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This paper presents the results of the latest calibrations of the CLUES model for each of total nitrogen, total phosphorus and Escherichia coli. The model provides estimates of in-stream annual loads of these contaminants for every river reach in the New Zealand River Environments Classification and has been used in New Zealand for catchment planning and policy development. CLUES has been calibrated nationally against loads estimated from data collected from water quality monitoring stations located across the country which could lead to parameter bias. To ascertain whether there is any systematic bias, the calibration residuals were evaluated against regional (geographical) location and a range of upstream catchment characteristics, namely land use, soil drainage properties, slope, network order, proportion of baseflow in total stream flow, climate, geology and source of flow. We found that CLUES gives reasonable load estimates at the catchment scale (Nash-Sutcliff efficiencies >0.8 for all the contaminants). However, there was significant uncertainty in the parameterisation. While several significant relationships were found between upstream catchment characteristics and the model residuals, these relationships were weak and are unlikely to point to any systematic bias in the calibration. [ABSTRACT FROM AUTHOR]

The Paris Agreement asserts that greenhouse gas emission pathways should be consistent with holding the increase in global temperature below 1.5 °C, or 2 °C above pre-industrial levels. The purpose of this paper is to assess the economic impact of this agreement on the cattle and food product sectors of New Zealand. We used a general equilibrium approach to evaluate the economic impacts, and the Global Timber Model to estimate forestry carbon sequestration. We simulated eight scenarios where we allow accounting/not accounting for sequestration, pricing/not pricing agricultural emissions, and linking/not linking the New Zealand Emissions Trading Scheme (ETS) with the European Union ETS. We found that significant negative impacts occur if sequestration is not accounted, the ETS remains unlinked and agriculture is priced. Competitiveness, in turn, is not significantly affected if sequestration is accounted, regardless of the linking scheme of the ETS. [ABSTRACT FROM AUTHOR]

Nitrogen concentrations are increasing and causing eutrophication in many New Zealand waterways, including Lake Rotorua. Groundwater (mean age 35 to 170 years) dominates lake inflows, and nitrogen losses from farmland may take several decades to reach the lake. This study collates published agricultural statistics and estimates farm losses from 1900-2015 using the OVERSEER model. Changes in survey methods, reporting only at district scale, and uncertainty in OVERSEER mean that uncertainty in losses averages ±50%. Nevertheless, there is a clear trend of increasing nitrogen losses arising from the intensification of farming which mimics the trend in measured stream loads. From 1958 to 2015 farm losses doubled and now comprise c. 80% of lake load. OVERSEER provides a quantitative index of the changes in nitrogen losses, which in a companion paper are routed to the lake accounting for groundwater lags and attenuation. [ABSTRACT FROM AUTHOR]

The New Zealand Government’s National Policy Statement on Fresh Water Management has resulted in increased scrutiny of New Zealand grazing systems with regards to their environmental impact. With this has been greater interest in nitrogen (N) loss mitigation options, including identifying crops with high nutritive value but low protein content. New Zealand data have been collated with key data fields: publication, experiment, site and, crop details and chemical analysis. This paper discusses these data with respect to the range of nutritive values observed in these New Zealand crops and feed supplements, including the implications for reducing N leaching risk. Feeds most likely to result in less urinary nitrogen (UN) excretion, and thus less nitrate (NO3−) leaching, include fodder beet, swedes, turnips, barley and wheat grain. The high soluble sugar and starch content of these feeds will support high animal production but may increase the risk of nutritional disorders. [ABSTRACT FROM PUBLISHER]

Assessing the effectiveness of mitigation measures for reducing contaminant losses to water from pastoral farming systems is a challenging task. Two important factors that contribute to this challenge are (i) the considerable spatial variability in landscape vulnerabilities to contaminant loss and (ii) differing land use pressures created by contrasting land management practices that are employed on farms. An approach is described that benchmarks nitrogen (N), phosphorus (P) and sediment discharges for representative dairy and sheep-beef farming types (hereafter referred to as 'typologies') that differ according to inherent landscape vulnerability features or land use pressures created by some key management practices. Landscape vulnerabilities can be defined as the soil, topography and climate factors that are known to influence the inherent risk of contaminant transport to water, whereas land use pressures reflect the diverse set of farm inputs and feed, stock and soil management practices that determine contaminant sources. The analysis was constructed using land use pressure information for the year 2015 contained within Dairybase records held by DairyNZ and farm class surveys reported by Beef + Lamb NZ. Published information sources and expert opinion from rural professionals were also used to define land use pressures for typologies in 1995. [ABSTRACT FROM AUTHOR]

In New Zealand the primary sector together with central and local government agencies have been promoting measures to mitigate the adverse effect of farming practices on water quality over the last few decades. We assessed the effectiveness of some key measures such as stock exclusion, riparian protection, and nutrient and effluent management on reducing losses of nitrogen (N), phosphorus (P) and sediment to water. Our aim was to determine how much progress has been made in decreasing contaminant discharges between 1995 and 2015 and to determine what the loads would have been if no mitigation had occurred. To do this we estimated losses from 37 dairy and non-dairy/sheep/beef farm typologies that captured the main attributes of production and contaminant loss pathways, nationally. We also accounted for the rate of uptake of measures. Our findings indicated that while the implementation of these measures has helped to reduce P losses (an estimated 20%–25% reduction) to water, they have not been sufficient to off-set estimated increases in N losses (25%) due to expansion of dairy land over the same period. National sediment load is estimated to have decreased (29%) because of afforestation and other soil conservation works. [ABSTRACT FROM AUTHOR]

