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This work measures the effectiveness of boundary delivery from a new computer-controlled aircraft bulk solid delivery system (Intellispread+). Computer controlled delivery of solid fertilisers by aircraft has been practised commercially in New Zealand since 2014. Aircraft position is determined in relation to a rate change polygon, aircraft ground speed, spread material characteristics, and control system parameters, and the hopper opening is altered to provide the correct rate. All these systems working simultaneously are computationally intense. Effective variable rate application depends on the response to boundary rate changes, aircraft GPS accuracy and update frequency, wind direction and speed, and particle ballistics that determine the deposition of fertiliser. Rapid responses to boundary rate changes improve fertiliser placement accuracy and mitigates off-target application near environmental sensitive areas. The system was tested on a block 200 m long by 18 m wide with 126, 0.5 m2 diameter collector cones, spaced 10 m apart longitudinally and 3 m laterally. A PAL Cresco 600 was flown at 64 ms−1 (130 knots) on three tests to measure performance, shutting off and opening at a boundary and changing rate halfway along the block. For all tests initiation of rate change and completion was achieved within 30 m. [ABSTRACT FROM AUTHOR]

Selliera radicans is a creeping halophyte herb native to Australia, New Zealand and Chile. It is being used on the lawn to replace traditional grass in gardens. It holds up well against foot traffic and does not need to be mown. It is grown in nurseries, but nutritional or fertilizing aspects are unknown. The aims of this study were to assess plant coverage, dry matter (DM) content and nutrient accumulation in containerized plants started from two-node rhizome fragments in a growing season, and to develop a preliminary fertilizing guideline. The plants received mist (without fertilizer) and were watered twice a week with nutrient solutions of 0 (control), 150, and 300 mg L−1 N based on a 18 N − 18 P2O5−18 K2O fertilizer. Increasing fertilization rate resulted in higher DM, plant coverage and nutrient accumulation. The species occurs naturally in coastal areas under saline conditions; Na from the water used for irrigation (17 mg L−1) was not detrimental, despite plant Na concentration being higher than 1 g 100 g−1 dry matter in all treatments. The general guideline proposes to fertilize with 1 g N, 0.5 g P and 0.95 g K per plant (plant started from a rhizome fragment and growing into a complex plant with several axis) during the growing season, under the experiment conditions. [ABSTRACT FROM AUTHOR]

Reliable data on the rate of cadmium (Cd) accumulation in soils that receive phosphorus (P) fertiliser is vital to help manage the impact of Cd in agricultural systems in New Zealand. Studies of the long-term P fertiliser trial at Winchmore, where soils have received 0, 17, or 34 kg P ha−1 yr−1 for > 60 years, have reported that soil Cd concentrations over the last 15 years have either plateaued or are still increasing. To address this discrepancy, new soil Cd analysis was conducted on a wider set of archived soil samples from the Winchmore trial, along with some re-analysis of soil samples for Cd. When soil Cd data from previous studies were combined with the more recent set of Cd data, regression analysis indicated soil Cd concentrations in the 17, or 34 kg P ha−1 yr−1 fertiliser treatments are still increasing linearly over time. It is recommended soil samples from the long-term Winchmore trial continue to be analysed for Cd to confirm long-term trends, avoiding short-term perturbations. Such long-term trials are invaluable for providing robust information that will help in the ongoing management of Cd in New Zealand. [ABSTRACT FROM AUTHOR]

Managed grasslands have the potential to store carbon (C) and partially mitigate climate change. However, it remains difficult to predict potential C storage under a given soil or management practice. To study C storage dynamics due to long-term (1952–2009) phosphorus (P) fertilizer and irrigation treatments in New Zealand grasslands, we measured radiocarbon (14C) in archived soil along with observed changes in C stocks to constrain a compartmental soil model. Productivity increases from P application and irrigation in these trials resulted in very similar C accumulation rates between 1959 and 2009. The ∆14C changes over the same time period were similar in plots that were both irrigated and fertilized, and only differed in a non-irrigated fertilized plot. Model results indicated that decomposition rates of fast cycling C (0.1 to 0.2 year−1) increased to nearly offset increases in inputs. With increasing P fertilization, decomposition rates also increased in the slow pool (0.005 to 0.008 year−1). Our findings show sustained, significant (i.e. greater than 4 per mille) increases in C stocks regardless of treatment or inputs. As the majority of fresh inputs remain in the soil for less than 10 years, these long term increases reflect dynamics of the slow pool. Additionally, frequent irrigation was associated with reduced stocks and increased decomposition of fresh plant material. Rates of C gain and decay highlight trade-offs between productivity, nutrient availability, and soil C sequestration as a climate change mitigation strategy. [ABSTRACT FROM AUTHOR]

There is need for information on the general crop physiology and nitrogen (N) fertiliser responses of beetroot in New Zealand. We investigated the responses to N of beetroot grown in a silt loam near Hastings, Hawke's Bay. Four fertiliser treatments (0, 160, 320 or 480 kg N ha−1) were applied as urea, split evenly over four application times. The canopy light extinction coefficient averaged 0.64. Radiation use efficiency averaged 1.05 g MJ−1 for the treatments that received N fertiliser. Maximum yield occurred at an N fertiliser rate around 320 kg N ha−1. Published recommendations suggest only 225 kg N ha−1 would have been needed. This underestimation would have led to a yield penalty of only about 6%, but decreased the risk of significant mineral being N left in the soil. We discuss approaches to account for N supply from the soil when forecasting residual mineral N and N leaching risk. [ABSTRACT FROM AUTHOR]

