The actual intake requirements of kale and swedes for maintenance and gain are not well defined for pregnant cows in winter. Farmer observations of cows grazing brassicas suggested that the winter feed requirements appeared much greater than those calculated using industry standards. Two balanced groups of dairy cows were grazed under similar management practices on a kale or swede brassica crop for a 5-week period during winter to estimate total energy intake and intake rate. Brassica intake rates did not differ significantly except for the period 5–24 hours after the commencement of grazing, when the swede group cows consumed more crop than the kale group (P=0.042). Body condition score change was higher (P<0.05) for the swede grazing group than the kale group. This was attributed to a higher overall consumption of crop and supplement, as estimates of total energy intake over the 5-week experimental period were 132 and 149 MJ ME/day for kale and swedes, comparing favourably with estimated energy requirements of 126 and 140 MJ ME/day. Allocation of feed has a much greater effect on changing condition score in cows than the type of crop fed. Keywords: body condition score, energy intake, intake rate, kale, swedes.
Pasture pests are often held in check by natural enemies but we have observed that severe pest attack over a wide area can occur after large scale land use change. Data were reviewed from current projects and databases for pest density and damage records covering the past 30 years. The focus was on areas where large scale land change has been implemented, including new irrigation schemes, pasture development from tussock or scrub, and land moulding for drainage via “flipping” or “hump and hollow”. In these situations, pest outbreaks reached unprecedented levels, e.g. 2200 grass grub larvae/m2 in the Amuri irrigation scheme, 770 porina larvae/m2 on the East Otago Plateau and 3500 manuka beetle larvae/ m2 at Cape Foulwind on the West Coast. With major land use change, a new environment is created where pest species are provided abundant resources and the initial invaders multiply rapidly, free from the pressure of natural enemies. Monitoring systems, to provide early warning of pest attack, and remediation strategies can be used to overcome damage by these pests. Keywords: Land development, pest outbreaks, grass grub, manuka beetle, porina
The novel endophyte, AR37, in ryegrass has reduced porina larval survival and plant damage in pot trials. To determine the effect of AR37 on larvae in the field, populations were estimated in two ryegrass field trials in Canterbury. Plant damage and plant densities were also scored in one trial. At Ceres Farm, no porina were found in Italian ryegrass ‘Status’ infected with AR37 whereas low populations (<10 m-2) were present in endophyte-free and AR1-infected ryegrass of the same cultivar. In the third year of an endophyte ryegrass trial near Oxford, density of porina tunnels was 60% lower in the tetraploid perennial ryegrass ‘Halo’ with AR37 than in ‘Bealey’ with NEA2. In the diploid perennial ryegrass cultivars, ‘Commando’ and ‘One50’, porina populations were 81–84% lower in AR37-infected plots compared with the same cultivars infected with AR1or with low level Wild-type infection. Plant damage was on average 71% lower and plant densities 63% higher in AR37 than in the AR1 and low endophyte treatments. Keywords: tetraploid, diploid, Wiseana, root aphid, AR1, NEA2
The expansion of the southern dairy herd in New Zealand has raised a number of concerns about the sustainability of grazing brassica forage crops. Here we provide an assessment of the contribution of these crops to the potential for N losses to water at a wholefarm system level, and compare these with metrics derived for systems that use alternative approaches for wintering cows. The risks of nutrient losses to water from six Monitor Farms that use contrasting approaches to dairy cow wintering were assessed using the Overseer® Nutrient budgets model (Overseer). This modelling assessment was supplemented with detailed information about the management of effluent generated from off-paddock cow wintering facilities such as wintering pads and covered housing. Predictions of N losses from individual farm blocks indicated that both winter- and summer-grazed brassica forage crops have a relatively high potential for N leaching losses. Expressed at a whole-system level (i.e. accounting for the milking platform, winter forage crop and other support land), the winter forage crops accounted for between 11 and 24% of total N leaching losses, despite representing only 4 to 9% of the area. The high N leaching losses predicted for summer-grazed forage crops were attributed to the limited opportunity for N uptake of excreted urinary N by the following new pasture. Another risk identified for some farms was the current practice of applying effluents collected from off-paddock facilities to land during winter. These assessments suggest that off-paddock cow wintering systems can help to minimise N losses from farms to water, although the storage and safe return to land of effluents and manures generated from the housing facilities is essential if this potential benefit is to be realised. Our assessments also suggest that summer crop paddocks have a relatively high potential for N leaching losses, although further research is needed to confirm this. Keywords: dairy cow wintering, Southland, nitrate leaching, grazed brassica forage crops.
