Hill Country Pastures Research Articles

Multi-year performance of white clover oversown into eastern North Island hill country

Animal performance on summer-dry North Island hill country pastures is limited by soil fertility and the challenge of establishing and retaining a strong legume base in swards on steeper slopes. However, this can be overcome by 1. selecting legume species adapted to the various slope, aspect and soil type combinations; and 2. following well-recognised establishment and management techniques developed in the 1980s. We broadcast white clover in two large southerly aspect paddocks on Tangihanga Station, Gisborne, in the autumn of 2019. Establishment methods involved resident pasture control by hard grazing and selective herbicide to supress dominant low-fertility grasses, broadcasting at high sowing rates and trampling of seed with sheep. We followed white clover persistence and animal performance over the subsequent 5 seasons of rotational cattle grazing with heifers and steers, in comparison with adjacent unsown paddocks. The cost of establishment was c. $220/ha. White clover abundance remained high throughout the 5 years, between 25-40% of cover, compared with 7-17% in unsown paddocks. This increase in clover content of the pastures translated into both increased stocking rates and per head growth rates, with overall annual LWG increasing by 67-169% depending on season. The investment was paid back within the first year.

The effects of pastoral hill country natural landscape features and land management practices on nitrate losses and its potential attenuation for improved water quality

AbstractPastoral farming on hill country landscapes influences nitrogen (N) dynamics and its losses to freshwater. This study reviewed the current literature identifying key effects of pastoral hill country landscape features and land management practices on nitrate losses to receiving waters. The review also highlighted the potential effects of inherent landscape features on nitrate attenuation pathways for better water quality outcomes. Intensive land use activities involving high rates of fertiliser application, higher stocking rates and cattle grazing, relative to sheep grazing, are more likely to increase nitrate loss, especially on lower slopes. However, soils with a high carbon (C) storage capacity such as allophanic soils potentially limit nitrate loss via denitrification in subsoil layers. Hill country seepage wetlands also offer an opportunity to attenuate nitrate loss, though their efficacy is largely impacted by hydrological variations in their inflows and outflows. By enhancing the natural nitrate attenuation capacity of seepage wetlands, mapping and strategic use of high subsoil denitrification potential, effective riparian management, efficient fertiliser and grazing practices and the incorporation of these farm management strategies into Freshwater Farm Plans (FWFPs), wider environmental and farm productivity/profitability goals, including improved water quality, would be achieved on pastoral hill country landscapes.

Potential for biocontrol of Silybum marianum (variegated thistle): 1. Survey of natural enemies in New Zealand

ABSTRACT Silybum marianum (L.) Gaertner (variegated thistle, milk thistle) is one of the worst weeds of hill country pasture in the east coast regions of New Zealand. As part of an initial investigation into the potential for biocontrol, a survey of the phytophagous insects associated with S. marianum in New Zealand was carried out at 16 populations from 29 November to 16 December 2021. Phytophagous associations were determined by collecting insects on the plant and by seedhead dissections. The species collected were grouped into three categories: ‘specialists’, ‘generalists’, and ‘tourists’ that comprised 27.4%, 66.3%, and 6.3% of the total number of specimens collected, respectively. The specialist group was almost entirely comprised of the seedhead weevil, Rhinocyllus conicus (Frölich). While adults of R. conicus were commonly collected on variegated thistle, only 6.5% of seedheads contained larvae of the weevil, indicating that S. marianum is not a common developmental host. Generalist species commonly collected on S. marianum included: Nysius caledoniae Distant, Rhypodes clavicornis (F.), Closterotomus norwegicus (Gmelin) and Nezara virdula (L.). Overall, the field surveys document low levels of attack from generalist herbivores and minimal attack by the specialist weevil, R. conicus. Vacant niches are present on the weed in New Zealand, providing a strong case for introducing specialised biocontrol agents.