Environmental farm planning in New Zealand dates to the 1950s when soil conversation plans were first undertaken. Since then the extent and complexity of whole farm sustainability along with regulatory drivers and environmental compliance targets has increased. The public, and consumers, both domestically and internationally, are placing ever increasing demands and expectations on farmers to deliver high-quality produce with strong environmental values. Regulatory reform is challenging, with the details around the implementation process varying and far from clear. National-scale freshwater farm plans will be mandatory and enforceable in New Zealand within a few years. How this will deliver a clearer pathway to integrated resource management and provide the primary sectors with a tool to be world leaders in environmental management will depend upon plans being farmer centric and owned and adding value to their business. [ABSTRACT FROM AUTHOR]

To meet the water quality outcomes sought by catchment communities and regulators, the losses of nitrogen (N), phosphorus (P) and sediment from dairy and sheep/beef farms must be reduced across many catchments. We conducted a high-level desktop analysis of farm typologies and established that if mitigation actions were fully implemented across dairy and sheep/beef farms, losses of N and P could have been decreased by up to 16 and 23%, respectively, compared to the estimated losses for 2015 (where established actions were only partially implemented). Potential decreases were greater for dairy land (34% N and 26% P) because of its greater per hectare yield and number of mitigation actions available before land use change is required. If established and developing mitigation actions were fully implemented by 2035, potential N, P and sediment losses may decrease by up to 34, 39 and 66%, respectively, compared to actual 2015 losses. These results can inform investment and planning by the rural sector as part of an assessment of the potential for on-farm actions to mitigate losses from existing land use. [ABSTRACT FROM AUTHOR]

We employ a two-stage data envelopment analysis technique to assess the ecological-economic performance or 'eco-efficiency' of dairy farms in New Zealand. 108 dairy farms were surveyed over one year period across the country to analyse farming eco-efficiency. Survey data on milksolids production and production costs are used to estimate the economic performance (i.e. profits), while data on greenhouse gas emissions and estimated nutrient leaching are used to analyse environmental performance. Information on geophysical characteristics and management practices that could indirectly affect farm eco-efficiency, is also incorporated into the analysis. In the first stage, we estimate eco-efficiency scores for each sampled farm using data envelopment analysis which estimates the maximum possible reductions in environmental outputs while retaining the current level of profits. In the second stage, the effects of geophysical characteristics and management practices on the calculated eco-efficiency scores are estimated using an integrated truncated regression and bootstrapping procedure. The results show that, on average, a reduction of 27% in adverse environmental externalities is achievable while maintaining the same level of economic output. Adopting on-farm management practices can be an option to improve dairy efficiency. In addition, soil topography and higher temperatures are associated with reduced levels of eco-efficiency. [ABSTRACT FROM AUTHOR]

A hydrological framework encompassing nitrogen (N), phosphorus (P) and microbial (E. coli) transfer from land to water was developed to provide a consistent and rapid approach for assessing the potential impacts of land activity on water quality in New Zealand. A flow partition approach was used to route precipitation via surface and subsurface pathways from land to water. The framework included a typology-based inventory that estimates annual yields of transportable N and P from land, a regional-scale spatial layer that attenuates N in groundwater, and literature-based estimates of E. coli concentrations in surface runoff and artificial drainage. Application of the framework in four catchments highlighted the importance of local catchment knowledge of dominant hydrological processes that was needed to ensure flow partitions derived were a realistic representation of transport processes. While the approach was promising, additional refinements are needed to improve process representation (e.g. effects of groundwater lags) and ensure input data (e.g. soil attributes) have appropriate resolution to describe hydrological pathways. We contend that such a framework would provide a consistent and relatively rapid approach for identifying contaminant transfer pathways from land to water that can inform assessments of the potential consequences of land use change and intensification. [ABSTRACT FROM AUTHOR]

Abutilon theophrasti (velvetleaf, butterprint), a problematic weed of crops in some temperate countries, was introduced into New Zealand in 1948 as a potential fibre crop. It has naturalised in the North Island in the Waikato and Auckland regions but its status at the many sites where it was inadvertently sown in 2015 as a contaminant of Beta vulgaris seed lines remains unknown. To determine the potential distribution of the species in New Zealand we used an existing and a newly developed climate niche model, both constructed using the modelling software CLIMEX and a current global climate surface dataset. The Holt & Boose model, published in 2000, fitted only 54% of the known 3825 global occurrences of the species. It predicts that most of the North Island is climatically optimal and that most of the South Island is unsuitable. By contrast, the new model, parameterised using a geographically wider set of global occurrences, fitted 98% of the global occurrences. This more robust model predicts that almost all New Zealand, including all agricultural land, is currently climatically suitable for the species. We conclude that velvetleaf could become a weed throughout the country. [ABSTRACT FROM AUTHOR]

The importance of pasture soils to the New Zealand economy and global food security cannot be understated. Additionally, the importance of soil biodiversity to soil ecosystem functioning and, consequently, food production is becoming apparent. Despite this, our understanding of soil biodiversity is still developing. Here, we review the literature on soil microbial communities inhabiting pasture soils across New Zealand in order to summarise the key properties that impact microbial distributions. This work also includes an examination of 16S rRNA sequencing data from 92 pasture sites. The goal of this examination is to re-test the properties identified in the review on a prokaryote-focused dataset generated by contemporary techniques. Results from this work indicate that pH strongly influences soil microbial communities on a landscape scale, and that this conclusion can be drawn using a range of experimental methods. Geographic region, land use and soil classification serve as secondary modifiers, indicating that these factors may interact resulting in the broad impact of pH. [ABSTRACT FROM AUTHOR]

Leptin is a protein hormone secreted by white adipose tissue, and variation in leptin gene (LEP) has been described to affect milk production traits in different cattle breeds. The purpose of this study was to investigate whether nucleotide sequence variations identified in exon 3 of LEP were the same as those reported previously, and ascertain whether the variations detected affected milk traits in New Zealand (NZ) Holstein-Friesian × Jersey-cross (HF×J-cross) cows. Polymerase Chain Reaction – Single Strand Conformation Polymorphism (PCR-SSCP) analysis coupled with nucleotide sequencing, enabled 443 HF×J-cross dairy cows to be studied. The PCR-SSCP and nucleotide sequencing revealed three variant sequences (A, B and C), with a total of five single-nucleotide substitutions. There were no associations revealed between LEP genotypes and milk yield and fat percentage. However, cows carrying the AB genotype had a decreased percentage of protein in their milk. This is the first time such findings in NZ HF×J-cross cows have been reported, and they suggest that variation in exon 3 of LEP may be useful for selecting cows for improvement in key milk traits. [ABSTRACT FROM AUTHOR]