Phosphate ores can contain high levels of 238U and its decay products. Of these decay products 226Ra is an important environmental contaminant, while 228Ra from 232 Th day may also be present, albeit at lower activity concentrations. Acid processing of phosphate ore to triple superphosphate elutes a large proportion of the 226Ra from the final product. However, fertiliser production in New Zealand generally avoids acid processing and instead uses single superphosphate and reactive phosphate rock to maintain crop yields, meaning that 226Ra is retained in the final product. As a first step towards characterising the human health impacts from fertiliser-borne radium, research was undertaken to identify loading and long-term accumulation of 226Ra and 228Ra in New Zealand agricultural soils, as well as the fractionation of 226Ra into different soil phases. Activity concentrations for 226Ra of up to 1.6 kBq/kg were determined in phosphate-containing fertilisers used in New Zealand. In contrast, 228Ra did not exceed 75 Bq/kg. Analysis of 40 New Zealand soils, covering a range of agricultural uses, showed activities of between (27–88) Bq/kg 226Ra and (21–102) Bq/kg 228Ra. Unexpectedly, there was also a strong correlation between the two radium isotopes. In 13 of the agricultural soils, all with very high available phosphate levels, the fractionation profile of 226Ra was determined. These data indicated that 226Ra largely remains immobile in the residual phase of the soil. Calcium and available phosphate were significantly correlated with binding of 226Ra into labile and non-labile fractions. Barium is also hypothesised to play a significant role in co-precipitating 226Ra into non-labile soil fractions. While a high percentages of 226Ra immobile in the non-labile fraction would allow for marked accumulation over time it may limit the availability for uptake into crops and thus the ionising radiation dose for consumers. • Phosphate fertilisers used in New Zealand contained upto 1.6 kBq/kg 226Ra. • New Zealand soils had ranges of 27–88 Bq/kg 226Ra and 21–102 Bq/kg 228Ra. • 226Ra and 228Ra displayed strong linear correlation in agricultural soils. • 226Ra largely remains immobile in the residual fraction of New Zealand soils. • Ca and available P correlate with 226Ra in labile and non-labile fractions. [ABSTRACT FROM AUTHOR]

The area of indigenous vegetation and habitat remaining on New Zealand's primary agricultural lands continues to decrease, but it has been difficult to obtain reliable estimates of the extent and causes of loss. We assess change and identify predictors of vegetation clearance in 856 recommended areas for protection (RAPs) from 35 ecological districts in the North and South Islands, New Zealand, for the period 1989 to 2015. Over 27 years, 7152 ha of these RAPs were cleared (2.3% by area), with rates varying over space and time. Native forest was least commonly cleared (422 ha removed), followed by native non-woody vegetation (1294 ha), native shrubland (1378 ha), and 'other' vegetation (4058 ha). The probability of clearance peaked during 2001 to 2008 at 0.14% yr-1, but it was still nearly double the 1989-2001 levels (0.06% yr-1) from 2008 to 2015 (0.11% yr-1). The annualised clearance probabilities after 2001 were comparable to the rates of deforestation in the pre-1840 period of human settlement and about a third of that recorded from 1840 to 1970, the most intensive known period of anthropogenic clearance in New Zealand. Clearance rates were higher around the edges of small RAPs without legal protection and in drier, cooler areas, generally and increasingly over time. Amount of surrounding cropping/horticulture was negatively associated with clearance, as initially was dairy before developing a slightly positive association. Forestry was positively associated with clearance up until 2008. Our results show proportionally greater clearance of marginal agricultural land with high biodiversity values as time goes on, probably facilitated by the increasing use of technology, such as irrigation and fertilisation, to circumvent environmental limitations to plant growth. These results demonstrate ongoing attrition of the highest-value native habitat remaining on private land, and the inadequacy of the current protection framework to safeguard it. [ABSTRACT FROM AUTHOR]

The enrichment of phosphorus (P) in streams and rivers can impair water quality, but concentrations have decreased. We found little evidence that this improvement was caused by a decrease in soil Olsen P concentrations or imported P (e.g. fertiliser), a change to low water-soluble P fertilisers, or that greater nitrate loads were assimilating P from groundwater or sediments. Possible causes of improvement were that land use change had decreased erosion, more nitrogen fertiliser use was assimilating soil P, and a greater awareness of P as an environmental issue. However, the most probable causes were that strategies were mitigating P loss from land, guidelines were directing where to best use strategies, and policy instruments were including P management. These findings support the development and implementation of mitigations, supported by voluntary guidelines and regulation. However, our findings can be strengthened if data are referenced to equivalent, and finer spatial and temporal scales. [ABSTRACT FROM AUTHOR]