Potential for biocontrol of Silybum marianum (variegated thistle): 2. Literature search and prioritisation of biocontrol agents

ABSTRACT Silybum marianum (L.) Gaertner (variegated thistle, milk thistle) is one of the worst weeds of hill country pasture in the east coast regions of New Zealand. A recent field survey in New Zealand found low levels of attack from generalist herbivores and minimal attack by the specialist weevil, Rhinocyllus conicus (Frölich). In the native range of Europe there are at least 41 insects and 12 fungi sufficiently specialised to be considered for biocontrol. The literature search revealed some potential biocontrol agents not known during the historical biocontrol surveys for S. marianum. These include the specialised biotypes of the tephritid fly, Terellia fuscicornis Loew, and the seedhead weevil, Larinus latus Herbst. The literature search also revealed the discovery of the stem-galling cynpid wasps, Aulacidea freesei Nieves-Aldrey and Phanacis zwoelferi Nieves-Aldrey, that are likely specific to S. marianum. The discovery of the smut fungus, Microbotryum silybum Vanky & Berner, host specific to Silybum species, is another promising biocontrol candidate. A shortlist of nine priority agents (eight insects and one fungal pathogen) were selected based on reported affinity for S. marianum, evidence for impact on the weed, and niches attacked. In the case of S. marianum, there are sufficiently specialised agents that attack several niches, including seeds, stems, and the root or root collar. Testing for complementary agents that attack different niches is likely to improve the chance of successful biocontrol. It is recommended that S. marianum be considered a priority target for classical biocontrol in New Zealand.

Biocontrol of St John’s wort (Hypericum perforatum) provides huge ongoing benefits to New Zealand agriculture

ABSTRACT An ex-post economic evaluation of biocontrol of St John’s wort (SJW), Hypericum perforatum, in New Zealand (NZ), used ecological niche modelling, GIS-mapped land-use vulnerabilities and a logistic equation to predict that SJW could have infested 660,000 ha of low-value hill-country pasture. To calculate productivity losses, we assumed serious infestations of SJW caused 30% decreases in farm income per hectare. Investment in SJW biocontrol totalled NZ$0.28 million (2022 rates) associated with the 1943–1992 releases of the chrysomelid beetles, Chrysolina hyperici and C. quadrigemina, and the cecidomyiid gall midge, Zeuxodiplosis giardi. Biocontrol effectiveness increased linearly in our model from 1943 (when initial local defoliation occurred) to reach 99% control nationwide by 1993 (when SJW was no longer considered a significant agricultural weed). We estimate that SJW biocontrol in NZ provided a national benefit of NZ$15.5 million in 2022, with a historical benefit–cost ratio of 6254:1. Both figures remained large in sensitivity testing. Uncertainties remain concerning whether biocontrol caused all reductions in SJW, or whether SJW infestations were partially replaced by other weeds. Despite such caveats, benefits of SJW biocontrol to NZ appear huge and sustainable.

Analysis of Poplar’s (Populus nigra ita.) Root Systems for Quantifying Bio-Engineering Measures in New Zealand Pastoral Hill Country

Populus nigra ita. is an important tree species for preventing rainfall-triggered shallow landslides and hydraulic bank erosion in New Zealand. However, the quantification of its spatial root distribution and reinforcement remains challenging. The objective of this study is to calibrate and validate models for the spatial upscaling of root distribution and root reinforcement. The data were collected in a 26-year-old “Tasman” poplar stand at Ballantrae Hill Country Research Station in New Zealand. We assessed root distribution at different distances from the stem of four poplar trees and from eleven soil pits along a transect located in a sparse to densely planting poplar stand. 124 laboratory tensile tests and 66 field pullout tests on roots with diameters up to 0.04 m were carried out to estimate root mechanical properties. The results show that the spatial distribution of roots can be well predicted in trenches of individual tree root systems (R2 = 0.78), whereas it tends to overestimate root distribution when planting density was higher than 200 stems per hectare. The root reinforcement is underestimated within single tree root systems (R2 = 0.64), but it performs better for the data along the transect. In conclusion, our study provided a unique and detailed database for quantifying root distribution and reinforcement of poplars on a hillslope. The implementation of these models for the simulation of shallow landslides and hydraulic bank erosion is crucial for identifying hazardous zones and for the prioritization of bio-engineering measures in New Zealand catchments. Results from this study are useful in formulating a general guideline for the planning of bio-engineering measures considering the temporal dynamics of poplar’s growth and their effectiveness in sediment and erosion control.