Herb-clover mixes have resulted in faster lamb liveweight gain than perennial ryegrass over summer, but it is not known if this would occur in spring. Lamb liveweight gain in spring was compared on three treatments: Pasture mix: perennial ryegrass and white clover; Plantain mix: plantain, white clover and red clover; and Chicory mix: plantain, chicory, white clover and red clover, over a 28-day period. Average daily liveweight gain (g/day) was higher (P<0.05) on the Chicory mix (360 ± 20.0) than the Pasture mix (322 ± 10.0). Individual carcass weight was higher (P<0.05) on the Plantain and Chicory mixes than on the Pasture mix. Plantain mix produced 162 kg net carcass weight per ha compared to the Pasture mix (141 kg/ha) and Chicory mix (146 kg/ha). Farmers can obtain greater individual carcass weights and net carcass weight per ha by feeding herb-clover mixes rather than ryegrass pasture during the spring. Keywords: herb-clover mixes, lamb growth, carcass weight
This paper presents results from a breeding program which, using seed mutagenesis combined with traditional plant breeding techniques, has resulted in the development of the Cleancrop™ Brassica system. Seedlings of Brassica napus with increased chlorsulfuron resistance were identified following seed mutagenesis with ethyl methanesulfonate (EMS) and in vitro screening of seedlings in the presence of the herbicide. Surviving herbicide resistant seedlings were used in a traditional breeding program to introgress resistance into leafy turnip, bulb turnip, rape and swede. Acceptable herbicide resistance to at least a double application of chlorsulfuron from either a preemergence or a 4-leaf post emergence timing has now been produced in all these crops. Results from trials sown at Lincoln, Canterbury and Knapdale, Southland with chlorsulfuron herbicide application at both these timings with HT-S57 swede showed excellent weed control and no noticeable crop phytotoxicity. The preemergence herbicide application produced significantly more total dry matter per hectare than the untreated control. This weed management system represents a new tool for New Zealand farmers which will expand the use of forage brassica crops into more marginal areas which historically have had difficult to control weed problems. Keywords: Seed mutagenesis, chlorsulfuron, acetolactate synthase, field plant breeding, Cleancrop™ Brassica System, HT Brassica™
Economic values (EVs) are an estimate of the change in farm system profit per unit of change in a defined plant trait. Cultivars within species such as perennial ryegrass differ in the major production traits of dry matter yield, nutritive value and persistence, but the impact of those differences on farm financial performance is seldom calculated and reported. This paper explains what EVs are, describes how they can be calculated, and discusses some of the associated methodological issues. EVs have been derived for seasonal dry matter yield in New Zealand dairy systems. Extra feed produced in late spring has consistently low economic value, while extra feed produced in early spring has consistently high value. There have been no systematic investigations into the EVs of nutritive value and persistence in New Zealand pastures; this is a clear opportunity for future research. The lack of data on cultivar differences in these traits will restrict the application of EVs to pasture cultivar evaluation. This gap is now being addressed by new industry initiatives. Keywords: pasture cultivars, evaluation, traits, economic values, performance values
Inter-annual weather variation has profound effects on pasture production and pastoral farm performance. However, the relationship between the variation in herbage and animal production and farm economic and environmental (nitrate leaching and greenhouse gas emission) outcomes are not clearly quantified, especially with varying farm management strategies applied under variable weather scenarios. We used a pasture model (APSIM-AgPasture), corroborated by measured pasture growth data, to generate pasture growth curves for a typical sheep and beef farm in northern Southland for the past 39 years, and grouped them into five weather scenarios. We fed these curves into a farm system model (Farmax) to examine the changes in farm performance with various management adaptations. We found that farm economic and environmental outcomes did not respond proportionally to pasture production; compared with the variation range in herbage production, the variation range in animal production was smaller, but the variation range in farm profitability was larger. Environmental efficiency (nitrate leaching and greenhouse gas emissions per unit of animal products) was high in wet years. Our results highlight the importance of considering the nonproportional changes among pasture production, animal production, profitability, and environmental outcomes of pastoral farming when selecting farm management strategies and tactics to adapt to weather variations, and indicate the necessity of incorporating these non-linear relationships in the development of farm management decision support tools. Key words: Climate variability, pasture herbage production, animal production, production efficiency, environmental efficiency, management adaptation
The establishment and growth of ‘Stamina 5’ lucerne (Medicago sativa) seed sown with three inoculant carriers (ALOSCA®, coated, and peat slurry treated) or as bare seed (control) on five dates (21 October 2010, 9 November 2010, 8 December 2010, 13 January 2011 and 3 February 2011) was investigated on a Lismore stony silt loam soil at Ashley Dene dryland research farm in Canterbury. Initial lucerne populations were 300 plants m-2 from coated seed and on average 200 ± 11.2 plants m-2 from bare seed, ALOSCA® and the peat slurry inoculated seed. The higher population from coated seed treatments did not confer a herbage yield advantage. In the establishment year, yield was lowest (0.59 t DM ha-1) from the last sowing (3 February 2012) and highest from sowing dates (SD) 2 and 3 (2.6 ± 0.12 t DM ha-1). Yields were restricted by the low volumetric soil moisture content from November until March. The declining autumn photoperiod (14.9 to 14.1 hours) probably increased the partitioning priority of assimilates to the roots, reducing the above ground DM in the later sowing dates. In most cases, DM yields in Year1 were unaffected by seed inoculant treatments. In Year 2, DM production from the peat slurry treated seed (8.0 t ha-1) was highest, while coated seed crops were lowest (6.0 t ha-1). The effects of sowing date carried through to the second year with lower DM yields from SD4 and SD5 (6.0 ± 0.18 t ha-1) compared with 7.3 ± 0.18 t ha-1 from the earlier sowing dates. Keywords: alfalfa, ALOSCA®, bare seed, coated seed, Ensifer meliloti, peat slurry treated seed, rhizobia, sowing date
The agronomic performance of a range of perennial ryegrass cultivar-endophyte combinations was compared in 16 trials conducted at sites throughout New Zealand. Each trial was run for 3 years according to seed industry evaluation protocols, measuring variables including: dry matter (DM) yield (total annual and seasonal DM yield), ryegrass ground cover at the end of 3 years, susceptibility to plant pulling, and rust incidence. The change in DM yield over the 3-year term of each trial was also analysed. There were significant differences among cultivars in total annual DM yield, and in seasonal DM yield for each of the five periods of the year among which yield was split (winter, early spring, late spring, summer, and autumn). Mean annual yield declined between Year 1 and Year 3 in all regions except Taranaki, by between 0.8 t DM/ha (Canterbury) and 5.3 t DM/ha (Waikato). There were significant region, year, region × year, and cultivar × year interactions in yield change. Significant differences in ground cover score for perennial ryegrass at the end of 3 years were recorded among cultivars. However, these differences did not mirror on-farm observations of ryegrass persistence in the Waikato during the drought of 2007/08, suggesting that the standard trial protocols currently used do not adequately test persistence. It is recommended that industry cultivar testing needs to more accurately assess perennial ryegrass persistence, using new protocols including running trials on commercial farms, for more than 3 years, and using mixed swards. Genetic differences in persistence could be generated more quickly by choosing sites known to challenge perennial ryegrass growth and survival. Keywords: perennial ryegrass, cultivar evaluation, DM yield, persistence testing, plant pulling, rust
One of the problems which arises when analysing and interpreting results from field trials designed to test the efficacy of fertilisers and fertiliser-type products on pastures and crops is the conundrum of Type 1 and Type 2 statistical errors: is the product having literally no effect, or is the trial not “powerful” enough to detect small differences. This problem can be objectively and pragmatically solved, when sufficient trial data are available, by using cumulative frequency distribution functions. In this paper we explain what cumulative frequency distribution functions are and their usefulness for determining the agronomic effectiveness of products. This technique is then applied to field trial data testing the effectiveness of a number of fertiliser and fertiliser-type products used in agriculture today. It is concluded that this approach provides a more objective basis for determining the efficacy or otherwise of fertilisers. Keywords: fertilisers, agronomic effectiveness, testing, field trials, cumulative frequency distribution.