An amino acid substitution (K232A) in the enzyme diacylglycerol acyl-CoA acyltransferase 1 (DGAT1) has been reported to explain variation in milk traits and milk fatty acid (FA) profile. In this study, associations between K232A, and milk traits including milk FA composition, were studied in wholly pasture-fed New Zealand Holstein-Friesian × Jersey cross-bred (KiwicrossTM) dairy cows. With a high frequency of K variant (61.9%), the KK cows produced more milk fat on average (5.41 ± 0.04%), than the AA cows (4.43 ± 0.06%). The milk volume, fat concentration and protein concentration for the AK cows were between the values for the genotypes AA and KK. More C16 : 0 (saturated fatty acid), conjugated linoleic acid (CLA) and polyunsaturated fatty acid (C18:3 cis-9, 12, 15) were found in the milk of the KiwicrossTM cows, and the influence of DGAT1 K232A on these FAs during the mid- and late- stage of lactation were significant. The AA cows produced more (P < 0.001) CLA (1.137 ± 0.047 g/100 g) and C18:3 cis-9, 12, 15 (0.855 ± 0.015 g/100 g), but less C16:0 (35.170 ± 0.355 g/100 g) than the KK cows (0.934 ± 0.025 g/100 g, 0.778 ± 0.009 g/100 g and 38.010 ± 0.250 g/100 g respectively). [ABSTRACT FROM AUTHOR]

Subterranean clover (Trifolium subterraneum L.) is an important legume in dryland hill pastures in New Zealand. In this environment plants adapt to low temperatures (<10°C) through a series of physiological mechanisms, such as the foliar biosynthesis of pigments, to protect vulnerable tissues. The biosynthesis of anthocyanins is one of the most important physiological responses for cold acclimation in plants. In this study we investigated anthocyanin concentration by accessing leaf reddening in 14 cultivars from three subspecies (yanninicum, brachycalycinum or subterraneum) during winter growth. The effect of anthocyanin production on spring herbage productivity was further quantified in the field and in the glasshouse. Leaf concentration of anthocyanins increased 10-fold as a consequence of cold exposure (mean daily air temperature was below ∼7°C) in red leaves compared with green leaves. There were large cultivar differences with yanninicum ssp. cultivars having the highest leaf reddening at >60%. Lowest values were observed in 'Antas' (brachycalycinum ssp.) and 'Denmark' (subterraneum spp.) at <20% of leaf reddening. Australian subterraneum ssp. cultivars had 13% higher leaf reddening values than Italian cultivars. Leaf reddening was a temporary, cold induced, anthocyanin response that did not affect subsequent subterranean clover plant growth. [ABSTRACT FROM AUTHOR]

New Zealand pastoral productivity relies heavily on biological nitrogen (N) fixation from rhizobia bacteria. Cadmium (Cd), present in pasture soils as an impurity in phosphate fertilisers, may have toxic effects on both plant growth and rhizobia activity. Effects of Cd on growth of seedlings of a white clover cultivar 'Grasslands Tribute', in the absence and presence of the N2-fixing Rhizobium leguminosarum bv. trifolii strain TA1, were assessed in vermiculite microcosm assays. The lowest observable effect concentrations resulting in significantly lower white clover shoot weights than those grown without Cd were 0.07 mg Cd kg−1 (measured as Ca(NO3)2-extractable Cd, Cdextractable) in the absence of Rhizobium, and 2.33 mg Cdextractable kg−1 for Rhizobium-inoculated seedlings. Shoot N content was unaffected in white clover exposed to <5 mg Cdextractable kg−1. The results indicate symbiosis with Rhizobium strain TA1 conferred tolerance to white clover 'Grasslands Tribute' against Cd toxicity, and that this symbiosis is unlikely to be adversely affected by Cd concentrations reported (<0.003 mg Cdextractable kg−1) in New Zealand pasture soils. [ABSTRACT FROM AUTHOR]

In New Zealand, a commonly sown pasture combination is perennial ryegrass with white clover. The hydrothermal time model (HTT) was used to quantify germination under different temperature (T) and water potential (WP) conditions for white clover 'Nomad' and perennial ryegrass 'Stellar AR1'. Seeds were germinated in vitro under a range of T × WP combinations, and HTT models were fitted to germination time course data. Rapid germination of white clover under optimum T and WP was reflected by a much lower value for its HTT constant compared with perennial ryegrass (10.8 vs 80.7 MPa °C d). However, the lower base water potential for perennial ryegrass (−1.29 vs −0.495 MPa) and a higher threshold temperature for thermoinhibition (21.8 vs 18.3°C), meant that predicted perennial ryegrass germination was more resilient in warm dry conditions. HTT models can be used to assist decisions about the timing of perennial ryegrass and white clover sowing. [ABSTRACT FROM AUTHOR]

