Urine patches from grazing ruminants contain high concentrations of nitrogen (N) and are the main source of N leaching from grazed pastoral farming systems. While there have been various options identified to substantially reduce N leaching, in general these practices increase the cost of production or reduce production per hectare. In New Zealand, multi-species pastures were evaluated as a cheaper option that would potentially retain productivity. Early research showed these pastures had lower urinary N excretion from grazing animals and increased plant N uptake, compared with standard New Zealand perennial ryegrass/white clover (PR-WC) pastures. Further research highlighted the beneficial attributes of the pasture herb narrow-leaved plantain (Plantago lanceolata; PL), specifically: reduced urine N concentration, reduced urine N excretion, and reduced rate of soil nitrification. Significant reductions (14%-89%) in N leaching were found from cow urine applied to lysimeters with pastures including PL, compared with PR-WC pasture. Paddock-scale measurements confirmed the effects of PL, with 20%-60% lower N leaching when PL comprised 30%-40% of the dry matter (DM) of PL-PR-WC grazed pastures. There were no negative effects on milk production and composition when feeding PL to dairy cows, but small positive effects on fatty acid profiles. However, weed and pest management, palatability and persistence remain challenging in pastures containing PL on commercial farms. Management options need to be clarified to ensure successful establishment and maintenance of PL. Additionally, the cultivar differences in secondary compounds and their impact on nitrification rate and N leaching need to be better understood.

Maintaining and improving the health of pastoral soils is important to enable the provision of ecosystem services for sustainable production. We investigate the impacts of increasing pasture species diversity and reducing nitrogen (N) fertiliser inputs on pasture productivity and the flow on effects for soil health on four irrigated dairy farms in Canterbury. The soils had generally good health prior to pastures being resown. During the establishment of both simple and diverse pastures there was a decline in Olsen P, soil organic carbon (C), total N and potentially available N to below target levels. In the year following pasture establishment there was no difference in herbage accumulation between the simple and more diverse pastures under irrigation. For both simple and diverse pastures, grass species contributed approximately 50%, legumes 15%, and herbs 20% of the total dry matter harvested. Although there was a reduction in pasture growth as N fertiliser inputs were reduced, legume content did not decline significantly and differences in soil health were not observed at this stage. Despite the farms being intensive dairy systems, the data suggests good soil health prior to pasture establishment. Hence maintaining soil health as well as its restoration following disturbance present opportunities for these farms.

Pastures represent about half of the global agricultural area and productivity losses from weeds are significant. The complex interactions between them and other pasture plants, livestock and the environment imply a need for innovative research that transforms pasture management. To this end, a horizon scan was conducted to identify relevant issues, questions, opportunities, and drivers. The drivers were ranked using three criteria: (1) is this a horizon (is the driver likely to become important in 10-20 years?); (2) will the research require stretchy science (is it currently not well addressed by the science community?); (3) is the research transformative (will successful scientific research in this area lead to significant changes to weed management in pastures?). We identified 11 major issues and 46 subordinate ones. The three highest ranked major issues were: (1) anticipated reductions in access to herbicides; (2) rethinking weed management under an ecosystem services paradigm; (3) responding to shifts in best practice and the regulations that are altering farm system planning to reduce farming's environmental impacts. We conclude that fundamental interdisciplinary research is needed that addresses biosecurity and weed management issues, while reducing the environmental footprint of farming and maintaining productivity.

Increasing the input and turnover of root tissue is considered to be one method that may increase carbon (C) inputs and storage in soil. The use of herbicide during pasture renewal (periodic re-sowing of pasture) is expected to increase root inputs and turnover as plants die. The objective of this study was to quantify the short-term impact of pasture renewal on root turnover and C input to soil of ryegrass-clover pastures.

In the context of dairy grazing systems, pasture mixtures including tall fescue, lucerne and plantain have been identified by animal modelling as having potential to both improve milk production and reduce urinary nitrogen excretion. A grazed paddock-scale trial was established in the Waikato in September 2015 to test this in two short-term grazing trials including these species. This paper presents the pasture production, botanical composition and nutritive value data generated from four pasture mixtures sown in spring 2015 and sampled until autumn 2017 (18 months). The pasture mixtures represented a comparison between perennial ryegrass and tall fescue, with and without the herb narrow-leaved plantain. The inclusion of plantain in grass-lucerne mixtures had a positive effect on firstyear herbage dry matter (DM) production, by ~2.6 t DM/ha/year in ryegrass-based pastures and ~1.6 t DM/ ha/year in tall fescue-based pastures. Where plantain was included, the proportion of grass was reduced by more than half from autumn 2016 through to summer 2016-2017, while the proportion of lucerne was reduced to a lesser degree. The proportion of plantain was 35-70% through most of the first year, declining to

