Speaker
Description
Introduction
Subterranean clover (Trifolium subterraneum L.) is a valuable component of regenerative agricultural systems. This legume naturally regenerates from seeds set in previous seasons, which eliminates the need for re-sowing because it maintains a seed bank of ‘hard’ seeds. Some of these remain dormant for germination in later years. The ability to avoid drought by producing dormant seeds and burying them, ensures survival and persistence (Moss et al. 2022).
It is a common winter annual clover species present in European grasslands (Vasileva and Vasilev, 2020) and summer dry environments in Oceania (Goward et al 2023). It provides high-quality (ME and crude protein) biomass during late winter and early spring and fixes atmospheric nitrogen. This contributes to nitrogen cycling, and pasture productivity.
We quantified subterranean clover life cycle at multiple scales to optimize the use of subterranean clover for animal productivity given the importance to both local and nationwide pasture productivity and persistence in hill country landscape.
Material and Methods
Subterranean clover phenological events in complex hill country topography was evaluated on a nationwide aspect map raster of the slope direction of each cell created from a digital elevation model (DEM) using GIS. Aspect is the compass direction that a slope faces which determines microclimate, vegetation, and soil erosion of a hill country terrain. Slopes were classified in north, northeast, northwest, east, southeast, south, southwest, west aspects.
Figure 1. New Zealand map displaying the selected hill country zones. The red pixels represent the >= 15-degree slopes.
The assessment excluded the areas below 15 degrees because the aspect effects on those relatively flat areas were minor. The vegetative (fourth trifoliate leaf, V6) and reproductive (50% plants flowering, R3) phenophases were quantified by considering a mean value estimated (expressed as Julian days) from a 45-year timespan (1972-2017) for late flowering cultivars. Regressions were derived from field observed data and published. Only sowing periods occurring in a decreasing photoperiod direction (autumn to winter) were considered (Guo et al. 2022).
Results
For late maturity cultivars, the mean time to reach V6 was 124.5 ±12.61 days on an east aspect, 125.3 ± 13.09 days on the north face aspect and 127.7 ± 15.26 days on west aspect. On the northern aspects of the North Island the times to reach V6 and R3 were 105.9 ± 2.12 and 277 ± 7.21, respectively. In contrast, in the southern aspects of the South Island plants required a longer time to reach V6 and R3 (129.4 ± 22.27 and 334.6 ± 23.64).
Discussion and Conclusions
Understanding how subterranean clover phenological development changes with aspect can assist agronomic management decisions on a catchment or farm level. The quantification of key phenological events of subterranean clover on different land aspects demonstrated the opportunities to refine pasture management in complex hill country environments. It ensures that forage of higher quality and yield can be integrated on hill country farm systems and allows farmers to make informed decisions around pasture management for more resilient and longer lifetime pastures.
Acknowledgment
Beef + Lamb New Zealand ”Advancing AgYields to support forage/crop decision making” (Project Number: 21195-3), the “Extension tools for Hill Country Futures’ (Project Number: 21126) and Kathleen Spragg Research Trust (G-202305-05830).
References
Goward, L.E., Haling, R.E., Smith, R.W., Penrose, B. and Simpson, R.J., 2023. Flowering responses of serradella (Ornithopus spp.) and subterranean clover (Trifolium subterraneum L.) to vernalisation and photoperiod and their role in maturity type determination and flowering date stability. Crop and Pasture Science.
Guo, J., Teixeira, C.S., Barringer, J., Hampton, J.G. and Moot, D.J., 2022. Estimation of time to key phenological stages to guide management of subterranean clover (Trifolium subterraneum L.) in New Zealand. European Journal of Agronomy, 134, p.126451.
Moss, W.M., Nichols, P.G.H., Foster, K.J., Ryan, M.H., Erskine, W. and Guzzomi, A.L., 2022. A century of subclover: Lessons for sustainable intensification from a historical review of innovations in subterranean clover seed production. Advances in Agronomy, 171, pp.305-339.
Vasileva, V. and Vasilev, V., 2020. Agronomic characterization and the possibility for potential use of subterranean clover (Trifolium subterraneum L.) in the forage production in Bulgaria. Pakistan Journal of Botany, 52(2), pp.565-568.
| Keywords | Grassland, legume, microclimate, phenology, regeneration |
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