A comparison of the intake of cows grazing swedes and kale and
consequent condition score change.
B.R. THOMPSON and D.R. STEVENS
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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.
Anticipating the unexpected – managing pasture pest outbreaks
after large-scale land conversion
T.A. JACKSON, R.J. TOWNSEND, J.E. DUNBAR, C.M. FERGUSON,
S.D.G. MARSHALL AND S.M. ZYDENBOS
view more
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
AR37 endophyte effects on porina and root aphid populations and
ryegrass damage in the field
A.J. POPAY, B. COTCHING, A. MOORHEAD and C.M. FERGUSON
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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
Assessments of N leaching losses from six case study dairy farms
using contrasting approaches to cow wintering
J. M. CHRYSTAL, R.M. MONAGHAN D. DALLEY and T. STYLES
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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.
Can herb-clover mixes increase lamb liveweight gains in spring?
S.C.S. SINHADIPATHIGE, P.R. KENYON, P.D. KEMP, S.T. MORRIS and P.C.H. MOREL
view more
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
Cleancrop™ Brassica System: The development of herbicide
resistant brassica crops for New Zealand farming systems
A. DUMBLETON, S. GOWERS, A. CONNER, M. CHRISTIE, P. KENNY, H. MULCOCK, and B. CHARTERIS
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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 for evaluating pasture plant traits
D.F. CHAPMAN, J.R. BRYANT, W.H. McMILLAN and E.N. KHAEMBAH
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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
Effects of weather variability on sheep and beef farming in northern
Southland, New Zealand: A modelling analysis
F.Y. Li, R. Vibart, R.A. Dynes, I. Vogeler and M. Brown
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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
Establishment of lucerne (Medicago sativa) sown on five dates with
four inoculation treatments
K. WIGLEY, D.J. MOOT, Q. KHUMALO and A. MILLS
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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
Evaluating perennial ryegrass cultivars: improving testing
G.A. KERR, D. F. CHAPMAN, E. R. THOM, C. MATTHEW, A. VAN DER LINDEN, D. B. BAIRD, E. JOHNSTON and J. R. CORKRAN
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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
Evaluating the Agronomic Effectiveness of Fertiliser Products
D. C. EDMEADES and R. M. McBRIDE
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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.
Farmlet testing of the DairyNZ Conservation Demo
C.G. ROACH, P.C. BEUKES and A.J. ROMERA
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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 – modelling the financial benefits of control on a
Golden Bay dairy farm
GRAEME BOURDÔT, WARREN KING and GRANT RENNIE
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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
Has the eco-efficiency of sheep and beef farms changed
in the last 20 years?
A.D. MACKAY, A.P. RHODES, I. POWER and M.E. WEDDERBURN
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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
Integrating high yielding crops into a Taranaki dairying system
K.A. Macdonald, J. Clough, J.M. de Ruiter, C.B. Glassey T. Sears and N. Sears
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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
Issues related to the management of nutrients on organic dairy
farms: Nitrate leaching and maintaining soil nutrient levels
D. J.HORNE, E.F. DIJKSTRA, A. S. PALMER and P. CAREY
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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
Long term pasture growth patterns for Southland New Zealand:
1978 to 2012
L. C. SMITH
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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
Modelling the impact of surplus pasture management techniques on
production and profit in a pasture-based dairy system
K.T. Wynn, P.C. Beukes and A.J. Romera
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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
Nitrogen loss mitigation using duration-controlled grazing: Field
observations compared to modelled outputs
C.L. CHRISTENSEN, M.J. HEDLEY, J.A. HANLY and D.J. HORNE
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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
Nutritional evaluation of five species of forage brassica
Nutritional evaluation of five species of forage brassica
view more
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
Opportunities to decrease the water quality impact of spring forage
crops on dairy farms
S.J. DENNIS, R.W. MCDOWELL, D.R. STEVENS AND D. DALLEY
view more
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.
Pasture growth and quality on Southland and Otago dairy farms
D. E. DALLEY and T. GEDDES
view more
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
Pasture growth and quality on West Coast dairy farms
D. E. DALLEY and G. GARDNER
view more
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
Performance of new dairy pastures
A.L.TAYLOR, T.J. FRASER and W.MCG. KING
view more
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
Plant population, yield and water use of lucerne sown in autumn at
four sowing rates
D.J. MOOT, K.M. POLLOCK and B. LEWIS
view more
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
Potential water quality impact and agronomic effectiveness of
different phosphorus fertilisers under grazed dairying in Southland
R. W. McDOWELL and L. C. SMITH
view more
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.
President’s address 2012
JACQUELINE ROWARTH
view more
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.
Progress towards marker-assisted selection in forages
M.J. Faville, A.G. Griffiths, M.Z.Z. Jahufer and B.A. Barrett
view more
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
Reducing nitrous oxide emissions from grazed winter forage crops
T.J. van der Weerden and T.M. Styles
view more
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.
RPR revisited (1): Research, recommendations, promotion and use in
New Zealand
B. F. QUIN and M. ZAMAN
view more
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
RPR revisited (2): Long-term farmer experience helps define the role
of RPR in grazed pastures
M. ZAMAN and B. F. QUIN
view more
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
Seasonal differences in the capacity of perennial ryegrass to
respond to gibberellin explained
C.C. BALL, A.J. PARSONS, S. RASMUSSEN, C. SHAW, and J.S. ROWARTH
view more
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.
Status of clover root weevil and its biocontrol agent in the South
Island after six years.
C.M. FERGUSON, M.R. McNEILL, C.B. PHILLIPS, S. HARDWICK, D.M. BARTON and J.M. KEAN
view more
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
The changing face of southern New Zealand farming: opportunities
of land use change
R.J. COPLAND, D.R. STEVENS
view more
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.
The effectiveness of the nitrification inhibitor dicyandiamide (DCD)
for mitigating nitrogen leaching losses from a winter grazed forage
crop on a free draining soil in northern Southland.
L C SMITH, T ORCHISTON, R M MONAGHAN
view more
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.
The use of a nitrification inhibitor (DCn™) to reduce nitrate leaching
under a winter-grazed forage crop in the Central Plateau
M. SHEPHERD, A. STAFFORD and D. SMEATON
view more
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
Understanding Plantain (Plantago lanceolata L.) responses to
defoliation in Uruguay
W. AYALA, E. BARRIOS, R. BERMÚDEZ, N. SERRÓN
view more
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
Understanding the role of spring grazing of lucerne in the Central
Otago environment
D.R. STEVENS, B.R. THOMPSON, A. CARRUTHERS, A.J. Wall, M.J. Casey,
R. Phiskie, P. Young and D.J. Moot
view more
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.
Using nitrogen fertiliser to decrease phosphorus loss from high
phosphorus soils
R.J. DODD, R.W. McDOWELL and L.M. CONDRON
view more
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.
Which way forward in the quest for drought tolerance in
perennial ryegrass?
C. MATTHEW, A. van der LINDEN, S. HUSSAIN, H.S. EASTON, J.-H.B. HATIER and D .J. HORNE
view more
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
Winter management practices to optimise early spring pasture
production: a review
A.J. WALL, D.R. STEVENS, B.R. THOMPSON and C.L. GOULTER
view more
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.
Yield of Italian ryegrass mixed with red clover and balansa clover
T.P. RYAN-SALTER and A.D. BLACK
view more
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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