Papers by Katherine Tozer
Journal of New Zealand Grasslands
Hill country farms in New Zealand are faced with having to exclude cattle from waterways to limit... more Hill country farms in New Zealand are faced with having to exclude cattle from waterways to limit their negative impact on water quality. Virtual fencing technology offers the potential to control the access of each animal to its physical environment and, meet the requirement of excluding stock from waterways. Understanding farmer willingness to uptake virtual fencing technology requires exploring farm system changes that would occur when moving from using conventional fences to virtual fencing. This paper describes the investigation of a multiagent framework to explore potential futures that may be created by the application of virtual fencing technology. Compared to conventional fencing, virtual fencing of beef cattle on hill and steep land is a financially viable option to exclude cattle from waterways. Compared to no fencing of waterways, virtual fencing reduced farm annual profitability by 9% and 17% for rolling and steep farms respectively, whereas conventional fencing reduced...
Journal of New Zealand Grasslands
Availability of research farms owned by research institutions is declining due to their high oper... more Availability of research farms owned by research institutions is declining due to their high operational cost, asset value, and limited distribution. The goals of this paper are to review their role and value in pastoral science and to identify challenges and opportunities for on-farm research. Research and commercial farms as trial sites may be mutually exclusive, complementary, or substitutes. Research farms are essential where science requires expensive facilities and/or rigorous control to maintain ethics and quality commitments. They can also provide information independent of scientific and commercial bias. Commercial farms provide access to more diversity, help scientists understand benefits and identify and resolve on-farm issues, and build industry credibility. Since the number of research farms is unlikely to increase, several lessons are important. Delivery, ethical, and science quality risks can accrue when the full cost of working with commercial farms is not considered...
Journal of New Zealand Grasslands
Pukekauri Farm is a 295 ha mixed livestock hill country property in the western Bay of Plenty. Ov... more Pukekauri Farm is a 295 ha mixed livestock hill country property in the western Bay of Plenty. Over the last 20+ years the owners have been on a development journey with a focus on the multiple dimensions of sustainability – economic, environmental, and social. This paper seeks to document that journey, with supporting resource, production, financial and environmental data to quantify progress. Some of the most useful tools have included high quality forage crops, deferred grazing, sheep genetics, accounting software and paddock-scale soil and water resource maps. Key lessons include the value of knowledge networks and modelling tools, the power of a farm plan for optimising land use and management, the importance of both profitability and grants to underwrite development investment, and the emergence of secondary benefits from decisions focused on system-wide improvement. Over 20 years, despite areduction in grazed area of 20%, meat production has increased by 16%, EBITR/ha has inc...
Journal of New Zealand Grasslands
A pasture and farm management survey was conducted on thirteen geographically paired regenerative... more A pasture and farm management survey was conducted on thirteen geographically paired regenerative and conventional beef and sheep farms in the upper North Island to identify differences in pasture attributes and management practices. Farms were paired by geographical location and livestock type. When compared to conventional pastures, regenerative pastures had a similar number of grass, legume and broadleaf species (averaging 4, 1 and 3 species respectively), three times as much legume (13 compared to 4% content) and 30% less perennial ryegrass in total DM (P<0.01) but a similar broadleaf content. There was no difference between pasture types in pre- or post-grazing covers. Compared to conventional pastures, soils sampled from regenerative pastures had a higher pH, and herbage had higher levels of calcium, boron, molybdenum (P<0.05) and a trend towards lower Olsen P values (P=0.052). There was a divergence between farm types in fertiliser policies, with regenerative farmers ge...
NZGA: Research and Practice Series, 2007
Pasture growth, botanical composition and sheep grazing preference were measured over 20 months i... more Pasture growth, botanical composition and sheep grazing preference were measured over 20 months in tall fescue (cultivar Advance), without endophyte (Nil) or infected with AR542 (MaxPTM) endophyte, and clover pastures sown into a dryland soil, Canterbury, New Zealand. Pastures were rotationally grazed with sheep, with grazing preference for the two endophyte treatments measured in late autumn and early spring. Annual dry matter production from April 2004 to April 2005 was not significantly different between AR542 (6293 kg DM/ha) and Nil (5864 kg DM/ha) tall fescue. The number of tall fescue plants/m2 and their basal diameter was greater for AR542 (35 plants/m2, 7.5 cm diameter) than Nil endophyte tall fescue (28 plants/m2, 6.8 cm diameter). AR542 endophyte tall fescue pastures had fewer weeds, mainly annual grasses, than Nil endophyte pastures throughout the trial. Grazing preference, measured by the number of sheep grazing each plot, and decline in pasture height did not differ bet...