The DairyNZ Modelling Group has developed a model called the Conservation Demo to assist in identifying and conserving surplus pasture on dairy farms. The hypothesis was that a computer algorithm would be able to make decisions concerning timing and amount of conservation similar to an experienced pasture manager. Weekly grazing decisions on DairyNZ farmlets, with stocking rates of 2.6 to 3.5 cows/ ha, were made by a team of research staff over three years. The model was run for each farmlet to compare its recommendations with the conservation decisions made by the research team. In spring on all farmlets and in summer on the higher stocked farmlets, the model was more conservative than the team in recommending paddocks to be closed in all seasons. In summer 2011/12 the recommendations from the model were more variable week-to-week (paddocks being closed one week and not the next), and on the lower stocked farmlet the model was more aggressive than the team. The Conservation Demo is a useful tool for identifying surplus pasture if the output is moderated by the farm manager, and the use of a feed wedge in conjunction with the model would improve the decisions. However the model requires pasture covers for each paddock, ideally at least weekly, and currently <20% of dairy farmers collect these data on a regular basis.
Giant buttercup (Ranunculus acris L. subsp. acris), a weed of European origin with a potential distribution embracing all of New Zealand, currently infests pastures in six of 17 dairying regions. It reduces the quantity of pasture consumed by deterring grazing, but its impact on whole-farm profitability is not well understood. To redress this, the effect of the weed and the impact of herbicides varying in efficacy were modelled with Farmax Dairy Pro®. On a dairy farm “typical” of the Golden Bay area, with the ground cover of giant buttercup peaking at 12% in November (the average per paddock cover measured on an infested farm), profit was reduced by $1040/ha ($1830 vs. $2870). Synthetic herbicides applied at label rates increased profitability, but only where the control was better than ca. 30% with MCPA or ca. 60% with flumetsulam. By contrast, a hypothetical biological herbicide giving 50% control had a break-even cost of $485/ha. The models show that giant buttercup reduces the profitability of a typical Golden Bay dairy farm by 36% and that its effective control can bring large financial gains. Keywords: dairy pasture, economics, Farmax Dairy Pro®, model, profitability, weed control
It is timely, with farming within biophysical limits as an emerging feature of the future operating environment for the sector, to explore whether the substantial productivity gains seen in the sheep and beef sector over the last 20 years translate into improved ecoefficiency and a reduction in the sector’s environmental footprint. In this paper the changes in the relationship between inputs (e.g., livestock numbers, nutrients) and outputs (e.g., meat and fibre, greenhouse gas (GHG) emissions, nitrate) of the MAF Sheep and Beef Farm Monitoring models that cover hard hill country (Gisborne and Central North Island) and easy hill finishing (Manawatu) over the last 20 years were explored using the Overseer nutrient budget model. For the hard hill country extensive sheep and beef farm operation, the productivity gains made since 1989/90 translate into significant eco-efficiency gains, including a 47% increase in saleable product/ha (107 to 167 kg per ha), 21% reduction in nitrate leaching per kg of saleable product (0.065 to 0.054 kg N per kg animal product) and 40% reduction in the GHG emissions per kg of saleable product (27 to 19.2 kg CO2-e per kg animal product). The improvements have come through increased meat production. In contrast, the contribution from wool has been unchanged since 1989/90. These eco-efficiency gains, however, did not extend to include an overall reduction in N leaching or GHG emissions per hectare. In the easy hill finishing operation, where the MAF model farm size more than doubled over the last 20 years, there was little change in the eco-efficiency, but again also little change in total emissions. As we move to an operating environment where there are limits on emissions to the environment, understanding how to quantify eco-efficiency and monitor changes in this performance indicator becomes more than just an academic exercise. Keywords: Sheep and beef, eco-efficiency, meat and fibre production, N leaching, hill country
Cropping sequences were introduced to a pasture-based dairy system with the aim of improving the annual feed supply, herd productivity and overall profitability. Two farmlets were established on the Waimate West Demonstration Farm (Taranaki) in June 2007 and ran for 5 years. The All-grass farmlet was a pasture-only system (except for 70 kg/cow palm kernel expeller in one year) and the Cropping farmlet had on average 12.5% of the farm cropped each year plus palm kernel expeller (250 kg/cow/year over 3 years). Crop sequences varied in duration from 12 to 28 months. Crops grown were maize (for silage), turnips, chicory, rape, oats, barley and triticale. Stocking rates were 4.0 and 4.2 cows/ha for the All-grass and Cropping farmlets, respectively. Pasture growth for the two farmlets was similar, averaging 16.6 t DM/ha/year. The inclusion of crops added an extra 1.7 t DM/ha/year over the Allgrass treatment, averaged over the 5-year trial. In the first 2 years, milksolids (MS) production per hectare was 2% lower for the Cropping farmlet (1145 kg MS/ ha) than for the All-grass farmlet (1165 kg MS/ha), but was 11% higher (1237 vs. 1112 kg MS/ha) over the next 2 years, increasing to a 27% advantage (1453 vs. 1143 kg MS/ha) in the fifth year. Financial analysis indicated a $338 lower operating profit for the Cropping farmlet for the first 2 years but there was an advantage of $560/ ha/annum over the next 3 years. Introducing cropping onto a dairy farm system can increase MS production and profit. Careful consideration must be given to the choice of crops to maximise DM yield and minimise the cost of production. Cropping on dairy farms can be successfully implemented, but is dependent on successful crop establishment and efficient feed management. There is potential for sustained higher MS production per cow and higher per ha by including crops in the system, but the potential may not be realised immediately due to reduced area for grazing while the first crops are being established. Keywords: cropping, milksolids, operating profit