Earthworms help maintain and enhance the physical condition and function of soils. Their contribution to soil services, such as the flow of water, nutrients and gases, is influenced by earthworm abundance and diversity. In this study mesocosms with either low (dominated by epigeic Lumbricus rubellus) or high earthworm abundance and diversity (L. rubellus, Aporrectodea caliginosa and Aporrectodea Tonga) were established to explore the relationship with plant production, soil porosity and soil moisture over 444 days. Mesocosms with an abundant and diverse earthworm community had 5% more micro-pores and 70% more macropores. Volumetric soil moisture contents were consistently lower in the mesocosms with an abundant and diverse earthworm community and above-ground accumulation of plant biomass was 35-70% higher over the last 5 months of the study. There was a strong positive relationship between earthworm abundance and diversity, drainage and plant growth and negative relationship with soil moisture. The influence of earthworms on pasture growth was greatest during winter and spring, while their effect on drainage volume was more pronounced during the drier period. This work provides baseline information demonstrating how to relate earthworm abundance and diversity to soil services, and highlights the need to consider their changing influence throughout the season.

Wide-spaced trees on pastoral land (pasture-tree (PT) systems) are a widespread feature of many farmed landscapes. They offer the potential to increase carbon (C) storage, with implications for reducing atmospheric CO2-C. The effect of PT systems on soil C stocks to 1 m depth was determined for trees aged 14-16 years at densities of 73-111 stems per hectare at four North Island sites (two with poplar, two with alder). Across sites, mean soil C concentration was 1.9-8.5% and mean total soil C mass was 120-455 tonnes C/ha. For alder systems, total C mass of PT was 37% less than adjacent pasture (Open) at Poukawa (120 versus 189 tonnes C/ha), whereas at Ruakura, there was no significant difference between systems. Total C mass of PT systems involving poplar did not vary significantly from adjacent Open systems at Tikokino (328 versus 352 tonnes C/ha) and Woodville (154 versus 202 tonnes C/ha). Soil at 0.3-1.0 m depth comprised up to half of total C mass. Results suggested that poplar and alder had different effects on soil C. Keywords: pastoral hill country, wide-spaced trees, carbon sequestration, greenhouse gas (GHG) mitigation

Pastoral hill lands deliver a range of contaminants to receiving environments that are of concern to the wider sector stakeholder community: principally sediment, phosphorus, nitrogen and faecal microorganisms. Thermal energy may also be considered a contaminant. Pastoral waterways generally have higher concentrations of suspended sediments, nutrients, faecal micro-organisms, and water temperature relative to forested waterways. These effects can be quantitatively linked to animal stocking rates and management. The large variation in the micro-climates, parent materials, soil types and vegetation resources inherent in hill country is the major driver of spatial and temporal dynamics of contaminant losses. This variation is modified by animal behaviour and physiology. Stores of contaminants in surface or sub-surface flow paths create important temporal lags resulting from land use and management change. The concept of critical source areas has become a key focus for the development of mitigation options. A wide range of biophysical options are now available, covering multiple scales and levels of cost-benefit. The use of farm planning tools is critical in balancing the implementation of mitigations with farm system objectives to improve whole-system sustainability. More research is needed on long-term impacts, given spatial and temporal variation in drivers and known spatial and temporal lag effects. There will be ongoing demand for mitigations that have been developed through co-innovation processes. Keywords: environmental mitigations, erosion, hill country, nutrient loss, pastoral, sediment export

Land use and management change is a feature of New Zealand farm systems, driven by a range of factors including volatile markets and exchange rates, variable weather and climate patterns, continuous policy evolution and the inherent innovation of New Zealand farmers. Yet the common indicators used to evaluate the impact of change appear to be limited to the link between productivity (of land/labour/capital) and profitability. However, if farm system "owners" seek truly sustainable systems they should consider a wider set of indicators to guide investment. Sustainability is considered in terms of the ability of the pastoral farm system to fulfil its primary purpose in the long-term, i.e. "to derive value from the natural capital of a land and water resource that is sufficient to support the objectives of the resource owner" and fulfil secondary objectives considered important by other stakeholders (e.g., product and environmental quality). The objective of this study was to develop an integrated assessment framework for sustainability indicators that was useful for guiding change decisions at the farm system scale, a key determinant of regional economic, environmental and social outcomes. The approach is based on the fundamental properties of a complex adaptive system: existence, effectiveness, freedom of action, security, adaptability and coexistence, applied to six key system drivers (financial, environmental, social, cultural, technological and regulatory). This framework could support decision-making in terms of the investment of human, natural and financial capital at the farm system scale and contribute to larger scale information imperatives (e.g., value chains, catchments). Keywords: integrated assessment, pastoral farm systems, sustainability, systems properties

