EFFECTS OF FERTILISERS AND ENVIRONMENT ON LOTUS PRODUCTION ON HIGH COUNTRY ACID SOILS IN OTAGO

Abstract

To test the performance and nutrient requirements of Grasslands Maku lotus (Lotus pedunculatus) on high country acid soils under tussock grassland, the effects of phosphorus (P), sulphur (S) and lime on lotus and clover yields were measured in cut plots on sites ranging in altitude from 700 from 1200 m on the Remarkables Range (topsoil pH 5.5 - 4.8), and on the East Otago (Lammerlaw-Lammermoor) uplands (topsoil pH 5.2 - 4.4). On the Remarkables, mean annual yields for P + S treatments decreased from about 7000 to 3500 kg DMlha and on the Lammerlaw- Lammermoor sequence the decrease over the same altitude range was from about 2000 to 200 kg DMlha. Soi! !pSt va!lJes fgr S 2nd p were !c):l' cu.+. -C1A1,* 1 LQU-lml,,-l-l'r-l*I*~, ""-L'S-L-II-II-II-~-I^lll-""-l sites: S-deficiency was so severe that there was very little response to P until S was added and in most cases there was little response to S in the absence of P. On the Remarkables soil test values were more variable and lotus yields were closely related to soil test values. Fertiliser requirements of lotus were generally similar to those of clover, but clover occasionally continued to respond to higher rates of P than lotus. In contrast to clover, lotus showed little or no response to lime, except at the highest altitude (i.e. lowest pH) on the Lammerlaws. In both Remarkables and Lammerlaw-Lammermoor sequences lotus and clover yields were similar up to 1000 m but above this altitude lotus production exceeded clover on the Remarkables. On the Lammerlaws yields dropped off sharply at the highest altitude but clover yields where lime was applied were significantly higher than lotus. Decreasing lotus yield with increasing altitude is attributed to increasing severity of climate (probably low temperatures). The lower yields and greater decrease on the Lammerlaws suggest that the limitations are more severe there than at corresponding altitudes on the Remarkables. Keywords: Lotus, high country, fertiliser, lime, climate