It is often claimed that nutrient management in organic dairying is more environmentally sustainable than its conventional counterpart. Organic dairy farmers often focus on pH, trace elements and nutrient ratios rather than the major nutrients such as phosphorus. As a consequence of less nutrient input, the environmental impacts of organic dairy systems may be smaller than for conventional farms. Some of these issues were explored by surveying eight organic farms in the North Island. The objectives of the nutrient management plans along with trends in soil test values were examined. OVERSEER® Nutrient Budgeting software was used to quantify maintenance fertiliser requirement for the organic dairy farms and likely trends in nutrient status. Nitrogen leaching from the organic farms was also assessed using OVERSEER®. This study suggest that while the current nutrient status of organically managed soils is not dissimilar to that found on conventional farms, sustainable nutrient management on organic dairy farms is an emerging challenge. Of particular note here is a decline in phosphorus status. While organic dairy farms leach much less nitrogen than conventional farms, some of these advantages are eroded when efficiency indicators are invoked. A field trial has been established to identify products that will help organic farmers increase soil nitrogen and phosphorus nutrition. Keywords: organic dairying, nutrient management, nitrogen leaching, nitrogen conversion efficiency, environmental efficiency
Pasture growth rates for Southland were reported by several researchers in the late 1970s and early 1980s. However, pasture species and farm management systems have changed somewhat since then. This paper presents data from measurements at Woodlands, near Invercargill, that have been ongoing since 1977, and discusses some of the variability that has occurred over the years. Measurement of pasture growth was done using a standardised cutting method known as “rate of growth” or moving cages, with measurements every 3 weeks. Annual yields were calculated from 1 June to 31 May of the next year. The pasture growth at Woodlands is characterised by a spring-summer peak of growth followed by a deep winter trough where growth is minimal. Long-term average annual growth was 11.8 t DM/ha for older ‘Ruanui’ based pasture and 12.7 t DM/ ha for newer ‘Nui’/‘Supreme’/‘Greenstone’ ryegrass based pasture. However the newer pasture produced considerably more (ca.14.2 t DM/ha/year) for an initial period of 3 years, after which time the production dropped back to be similar to the old pasture (ca.12.0 t DM/ha/year). Key words. pasture growth; long-term; annual variability
Three options for controlling surplus pasture on Northland dairy farms were modelled to determine the impact of each on production and operating profit. The three options were a) Light cut, fixed break size (LCFB): Paddock cut for silage as soon as surplus was identified. No effect on rotation length. b) Bulk cut, fixed break size (BCFB): Paddock closed until cover of 4000 kg dry matter (DM)/ha was reached then cut for silage. Rotation length was shortened. c) Bulk cut, variable break size (BCVB): Paddock closed until cover of 4000 kg DM/ha was reached then cut for silage. Rotation length was maintained thus reducing available grazing area. The hypothesis was that LCFB would translate into the most profitable option as pasture is being cut as soon as a genuine surplus is realised, optimising silage feed quality. Results showed LCFB to be $100/ha more profitable (operating profit) compared with BCFB and BCVB at only one of the three sites investigated (P<0.05). The LCFB option resulted in a significantly higher (P<0.05) pasture yield at both the Northland Agricultural Research Farm and Whangarei sites, however, there was no effect of silage-making option on milk production at any of the sites. This modelling exercise showed that LFCB was not consistently more profitable across sites, that it is a simplification to assume that “one size fits all” and that the same pasture conservation rules can be applied across different sites and pasture types. This suggests that farmers can be flexible in choosing pasture conservation practices to help balance competing demands on labour and other resources without risking a loss in profit. Key words: dairy farm, pasture surplus, production, profit, whole farm model
Dairy farmers in New Zealand are encouraged to adopt a range of management strategies, both well established and emerging, to reduce nitrogen (N) losses to waterways. In most regions the OVERSEER® nutrient budgeting software (Version 6) (hereafter referred to as Overseer) is the tool of choice in the assessment of N losses for both regulatory and monitoring purposes. As part of these processes, Overseer is used to assess the impact of improved farm practices on N leaching and runoff from individual farms. In a 3-year dairy system field trial at Massey University, N losses in leaching and runoff under duration-controlled grazing (DC; 4 hours per grazing) were compared with those under standard grazing (SG; 7 hours per day-grazing, 13 hours per night-grazing). A 36% reduction in total nitrogen (TN) losses under DC grazing was measured (14 kg TN/ha) relative to standard grazing (22 kg TN/ha). Farmers adopting DC grazing as a mitigation strategy will only be able to claim the reduction in TN losses estimated by Overseer, and thus observations from the field trial were compared with outputs from Overseer. There was good agreement between the Overseer predictions of N leaching and values measured at the trial site for both the SG and DC grazing treatments. A second Overseer simulation of a DC system suggests that while Overseer is able to predict the reductions in N leaching under DC grazing reasonably well, some issues such as runoff losses and storage of effluent need further consideration. Keywords: Duration-controlled grazing; OVERSEER®; N leaching