Total annual and seasonal DM production of improved and unimproved resident pastures at three farms in Canterbury

Yield differences between resident and improved pastures were quantified over a 3-4 yr period on three rainfed farms located in North Canterbury (Stockgrove, north of Amberley), Banks Peninsula (Willesden Farm) and the Mid-Canterbury foothills (Inverary Station). Improved pastures produced two- to three-times more feed annually than unimproved resident pastures at each property. At Stockgrove, improved chicory/white clover-based pastures produced 14.1±0.66 t DM/ha/yr compared with 4.36±0.41 t DM/ha/yr from unimproved pastures. Spring accounted for 85% (improved) and 72% (unimproved) of total annual DM production. At Willesden, lucerne monocultures produced 11.5±0.97t DM/ha/yr, which was more than the 4.44±0.45 t DM/ha/yr produced from resident pastures. Improved pastures at Inverary yielded 7.31±0.59 t DM/ha in summer/autumn of 2018/19, which was more than double the 3.34±0.43 t DM/ha from unimproved pastures. In 2019/2020, improved pastures produced 11.7±1.45 t DM/ha compared with 4.45±0.73 t DM/ha. In the third growth season (2020/2021) improved pastures produced 14.1±1.76 t DM/ha compared with 6.67±1.38 t DM/ha from unimproved pastures. In Year 4 (2021/22) the 12.6±1.29 t DM/ha from improved pastures was 56% more than the 8.07±0.85 t DM/ha from the unimproved pastures. Substantial increases in annual and seasonal feed supply patterns can be achieved through hill country pasture improvement.

Total annual and seasonal DM production of improved and unimproved resident pastures at three farms in Canterbury

Yield differences between resident and improved pastures were quantified over a 3-4 yr period on three rainfed farms located in North Canterbury (Stockgrove, north of Amberley), Banks Peninsula (Willesden Farm) and the Mid-Canterbury foothills (Inverary Station). Improved pastures produced two- to three-times more feed annually than unimproved resident pastures at each property. At Stockgrove, improved chicory/white clover-based pastures produced 14.1±0.66 t DM/ha/yr compared with 4.36±0.41 t DM/ha/yr from unimproved pastures. Spring accounted for 85% (improved) and 72% (unimproved) of total annual DM production. At Willesden, lucerne monocultures produced 11.5±0.97t DM/ha/yr, which was more than the 4.44±0.45 t DM/ha/yr produced from resident pastures. Improved pastures at Inverary yielded 7.31±0.59 t DM/ha in summer/autumn of 2018/19, which was more than double the 3.34±0.43 t DM/ha from unimproved pastures. In 2019/2020, improved pastures produced 11.7±1.45 t DM/ha compared with 4.45±0.73 t DM/ha. In the third growth season (2020/2021) improved pastures produced 14.1±1.76 t DM/ha compared with 6.67±1.38 t DM/ha from unimproved pastures. In Year 4 (2021/22) the 12.6±1.29 t DM/ha from improved pastures was 56% more than the 8.07±0.85 t DM/ha from the unimproved pastures. Substantial increases in annual and seasonal feed supply patterns can be achieved through hill country pasture improvement.

Grasses procure key soil nutrients for clovers.

Rhizobial nitrogen fixation in legumes provides spillover benefits to neighbouring plants such as pasture grasses. Generally, it is understood to be unidirectional between plant functional groups, providing a benefit from legumes to grasses. We question whether bidirectional complementarity also exists in terms of exploiting the wider soil nutrient pool. We test this hypothesis using soil cores with their component vegetation assemblages sampled from a hill country pasture in South Island, New Zealand. The soil was deficient in key essential elements: P, S, B, Mo and Ni. Facilitation from grasses to clovers was evident; legume-grass mixtures procured more nutrients from the soil than when either species was growing alone. When grasses and clover grow together in unfertilized grassland, more nitrogen is procured by the plant community, and other limiting plant nutrients in the soil are better exploited. Coexistence with grasses is favourable to clovers in terms of soil biogeochemistry.

Meat quality of beef-cross-dairy cattle from Angus or Hereford sires: A case study in a pasture-based system in New Zealand

Meat quality of beef-cross-dairy cattle born in the dairy industry and finished on hill-country pastures is not well characterised. This experiment aimed to objectively evaluate meat quality traits of 15 Angus and 18 Hereford sires via progeny testing of their 326 beef-cross-dairy offspring, and to compare the intramuscular fat (IMF) percentage with the AUS-MEAT marble scores. Beef-breed sires had similar and overall good objective meat quality characteristics. Ultimate pH was not affected by sire (P > 0.05). The differences among sires in meat quality (fat yellowness b*, meat redness a*, yellowness b* and chroma C*, cook loss and shear force, P < 0.05) were small and all values were within the normal range for beef. Marble scores could capture the variation of IMF at marbling score 1–3, but was not effective to distinguish between 0 and 1. In conclusion, the effect of sire on the meat quality of the beef-cross-dairy progeny in this study was of minor importance.