NZGA: Research and Practice Series, 2021
Deferred grazing is a common management practice in which pastures are rested from grazing betwee... more Deferred grazing is a common management practice in which pastures are rested from grazing between mid-spring and the end of summer/early autumn. It has been used to rejuvenate pastures and better manage the spring pasture surplus although its impact on farm profitability is unknown. FARMAX was used to explore the impact of deferred grazing on profitability on a north-western Waikato beef and sheep hill country farm based on experimental data and likely management responses. The Base Scenario modelled farm profitability assuming spring surplus in a typical year. When 15% of the farm was deferred and it was assumed that the increased grazing pressure on the rest of the farm led to greater control of the spring feed surplus and improved pasture quality, there was an increase in ewe performance and the number lambs sold at target weight. Per head and total farm gross margins increased by 8%. Results demonstrate how the use of deferred grazing as a pasture management tool to increase re...
NZGA: Research and Practice Series, 2016
Steep, non-cultivable hill country below 1000 m comprises about 40% of New Zealand's land sur... more Steep, non-cultivable hill country below 1000 m comprises about 40% of New Zealand's land surface and is known as "hill country". It is used predominantly for mixed livestock farming, and makes a large contribution to the national economy. Recently there has been renewed interest by industry and government in germplasm introduction through pasture establishment to increase forage supply in these difficult environments. In this review, establishment is defined as development of a sown pasture species to a stage where it is able to reseed. The aim of this review was to determine the effect of key factors associated with pre-sowing management, sowing, and post-sowing management on establishment, including: site selection, herbicides, the role of litter, grazing management, burning, weed and pest control, fallow, fertiliser, species selection, seed quality, sowing time, sowing method, sowing rate, seed inoculation, coating and pelleting, natural reseeding and dissemination...
NZGA: Research and Practice Series, 2021
Pasture is the main source of nutrition for the New Zealand ruminant livestock industry. Changing... more Pasture is the main source of nutrition for the New Zealand ruminant livestock industry. Changing climatic conditions and relentless intensification are putting the ability of pastures to provide that nutrition under pressure. Recent understanding of the interactions between grazing management and the life cycle of roots, leaves and seedheads of pasture species creates further opportunities to increase pasture resilience. Root production is directly related to, though lagging, leaf production and turnover. Tiller production is modified by temperature and seedhead production. Matching grazing patterns to maximise the production of each of these features is generally impossible at the farm scale. However, matching some of these characteristics on some of the farm can be achievable, and have long-lasting benefits for pasture resilience. Therefore, grazing management practices such as deferred grazing in late spring, summer and autumn may be used both to provide a boost to root and till...
Journal of New Zealand Grasslands, 2020
Deferred grazing is a commonly used tool to manage feed surpluses. The effect of deferred grazing... more Deferred grazing is a commonly used tool to manage feed surpluses. The effect of deferred grazing on pasture nutritive value and productivity was quantified in a split-paddock trial on three hill country farms in Waikato and Bay of Plenty from October 2018 until May 2020. Livestock were excluded from the deferred pasture between mid-October 2018 and March 2019. Thereafter, both treatments were rotationally grazed in common with cattle or sheep depending on the farm. Total annual dry matter production was 15% greater in the deferred than grazed treatment for the 12 months after deferring (8.9 vs 7.7 t DM/ha, P<0.05). Metabolisable energy (ME) values at the end of the deferred period were lower in the deferred than grazed treatment (P<0.01) but similar in both treatments thereafter. The content of legumes other than white clover (Trifolium repens) was higher in deferred than grazed pastures in spring 2019 on one of the farms (treatment × farm interaction P<0.05). Ground cover...
Journal of New Zealand Grasslands, 2018
Variegated thistle can dominate north-facing slopes on North Island East Coast hill-country reduc... more Variegated thistle can dominate north-facing slopes on North Island East Coast hill-country reducing pasture production and livestock carrying capacity. On a hill-country sheep and beef property near Gisborne, the herbicides 2,4-D + clopyralid were applied in early-May by knapsack in combination with a June aerial application of 2,4-D ester. This was more effective than a single June aerial application of 2,4-D ester in reducing the abundance of variegated thistle and enabling grasses from the seedbank to colonise the bare ground in the herbicide-treated patches. Mixtures of grasses, legumes and herbs, oversown onto bare patches previously occupied by thistle plants, did not establish on a north-facing slope. While they did establish on a south-facing slope, the sown species did not persist, most likely due to selective grazing. To establish competitive pasture, natural germination from the seedbank may be less risky than oversowing seed into thistle patches, if desirable species ar...