Despite a growing interest in ruminant nutrition and the ongoing, widespread use of forage brassicas, there is an absence of data that adequately describe the nutritional value of modern brassica cultivars in New Zealand. Five forage brassica species represented by 30 cultivars were evaluated in single-site, single-year trials in the South Island. Replicated plots of leafy turnips, bulb turnips, rape, swede and kale were harvested at 53, 91, 98, 181 and 186 days after sowing, respectively. Whole plants were dissected to leaf, stem and bulb and/or petiole and components assessed for nutritive value. Quality differed significantly among and within brassica species. Within species, percent dry matter (DM) was consistent for rape, bulb turnip and leaf turnip, but differed significantly among cultivars in kale and swede. Mean metabolisable energy (MJ ME) content at harvest was highest for swede (13.8 MJ ME/ kg DM) and lowest for kale (11.2 MJ ME/kg DM). For all brassica species, fibre content as estimated by neutral detergent fibre (NDF) content was below optimum for ruminal function, highlighting the importance of high NDF supplementary feeds for brassica-fed stock. For some but not all brassica species, nutritive value may be modified by cultivar selection however factors not investigated in this study including sowing rate and time from sowing to harvest remain important potential moderators of forage brassica quality. Keywords: Forage brassica, leafy turnip, bulb turnip, forage rape, swede, kale, nutritive value, feed testing
Currently spring forage crops are used to manage late calving cows on the dairy platform, protect spring pasture from pugging damage, and allow the animals to feed on a mix of brassica and pasture to transition to a pasture-based diet. In addition, like winter forage crops, they could contribute considerable water quality contaminants via surface runoff. However, it may be possible to manage farms without spring forage crops. Two Southland dairy farms were used to show: 1) flowweighted mean concentrations of many water quality contaminants in surface runoff from a spring-grazed forage crop were similar to those found in studies of winter-grazed forage crops; and 2) that, using growth rate data for 2007–2012, in no year was the modelled forage crop beneficial from a feed supply perspective, and in all years the farms had similar financial performances and fewer feed deficits under all-grass management. Hence, good pasture management (e.g. avoiding treading damage using a stand-off pad and short grazing times) may negate the need for a spring forage crop, decreasing contaminant losses while not impairing farm profitability. Keywords: surface runoff, transition diet, water quality, winter forage crop.
There is debate on how pasture growth rates and annual production on dairy farms in Southland/Otago compare to the comprehensive data collected at AgResearch Woodlands under sheep grazing. Additionally, there are no good data on seasonal variation in dairy pasture quality from the region. Six farms in different geographical regions of Southland and south and west Otago were monitored from spring 2007 until May 2012 to measure pasture growth rate, soil temperature and pasture nutrient composition (with the exception of south Otago). Pasture growth rates varied between farms and between years. The highest growth rates were recorded in coastal Southland and the lowest in northern Southland. Rainfall and soil temperature differences explained some of the changes in pasture growth rate throughout the seasons. Sharp drops in pasture quality in early summer were recorded on all farms. Considerable variation in pasture growth rate occurs across the Southland/Otago regions. Times of year when the greatest variability occurs have now been identified for each region. Keywords: Southland, Otago, pasture growth, pasture quality, dairy
Variation in rainfall, soil type and growing degree days across the West Coast creates wide variation in pasture growth rates. Farmers require pasture growth rate and quality information local to their environment to assist them with their on-farm decision making. Four farms in different geographical regions of the South Island’s West Coast were monitored for four years to measure pasture growth rate (weekly, plate meter), nutrient composition (fortnightly, pre-grazing) and soil temperature (weekly, 10 cm depth). Average monthly pasture growth rate varied between the farms, however the seasonal trends were similar in all regions. There was significant variation in average monthly growth rate between years for individual farms. Soil temperature explained some of the trends in pasture growth rate, particularly in winter and early spring. Pasture quality was lowest during the summer months when neutral detergent fibre concentrations were greater. Pasture crude protein concentration exceeded 25% in 63% of the samples collected. Information reported will allow dairy farmers and their advisors to develop feed budgets and assess the appropriateness of the stocking rate and calving date of the farm relative to the annual pasture growth patterns. Times of year when the greatest variability occurs have now been identified for each sub-region. Keywords: West Coast, pasture growth, pasture quality, dairy
It is common practice to renew old and “run-out” pastures that are not performing. Renewing pasture is costly so it is critical that the regrassing pays off. This trial on ten irrigated dairy farms from North Canterbury to North Otago was initiated to determine the value of regrassing on long term production and persistence of the new pastures. A pasture, deemed as run-out by the farmer, was subdivided and one half was renewed to a novel endophyte ryegrass pasture while the remainder of the paddock remained in the old pasture. The new pasture was compared with the original and another pasture on the same farm, considered by the farmer to be high performing. Pasture composition, production, and quality and pasture pests and endophyte infection have been monitored for two years. Herbage production is presented for the first 2 years of an ongoing trial, with quality and determination of wild/novel endophyte. When averaged across all 10 farms, the “control”, “new” and “good” paddocks have all produced 15 t DM/ha in the year to May 2012. Levels of novel endophyte have remained high in the majority of new paddocks over the first 2 years. Clover root weevil is now present on all ten farms, at high levels (>200/m2) in some paddocks. Production from the new pastures equalled the total DM production from old pastures within 10 months of sowing. However, 2 years following pasture renewal, there has been no production advantage achieved from regrassing a stable old pasture. Keywords: pasture renewal, pasture persistence, irrigated dairy pastures, endophyte, pasture production, pasture composition
