Tokaroa Farm is a 608-ha sheep and beef farm, in the Wairarapa. Paddock slopes range from flat to steep (>25°) with a predominance of gentler north facing slopes and steeper south facing slopes. Annual rainfall is 810 mm and average summer dry is three months. Resident subterranean (sub) clover (Trifolium subterraneum L.) populations were identified on an uncultivatable north-west facing hill slope in 2015, and a management plan devised to increase its contribution to pastures. Exclosure plots showed that an eight-week spell in spring 2016 increased resident sub clover groundcover from 13 to 54%, while in the lightly grazed paddock control sub clover increased from 10 to 28%. There was a positive linear relationship (R2=0.51) between the total number of established sub clover seedlings on 30 March 2017 and the previous spring sub clover groundcover (%) on 25 November 2016. In October 2017, the effect of the spring 2016 exclosure treatments was still evident with 57% sub clover groundcover in the eight-week spelled areas compared with 37% in the control despite all the exclosures being grazed in 2017.Sub clover management strategies were developed, using slope and aspect, and applied to a GIS map of Tokaroa Farm. This suggested that 53% of the farm could have sub clover overdrilled into it and 29% could have the resident sub clover population actively managed and/or oversown with sub clover seed.

Diagnosis of clover nutrient status is important for legume-based pasture systems. The protocols for sample collection and setting of nutrient guidelines are ill-defined. This research quantified how nutrient concentrations differed between laminae (leaflets) and petioles (leaf stems) of subterranean (sub) clover (Trifolium subterraneum) and white clover (T. repens) as a first step in developing appropriate sampling procedures to examine the nutrient status of clover species. Field samples of sub and white clovers from three pasture sites in the Wairarapa and Canterbury were separated into lamina and full petiole and chemically analysed for nitrogen (N), phosphorus (P), potassium (K) and sulphur (S). Lamina + petiole K concentrations were lower in sub clover (2.3%) than white clover (3.2%). Across both species, the lamina concentrations of N (4.9%), P (0.36%) and S (0.28%) were higher than in the petiole (1.8%, 0.29% and 0.12% respectively) but the reverse was found for K (1.8 % lamina, 3.7% petiole). As a consequence, increasing the proportion of petiole added with the lamina affected the nutrient concentration of lamina + petiole samples so that N, P and S% declined but K% increased. In a subset of samples, NIR analysis found the crude protein of lamina + petiole in white clover was 24% compared with 21% in sub clover. Clover laminae of both species had 33% crude protein compared with only 11% in the petiole. The diagnosis of clover nutrient status for fertiliser recommendations should be based on lamina-only samples. In contrast, mixed pasture samples for nutritive value analysis should include clover laminae and petioles, plus grass and herb pasture components, to simulate grazing intake by livestock. The lack of defined sampling protocols may explain some of the difficulties previously reported in herbage nutrient interpretation and reconciling soil test results.

This study quantified the temporal productivity of monocultures of four annual and two perennial clover species in a summer dry environment at Lincoln University, Canterbury, New Zealand. Clovers were ungrazed in the first year to enable natural re-establishment of the annuals, but grazed in the second year. In 2019 clover cultivar affected (P<0.001) yield in early spring (24th September) with ‘Viper’ balansa (Trifolium michelianum) producing 5.0 t DM/ha compared (P<0.05) with 3.5 t for ‘Arrotas’ arrowleaf (T. vesiculosum), 3.2 t for ‘Antas’ and ‘Woogenellup’ sub clovers (T. subterraneum), 1.6 t for ‘Kopu’ white clover (T. repens) and 1.2 t for ‘Relish’ red clover (T. pratense). ‘Arrotas’ grew 111 kg DM/ha/d from 14th to 28th August, ‘Viper’ grew 123 kg DM/ha/d from 28th August to 24th September and then 183 kg DM/d to 9th October. After a dry autumn in 2020, ‘Kopu’ white and ‘Relish’ red persisted, but only sub clovers ‘Napier’ and ‘Woogenellup’ successfully re-established. By 17th September, accumulated dry matter yield (t) differed with ‘Woogenellup’ sub (4.3) and ‘Relish’ red (3.7) producing more than ‘Kopu’ white  (2.8) and ‘Napier’ sub (2.2). ‘Woogenellup’ sub clover grew at 72 kg/ha/day from 20th August to 17th September, which was more than twice the rate of the other clovers (~30 kg/ha/day). These four clovers continued to provide grazable herbage through the second year. In 2020 the re-establishment of arrowleaf, balansa and Persian (T. resupinatum) clovers was poor, and each yielded <0.5 t/ha by 17th September, with their plots dominated by weeds. These results confirm monocultures of top flowering annual clovers are productive in their first year but poor re-establishment may occur in their second year. They may therefore be best suited as one-year specialised crops for grazing or conserved feed. The earlier growth profiles of the annual compared with perennial clovers suggests there is potential to increase their use in summer dry environments to meet early spring feed requirements of ewes and lambs.

The ‘Red Flats’ on Omarama Station in the Mackenzie Basin, has a winter cold, summer dry environment and soils with low plant available water (<60 mm in the top 1 m), and low pH(H2O) (5.2) and high aluminium (8 mg/kg) below 75 mm. The site received 3 t of lime, 300 kg sulphur-super, boron (B), molybdenum (Mo) and herbicides to eliminate hieracium (Hieracium pilosella). Twelve cultivars of subterranean clover (Trifolium subterraneaum), ‘Bolta’ balansa clover (T. michelianum), and perennial ‘Rossi’ red clover (T. pratense), were direct-drilled in February 2016. Over the next 3 years their frost tolerance, productivity and persistence were compared with the resident haresfoot clover (T. arvense). Balansa and the subterranean clovers all survived the 2016 and 2017 winters. The subterranean clovers maximum yield was 4.3 t DM/ ha after successful germination in February 2016 when sufficient rain extended the spring growing season into November. Subterranean clover cultivars from subspecies subterraneum yielded well in 2016, averaging 3.3 t DM/ha, as did the brachycalycinum ‘Antas’ with 3 t DM/ha. During the short season of 2017, the subterraneum ssp. cultivars ‘Denmark’ and ‘Karridale’ established the highest ground covers and ‘Antas’ the lowest. In 2018, ‘Antas’ had the lowest emergence rate and autumn yield. ‘Karridale’ had the highest re-establishment rate and the yanninicum ‘Trikkala’ the highest autumn yield (1.3 t DM/ha). Cultivars with low hardseededness ratings were the most successful at re-establishment in autumn 2017. Balansa clover was also persistent. In the favourable 2016 growing season the late-flowering resident haresfoot clover grew into early summer and yielded 3.7 t DM/ha. Red clover yielded 1 t DM/ha in 2016, but did not persist. Results suggest that medium-late flowering softer seeded subterranean clover cultivars and ‘Bolta’ balansa clover, are suitable for this environment.

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