Acetyl-coenzyme A carboxylase (ACCase) inhibitors such as haloxyfop, pinoxaden and clethodim selectively control grass weed species in many types of crop. Here, we characterised two populations of Lolium multiflorum (Italian ryegrass), R and RV, from South Canterbury and Central Otago respectively, that were suspected to be resistant to ACCase-inhibiting herbicides. Based on 50% reduction in biomass (GR50), in two dose–response experiments, both populations were highly resistant to haloxyfop with resistance factors (RF) >400 times, but resistance to pinoxaden was low (RF of 2). Furthermore, population R was found to be moderately resistant to clethodim (RF >4, based on 50% reduction in survival (LD50)), but population RV had RFs barely greater than 1, based on GR50. Gene sequencing showed that the same target site mutation (Ile-2041-Asn) was associated with resistance to the three herbicides in both populations. The zygosity of the resistance alleles in the plants tested could cause the differences in resistance to clethodim observed between the populations, even though they carried the same mutation. This is the first report of the mechanism of resistance to ACCase-inhibiting herbicides in Italian ryegrass from New Zealand. [ABSTRACT FROM AUTHOR]

Seedlings of kale cultivars in New Zealand are highly susceptible to direct feeding by the wheat bug Nysius huttoni (Hemiptera: Lygaeidae), an endemic insect pest. Two assays (choice and no-choice) were conducted to compare the relative susceptibility of seedlings of the six most popular kale cultivars in New Zealand (Kestrel, Gruner, Sovereign, Regal, Corka and Coleor). The earliest occurrence of feeding damage in the choice assay was on cv. Kestrel, significantly earlier than on Corka and Gruner. In the no-choice assay, significantly more wheat bugs were found on Kestrel than on Corka. Damage to Kestrel occurred significantly earlier than on all the other cultivars except Corka. Reduction in plant dry weight was significantly higher on Coleor and Kestrel. These results are important for developing integrated pest management protocols for kale pests. [ABSTRACT FROM AUTHOR]

Ryegrass is the primary pasture crop in New Zealand; however, despite this importance, gains in yield through conventional breeding have been marginal. Other significant crops, particularly maize and rice, have benefited from hybrid breeding programmes whereby heterosis has been exploited. Ryegrass presents many challenges to breeders wishing to produce F1 hybrid progeny on a large scale such as self-incompatibility, inbreeding depression, and a lack of genetic tools for creating and maintaining male-sterile lines for crossing. Many of these challenges have been overcome in other species, providing a basis for addressing them in ryegrass. With the advent of new technologies such as CRISPR gene editing and the genome sequence for ryegrass, F1 hybrid production is now possible on a large scale. Regulations in New Zealand surrounding new genetic tools are a hurdle which must be addressed to allow the agricultural industry in New Zealand to apply these advanced technologies. [ABSTRACT FROM AUTHOR]

I summarised cadmium concentrations from soil samples collected by the fertiliser industry between 2006 and 2015, and from soil samples collected by regional councils. Using these data, a statistical model was used to estimate soil cadmium concentrations on agricultural land within each territorial authority. Across New Zealand, most territorial authorities (56 of 66), including all the South Island, had mean soil cadmium concentrations below 0.6 mg Cd/kg. The highest mean soil cadmium values on agricultural land were in the Otorohanga and Matamata-Piako districts (0.90 and 0.89 mg Cd/kg, respectively). In these districts, around 1% of properties were estimated to have mean soil cadmium in excess of 1.8 mg Cd/kg. The fertiliser industry requires that cadmium concentrations in phosphate fertiliser are below a voluntary limit of 280 mg/kg P. The mean cadmium concentration in fertiliser samples taken between 2003 and 2015 was 184 mg Cd/kg P, 66% of the voluntary limit. [ABSTRACT FROM AUTHOR]

Illthrift, defined as low body condition score (BCS), is a problem in adult ewes on many farms in New Zealand, and nematode parasites are often considered a significant contributing factor. Here we test the hypothesis that, over the lambing-lactation period, parasites are a significant causal factor in ewe illthrift, and that anthelmintic administration to low BCS ewes results in a greater improvement in condition than treatment of other ewes. Faecal nematode egg count (FEC) prior to lambing and ewe liveweight change over the study period were poorly correlated, and both were independent of pre-lambing BCS, as was ewe response to anthelmintic treatment. Some ewes lost, or gained, considerable amounts of weight independent of their BCS, the number and size of lambs reared, and anthelmintic treatment. We find no evidence that ewes of low BCS have higher FECs, or a larger response to anthelmintic treatment than ewes in better condition. [ABSTRACT FROM AUTHOR]

Environment Southland is setting water quality limits in Southland, New Zealand. It has been well-documented that restrictions on nutrient losses from dairy farms are likely to negatively impact on farm profitability. Less understood is the influence of these regulations on rural land values. Dairy land values have traditionally been driven, in part, by changes in profitability expectations, although lags exist. Therefore, there is a risk that the costs of implementing water quality limits will impact on rural land values. Farm systems modelling was used to investigate the cost of reducing nutrient losses. Present valuation methodology was then used to examine the potential impact of this cost on dairy farm land values. Results show that mitigating nutrient losses from dairy farms in Southland reduces operating profit, resulting in a reduction of land value. Modelling suggests a 20% reduction in nitrogen leaching reduced operating profit by 14% and land value by 17%. The 25th and 75th percentile for the reduction in operating profit was −17.2% and −10.5% respectively. The 25th and 75th percentile for the reduction in land value was −21.5% and −13.1% respectively. [ABSTRACT FROM AUTHOR]

Two short-term dairy cow grazing experiments in mid-lactation (late spring) and late-lactation (late summer), were conducted in the Waikato region of New Zealand, to determine the effect of pasture species mixtures on urinary nitrogen (N) concentration and milk solids production. The mixtures included perennial ryegrass, tall fescue, lucerne and narrow-leaved plantain (cv. Tonic), structured to compare the two grass species, both with and without plantain. With plantain, apparent intake of plantain was 46%–70% of dry matter intake and estimated water intake was increased by 8%–21% over grass-lucerne swards. This led to significantly lower N concentrations of spot-sampled urine, by 38% in summer and 21% in spring, but no difference in milk production. A decline in apparent N intake was also implicated in summer. The effect of relatively high levels of plantain intake on reducing urinary N concentration is likely to be positive for reducing N leaching risk, particularly in late-lactation. [ABSTRACT FROM AUTHOR]