The potential animal performance and greenhouse gas (GHG) abatement benefits from pastures and wide-spaced poplars on a typical lower-North Island sheep and beef farm operation were explored using farm-scale models. The analysis included reductions in understory pasture production, increased ewe reproductive performance (i.e., lambing and weaning percentage) with additional tree shelter and increased dry matter intake from poplar foliage. The pasture-tree systems demonstrated reductions in sheep stocking rates and total meat production, but increases in ewe efficiency and emissions intensity, reflecting a shift in feed energy use from maintenance to production. Inclusion of ewe fecundity and supplementary feed benefits largely overcame reductions in stocking rate and meat production due to pasture shading. An integrated assessment of the multiple benefits of pasture-tree systems should be incorporated in future farming scenario testing, strengthening our knowledge on the impacts of these systems compared with pastureonly systems. Keywords: pasture-tree systems, animal performance, greenhouse gas emissions.

A strategy to increase soil C under pasture-based systems is to increase the root mass inputs or increase rooting depth of plants. Our objective in this study was to measure the seasonal dynamics of root mass and C inputs under two different pasture types (ryegrass-clover vs moderately diverse) that differ in plant diversity and which are commonly used in New Zealand agriculture.

Development of mānuka (Leptospermum scoparium) and gorse (Ulex europaeus) is a widespread problem on pastoral hill country and is associated with reduced fertiliser inputs and grazing pressures. Using mānuka as a source for specialty products offers a potentially new, profitable enterprise alongside livestock and forestry. However, there is a lack of quantitative information on the optimum soil nutrient status and associated fertiliser programme to encourage presence and growth of this species. In a survey across 324 grazed sites, mānuka had greatest presence on steep slopes (>25o) and soils with Olsen P

Summary The effect of different earthworm functional groups on the incorporation of maize ( C4 plant) dung into a soil ( C3 organic matter background) sown with ryegrass ( C3 plant) was explored by using differences in the carbon ( C ) isotope ratios ( 12 C and 13 C ) between plant and soil samples in a field mesocosm study. The abundance of earthworms increased with dung inputs, reaching over 4000 earthworms per m 2 , presumably because of the increased food resources used. The amount of dung C incorporated into the soil profile in the presence of earthworms was dependent on the amount of organic matter deposited on the soil surface (925–4620 g C m −2 ) and reached rates of 1200 g C m −2 annually in the treatment receiving repeat dung applications. Dung incorporation was largely concentrated in the surface 0–75 mm, although small amounts of dung‐derived C were observed to a depth of 300 mm. This was especially so in the presence of anecic earthworms, equating to an extra 70 g C m −2 annually for the 150–300 mm depth increment. It is important to note, in calculating C incorporation rates from earthworms, that only 10–20% of the soil surface in grazed pastures is covered by dung. After 444 days, less than 32% of the applied dung was detected within the upper 300 mm of the soil profile. This study emphasized the need for all three earthworm functional groups to be present within the soil in order to maximize the amount of surface dung that could be incorporated into soil organic matter.

We conducted two field experiments to examine the potential of three methods to detect simulated animal urine patches after deposition, by means of soil electrical conductivity (EC) measurements, ammonia (NH3) volatilisation measurements and soil surface temperature measurements (infrared imaging). All three techniques were successful at distinguishing simulated urine patches from non-patch areas, over varying periods of time post-deposition. Electrical conductivity measurements were effective for at least 7 days, NH3 volatilisation measurements were effective for at least 3 days, and thermal measurements were effective for up to 140 minutes, under the ambient experimental conditions (soil surface temperatures of ~14°C and soil moisture ~40%). Further experimentation could usefully explore the range of conditions (soil type, pasture cover, moisture and temperature) under which this effectiveness extends. Practical considerations in the application of these approaches will dictate their utility.

We describe a bio-economic model for Nassella neesiana (Chilean needle grass) that estimates the net benefit of a containment programme for the weed in Canterbury as the difference between the cost of containment and the costs incurred over time should the weed spread within sheep and beef pastoral systems. Logistic spread is assumed with the maximum area that could be invaded (772,080 ha) determined by constraining a climate niche model for the weed to susceptible farm system types within productive land use capability classes. The current size of the invaded area (80 ha) was determined by field observations in Canterbury in 2008, and the spread rate (201 years to 90% saturation) was derived from observations in the adjacent Marlborough region. With these assumptions, and discounting at 8% per year over 100 years, the net benefit is negative NZ$173,178 ($83,900–$257,078) and containment would not be economically worthwhile. However, the net benefit is positive over a range of lower discount rates and higher spread rates, revealing a need for robust estimates of these parameters. The model presented here provides a generic blueprint for meeting the requirements of the Biosecurity Act with respect to evaluating proposed regional weed management programmes.