Successful establishment of lucerne requires an adequate plant population to maximise yield and maintain stand persistence. The impact of autumn sowing lucerne at four sowing rates was investigated in a split-plot experiment at Lincoln University, Canterbury from 2007–2012. Emerged seedlings represented about 50% of the seeds sown regardless of the 7–16 kg/ha sowing rate. Self-thinning occurred at a faster rate from the higher sowing rates with populations of 80 plants/m2 in all treatments by Year 6. These populations ensured annual DM yields were maximised and similar across sowing dates and rates, in all years. However, the 10 t DM/ha yield in Year 1 was below the 13 t/ha average from Years 2–5. This suggests Year 1 crops were still in an establishment phase in their first spring after autumn sowing. This is supported by the initial spring water use efficiency (WUE) in Year 1 crops of 15–20 kg DM/ ha/mm of water used. This was lower than the 30–40 kg DM/ha/mm in subsequent years, and is consistent with Year 1 crops partitioning a higher proportion of assimilate below ground during the establishment phase. These calculated WUE values were probably overestimated because they were based on NIWA assumptions of 150 mm of available water for pastures, which appears to be too low for lucerne. Keywords: alfalfa, Medicago sativa
Phosphorus (P) loss from land is a central factor in poor surface water quality in Southland. Much loss of P can occur if surface runoff occurs soon after the application of highly water soluble P fertilisers (e.g. superphosphate). Three P fertilisers (superphosphate, serpentine super, and a Ca-phosphate) of different water solubilities were applied (30 kg P/ha in spring) to a grazed dairy pasture, and the relative agronomic effectiveness and P losses determined. Across all 3 years, there were no differences in annual pasture production among the different types of P fertilisers. For 2 years out of 3, significantly more P was lost via surface runoff from the superphosphate-treated plots than from plots treated with either serpentine super or the Ca-phosphate. On average, the use of low water soluble Ca-P fertiliser decreased P losses by an average of 47% over the 3 years. It is currently recommended that to decrease P losses associated with fertiliser, applications should be timed when runoff events are unlikely for at least 3 weeks following application. If this runoff cannot be avoided, or to ensure P losses are as low as possible, the use of a low water soluble P product may be of benefit. Key words: Surface runoff, phosphate fertilisers, phosphorus loss, superphosphate.
We live in interesting times. The words above used to be associated with a Chinese curse but now “interesting times” are simply life as we know it. The past 12 months in global agriculture have encompassed rapidly changing commodity prices, floods, fires, tsunamis, earthquakes, the emissions trading scheme discussions, statements about water quality and debates on alternative product and farm ownerships. Resilience is increasingly the call, at the same time as farmers are being urged to increase productivity by adopting new technologies whilst living within increasingly stringent regulations. A remarkable number of reports containing implications for agriculture have been released over the last few months addressing the same issues from different perspectives. Bringing them together indicates a role for New Zealand agriculture beyond that of increasingly efficient food productivity – also known as Business As Usual (BAU). The challenge, as always, is how to achieve that role.
In developing marker-assisted selection (MAS) for herbage yield and persistence traits in forages, traitlinked markers were tested in elite breeding populations of complex parentage, to identify population-specific marker:trait associations. The effectiveness of these were subsequently evaluated in progeny generated by MAS. In white clover (Trifolium repens), markers detected significant (P<0.005) within-population differences in node number, a trait contributing to plant persistence. Progeny carrying beneficial marker variants exhibited a 19% increase in node number compared to those lacking these markers. In perennial ryegrass (Lolium perenne), a single marker detected a herbage yield differential of up to 23% within the populations tested, and progeny from divergent MAS exhibited a similar performance difference. These findings show that traitlinked markers can be used to manipulate quantitative traits in elite breeding populations of forage species and may subsequently contribute to development of improved cultivars. A next generation of marker technology will support expansion from single locus selection approaches to genomic selection, applied directly in breeding populations, offering enhanced contribution to genetic gain. This proof of concept for MAS for yield and persistence traits in forage breeding is an important step toward acceleration of genetic gain in forages, underpinning the ongoing competitiveness of New Zealand’s pastoral sector. Keywords: herbage yield, persistence, quantitative trait locus, simple sequence repeat, plant breeding
Wintering cows on forage crops leads to urine being excreted onto wet, compacted soils. This is likely to result in significant gaseous emissions of nitrous oxide (N2O), which may be reduced through strategic applications of nitrification inhibitors. A study was established on a winter swede crop to (i) determine N2O emissions from compacted soil treated with cattle urine, and (ii) quantify the effectiveness of a nitrification inhibitor, dicyandiamide (DCD), in reducing these emissions. Nitrous oxide emissions from the urine + compacted soil were significantly greater (P < 0.001) than from compacted soil without urine, with 3.2% of the urine-N being lost as N2O. DCD application significantly reduced this loss (P < 0.05) to 0.8% of the applied urine-N. Expressed at a paddock scale, total N2O emissions from the winter-grazed swede crop were 7.9 kg N ha-1, which was reduced to 3.4 kg N ha-1 when DCD was applied. Keywords: urine, dicyandiamide, nitrification inhibitor, soil compaction, nitrous oxide.