The invertebrate pests most commonly affecting New Zealand's pastoral-based production in 'average' years cause losses of between $1.7B and $2.3B p.a. of which up to $0.9B occur on sheep and beef farms and $1.4B on dairy farms. The native scarab grass grub is the most costly pest causing losses of $140-380 M on dairy farms and $75-205 M on sheep and beef farms annually. The exotic scarab, black beetle, although only affecting approximately 1 M ha, costs dairy farmers up to $223 M and sheep and beef farmers up to $19 M annually. Porina cause losses up to $84 M and $88 M respectively. Pasture nematodes are estimated to cost up to $274 M p.a. for dairy farmers and $326 M p.a. for sheep and beef farmers. Two exotic pests, Argentine stem weevil (ASW) and clover root weevil (CRW) are causing damage estimated at up to $200 M p.a. and $235 M p.a. respectively in dairy and sheep and beef pastures. While CRW is subject to successful biological control management it still causes considerable losses. Lesser pests also contribute to lost production, particularly as they often coexist with more major pests. However, their economic cost to New Zealand is difficult to calculate due to the variable nature of infestations on both temporal and spatial scales. At farm and paddock level, it is abundantly clear that substantial savings could be made if pest management is achieved. It is equally clear that in many instances the tools to do so are limited but if developed would contribute substantially to farm profitability. [ABSTRACT FROM AUTHOR]

Nitrate leaching from soil is a major problem in New Zealand pastoral systems, requiring development of practical methods to manage accumulation of nitrates. Nine feed trials were carried out in the Waikato (n = 3) and in Canterbury (n = 6) between 2013 and 2016; from which 424 samples were selected for forage quality testing. Only tick beans and forage rape met the lactating feed criteria for adequate crude protein (CP; > 16% DM) and soluble sugars and starch (SSS; > 25% DM). When an 'environmental' criterion was added to a feed value for lactating cows this reduced the options to fodder beet only. However, the CP measurements for fodder beet were suboptimal for milk production, requiring the fodder beet to be mixed with high protein feeds such as pasture or pasture silage. The lower protein requirements for non-lactating cows, including an additive environmental criterion enabled a wider range of feeds to be considered e.g. kale, sunflowers and swedes in Canterbury (12 entries) and fodder beet and rape in the Waikato (21 entries). Addition or restriction of nitrogen fertiliser was the only agronomic management intervention that consistently altered animal feed quality and potentially changed N excretion. Crop choice was likely to have the greatest impact at the farm level. By limiting feed quality assessment to CP, SSS and their ratio (SSS:CP) we were able to define a selection/feed monitoring method to minimise N content of feed, maximise SSS feed value and limit excess N intake to reduce the nitrate leaching risk. [ABSTRACT FROM AUTHOR]

Characterising the dissolved organic carbon (DOC) concentration and denitrification capacity of the soils and slopes in hill country is important in order to manage the leaching and availability of nitrate in ground and surface waters. This study investigated the DOC concentration and denitrification capacity of the soils and slope classes of a sub-catchment within a hill country farm, in Palmerston North, New Zealand. Fifty locations comprising of 2 soil orders (Pallic, Brown), 8 soil types (3 drainage classes) and 3 slope classes were sampled from different soil depths down to 1 m. The results suggest that compared to slope, soil type had a greater effect on denitrification capacity within the subcatchment. The Ramiha soil had the highest DOC concentration (105 mg kg-1 within 0.3-0.6 m depth) and moisture content, and hence the highest denitrification capacity (10 μg kg-1 h-1). This suggests that farms or catchments with similar soil types may have a greater capacity to attenuate nitrogen losses to the environment. [ABSTRACT FROM AUTHOR]

Dairy sheep produce an effluent stream from the milking parlour that is either applied directly to land via a sump and spray irrigator, or is stored in an effluent pond before application. In order to characterise this effluent stream, a monitoring programme was undertaken with effluent samples collected from two case study sheep milking farms over two lactation seasons (2014/2015 and 2015/2016), and a third over one lactation period (2015/2016). Typical effluent volumes generated ranged between 4 and 10 L ewe−1 day−1for the 130–200-day lactation. The mean physical and chemical attributes of effluent samples generated by the milking parlours were: 0.54% dry matter (DM), 220 g nitrogen (N) m−3, 32 g phosphorus (P) m−3, 150 g potassium (K) m−3and 22 g sulphur (S) m−3. The mean nutrient concentrations of dairy sheep effluent are lower than values reported for dairy goat (P & S only) and dairy cow effluents (N, P, K and S). [ABSTRACT FROM AUTHOR]

New Zealand accounts for just 3% of global milk production, yet it is the largest global trader of milk across borders. In contrast to other milk-producing countries, less than 5% of New Zealand milk is consumed within the country so producers must be constantly aware of changing global forces with respect to supply of, and demand for, their products. This study involved a multitude of stakeholders and used scenario analysis as a tool to arrive at four future scenarios for dairy in New Zealand. It was demonstrated that by using this approach, it is possible to arrive at a robust description of possible, plausible, futures which can guide the design of future farm systems, facilitate the understanding and recognition of factors that might shape the future of agribusiness and provide a rich source of material that can be used to inform and possibly frame and test strategy and policy. [ABSTRACT FROM PUBLISHER]

In New Zealand, little is known about the preferences of sheep farmers for different information providers and technology transfer methods. A survey was undertaken to determine the usefulness of these sources of information and the influence of demographic factors such as age, education and farm size. The results of the survey indicated that preference for information providers and technology transfer methods varied widely. In addition, for the majority of information providers and technology transfer methods at least one demographic factor (education, farm size or age) influenced their perceived usefulness. The delivery of information to farmers, therefore, needs to be conducted in a targeted way using a number of different information sources and methods to ensure maximum uptake of the information. Providing information in a way that combines a number of information sources and delivery methods is likely to have the greatest impact. [ABSTRACT FROM PUBLISHER]