Anecic earthworms have the ability to incorporate carbon (C) from the surface to depth in the soil. This study aimed to quantify the rate of spread of Aporrectodea longa, and their influence on the amount of C stored, in two contrasting soils where this earthworm was introduced in the 1980s. The rate of spread of A. Longa at both sites (5.3-12.5 m/y) is similar to endogeic species. Over several decades there was a decrease in soil C in the presence of A. longa in the Pallic soil (78 912 vs. 85 796 kg C/ha for 0-300 mm) while soil C tended to increase in the Allophanic soil (141 845 vs. 111 076 kg C/ha at 0-300 mm). In the Pallic soil, bulk density tended to be lower in the presence of anecic earthworms at 150-300 mm depths and may have encouraged the decomposition of more stable C. Further, the interaction with higher abundances of endogeic earthworms and lower organic matter inputs in the Pallic soil than the Allophanic soil may help explain the lower soil C in the Pallic soil. The conflicting results in the two soils highlight the influence of the earthworm community and soil properties on C dynamics. (C) 2014 Elsevier Masson SAS. All rights reserved.

The capacity of a soil to sequester organic carbon can, in theory, be estimated as the difference between the existing soil organic C (SOC) concentration and the SOC saturation value. The C saturation concept assumes that each soil has a maximum SOC storage capacity, which is primarily determined by the characteristics of the fine mineral fraction (i.e. <20 µm clay + fine silt fraction). Previous studies have focussed on the mass of fine fractions as a predictor of soil C stabilisation capacity. Our objective was to compare single- and multi-variable statistical approaches for estimating the upper limit of C stabilisation based on measureable properties of the fine mineral fraction [e.g. fine fraction mass and surface area (SA), aluminium (Al), iron (Fe), pH] using data from New Zealand’s National Soils Database. Total SOC ranged from 0.65 to 138 mg C g−1, median values being 44.4 mg C g−1 at 0–15 cm depth and 20.5 mg C g−1 at 15–30 cm depth. Results showed that SA of mineral particles was more closely correlated with the SOC content of the fine fraction than was the mass proportion of the fine fraction, indicating that it provided a much better basis for estimating SOC stabilisation capacity. The maximum C loading rate (mg C m−2) for both Allophanic and non-Allophanic soils was best described by a log/log relationship between specific SA and the SOC content of the fine fraction. A multi-variate regression that included extractable Al and soil pH along with SA provided the “best fit” model for predicting SOC stabilisation. The potential to store additional SOC (i.e. saturation deficit) was estimated from this multivariate equation as the difference between the median and 90th percentile SOC content of each soil. There was strong evidence from the predicted saturation deficit values and their associated 95 % confidence limits that nearly all soils had a saturation deficit >0. The median saturation deficit for both Allophanic and non-Allophanic soils was 12 mg C g−1 at 0–15 cm depth and 15 mg C g−1 at 15–30 cm depths. Improving predictions of the saturation deficit of soils may be important to developing and deploying effective SOC sequestration strategies.

Ecological studies often suggest that natural grasslands with high species diversity will grow more biomass and leach less nitrogen (N). If this diversity effect also applies to fertilised and irrigated pastures with controlled removal of herbage, it might be exploited to design pastures that can assist the dairy industry to maintain production while reducing N leaching losses. The purpose of this study was to test whether pasture mixtures with a high functional diversity in ryegrass traits will confer on the system higher water- and N-use efficiency. The hypothesis was tested using a process-based model in which pasture mixtures were created with varying levels of diversity in ryegrass traits likely to affect pasture growth. Those traits were: the winter- or summer-dominance of growth, the ability of the plant to intercept radiation at low pasture mass, and rooting depth. Pasture production, leaching and water- and N-use efficiency were simulated for management typical of a dairy pasture. We found that the performance of the diverse ryegrass–clover mixtures was more strongly associated with the performance of the individual components than with the diversity across the components. Diverse pasture mixtures may confer other benefits, e.g. pest or disease resistance and pasture persistence. The testing here was within a selection of ryegrasses, and the greater possible diversity across species may produce different effects. However, these results suggest that highly performing pastures under fertilised and irrigated grazed conditions are best constructed by selecting components that perform well individually than by deliberately introducing diversity between components.