October (Oct-FB), 17 November (Nov-FB), and 15 December (Dec-FB) were used. Dry matter (DM) yield was determined on 15 June 2015. Yield was 27 t DM/ha for both Sep-FB and Oct-FB and was reduced by 23 and 32% in Nov-FB and Dec-FB, respectively. The total annual yield for “Pasture only” was 16.7 t DM/ha compared with adjusted yield of 29.5, 30.2, 25.7 and 24.9 t DM/ha for “Pasture+Sep-FB”, “Pasture+Oct-FB”, “Pasture+Nov-FB” and “Pasture+Dec-FB”, respectively. Production cost was NZ$0.08/kg DM each for “Pasture+Sep-FB” and “Pasture+Oct-FB”, which was lower than NZ$0.09/kg DM for “Pasture only”. Production costs increased to NZ$0.11/kg DM for “Pasture+Nov-FB” and NZ$0.12/kg DM for “Pasture+Dec-FB”, but revenue from sale of surplus feed partially offset these costs. Our results show that sowing in October was the most profitable option. Yield gains from sowing fodder beet in September are unlikely because of low temperatures limiting crop growth. Delaying sowing can increase production costs and yield penalty, but potential returns are greater, compared with “Pasture only”

Irrigation Management Strategies for Fodder Beet (\u3ci\u3eBeta vulgaris\u3c/i\u3e L.) Crops

The production of fodder beet (Beta vulgaris L.) in New Zealand is concentrated in the South Island, and often requires irrigation to achieve high yields. Development of efficient irrigation management strategies requires information on the effect of timing and rate of irrigation on crop growth. A field study was conducted on a moderately deep soil at Chertsey, Canterbury, New Zealand, to evaluate crop growth responses to five irrigation managements: Rain-fed (control), weekly replacement of full evapotranspiration (FullET-weekly), and 50% of evapotranspiration replaced weekly (HalfET-weekly), fortnightly (HalfET-2weekly) or 3-weekly (HalfET-3weekly). Irrigation to replace ET was adjusted to account for rainfall received between irrigation events. The crop was sown on 11 October 2015. Dry matter (DM) and green leaf area index (LAI) were quantified at 4-weekly intervals from 21 December 2015 until 16 May 2016. Water use efficiency (WUE) was calculated from weekly time domain reflectometry and neutron probe measurements of volumetric soil water content (to 0.8 m depth) and crop biomass. Final yield was lowest for Rain-fed (17.1 t DM/ha) and highest for FullET-weekly (28.9 t DM/ha) treatments. The remaining treatments did not differ in yield, producing 22.4±1.6 t DM/ha, but differed significantly from the Rain-fed and FullET-weekly treatments. Yield differences were associated with the rate of leaf area expansion and duration of critical LAI values (≥ 3.0 m2/m2), which were greater for FullET-weekly than for other treatments. Rain-fed and FullET-weekly treatments resulted in the highest and lowest WUE (81 versus 47 kg DM/ha/mm). The remaining treatments did not differ in WUE, averaging 67±3.6 kg DM/ha/mm. Our results show yield benefits from irrigation, with the best outcome from FullET-weekly given the soil type and weather conditions. However, under water restriction conditions, the HalfET-3weekly management is recommended over more frequent partial ET replacements because it would reduce irrigation costs without penalising yield