This study used the DairyNZ Whole Farm Model to assess the cost–benefit of duration-controlled grazing (DCG) to reduce the time dairy cows spend on pastures with high soil water content. Within the model, grazing duration was reduced from 21 hours down to 17, 13 or 0 hours when soil moisture was above a critical water content. Scenario farms encompassed four climatic regions of New Zealand and two soil types. Regardless of region, soil type or grazing duration, implementation of DCG was not profitable except in one single instance. Furthermore, increased pasture production in response to DCG was minimal due to poor pasture management. Farms located on poorly drained soils experienced more wet days per year, thereby increasing the frequency of standoff pad use and higher operational costs. Results indicate that any financial benefit that was gained from protecting imperfectly drained and poorly drained soils through DCG was diminished by a high capital repayment and operational cost associated with the off-paddock facility. [ABSTRACT FROM PUBLISHER]

Soil organic matter is a potential sink of atmospheric carbon (C) and critical for maintaining soil quality. We reviewed New Zealand studies of soil C changes after conversion from woody vegetation to pasture, and under long-term pasture. Soil C increased by about 13.7 t C ha−1to a new steady state when forests were initially converted to pasture. In the last 3–4 decades, resampling of soil profiles demonstrated that under long-term pasture on flat land, soil C had subsequently declined for allophanic, gley and organic soils by 0.54, 0.32 and 2.9 t C ha−1 y−1, respectively, and soil C had not changed in the remainder of sampled soil orders. For the same time period, pasture soils on stable midslopes of hill country gained 0.6 t C ha−1 y−1. Whether these changes are ongoing is not known, except for the organic soils where losses will continue so long as they are drained. Phosphorus fertiliser application did not change C stocks. Irrigation decreased carbon by 7 t C ha−1. Carbon losses during pasture renewal ranged between 0.8 and 4.1 t C ha−1. Some evidence suggests tussock grasslands can gain C when fertilised and not overgrazed. When combined to the national scale, different data sets suggest either no change or a gain of C, but with large uncertainties. We highlight key land-use practices and soil orders that require further information of soil C stock changes and advocate for a better understanding of underpinning reasons for changes in soil C. [ABSTRACT FROM AUTHOR]

Concern about the environmental biosafety of transgenic plants could be mitigated by the development of robust testing methods and selection of appropriate non-target (NT) test species. White clover (Trifolium repensL.) plants with either high or low hydrogen cyanide (HCN) levels were used as surrogate transgenic insecticidal and control plants, respectively. Survival, feeding, larval weight and fecundity of two grassland-dwelling native insects,Nicaeana cervinaBroun (Coleoptera: Curculionidae) andZizina oxleyiFelder & Felder (Lepidoptera: Lycaenidae), exposed to these plants were measured. For one of four assessments,Z. oxleyisurvival and larval weight was higher on high HCN plants. However, larval weight and developmental time was consistently lower for offspring of one of three parent butterflies irrespective of treatment. Weevil feeding was reduced on high HCN plants. Both test insect species were considered suitable for biosafety assays with genetically modified white clover, and the importance of considering genotype of test insects is discussed. [ABSTRACT FROM AUTHOR]

A grazed trial established in 1980 evaluated the effects of superphosphate fertiliser application on pasture growth on Easy (10°–20° slope) and Steep (30°–40° slope) land in the Waikato, North Island, New Zealand. Continuous and rotational grazing showed no effects on pasture responses to fertiliser. Mean annual pasture dry matter (DM) production ranged from 11,275 to 14,155 kg DM ha−1on Easy, and 6413 to 7480 kg DM ha−1on Steep slopes through the range of 10–100 kg ha−1 yr−1of phosphate (P) fertiliser rates. Initial fertiliser effects on Olsen P tests were in the 0–3 cm depth only, and in the 7–15 cm soil depth only in the 100 kg ha−1 yr−1treatment by year 4. Near maximum (97%) annual production, derived from relative yield analysis, was obtained at 0–7 cm depth soil tests of 30 on Easy slopes and at 12 on Steep slopes. Results from this trial are directly relevant to the variable fertiliser rate aerial application technology currently being developed. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) emissions from agricultural soils account for more than 10% of New Zealand’s greenhouse gas emissions. Livestock urine deposition drives N2O losses from these soils. It has been speculated that non-urea nitrogen compounds (UNCs) in ruminant urine could reduce or inhibit urine patch N2O emissions. However, we hypothesise that UNCs will have no effect on N2O emissions due to their potentially rapid degradation by plants and soil microbes. Our review suggests that plant secondary metabolites (PSMs) are more likely to perform a role in reducing N2O emissions since many PSMs have known antimicrobial properties. Aucubin, found inPlantago, and isothiocyanates, found inBrassica, have been shown to inhibit a key step in N2O production. Future studies should explore this promising research gap by evaluating forages for potential inhibitory PSMs, assessing whether PSMs are excreted in urine after consumption, and determine whether excretal PSM concentrations are sufficient to reduce N2O emissions. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) losses from acidic organic soils amended with phosphate fertiliser are potentially important for the assessment of Cd accumulation, but are currently poorly understood. This study investigated the effect of soil pH and single superphosphate (SSP) fertiliser at application rates of 0, 50, 100 and 200 kg P ha−1on Cd leaching and plant uptake from an organic soil in a lysimeter study. Average leaching losses ranged from 0.14–0.39 g Cd ha−1. The greatest leaching losses were from soils at pH 4.5 at the highest rates of P application (100 and 200 kg P ha−1). In comparison, there was no significant difference in the amounts of Cd lost at pH 5.5 or 6.5 at any rate of P application. Losses equated to <1% of the Cd added to the soil from an application of 200 kg P ha−1. Average ryegrass Cd concentrations ranged from 0.03–0.09 mg kg−1dry weight. Soil pH had no significant effect on concentrations for the two lowest SSP application rates, whereas at the two high SSP treatments, Cd concentrations increased between pH 4.5 and 5.5, but decreased between pH 5.5 and 6.5. Cadmium losses from both leaching and plant uptake are low in this organic soil, highlighting the important role that organic matter and pH provide in retaining Cd. [ABSTRACT FROM PUBLISHER]