Sheep dung disappearance from grazed hill country landscapes

Two experiments were conducted to examine the effects of biological (composition and site history) and topographic (slope and aspect) factors affecting sheep dung disappearance rates in hill country pastures. We used three of the farmlets that have been receiving 0 (NF), 125 (LF) or 375 (HF) kg of single superphosphate (SSP)/ha since 1980) from the long-term phosphorus fertiliser trial at Ballantrae. Experiment one examined the effect of farmlet, slope (low and medium slope class), and aspect (E, SW, NW), whereas Experiment two examined the effect of farmlet, both as a source of dung (from LF or HF farmlets) and as a site in the landscape (on LF or HF farmlets). In both experiments, disappearance of dung followed a quadratic curve, and no improvements were made using higher-order polynomials. Despite a lower fibre concentration, dung from sheep grazing the HF farmlet did not disappear at a faster rate than dung from the other farmlets, but soil activity in situ (placement) was pivotal to the rate of dung disappearance. A faster rate of dung disappearance on the HF farmlet is consistent with a greater capacity for turnover of plant biomass and animal excreta in this high fertility environment. These experiments contribute to our understanding of the influence of biological and topographic drivers of dung disappearance rates, and enable further advances to be made in the modelling of nutrients in these topographically complex agroecosystems.

Estimated Breeding Values of Beef Sires Can Predict Performance of Beef-Cross-Dairy Progeny.

On average, half of the animal’s estimated breeding value (EBV) is passed on to their progeny. However, it is not known how the performance of beef-cross-dairy cattle relates to the EBV of their beef sire. Such information is required to determine the genetic potential of beef sires selected based on existing EBV to be used on dairy cows in New Zealand. This study evaluated the relationship between the EBV of 30 Angus and 34 Hereford sires and the performance of their progeny for birth, growth, and carcass traits, via progeny testing of 975 beef-cross-dairy offspring born to dairy cows and grown on hill country pasture. Overall, BREEDPLAN EBV did predict progeny performance of the beef-cross-dairy cattle from this study. Gestation length and birthweight increased with increasing sire EBV (mean 0.37–0.62days and 0.52–0.64kg, respectively, p<0.05). Age at weaning decreased with increasing sire EBV for liveweight at 200days (0.17–0.21days per extra kilo of sire EBV, p<0.05) but sire EBV for liveweight at 200days had no effect on the liveweight of the progeny at 200days for either breed (p>0.05). Liveweight increased with sire EBV for liveweight at 400, 600, and 800days, by a similar amount for both breeds (between 0.23 and 0.42kg increase in progeny liveweight per extra kilo of sire EBV, p<0.05). The relationships were more inconsistent for carcass traits. For Hereford, carcass weight and eye muscle area increased with increasing sire EBV (0.27kg and 0.70cm2, respectively, p<0.05). For Angus, marble score increased by 0.10 with 1% extra in sire EBV for intramuscular fat (p<0.05). Rib fat depth tended to increase with sire EBV for both breeds (p<0.1). EBV derived from beef-breed data work in dairy-beef systems but maybe slightly less than the expected 0.5units of performance per unit of EBV. New Zealand farmers should consider BREEDPLAN EBV when selecting sires to mate dairy cows or when buying beef-cross-dairy calves for beef production, to ensure the resulting calves are born safely and on time and then grow well to produce carcasses of suitable meat and fat composition.

