Tagasaste silvopastures in steep-hill country. 1. Tagasaste edible dry-matter production and nutritive value

Abstract

Context. Tagasaste (Cytisus proliferus) has potential to supplement pasture production in steephill country and increase pasture resilience. Aims. To (1) quantify production of edible dry matter (EDM) of pruned 2-year-old tagasaste shrubs and branches from unpruned 10-year-old tagasaste trees, and (2) determine the effect of proximity of the 10-year-old tagasaste trees on selected pasture species established as spaced transplants. Methods. A site was established on the eastern coast of the North Island of New Zealand on steep-hill country (>20° slope). Tagasaste and pasture species production was measured over 3 years. Results. Tagasaste −1 shrubs produced an average of 2.7 kg EDM shrub −1 year and a tree branch produced 129 g EDM year −1 . The metabolisable energy content of tagasaste branches averaged 10.0 MJ kg EDM −1 , the crude protein content ranged from 18% to 27% and neutral detergent fibre content averaged 39%. Branch diameter and length were poor predictors of EDM branch −1 . There was no effect of increasing proximity to tagasaste on DM production of the resident pasture. Effects of increasing proximity to tagasaste on the growth and survival of selected pasture species are reported in a companion paper. Conclusions. Edible-DM production was much greater from shrubs than tree branches and it was not possible to predict branch EDM from branch diameter or length. Implications. A tagasaste silvopasture is likely to be more productive if tagasaste is managed for grazing in situ than if using mature trees for harvesting of branches for browse.

Tagasaste silvopastures in steep-hill country. 2. Effect of increasing proximity to tagasaste on growth and survival of companion pasture species

“…There were large differences among shade treatments in levels of solar and photosynthetic radiation throughout the study, but fewer differences among the shade treatments in soil moisture or soil nutrient content (Tozer et al 2023). This suggests that the effects of increasing proximity to tagasaste on plant growth and survival were strongly associated with increased shading, although competition for other resources cannot be ruled out.…”

“…There were large differences among shade treatments in levels of solar and photosynthetic radiation throughout the study, but fewer differences among the shade treatments in soil moisture or soil nutrient content (Tozer et al . 2023).…”

“…soil moisture, soil surface temperature, solar radiation), characteristics of the tagasaste trees (e.g. height, canopy spread), annual DM production and botanical composition of resident pasture, and site management are presented in Part 1 of this two-part series (Tozer et al . 2023).…”

“…Soil moisture content was measured as described in Tozer et al . (2023). In summary, soil moisture content was measured at a depth of 0–12 cm using a portable time domain reflectometry instrument (Hydrosense II; Campbell Scientific, Logan, UT, USA), calibrated for the field site using gravimetric soil moisture values.…”

“…2012); however, no data were available on tagasaste productivity when grown on steep-hill country (>20° slope). In the first paper of this two-part series, we reported on tagasaste edible dry matter (DM) production, mineral content and nutritive value when grown in perennial pastures on steep-hill country (Tozer et al . 2023).…”