Reactive phosphate rock (RPR) has been studied extensively in field trials and laboratory research in New Zealand since the 1930s. This paper looks at the different approaches to research over the decades, at what conclusions were drawn, at the recommendations made to farmers, and at the commercial promotion and sales of RPR. It is not an exhaustive literature review, but sufficiently comprehensive to demonstrate the large amount of research conducted, and to document the important issues that have arisen, particularly with respect to advice being given to farmers. RPR research has suffered from a series of mishaps which have hindered, in one way or another, the results being accurately interpreted and passed on clearly to farmers. There is a need for specific advice for farmers regarding managing or minimising any lag in production following a switch to RPR. New Zealand’s grazed pastures, water quality and “clean and green” image internationally are closely interlinked. Given the proven significant reduction in P losses in run-off to waterways with RPR, the conditions in which RPR can be successfully used in New Zealand’s pastoral agriculture have been reassessed. Key words: reactive phosphate rock, RPR, superphosphate, SSP, TSP, PAPR, long-term comparisons, plot trials, grazing trials, fertiliser recommendations, history
The commercial introduction of reactive phosphate rock (RPR) to the New Zealand market in 1987 was the subject of much dispute regarding its efficacy, and the differing interpretations of field trial results. Twenty-five years on, it was considered time to seek the views of farmers who are long-term users of RPR, across a wide range of geographic, soil type, fertility, climate and farming operations. The fact that the farmers interviewed have all been farming successfully with RPR for many years enables conditions suitable for RPR use to be identified more clearly compared to earlier advice. This progress is discussed in the context of utilising the proven reduced phosphorus (P) run-off with RPR to reduce P eutrophication in P-sensitive catchments. Key words: Reactive phosphate rock, RPR, superphosphate, SSP, long-term use, phosphorus runoff, eutrophication, water quality, recommendations
Perennial ryegrass plants (Lolium perenne) were taken from an established field at two different stages in the season (mid-winter and again at mid-summer). They were then grown in a controlled environment to both “lock in” their contrasting developmental states and to look at the role of nitrogen supply, temperature, and developmental state separately to evaluate the potential of plants to respond to exogenous application of gibberellin. Responses to exogenous gibberellin (gibberellic acid, GA) were significant but were far smaller in summer-derived than winter-derived plants. The major difference in response to GA (compared with controls) between winter-derived and summerderived plants suggests that seasonal changes in plant developmental state have a major effect in the field on the capacity for the plants to respond to exogenous GA application. This effect is greater than that of temperature and N availability. This raises new prospects for making sustained increases in plant growth, but only if the fundamental mechanisms by which plants control their responses to environmental signals (e.g., temperature and soil N status) can be understood. The role of gibberellins (endogenous as well as externally applied) in changes in plant growth strategy presents a new challenge for forage plant science.
Clover root weevil was first discovered in the South Island in 2006. Since then its distribution has been monitored. Although not yet occurring throughout all the South Island, it is widespread and has become common in many regions. The first releases of a biocontrol agent, the Irish ecotype of the parasitoid wasp Microctonus aethiopoides, were also made in 2006, with more made as suitable weevil populations were detected. In all areas where the releases have been monitored the biocontrol agent has established and extensive natural spread has occurred from the earlier release sites. As a consequence it is now established extensively in the northern South Island. Targeted releases have established the agent in Canterbury, Otago and Southland. Keywords: Biocontrol, clover root weevil, Sitona lepidus, Microctonus aethiopoides
Southern New Zealand has seen major changes in land use in the past 20 years with the rise in dairy cows in milk from 149 000 in 1994 to 682 000 in 2010, while breeding ewe numbers have declined from 11.2 million to 7.3 million over the same period. The development of milking platforms with a significant need for winter dairy grazing has opened up many opportunities for sheep, beef and deer farmers in the region. The need to remain profitable, displacement of sheep to more marginal land, and social influences such as retaining family ownership have encouraged farmers to make the most of potential land-use change opportunities. Three case studies outline the changes made and potential profitability increases in dairy conversion, flexible sheep and beef operations and improved deer production, with cash surplus after expenses being more than doubled in each case. Keywords: land use, profit, dairy, sheep, beef, deer.
Evidence suggests that the wintering of stock on forage crops is a significant contributor to N losses from livestock farming. Losses are likely to be exacerbated if crops are grown on shallow free-draining soils types and grazed by dairy cattle. A three-year trial (December 2008 – November 2011) was conducted in northern Southland on a soil classified as having severe vulnerability for nutrient leaching to groundwater. Porous ceramic cups were installed under a brassica crop which was grazed by dairy cows in June each year and the leachate collected regularly for N analysis. The treatments evaluated were with and without a single application of DCD applied at the time of crop grazing. Concentrations of nitrate-N in drainage water ranged from <1 mg/L initially to a peak of >40 mg/L in May 2011. Concentrations of dissolved organic N (DON) also increased from a low initial value (<4 mg/L) to peak at 48 mg/L in May 2011. Estimates of mean annual losses of total nitrogen (TN) in drainage to groundwater averaged 81 kg N/ha/yr and ranged from 8.5 kg N/ha in 2009 to 125 kg N/ha in 2011. The single post-grazing application of DCD did not significantly reduce nitrate leaching losses. Keywords: winter forage crop, cow urine, nitrate leaching, dicyandiamide, DCD.