The resilience of soil organic carbon stocks under contrasting hill country pasture management practices

In 2020 we measured the stability of soil organic carbon (SOC) concentrations and stocks under contrasting hill country pasture regimes, by sampling three slope classes and three aspect locations on each of three farmlets of a long-term phosphorus fertiliser and sheep grazing experiment. The farmlets included no annual phosphorus (NF), 125 kg of single superphosphate/ha (LF), or 375 kg superphosphate/ha (HF) that has been applied on an annual basis since 1980. Results from the 2020 sampling event were added to previous results reported from soil samples collected in 2003 and 2014. The SOC concentrations in the topsoil (0-75 mm depth), ranging from 4.23 to 5.99% across all slopes and aspects of the farmlets, fell within the normal range (≥3.5 and &lt;7.0%) required for sustaining production and environmental goals. A trend was shown for greater SOC stocks in the topsoil in the HF farmlet (34.0 Mg/ ha) compared with the other two farmlets (31.6 Mg/ha), but this trend was not evident in the deeper soil layers (75-150, 150-300, 0-300 mm). Under the current conditions, topographical features such as slope and aspect had a more profound influence on SOC stocks than management history.

Resident hill country pasture production in response to temperature and soil moisture over 20 years in Central Hawke’s Bay

The production of resident pastures on rolling hill country was measured in three paddocks over 20 years at Poukawa in Central Hawke’s Bay. The pastures had been routinely fertilised with 250 kg/ha/yr of superphosphate but no pasture renovation, nor nitrogen fertiliser application, occurred during the measurement period. Total annual dry matter (DM) yield ranged from 4.5 to 12.8 t/ha/yr, which shows the level of variability to be expected in this summer-dry environment. The greatest proportion (60-90%) of growth occurred in winter/spring with consistent mean growth rates of 50-62 kg DM/ha/d in September and October. These rates were calculated to be 5.49±0.55 kg DM/ha/°Cd when spring moisture was non-limiting. The pastures had a mean water use efficiency of 16.9±0.34 kg DM/ha/mm of water available (R2 = 0.93). The amount of water available was calculated from a soil water budget based on a plant available water holding capacity of 124 mm (0-1.0 m depth). The results provide coefficients that can be combined with readily available climate data to predict pasture growth rates for feed budgeting purposes. Rainfall data collected on-site was highly correlated (r=0.94) with that predicted from the NIWA virtual climate station network.

Dissolved Organic Carbon Concentration and Denitrification Capacity of a New Zealand Hill Country Soil After Forage Crop Establishment

Conversion from perennial pasture to forage cropping to increase animal feed production is widely adopted on steep pastoral hill country landscapes in New Zealand. However, the effect of this conversion on the leaching and availability of dissolved organic carbon (DOC) and soil denitrification is unknown. This study examined the effect of a forage crop (swede—Brassica napobrassica Mill.) establishment on the DOC concentration and denitrification capacity of a hill country soil (Typic Eutrudept) in the lower North Island of New Zealand. Pasture was cleared using selected agrochemicals and sown to swede via a unique surface sowing technique (no cultivation). Soil was sampled once before and multiple times after crop establishment. The sampled soils were compared to soils from adjacent pasture plots. The results suggest that DOC concentration in the subsoil (> 30 cm) and denitrification capacity of the soil profile (100 cm) were generally not affected by the establishment of the forage crop within a 1-year period, without animal grazing. However, forage crop establishment resulted in an initial increase (by > 55%) in the nitrate concentration of the surface 20 cm soil depth on the sixth month after crop establishment. However, the subsoil (> 20 cm) nitrate concentrations in the cropped system were similar to the pasture system. This suggests that the establishment of the brassica forage crop, using the surface sowing technique, did not pose a risk of increased nitrate leaching from this pastoral hill country soil.

Quantifying the influence of individual trees on slope stability at landscape scale

Silvopastoralism in New Zealand's highly erodible hill country is an important form of erosion and sediment control. Yet, there has been little quantitative work to establish the effectiveness of space-planted trees in reducing shallow landslide erosion. We propose a method to provide high-resolution spatially explicit individual tree influence models at landscape scale for the dominant species in pastoral hill country. The combined hydrological and mechanical influence of trees on slopes is inferred through the spatial relationship between trees and landslide erosion. First, we delineate individual tree crowns and classify these into four dominant species classes found in New Zealand's pastoral hill country. This is the first species classification of individual trees at landscape scale in New Zealand using freely accessible data, achieving an overall accuracy of 92.6%. Second, we develop tree influence models for each species class by means of inductive inference. The inferred empirical tree influence models largely agree with the shape and distribution of existing physical root reinforcement models. Of exotic species that were planted for erosion and sediment control, poplars (Populus spp.) and willows (Salix spp.) make up 51% (109,000 trees) in pastoral hill country at a mean density of 3.2 trees/ha. In line with previous studies, poplars and willows have the greatest contribution to slope stability with an average maximum effective distance of 20 m. Yet, native kānuka (Kunzea spp.) is the most abundant woody vegetation species in pastoral hill country within the study area, with an average of 24.1 stems per ha (sph), providing an important soil conservation function. A large proportion (56% or 212.5 km2) of pastoral hill-country in the study area remains untreated. The tree influence models presented in this study can be integrated into landslide susceptibility modelling in silvopastoral landscapes to both quantify the reduction in landslide susceptibility achieved and support targeted erosion and sediment mitigation plans.