Purpose: In New Zealand, the application of farm dairy effluent (FDE) on pasture soils is the third largest source of nitrous oxide (N2O) emissions from grazed grassland. Recently, new FDE treatment technologies have been developed to produce clarified water (CW) and treated effluent (TE) to recycle water and reduce the volume of fresh water used at the farm dairy. The aim of this study was to compare the effects of CW and TE with those of FDE on N2O emissions and the growth of ammonia-oxidising bacteria (AOB), ammonia-oxidising archaea (AOA) and denitrifiers, when the effluents were applied to a grazed pasture soil. Materials and methods: A microcosm incubation study was carried out to determine the effects of applying CW, TE and untreated FDE, with or without animal urine, on N2O emissions, and the abundance of AOB, AOA and the denitrifying functional genes, including nirS, nirK and nosZ. The soil used was a Templeton silt loam (Udic Haplustepsts). The effluents were applied at nitrogen (N) rates equivalent to 100 kg N ha−1 and the animal urine at 700 kg N ha−1. The soils were incubated at 12 °C to simulate autumn/winter soil temperatures in New Zealand, and the soil moisture was maintained at field capacity. Results and discussion: Results showed that the application of all the different effluents significantly increased the total N2O emissions (0.21–0.28 kg N2O-N ha−1) compared with that in the control (0.18 kg N2O-N ha−1). However, there were no significant differences in total N2O emissions between the different effluent treatments. Similarly, although the application of animal urine together with the different effluents further increased N2O emissions (7.7–8.8 kg N2O-N ha−1) above that from the urine only treatment (5.8 kg N2O-N ha−1), there were no significant differences among the different effluent plus urine treatments. These N2O results corresponded with the changing trends of the abundance of AOB, AOA, nirS, nirK and nosZ, that is the application of the CW, TE and FDE, with or without animal urine, had a similar impact on the growth dynamics of these microbial populations. Conclusions: These results indicate that the application of the CW and TE to dairy pasture soils would have a similar effect on N2O emissions, ammonia oxidisers and denitrifiers as that of the untreated FDE, with or without animal urine. The treated effluent or clear water from the new effluent treatment technology would therefore not increase N2O emissions nor adversely affect the key microbial populations involved in N cycling in soil. [ABSTRACT FROM AUTHOR]

Abstract Biowastes are unwanted materials of biological origin. They include biosolids, dairy shed effluent, and sawdust. When applied to soil, biowastes can provide plant nutrients, but also introduce heavy metals, pathogens, or xenobiotics. Biowastes could improve degraded or low-fertility soils and generate revenue through the production of non-food products such as essential oils. We grew New Zealand native plants, mānuka (Leptospermum scoparium J.R. Forst & G. Forst) and kānuka (Kunzea robusta de Lange & Toelken) in series of greenhouse experiments in low-to-medium-fertility soils (Bideford clay loam, Lismore stony silt loam, and Pawson silt loam) amended with either biosolids (up to 13500 kg N ha−1 equiv.), biosolids + sawdust (1:0.5–1250 kg N ha−1 equiv.) and dairy shed effluent (200 kg N ha−1 equiv.). Two types of biosolids from Kaikoura (KB) and Christchurch City Council (CB) were used in the experiments. CB (1500 kg N ha−1 equiv.) and dairy shed effluent (200 kg N ha−1 equiv.) increased the biomass of L. scoparium by up to 120% and 31%, and K. robusta by up to 170% and 34%, respectively. Adding sawdust to KB increased the biomass of L. scoparium and K. robusta although it offset the L. scoparium growth increase in the KB-only treatment. The growth response of K. robusta to biowastes was greater than L. scoparium with oil production in K. robusta increasing by up to 211% when 1500 kg N ha−1 equiv. of CB was applied to Lismore stony silt loam. Generally, the treatments had a negligible effect on oil concentration in all the soil types, except for the KB + sawdust treatment, which increased the oil concentration by 82%. Most of the EOs' major components were unaffected by biowaste addition in the soils, although some components increased in the Bideford clay loam following KB and KB + sawdust application. Biosolids increased foliar concentrations of Zn, Cu, and Cd, but these were below risk-threshold concentrations. Applying CB (up to 1500 kg N ha−1 equiv.) to low-fertility soils is recommended to establish ecosystems dominated by L. scoparium and K. robusta that annually would produce ca. 100 kg ha−1 of EOs worth US$ 26k and 24k, respectively. Adding sawdust to CB could have environmental benefits through reduction of N leaching. Field trials are warranted to elucidate critical ecological variables and production economics in biowaste management. Graphical abstract Image 1 Highlights • Biosolids and Dairy Shed Effluent increased growth on low-to-medium fertility soil. • Biosolids but not Dairy Shed Effluent increased essential oil production. • Oil production in Leptospermum scoparium and Kunzea robusta increased by up to 210%. • The optimal rates for biosolids addition was 1500 kg N ha−1 equiv. • Biowastes did not degrade the quality of the essential oils. [ABSTRACT FROM AUTHOR]

In this paper, the risk profile of two pastoral production systems in New Zealand are examined. All farmers must manage and mitigate a multitude of risks. Traditionally, a farm budget is solely undertaken to satisfy a lending institution. Limited variance analysis takes place, usually for output prices and inputs such as: interest rates, energy costs, and fertiliser. The authors of this paper use "@Risk", a risk profiling plug-in tool for Microsoft Excel to demonstrate how farm budgets can be more relevant to farmers. Many risk factors that affect farm financial performance, such as climate and commodity prices, are not controlled by the farmer. Wet summers help hill country sheep and beef pastoral farmers, as more grass growth occurs, which thereby reduces the cost of production and increases revenue, as more stock is finished. Whereas in drought years income falls as stock must be sold prior to finishing, in severe droughts capital stock may also be sold. Input costs also rise as pasture weed invasion occurs; health issues such as rye grass staggers may also add cost. Monte Carlo simulations on model farm budgets for a North Island sheep and beef property and a Canterbury dairy farm help demonstrate the risk profile of each farm type. [ABSTRACT FROM AUTHOR]