A survey of 26 pastures was conducted and soil and plant material analysed for total cadmium (Cd) and phosphorus (P), and soils further analysed for a variety of edaphic properties. Background Cd in pasture soils ranged from 0.06–0.85 mg Cd kg−1soil (mean of 0.23) and correlated closely with total P (R2 = 65.5;P < 0.001), while weaker relationships with Olsen P, nitrate-N and calcium were evident. Cadmium in the pasture dry matter had no correlation to underlying soil total Cd (P = 0.113) or soil P (P = 0.75). Strains ofRhizobiumspp. were isolated from a reference soil high in Cd (Morrinsville; 1.34 mg Cd kg−1soil) and a mid-range Cd soil (Whataroa; 0.32 mg Cd kg−1soil). The IC50of these strains, along with the commercial inoculant for white clover (Rhizobium leguminosarumbv.trifoliiTA1), to Cd were tested using a respiration sensitive assay (MicroRespTM). Rhizobia from the Whataroa soil had significantly greater tolerance to Cd than those from Morrinsville soil (P = 0.008). We propose a general stress-tolerance mechanism has evolved in the rhizobia from Whataroa, conferring metal co-tolerance. The Cd IC50ofRhizobiumTA1 was 3.06 ppm, but levels of respiration inhibition were evident at lower concentrations. Given the importance of the legume:rhizobia symbiosis to New Zealand's pastoral sector, determination of ‘no observable effect concentrations' is required forRhizobiumspp., pasture legumes and, most importantly, the establishment and function of symbiosis (nodulation and N2fixation, respectively). [ABSTRACT FROM AUTHOR]

In setting catchment nutrient limits aimed at meeting water quality objectives, some regional councils have adopted or are considering a natural capital approach to set farm-scale nutrient discharge allowances, whereby soils with a higher natural capital are given a higher discharge allowance. Land Use Capability (LUC) classes have been adopted as a proxy for natural capital. We examine the suitability of LUC for this purpose and identify issues that should be considered when using LUC in the context of a natural-capital-based approach to set nutrient limits, particularly in moisture-deficient areas where irrigation is becoming a major management tool, such as in Canterbury. The main issues are that LUC classes 1–4 are assessed on arable suitability not pastoral suitability, the high variability of pastoral productivity within an LUC class, and the limited correlation of LUC class with nitrogen losses. We propose some modifications to the LUC-based approach to address these issues. [ABSTRACT FROM AUTHOR]

The New Zealand dairy industry is pasture-based and more than 90% of milk products are exported. The breeding goal of the breeding programme of New Zealand dairy cattle is to improve the capability of the cow to convert feed into farmer profit. The breeding objective rewards yields of protein and fat but penalises milk volume and ignores lactose, despite it being an important component of milk powders. With the industry currently in deficit for lactose, this study investigated the expected response to selection over the next 10 years and its impact on the annual industry production of milk, its components and yields of dairy products based on expected cow performance, number of cows and a fixed area for dairying. After 10 years of selection (with no increase in herbage production), there was a 5% increase in milk production per hectare. Total milk exports increased by 5.9% and the lactose deficit increased by 14% when 60% of milk was processed into whole milk powder. [ABSTRACT FROM PUBLISHER]

Research in the 1980s showed thatRanunculus acrishad evolved resistance to the phenoxy herbicides MCPA and MCPB in New Zealand. Since then two ALS-inhibitor herbicides, flumetsulam and thifensulfuron-methyl, have been used but recently flumetsulam has been reported as being less effective. The mortality responses of seedling progeny of 15R. acrispopulations, differing in historical exposure to phenoxy and ALS-inhibitor herbicides, were compared using a log-series of five doses of MCPA, flumetsulam and thifensulfuron-methyl. The resulting mortalities were higher than expected at lower doses, meaning LD50values were not reliably estimated. In a second experiment, the responses of one population with no previous exposure to herbicides and one population with high exposure to flumetsulam were compared using a wider range of doses of flumetsulam (0.04 to 25 times). The LD50values differed 5.3-fold between the resistant and susceptible biotypes. In a third experiment, four populations varying in past exposure to both herbicide groups were treated with either flumetsulam or MCPA. Resulting LD50values were higher in populations with high previous exposure to both groups. These results confirm that resistance to both phenoxy and ALS herbicides can occur inR. acrispopulations through repeated use. Since these are the only two available groups for the selective control of this weed in dairy pastures in New Zealand, the options for control are reduced. [ABSTRACT FROM AUTHOR]

The amounts of farm dairy effluent stored in ponds and irrigated to land have steadily increased with the steady growth of New Zealand's dairy industry. About 80% of dairy farms now operate with effluent storage ponds allowing deferred irrigation. These storage and irrigation practices cause emissions of greenhouse gases (GHG) and ammonia. The current knowledge of the processes causing these emissions and the amounts emitted is reviewed here. Methane emissions from ponds are the largest contributor to the total GHG emissions from effluent in managed manure systems in New Zealand. Nitrous oxide emissions from anaerobic ponds are negligible, while ammonia emissions vary widely between different studies, probably because they depend strongly on pH and manure composition. The second-largest contribution to GHG emissions from farm dairy effluent comes from nitrous oxide emissions from land application. Ammonia emissions from land application of effluent in New Zealand were found to be less than those reported elsewhere from the application of slurries. Recent studies have suggested that New Zealand's current GHG inventory method to estimate methane emissions from effluent ponds should be revised. The increasing importance of emissions from ponds, while being a challenge for the inventory, also provides an opportunity to achieve mitigation of emissions due to the confined location of where these emissions occur. [ABSTRACT FROM AUTHOR]