New Zealand Plant Protection, 2007
Seeds of ripgut brome an annual grass can contaminate the wool pelt and carcasses of sheep grazin... more Seeds of ripgut brome an annual grass can contaminate the wool pelt and carcasses of sheep grazing on high country properties The distribution of ripgut brome on seven high country properties in Marlborough Canterbury and Otago was determined during December 2006 to February 2007 The presence of ripgut brome was measured in paddocks of different management intensities at altitudes ranging from 400 to 1400 m Ripgut brome grass presence was lower in sites managed less intensively (eg less fertiliser and oversowing) in hard than laxly grazed sites and in sites of high exotic perennial grass cover It was more prevalent on stock camps than off stock camps and on steeper slopes and sunny aspects but was unaffected by legume cover shrub presence or altitude The results suggest that increased grazing intensity and enhanced plant competition are methods that may be used to suppress ripgut brome on hill and high country properties
New Zealand Plant Protection, 2009
Weed and insect pests severely limit New Zealand pasture production and information on their mana... more Weed and insect pests severely limit New Zealand pasture production and information on their management is often fragmented and difficult for farmers to access While there are a number of good pest and weed websites available many of these are commercial in focus or do not combine both identification and management options relevant to New Zealand farmers PestWeb (wwwagresearchconz/pestweb) is a website being created to assist farmers and agricultural professionals in decisionmaking regarding weed and pest identification biology impact and management A pilot site has been developed for identification and management of grass grub porina Californian thistle and barley grass and it is aimed to include an additional 2025 key New Zealand pasture weeds and pests which will be chosen in consultation with key farming industry and research personnel This site will provide independent information in an easily accessible and intuitive format to assist farmers in weed and pest management decisio...
New Zealand Plant Protection, 2011
Aboveground botanical composition and seedling emergence from the soil seedbank were assessed in ... more Aboveground botanical composition and seedling emergence from the soil seedbank were assessed in 30 Bay of Plenty dairy pastures in spring 2010 Pastures ranged in age (young 12 years medium 34 years old 56 years) and included those with and without forage herbs (chicory and/or plantain) As pastures aged there was an increase in the percentage of total dry matter of unsown weed grasses (3 8 27) and unsown herbaceous weeds (5 18 39) in young medium and old pastures sown with herbs respectively Unsown weed grasses dominated the seedbank and together with herbaceous weeds comprised more than 99 of seedlings that emerged from the seedbank Farm managers ranked insect pests and climate (eg droughts/floods) as the primary factors causing the decline of sown species while grazing management was perceived as the most important factor that can improve persistence of sown species
New Zealand Plant Protection, 2019
Variegated thistle (Silybum marianum) is a prevalent weed on the East Coast of the North Island o... more Variegated thistle (Silybum marianum) is a prevalent weed on the East Coast of the North Island of New Zealand. Goats may provide a novel management tool to control thistles, but little is known about how cutting thistles prior to grazing affects thistle consumption by goats. This study investigated the extent to which goats consume either uncut entire variegated thistle plants or cut thistles. Eight groups of three goats were presented with thistle vegetation in each of two replicate 1-hour feeding sessions on 2 consecutive days. Averaged over both days, in the cut treatment, goats consumed 99% of the leaves that had been removed from the thistles and reduced the ground cover of the thistle plants by 68%. In the uncut treatment, ground cover of the thistles was reduced by 46%. A combination of cutting and goat grazing is likely to be a useful tool for stopping variegated thistle debris from smothering pasture and for inhibiting seed setting. Further work is required to test this at...
HortScience, 1997
Plants of genus Scaevola (family, Goodeniaceae), commonly known as “fan flowers,” are mostly ende... more Plants of genus Scaevola (family, Goodeniaceae), commonly known as “fan flowers,” are mostly endemic to Australia. Commercially popular species are Scaevola aemula, S. albida, S. striata, and S. phlebopetala. These plants are used as ground covers in Australia and as hanging baskets, window boxes, and garden bed plants in Europe and America. Two aspects of in vitro culture of Scaevola are reported here; micropropagation and direct shoot regeneration. A number of commercially available cultivars of S. aemula, S. phlebopetala, S. striata and wild-collected S. phlebopetala, S. glandulifera, S. hookeri, and S. ramonissima were used for micropropagation experiments. Micropropagation medium contained salts, vitamins, L-cysteine, sucrose, and agar. Tissue-cultured shoots were rooted in hormone-free medium. A high survival percentage (>95%) was obtained when plants were transferred to soil under glasshouse conditions. Results on in vitro shoot induction and regeneration response of leaf,...
Ecology and management of Vulpia spp. C. C. Gmelin in perennial pastures of southern Australia
Animal Production Science, 2015
For Australian and New Zealand dairy farms, the primary source of home-grown feed comes from graz... more For Australian and New Zealand dairy farms, the primary source of home-grown feed comes from grazed perennial pastures. The high utilisation of perennial pasture is a key factor in the low cost of production of Australian and New Zealand dairy systems and, hence, in their ability to maintain international competiveness. The major pasture species used are perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.), normally grown in a simple binary mixture. As pasture production has been further driven by increasing use of nitrogen fertiliser and irrigation, farms are getting closer to their economic optimum level of pasture utilisation. Increasing inputs and intensification have also increased scrutiny on the environmental footprint of dairy production. Increasing the diversity of pasture species within dairy swards presents opportunities to further increase pasture utilisation through additional forage production, extending the growing season, improving forage nut...
Scientia Horticulturae, 1999
Salt (NaCl) application as a tool to reduce the annual grass weed, ripgut brome, in New Zealand South Island hill/high country pastures
New Zealand Journal of Agricultural Research, 2013
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Papers by Katherine Tozer