Applications of urea fertiliser and farm dairy effluent (FDE) to New Zealand pastures are the second and third largest sources of nitrous oxide (N 2 O) emissions, after emissions from excreta deposited during grazing (urine and dung). New Zealand currently employs emission factors (EF 1 ) (percentage of N applied which is emitted as N 2 O) of 0.48% and 1% for urea fertiliser and FDE, respectively, for calculating its national N 2 O inventory. The country specific emission factors for urine and dung are 1% and 0.25% respectively. Because FDE has a higher organic nitrogen (N) content than urea, and because it is a diluted mixture of urine and dung, the mean FDE EF 1 is expected to be less than 1%. With a recent increase in research trials measuring EF 1 for FDE and urea, the objective of this study was to refine New Zealand-specific EF 1 values for these N sources. We analysed urea fertiliser and FDE N 2 O emission data from 45 EF 1 field trials conducted in New Zealand. This meta-analysis yielded a combined (urea and FDE) EF 1 mean of 0.46% (95% confidence interval of 0.07% and 0.90%), with EF 1 means for urea and FDE of 0.59% and 0.25%, respectively. There was no statistical difference between urea fertiliser and FDE EF 1 values. However, we recommend separate country-specific EF 1 means of 0.6 and 0.3% for urea fertiliser and FDE, respectively, for New Zealand’s agricultural soils N 2 O emissions inventory due to the different origin and characteristics of these N sources. [ABSTRACT FROM AUTHOR]

Over the past two decades there have been major increases in dairy production in New Zealand. This increase in intensity has required increased use of external inputs, in particular fertilizer, feed, and water. Intensified dairy farming thus incurs considerable environmental externalities: impacts that are not paid for directly by the dairy farmer. These externalities are left for the wider New Zealand populace to deal with, both economically and environmentally. This is counter-intuitive given the dairy industry itself relies on a 'clean green' image to maximize returns. This is the first nationwide assessment of some of the environmental costs of the recent increase of dairy intensification in New Zealand. Significant costs arise from nitrate contamination of drinking water, nutrient pollution to lakes, soil compaction, and greenhouse gas emissions. At the higher end, the estimated cost of some environmental externalities surpasses the 2012 dairy export revenue of NZ$11.6 billion and almost reaches the combined export revenue and dairy's contribution to Gross Domestic Product in 2010 of NZ$5 billion. For the dairy industry to accurately report on its profitability and maintain its sustainable marketing label, these external costs should be reported. This assessment is in fact extremely conservative as many impacts have not been valued, thus, the total negative external impact of intensified dairying is probably grossly underestimated. [ABSTRACT FROM AUTHOR]

Crop uptake of 226Ra over a range of key New Zealand agricultural and horticultural growing areas was analysed to establish the dietary implications of an increase in soil 226Ra activity concentrations. Thirty crop samples, covering both feed and food commodities, were quantified for 226Ra activity concentrations, and concentration ratio (CRs) from the soil activity were calculated. The calculated CRs correlated with international default values for estimating crop uptake. Variation in CRs established that there was no increase in the crop activity concentration, relative to soil 226Ra from pasture foliage at a fertiliser impacted site, with a gradient of soil 226Ra activity concentrations. Based on the calculated CRs, the upper bound of the theoretical range of dietary exposures to 226Ra was 78.1 μSv/yr for teenage boys. Future forecasting of the increased dietary dose of 226Ra that might occur at the current soil loading rate, based on current fertiliser activity concentrations, confirmed that long-term loading of soil with 226Ra is unlikely to present a dietary risk. The forecast model calculated that the increase in dietary ionising radiation burden is unlikely to reach thresholds requiring regulatory intervention for two millennia. • Uptake ratios for 226Ra examined for common food and feed crops grown in New Zealand soils. • Crop uptake ratios were consistent with the published IAEA mean ratios. • Analysis of pasture foliage on a soil gradient for 226Ra established uptake rates are not linear. • Increased dietary dose of 226Ra for teenage boys from current rates of soil loading were forecasted. • Long-term loading of agricultural soil with 226Ra is unlikely to present a dietary risk. [ABSTRACT FROM AUTHOR]

Abstract: Urea is the key nitrogen (N) fertiliser for grazed pastures, and is also present in excreted animal urine. In soil, urea hydrolyses rapidly to ammonium (NH4 +) and may be lost as ammonia (NH3) gas. Unlike nitrous oxide (N2O), however, NH3 is not a greenhouse gas although it can act as a secondary source of N2O, and hence contribute indirectly to global warming and stratospheric ozone depletion. Various urease inhibitors (UIs) have been used over the last 30years to reduce NH3 losses. Among these, N-(n-butyl) thiophosphoric triamide (nBTPT), sold under the trade name Agrotain®, is currently the most promising and effective when applied with urea or urine. Here we conduct a critical analysis of the published and non-published data on the effectiveness of nBTPT in reducing NH3 emission, from which adjusted values for FracGASF (fraction of total N fertiliser emitted as NH3) and FracGASM (fraction of total N from, animal manure and urine emitted as NH3) for the national agriculture greenhouse gas (GHG) inventory are recommended in order to provide accurate data for the inventory. We use New Zealand as a case study to assess and quantify the overall reduction in NH3 emission from urea and animal urine with the application of UI nBTPT. The available literature indicates that an application rate of 0.025% w/w (nBTPT per unit of N) is optimum for reducing NH3 emissions from temperate grasslands. UI-treated urine studies gave highly variable reductions (11–93%) with an average of 53% and a 95% confidence interval of 33–73%. New Zealand studies, using UI-treated urea, suggest that nBTPT (0.025% w/w) reduces NH3 emissions by 44.7%, on average, with a confidence interval of 39–50%. On this basis, a New Zealand specific value of 0.055 for FracGASF FNUI (fraction of urease inhibitor treated total fertiliser N emitted as NH3) is recommended for adoption where urea containing UI are applied as nBTPT at a rate of 0.025% w/w. Only a limited number of published data sets are available on the effectiveness of UI for reducing NH3 losses from animal urine-N deposited during grazing in a grazed pasture system. The same can be said about mixing UI with urine, rather than spraying UI before or after urine application. Since it was not possible to accurately measure the efficacy of UI in reducing NH3 emissions from animal urine-N deposited during grazing, we currently cannot recommend the adoption of a FracGASM value adjusted for the inclusion of UI. [Copyright &y& Elsevier]