This study used results from field experiments to calibrate the Agricultural Production Systems Simulator (APSIM) model for ‘Grasslands Kaituna’ lucerne (Medicago sativaL.) crops grown in the cool temperate climate of New Zealand. The field data allowed refinement of functions related to the seasonality of crop phenology and above- and below-ground growth. The model structure was adequate to accommodate the calibration of reproductive development in response to temperature and photoperiod in both release and calibrated versions (root mean squared deviation [RMSD] from 14% to 3% of the mean, respectively). Similarly, vegetative development, characterised by the rate of appearance of main-stem nodes, was simulated with acceptable accuracy (RMSD from 28% to 25% of the mean). Analysis showed a lack of current field data to accurately represent the number of main-stem nodes at the beginning of each regrowth cycle, which is required to further improve the accuracy of leaf appearance simulations. The simulation of leaf area index (LAI) was slightly more accurate when using a site-specific empirical canopy modelling approach for ‘Grassland Kaituna’ (RMSD = 34% of the mean) than with the more mechanistic approach in the release version used for Australian cultivars (RMSD = 40% of the mean). This is particularly important before canopy closure, when LAI has the greatest influence on light interception and biomass accumulation. ‘Grassland Kaituna’ showed a seasonal pattern of change in leaf size and specific leaf area that could not be parameterised using the approach in the release version. Finally, the model structure of the calibrated version was adapted to explicitly simulate the seasonal flow of biomass to shoots and roots. For that, the ‘shoot’ radiation use efficiency (RUE) was modified to a ‘whole plant’ RUE of 1.6 g/MJ total solar radiation and a seasonal rate of below-ground biomass turnover (i.e. respiration plus senescence) was incorporated to correct for the initial offset observed between simulated and observed root biomass. These changes improved the RMSD from 53% to 38% for shoot biomass and 29% to 18% of the mean for roots. This calibration illustrates the heuristic aspect of applying crop models to identify knowledge gaps for guiding future experimentation, including time of node appearance on basal buds and leaf area index dynamics of contrasting lucerne cultivars. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) emissions from soil are the result of complex interactions between physical, chemical and biological processes. We compared two process-based models (APSIM and NZ-DNDC) with measurements of N2O emissions, soilandcontent (0–75 mm) and water-filled pore space from a series of field campaigns where known amounts of animal urine-N were applied to four soil types under permanent pastures, in two regions within New Zealand, at different times of the year. We also compared cumulative N2O emissions with an N2O inventory emission factor approach (EF3method). Overall, the two process-based models performed less well than the EF3method for simulating cumulative N2O emissions over the complete data set. However, in winter, the APSIM model correlated well with measurements (r= 0.97), while NZ-DNDC performed well on the Otago soils (r= 0.83 and 0.92 for Wingatui and Otokia, respectively). The process-based models have the potential to account for the effect of weather conditions and soil type on N2O emissions that are not accounted for by the EF3method. However, further improvements are currently needed. The fractions of N lost to different processes within the complex soil–plant atmosphere system differed between the two models. The size of the predicted plant uptake,leaching and NH3volatilisation fluxes are large compared with N2O emissions and could affect the simulated soil N pools and thus the predicted N2O fluxes. To simulate N2O fluxes accurately, it is therefore important to ensure these processes are well modelled and further validation studies are needed. [ABSTRACT FROM AUTHOR]

The presence of nitrate (NO3−) in a water body can contribute to surface water eutrophication and can be harmful to the health of humans. The objective of this study was to determine suitable mitigation options for reducing NO3−leaching losses under dairy winter forage grazing conditions using dicyandiamide (DCD) and biochar in Canterbury, New Zealand. Total NO3−-N leaching losses from urine-treated soil was decreased by 38% from 379 kg NO3−-N ha–1to 237 kg NO3−-N ha–1with the addition of DCD. The addition of DCD in combination with biochar to urine-treated soil reduced the total amount of NO3−-N leached by 46% to 203 kg NO3−-N ha–1. However, the application of biochar to urine-treated soil did not significantly affect the total amount of NO3−-N leached. In addition, the urine + DCD and urine + DCD + biochar treatments significantly reduced both the soil NO3−-N concentration and ammonia oxidising bacteria (AOB)amoAgene abundance. However, the urine + biochar treatment had no effect on the abundance of AOB. The nitrification inhibitor DCD was found to be an effective mitigation tool for reducing soil nitrification rate and thus NO3−leaching losses. However, biochar was not effective in reducing NO3−leaching losses at the application rate used in this study. [ABSTRACT FROM AUTHOR]

There are currently few published estimates of genetic parameters for lactose yield or lactose percentage for dairy cows. Recent trends in milk standardisation for whole milk powder have resulted in whole milk being standardised with the ratio of protein to protein-plus-lactose of at least 0.39. Currently whole milk powder produced from New Zealand milk has a protein to protein-plus-lactose ratio of 0.43, thus requiring additional lactose to be imported to maximise the return from the current product portfolio. Estimates of genetic parameters were obtained using 15,366 test day records from 4378 first-lactation cows in the Livestock Improvement Corporation sire proving scheme in the 2011–12 dairy season, distributed across 70 herds. These data included milk, fat, protein and lactose yields; fat, protein and lactose percentages; somatic cell count; days in milk; and the protein to fat ratio and protein to protein-plus-lactose ratio. Mean milk yield was 13.8 L/day, containing 5.16% fat, 3.93% protein and 5.12% lactose. Heritability estimates were 0.22, 0.35, 0.32 and 0.25 for milk yield, fat, protein and lactose percentages, respectively, which were lower than those reported in the literature but enough to allow for selection of lactose percentage. [ABSTRACT FROM AUTHOR]