Sire Effects on Carcass of Beef-Cross-Dairy Cattle: A Case Study in New Zealand.

Simple SummaryCattle born in the dairy industry are a very important source of beef. This study evaluated the carcasses of cattle born to dairy cows and sired by a range of Angus and Hereford sires. Sire affected most carcass traits of their progeny, particularly size and fat traits. The heaviest sire had 46 kg greater carcass weight compared with the lightest sire, equivalent to NZ$266 greater value per progeny. Carcass fat traits (rib fat depth and marble scores) were the most variable among sires, indicating possibility of selection. Thus, using beef-breed sires chosen for greater carcass weight has the potential to increase the meat production of cattle born on dairy farms, while maintaining adequate fat levels and carcass quality to receive optimum payment.There is interest in increasing the carcass value of surplus calves born in the dairy industry that are reared for beef production in New Zealand. This experiment evaluated the carcass of Angus and Hereford sires via progeny testing of beef-cross-dairy offspring grown on hill country pasture. Weight and carcass traits were analyzed from 1015 animals and 1000 carcasses of 73 sires. The mean of the progeny group means was 567 kg for live weight at slaughter, 277 kg for carcass weight, 48.9% for dressing-out, 240.3 cm for carcass length, 73.6 cm2 for eye muscle area, 7.4 mm for rib fat depth, 0.91 for marble score, 3.05 for fat color score, 3.01 for meat color score, and 5.62 for ultimate pH. Sire affected (p < 0.05) carcass size and fat traits, but not fat color, meat color, or ultimate pH (p > 0.05). There was a 46 kg increase in carcass weight between the best and worst sires tested. Carcass fat traits were the most variable among sires. The use of genetically superior beef-breed sires over dairy-breed cows has the potential to increase carcass weights from surplus calves born in the dairy industry, while maintaining adequate fat levels and carcass quality.

Vegetation Options for Increasing Resilience in Pastoral Hill Country

Steep, uncultivable hill country below 1,000 m comprises about 40% of New Zealand's land surface area. Hill country farmers require options to increase the resilience of their farms to climatic and economic extremes while addressing soil conservation and water quality issues. We profile and discuss two options that can assist in transforming hill country. The first comprises a simple approach to grazing management in hill country pastures to increase pasture resilience and the second approach focuses on including selected forage shrubs (and trees) to create grazed pasture-shrublands. Deferred grazing, the cessation of grazing from flowering until seed dispersal of the desirable species in a pasture, is an old practice which has novel applications to improve resilience of hill country farming systems. We draw on current research and practitioner experience to demonstrate the impact of deferred grazing on the resilience of the deferred pasture and the farm system. We propose that deferred grazing will: (i) increase resilience of a pasture by enabling it to better recover from biotic and abiotic stresses and (ii) reduce the risk of nutrient and sediment losses in hill country by increasing ground cover, rooting depth and soil structural stability. Introducing woody forage shrubs into hill country pastures is another option that can improve farm profitability and resilience to current and future economic and climatic variabilities. The extensive root networks of shrubs can increase soil structural stability and reduce the risk of soil erosion. In addition, shrubs can supply many other ecosystem services, such as forage and shelter for livestock. In this paper, we discuss: (i) the potential benefits of a grazed pasture-shrubland at farm, landscape and national scales; (ii) candidate woody exotic and indigenous forage species; and (iii) priorities for research.

Sire Effects on Post-Weaning Growth of Beef-Cross-Dairy Cattle: A Case Study in New Zealand.