Objectives: Studies in animals have shown causal relationships between copper (Cu) deficiency and the development of thoracic aortic aneurysms (TAAs) [1, 2]. Cu deficiency is widespread in New Zealand (NZ) soils; the high soil pH from the use of lime fertilizers reduces the bioavailability of Cu for grazing animals and growing plants; this, in turn, reduces Cu availability in the NZ human food chain. Our study is a pilot study to explore associations between Cu and TAA. We measured Cu levels in aneurysmal aortic tissues in patients undergoing Bentall procedures and non-aneurysmal aortic tissue from coronary artery bypass graft patients., Methods: Aortic samples were collected from 2 groups of patients during elective open-heart surgery over 4 months between November 2017 and February 2018. The groups were a TAA group, patients with non-syndromic aortic aneurysm and without the bicuspid aortic valve or known infectious or inflammatory condition (ANEURYSM; n = 13), and a control coronary artery bypass graft group (CONTROL; n = 44). Standardized digested dry tissue weighed samples were analysed from both groups. Tissue extraction of trace elements was carried out using HCl-H2O2 digestion and a highly sensitive analytical technique, inductively coupled plasma mass spectrometry-used to measure elemental concentrations., Results: Cu concentration (mean ± SD) was significantly lower in ANEURYSM (3.34 ± 0.16 µg/g) when compared to the CONTROL group tissues (4.33 ± 0.20 µg/g) (dry weight; mean ± SD; Student's t-test, P < 0.05). Over 46% of the Aneurysm patients were Maori and live in a geographically Cu-deficient NZ territory., Conclusions: Cu deficiency may play a role in the development or progression of non-syndromic ascending aortic aneurysms in NZ. Maori patients are more at risk as they commonly live in rural NZ, dependent on locally grown nutritional sources. Further studies are required to confirm this exciting finding and to establish cause and effect relationship., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery.)

The invasive tree Solanum mauritianum Scop, has been targeted for biological control in South Africa and New Zealand, by deploying insect agents that could constrain its excessive reproductive output. The flower-feeding weevil Anthonomus santacruzi (Curculionidae) was approved for release in South Africa in 2007 but following the loss of the original culture in quarantine, new stocks were introduced from Argentina in 2008-2009. This study was initiated to confirm that the host range of the new culture was the same as that of the previous one, but also to assess the risks associated with the weevil's release in New Zealand. Different testing procedures, including no-choice tests and multi-choice tests in different arenas, produced inconsistent and ambiguous results. During no-choice tests, oviposition and larval development to adulthood occurred on three non-target species including two native South African and one native New Zealand Solanum species. However, subsequent multi-choice tests and a risk assessment suggested that the risks of anything more than collateral damage to non-target Solanum species are low. Overall, these data do not deviate substantially from the results of the original quarantine tests which facilitated the release of A. santacruzi in South Africa in 2009. Although we argue that none of the New Zealand native and cultivated species are at risk, stronger evidence from open-field trials and chemical ecology studies may be required to convince the regulatory authorities that A. santacruzi is suitable for release in New Zealand. [ABSTRACT FROM AUTHOR]

Abstract: Although there is an opportunity to increase the productivity of Pinus radiata plantations in New Zealand through nitrogen (N) fertilisation, this treatment may reduce the quality of drainage water through leaching of nitrate-N. To improve our understanding of the effects of N fertilisation on potential N leaching, N concentrations in soil water below the root zone and potential losses were investigated after N fertiliser was applied as urea at 200kgha−1 of N to 7–9year-old operational plantations at 10 sites in New Zealand. A water balance model was used to estimate soil water drainage on a daily basis. Annual drainage ranged from 70 to 1,199mm and was closely correlated with annual rainfall. Nitrate-N, ammonium-N and organic-N concentrations in unfertilised control plots ranged between 0.03–2.26mgL−1, 0.06–0.49mgL−1 and 0.44–0.95mgL−1 respectively. Fertilisation significantly increased nitrate-N concentrations at four sites but did not affect ammonium-N or organic-N concentrations. In the 2years after fertiliser application, fertiliser increased nitrate-N leaching at eight of the 10 sites by 0–15kgha−1 (average 6.4kgha−1 or 3.2% of the N applied). These values underestimate total nitrate-N loss as fertiliser enhanced leaching at two sites had not ceased after 2years. Nitrogen fertilisation caused much greater increases in nitrate-N loss at a low productivity, high rainfall site (28kgha−1of N), and a coastal sand site (90kgha−1of N). To reduce losses at such sites, fertiliser should be applied at reduced rates in multiple applications. Factors that seem to have pre-disposed sites to nitrate-N leaching following N fertilisation include a pasture land-use history, the presence of a high component of the N-fixer Ulex europaeus in the understory, and soil C/N ratios of 15 or lower. Organic-N dominated leaching at 7 of the 10 sites, consistent with the pattern observed in unpolluted old-growth southern hemisphere forests, but mineral-N dominated at three sites, two of which had a recent land-use history of fertilised pasture. [Copyright &y& Elsevier]