Grazing of brassica winter forage crops returns large amounts of excreted nitrogen (N) back to the paddock during winter when risk of leaching is high. This experiment measured nitrate-N leaching below 60 cm of 132 and 173 kg N/ha following June grazing by dairy cows of swede/kale crops in 2008 and 2009. Application of DCD immediately after grazing plus 6 weeks later decreased leaching by 20–27% (significant at P<0.05). The retained N was measurable in the soil (0–60 cm) at the end of drainage. We conclude that: grazing of winter forage crops can leach large amounts of N; DCD is one tool to decrease leaching; retained N needs to be utilised by the following crop or pasture and represents a valuable resource on the farm. Key words: Winter forage, nitrogen, leaching, DCD
This trial provided information about the effects of defoliation intensity and frequency on the productivity and plant population of a plantain pasture. Despite the restrictions in plantain management, the focus is to promote its use as specialised pasture for specific purposes. Maximum herbage production was 10.9 t DM/ha/year for a frequent and severely defoliation treatment. Frequency of defoliation affected productivity at different times, mainly in spring (P=0.0013), production being promoted by frequent defoliation intervals (21 days). Plant population was affected by defoliation strategies during the year, being promoted by infrequent and lightly defoliation regimes. Previous results showed that the effects of intense defoliation increased over time, reducing plant size and density. The understanding of plantain response to defoliation regimes will contribute to increased outputs of plantain pastures and extend species persistence, and allow management strategies to be defined according to the production system. Keywords: defoliation, intensity, frequency, population
The Lucerne for Lambs Sustainable Farming Fund project used on-farm data and whole-farm modelling to help farmers understand the impact of increasing the amount of grazing dryland lucerne on Central Otago farms. On-farm results from 2 years showed that spring stocking rate on lucerne-based pasture averaged 10 ewes and their lambs per hectare compared with 3 ewes and their lambs on dryland grass-based pasture. Lamb growth rate was approximately 50 g/day higher on lucerne-based pastures, resulting in a total lamb production of 358 kg liveweight/ha at weaning compared with 108 kg liveweight/ha on grass-based pastures. Whole-farm modelling showed that increased profitability could be achieved by the addition of significant areas of grazing lucerne. Profitability increased by $119/ha on a 5000 ha traditional merino property. Profitability of a 522 ha partially irrigated valley floor property running crossbred ewes was increased by $249/ha. Using lucerne for spring grazing also reduced the impacts of both winter and summer droughts in the variable conditions of Central Otago. Keywords: dryland, lamb growth, lucerne, modelling, profitability, stocking rate, whole farm systems.
Decline in soil phosphorus (P) concentrations is slow, and environmentally significant concentrations of P can be lost to water long after fertiliser application is decreased. One potential method to accelerate the decline in soil P concentrations is to increase plant uptake by applying nitrogen (N). A one-year lysimeter trial investigated P losses to leachate on three soil types receiving three rates of N fertiliser (0, 150 and 300 kg N/ha/yr) and zero or half maintenance P fertiliser, with regular cutting and removal of pasture. Increasing N input increased annual pasture yield and decreased DRP loss in leachate compared to the zero N treatment, without increasing nitrate or ammonium loss. Furthermore, treatments receiving half maintenance P at all N rates had lower P losses than the zero N and zero P treatment. Based on a cut and carry system, increasing N fertiliser in conjunction with decreasing P fertiliser has potential as a mitigation strategy to decrease P loss without compromising yields or increasing N leaching.
Pasture moisture stress for “summer” (November to March) was calculated for five main pastoral regions of New Zealand, and 9 or 10 years’ weather data were modelled in each case. Amelioration of water deficit with deeper rooting, stronger plant tissue osmotic potential for greater water extraction, or increased photosynthetic water use efficiency (WUE) was also modelled. Regional mean summer moisture deficits ranged from 34 mm in Taranaki to 447 mm in Canterbury. For a 10-cm increase in rooting depth, the model predicted an additional 16 mm water extraction. Increased plant osmotic potential was predicted to only slightly increase water extraction and paradoxically reduce yield. The assumed increase in photosynthetic WUE improved production by 240 kg DM ha-1 for the same water use. Drought tolerance traits exhibited by a range of ryegrass cultivars were measured in a series of glasshouse experiments and the potential to improve New Zealand ryegrass drought tolerance by introgression with germplasm originating from North Africa was assessed. North African germplasm possesses a trait of deep rootedness but has low summer productivity as a soil moisture conservation strategy and a high percentage of tillers flowering, so initial evaluations of this material for suitability for use in New Zealand are not promising. Ryegrass cultivars incorporating germplasm of Spanish origin appear to maintain summer production with enhanced WUE. Keywords: drought tolerance, root depth, Lolium perenne, perennial ryegrass, water deficit
The performance of the national ewe flock has increased significantly in the past 20 years. Pasture management in winter and early spring has a large impact on the success of the subsequent seasons. Overgrazing in winter can reduce spring pasture production by up to 80%. Treading and pugging damage can also decrease spring pasture production by 10% for every 10% of bare area created. Maintaining pasture cover at over 2000 kg DM/ha can improve pasture growth, and leaving a residual pasture mass of more than 1200 kg DM/ha also aids in pasture production in late winter. Techniques such as feed budgeting, longer winter feeding periods (4 day cf. 1 day shifting) and increasing the control of feed intake during late pregnancy can be used to help achieve the goals of higher pasture residuals and increased pasture growth and availability. More tools for managing the transition from winter rotational grazing to spring continuous grazing would help farmers. Keywords: early spring production, grazing management, pasture cover, residual cover, treading.
A mixture experiment was conducted at Lincoln University to investigate if mixtures of Italian ryegrass, red clover and balansa clover gave more high quality forage and suppressed weeds better than Italian ryegrass monocultures. Thirteen seed mixtures with varied species proportions were sown at 20 and 30 kg/ ha in March 2011. The minimum amount of Italian ryegrass was 50% of the total sowing rate. Plots were harvested six times over 12 months and were neither irrigated nor fertilised. Inclusion of red clover increased yield by 41% compared with the Italian ryegrass monocultures (13.79 vs. 9.75 t DM/ha), and provided effective weed suppression (<5% of total annual yield) and high quality forage (17.5% crude protein, 11.3 MJ/ kg DM metabolisable energy). No benefits were gained from mixing balansa clover with Italian ryegrass. The optimum seed mixture was 12 kg/ha of Italian ryegrass, 8 kg/ha of red clover and no balansa clover. Keywords: dryland, greenfeed mixtures, simplex design
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