Simple SummaryCattle born in the dairy industry are a very important source of beef. This study evaluated the growth of calves born to dairy cows and sired by a range of Angus and Hereford bulls. The sire had effects on live weights of their progeny at all ages. Growth trajectories differed among beef sires and the differences in live weights between the lightest and heaviest sires increased as live weight increased. Live weight at early age could explain a large proportion of live weights at later ages. Thus, using beef sires selected for growth has the potential to increase the live weight of cattle born on dairy farms for meat production. Little is known about the growth performance of beef sires used over dairy cows in New Zealand. This experiment aimed to evaluate the growth of Angus and Hereford sires via progeny testing of beef-cross-dairy offspring born to dairy cows and grown on hill country pasture. Live weights at 131, 200, 400, 600 and 800 days were analysed from a dataset of 5208 records from 1101 progeny of 73 sires. The means of the progeny group means for live weight were 118.6 kg at 131 days, 159.1 kg at 200 days, 284.2 kg at 400 days, 427.0 kg at 600 days and 503.6 kg at 800 days, and the overall daily growth rate was 0.58 kg/day from 131 to 800 days. The sire affected (p < 0.05) the live weight of their progeny at all ages. Differences in live weights between the lightest and heaviest progeny group means increased from 19 kg at 131 days to 90 kg at 800 days. Even though growth of calves was likely restricted to 200 days, live weight at 200 days explained 51–56% of the variation in live weights at 400 and 600 days (p < 0.05). Thus, the use of beef sires selected for growth has the potential to increase the live weight of cattle born on dairy farms for meat production.

Soil organic carbon stocks in hill country pastures under contrasting phosphorus fertiliser and sheep stocking regimes, and topographical features

Temporal and spatial measurements of soil organic carbon (C) under grazed pastures are needed to quantify the effects of different grazing management regimes on C stocks. We examined soil organic C stocks under permanent pastures at the Ballantrae Hill Country Research Station in southern Hawke's Bay, New Zealand. Soils were sampled to three depths (0–75, 75–150, 150–300 mm) in 2003 and to the two upper depths in 2014, in three farmlets under different annual phosphorus (P) fertiliser inputs and stocked with sheep to maintain similar grazing pressure (i.e., stock units per unit of pasture production) across farmlets since 1975. The farmlets examined were NF = no annual P applied, LF = 125 kg single superphosphate (SSP) ha−1, and HF = 375 kg SSP ha−1, on an annual basis since 1980. The permanent sites included three slope classes [low slope (LS; 1–12○), medium slope (MS; 13–25○), high slope (HS; >25○)], on three different aspect locations grouped relative to the true north [east (E; 35–155○), southwest (SW; 275–35○), northwest (NW: 155–275○)]. A year-by-farmlet interaction trend on soil C stocks in the upper depth (0–75 mm) was associated with linear numerical differences in soil C stocks in 2003 (30.9, 32.5 and 35.1 Mg C ha−1 on the NF, LF, and HF farmlets, respectively) but not in 2014. This trend was not seen in the deeper soil layers (75–150 and 150–300 mm). In contrast, slope and aspect had major effects on soil C stocks. Overall, soil samples collected on the steepest slope class (>25○) resulted in higher soil bulk densities (BD) and carbon-to‑nitrogen (C:N) ratios, and lower N and C concentration, and soil C stocks at all soil depths, compared with samples collected at the other two slope classes. Soil samples collected on the NW-facing slopes resulted in higher BD, and lower N and C concentration, and soil C stocks at all soil depths, compared with samples collected at the other two aspect locations. Both of these topographic features need to be considered in soil sampling regimes of hill grazing lands to obtain an accurate estimate of organic C stocks. Data from this long-term study provide science, policy and industry with invaluable insights on soil organic C stocks in grazing hill-country soils and highlight the value of long-term structured experiments for monitoring soil C stocks. ImplicationsSequestering of organic carbon (C) in soil offers an option for offsetting C in atmospheric emissions. We examined soil C accumulation under a long-term phosphorus (P) application and sheep stocking regime grazing experiment. The hill country experiment has been running since 1975, with three distinct farmlets that received either no P, an intermediate amount or an amount that exceeds annual maintenance. Farmlet per se had a minimal impact on soil C accumulation, but slopes and aspects had a substantial impact and need to be considered in the design of soil sampling regimes that monitor soil organic carbon over space and time.