Abstract: Copper is present in a range of fungicides as well as in some animal manures and biosolids that are applied to agricultural soils as fertilisers. Elevated and increasing levels of copper in agricultural soils are of worldwide concern. Copper is toxic to soil microorganisms and has been reported to reduce the ability of soil microorganisms to degrade pesticides. A glasshouse study was undertaken to determine if copper inhibited the degradation of atrazine and indoxacarb in soil. A fine sandy loam agricultural soil was fortified with copper at five concentrations over a concentration range of 0–1000 mg/kg copper, then field-aged for 6 months prior to treatment with either indoxacarb or atrazine at a rate of 2 mg/kg. The soils were sampled twice at intervals based on published half-lives. The samples were analysed for a range of parameters including total and bioavailable copper, urease and phosphatase activity, ergosterol and either indoxacarb or atrazine and its degradation products. The soil microbial biomass and enzyme activities decreased with increasing copper concentration (p < 0.05). There were no significant differences in soil atrazine and indoxacarb concentrations between the copper levels. At sampling time two, the concentrations of hydroxyatrazine in treatments containing the three highest copper concentrations were significantly greater (p < 0.05) than for the control soil. Our results indicate that copper does not inhibit the first step of indoxacarb and atrazine degradation, but may affect degradation of secondary metabolites like hydroxyatrazine in soil. [Copyright &y& Elsevier]

Winchmore Irrigation Research Station was established in the late 1940s in the Ashburton–Lyndhurst irrigation scheme in Canterbury, New Zealand, to investigate problems associated with the introduction of border-strip irrigation to farming. Two large-scale field trials were established. The first, in 1949, aimed to investigate water requirements of permanent pasture and the second, in 1952, to examine fertiliser requirements of irrigated pasture. Initially designed to supply farmers with practical solutions, because of their longevity (61 and 58 years to date), consistent management, meticulous record keeping and archiving of regular soil and plant samples, both trials have yielded a rich source of material for many studies, some of which are reported in other papers in this issue of the journal. [ABSTRACT FROM AUTHOR]

The article provides an overview on the cost-effectiveness of mitigation strategies for Australian and New Zealand dairy farms. The strategies are being group into edge-of-field mitigations, such as natural wetlands, amendments, such as Bauxite residue, and management, such as using low-water-soluble P fertilizers. The study shows that on-farm management strategies were the most cost-effective mean to mitigate P exports, while amendments, added directly to surface soil or tile drains, were labor intensive or frequently constrained by supply.

Managing the mineral nutrition of free-range grazing livestock can be challenging. On farms where grazing animals are infrequently yarded, there are limited opportunities to administer trace element supplements via feeds and concentrates. In New Zealand, where the majority of sheep, cattle, and deer graze pasture year round, inadequate intake of cobalt, copper, iodine and selenium is prevalent. Scientists and farmers have developed efficient strategies to monitor and treat these dietary deficiencies. Supplementation methods suited to grazing livestock include long-acting injections, slow-release intraruminal boluses, trace element-amended fertilisers, and reticulated water supplies on dairy farms [ABSTRACT FROM AUTHOR]

Nitrate concentrations exceeding Ministry of Health potable limits (11.3 mg/L nitrate-N) have been a problem for Waimea Plains groundwater for a number of years. This work uses nitrogen isotopes to identify the input sources of the nitrate. The results in relation to nitrate contours have revealed two kinds of nitrate contamination in Waimea Plains groundwater - diffuse contamination in the eastern plains area (in the vicinity and south of Hope) attributed to the combined effects of the use of inorganic fertilisers and manures for market gardening and other land uses, and point source contamination attributed to a large piggery to the south of Hope. Once nitrate is introduced to a groundwater system it can take many years for it to be flushed out. Tritium measurements in wells are interpreted to give mean residence times, and the spread of residence times around the mean, for groundwater in different parts of the plains. Mean ages are youngest in the area south of Hope, where nitrate concentrations are highest, and increase to the south, west and north. The age distributions have been used to produce a nitrate input history for the Upper and Lower Confined Aquifers by simulating the nitrate measurements in the various wells. The timing of the derived nitrate input history shows that both the diffuse sources and the point source were present from the 1940s, which is anecdotally the time from which there were increased nitrate sources on the plains. The large piggery was closed in the mid-1980s. Unfortunately, major sources of nitrate (including the piggery) were located on the main groundwater recharge zone of the plains in the past, leading to contamination of the Upper and Lower Confined Aquifers. The contamination travelled gradually northwards, affecting wells on the scale of decades. Input of nitrate to the groundwater has been decreasing since about 1988 due to closure of the piggery. The resulting decrease in nitrate concentrations is now also gradually travelling northward. Groundwater to the south and west already had relatively low nitrate because of river and/or rainfall recharge with low nitrate concentrations. Improved monitoring and practices (e.g., best management practices and nutrient budgeting) need to be encouraged among market gardeners and other land users, taking special account of the location of the groundwater recharge areas around and south of Hope. [ABSTRACT FROM AUTHOR]

The soil chamber technique is most commonly used for measuring gas exchange between soil surfaces and the atmosphere, to understand regulatory processes relevant to determine the greenhouse gas (GHG) emissions from soils and to improve the emissions inventory of agricultural systems. The chambers are inserted into the soil to avoid the lateral diffusion of the gases. However, soil disturbance caused by chamber insertion causes in degassing and can result in erroneous flux data from measurements made immediately following chamber insertion. Here we assess the effect of soil disturbance associated with the insertion of the chambers on nitrous oxide (N2O) and methane (CH4) fluxes with and without N fertilization, from a New Zealand pasture soil. We collected gas samples from the chambers at 0, 2, 4, 24, 96 and 168 h after chambers insertion. Our results show elevated levels of N2O inside the chambers (1.7 fold those of atmospheric concentrations outside the chambers) and greater fluxes within the first 4 h of installation compared to the values observed at 24 h and later; and negative CH4 flux in the same time period, but near to zero after 24 h. Our results suggest that for accurate measurement of gas fluxes, measurements should be taken after 24 h of chambers installation to avoid the degassing effect. [ABSTRACT FROM AUTHOR]

The article cites a research study that analyzes the dynamics of nitrous oxide at different sites along a braided river system in New Zealand over a one year period. It is said that greenhouse gas (GHG) nitrous oxide concentrations continue to increase 0.26% per year in the troposphere. In the Intergovernmental Panel on Climate Change (IPCC) methodology, nitrous oxide emissions associated with the leaching and runoff of nitrogen is determined by multiplying the mass of fertilizer and manure nitrogen lost from agricultural systems via leaching and runoff per annum by an emission factor.

Abstract: This study was conducted on irrigated and dryland wheat fields in Canterbury in the 2007–2008 harvest year based on an extensive process of data collection involving a questionnaire and interviews. Total energy consumption in wheat production was estimated at 22,566 MJ/ha. On average, fertilizer and electricity were used more than other energy sources, at around 10,654 (47%) and 4870 (22%) MJ/ha, respectively. The energy consumption for wheat production in irrigated and dryland farming systems was estimated at 25,600 and 17,458 MJ/ha, respectively. In this study, several direct and indirect factors have been identified to create an artificial neural networks (ANN) model to predict energy use in wheat production. The final model can predict energy consumption based on farm conditions (size of crop area), farmers’ social considerations (level of education), and energy inputs (N and P use and irrigation frequency), and it predicts energy use in Canterbury arable farms with an error margin of ±12% (±2900 MJ/ha). Furthermore, comparison between the ANN model and a Multiple Linear Regression (MLR) model showed that the ANN model can predict energy consumption relatively better than the MLR multiple model on the selected training set and validation set. [Copyright &y& Elsevier]

Abstract: Growing interest in the use of planted forests for bioenergy production could lead to an increase in the quantities of harvest residues extracted. We analysed the change in C and N stocks in the forest floor (LFH horizon) and C and N concentrations in the mineral soil (to a depth of 0.3m) between pre-harvest and mid-rotation (stand age 15years) measurements at a trial site situated in a Pinus radiata plantation forest in the central North Island, New Zealand. The impacts of three harvest residue management treatments: residue plus forest floor removal (FF), residue removal (whole-tree harvesting; WT), and residue retention (stem-only harvesting; SO) were investigated with and without the mean annual application of 190kgNha−1 year−1 of urea-N fertiliser (plus minor additions of P, B and Mg). Stocks of C and N in the forest floor were significantly decreased under FF and WT treatments whereas C stocks and mass of the forest floor were significantly increased under the SO treatment over the 15-year period. Averaged across all harvesting treatments, fertilisation prevented the significant declines in mass and C and N stocks of the forest floor which occurred in unfertilised plots. The C:N ratio of the top 0.1m of mineral soil was significantly increased under the FF treatment corresponding to a significant reduction in N concentration over the period. However, averaged across all harvesting treatments, fertilisation prevented the significant increase in C:N ratio of the top 0.1m of mineral soil and significantly decreased the C:N ratio of the 0–0.3m depth range. Results indicate that residue extraction for bioenergy production is likely to reduce C and N stocks in the forest floor through to mid-rotation and possibly beyond unless fertiliser is applied. Forest floors should be retained to avoid adverse impacts on topsoil fertility (i.e., increased C:N ratio). Based on the rate of recovery of the forest floor under the FF treatment, stocks of C and N in the forest floor were projected to reach pre-harvest levels at stand age 18–20. While adverse effects of residue extraction may be mitigated by the application of urea-N fertiliser, it should be noted that, in this experiment, fertiliser was applied at a high rate. Assessment of the sustainability of harvest residue extraction over multiple rotations will require long-term monitoring. [Copyright &y& Elsevier]

Abstract: This paper examines the energy consumption of wheat production in Canterbury province, New Zealand. This study was conducted within a 35,300ha of irrigated and dry land wheat fields in Canterbury in the 2007–2008 harvest year. Total energy consumption for wheat production was estimated at 25,600MJ/ha. On average, fertilizer and electricity were used more than other energy sources, at around 10,654 (47%) and 4870 (22%)MJ/ha, respectively. The energy consumption for wheat in irrigated farming systems and dry land farming systems was estimated at 25,600 and 17,458MJ/ha, respectively. The main source of energy in both systems is fertilizer and it consumed around 10,188 and 11,429MJ/ha for irrigated farming and dry land farming, respectively. The average operational energy consumption was 7997MJ/ha. In irrigated farming system, operational energy was approximately three times more than that in dry land farming. The maximum energy consumed in operational wheat production was about 7762 (71%)MJ/ha for irrigated farming systems, including irrigation, and it was 1451 (46%)MJ/ha for dry land farming including tillage. The average values of estimated output to input energy ratio for wheat in irrigated and dry land farming systems were 11.5 and 15.1, respectively. [Copyright &y& Elsevier]

Lake Brunner, located on the west coast of the South Island of New Zealand, has been identified as threatened by phosphorus (P) inputs from neighbouring dairy farms. A two-year study was undertaken to determine if the application of reactive phosphate rock (RPR) with or without the addition of aluminium (Al) sulphate (alum) at 20 kg Al ha-1 could decrease P losses in surface runoff from dairy pastures compared to the same rate of P applied as superphosphate (30 kg P ha-1). The study was conducted on nine humped and hollowed plots (1100-3500 m2). Frequent and reliable rainfall year round (totalling 4000-5000 mm yr-1) translated into more than 50 surface runoff events per year and large losses of P from superphosphate-treated plots (flow-weighted mean filterable reactive P (FRP) = 0.072 mg l-1; mean load 8.2 kg P ha-1 yr-1). In contrast, the flow-weighted mean FRP concentration in the RPR-treated plots was significantly less (0.034 mg l-1; mean load 4.0 kg P ha-1 yr-1). No effect was found on other P forms. Alum did not decrease P losses, most likely due to Al being washed off in surface runoff before it could bind to the soil. Enhanced P losses from superphosphate-treated plots were attributed to the greater availability of P within 21 days of application (water solubility 80-95%) compared with RPR (≈1% water soluble), and the occurrence of surface runoff during this period (especially in year 1). The use of RPR is recommended as one management practice to decrease FRP inputs to Lake Brunner and may be useful in other regions where rainfall and soil pH allow. [ABSTRACT FROM AUTHOR]

The article offers information on the changes in the pasture based dairy systems that may impact the health of cattle in New Zealand and Australia. It is stated that the increased intensification of milk production can increase the risk if of mastitis and culling of udder health, which, can be decreased through increased milking frequency. The intensive grazing patterns linked with higher grass yields using better cultivars and fertilizers favor nematodes and there is a reported evidence of anthelmintic resistance in nematodes and liver fluke that the veterinarians are suggested to be aware of. Though pasture fed cattle are better addressed in the control of milk fever, hypomagnesaemia and trace element deficiencies, they reportedly show higher prevalence of acidosis.

Trials were carried out at 20 sites in 2004-05 and at three sites in 2006-07 to determine if micronutrient application is required to maximise wheat yields in Canterbury, New Zealand. Micronutrients were applied at recommended rates as solid fertiliser (zinc (Zn) and boron (B)), foliar spray (manganese (Mn)), or both (copper (Cu)). Foliar treatments increased Cu and Mn in vegetative tissue, but not in grain. Soil-applied CuSo4 had little or no effect on plant Cu. Sodium borate (2.3 kg B/ha) increased plant B by an average of 68% at mid-late tillering (Zadoks growth stage 22-29). Zn (4.4 kg/ha as ZnSo4) gave small improvements in plant Zn (generally <20%). in 2004-05, there was no yield response to the treatments, even though about half the sites were below the suggested critical soil thresholds for Cu and Zn. in 2006-07, two sites showed yield responses (up to 0.9 t/ha) to Mn, but not to Zn or Cu. The soil EDTa (ethylenediaminetetraacetic acid) test was generally a poor indicator of wheat micronutrient status. The critical tissue Mn concentration to achieve 95% of maximum yield was estimated at 13 mg/kg at ear emergence. our results suggest that wheat crops with >12 mg Zn/kg at mid-late tillering or >10 mg Zn/kg at ear emergence do not respond to applied Zn. Crops with ≥2 mg Cu/kg at mid-late tillering were not responsive to Cu. [ABSTRACT FROM AUTHOR]

Six fertiliser application scenarios were considered on a hill-country case study farm. The scenarios were developed for input into a decision tree model and were compared to a base line scenario that uses the farm's current blanket application techniques. A further blanket application was considered along with several variable rate application scenarios. Throughout this study, variable rate application technology outperformed the fixed rate applications in terms of pasture production and fertiliser utilisation. One scenario, which used full variable rate application and a model optimised prescription map, produced the highest annual pasture yield across the 2518 ha Limestone Downs property, North Island, New Zealand, with 24 789 t DM, some 4854 t DM more than the property is currently modelled to produce. The blanket application techniques which are currently employed on this property produced the lowest annual pasture production with 19 935 t DM yr-1. Variable rate techniques were predicted to increase annual production considerably, from 19 935 t DM yr-1 to between 21 239 and 24 798 t DM yr-1; in these cases, an increase in the production variability is also expected. Increased annual production from targeting additional fertiliser resources at more productive areas was identified through the decision tree modelling. Some areas were identified as having poor response to fertiliser, and fertiliser application to those areas was considered uneconomic. [ABSTRACT FROM AUTHOR]

Field trials were conducted to identify effective methods of increasing selenium (Se) in wheat (Triticum aestivum) grown on low-Se soils in Canterbury, New Zealand. Various rates (5-20 g Se/ha) and methods (soil-applied fertiliser, seed treatment, foliar application at flowering) of applying Se (sodium selenate) were evaluated in autumn- and spring-sown crops on an irrigated site at Wakanui and on a dryland site at Methven. Several Se fertiliser treatments were included to examine the effects of timing of application (Se applied at sowing or growth stage 31) and to determine whether applying other fertilisers (superphosphate, urea) with Se would affect its uptake. two cultivars were grown in the autumn and spring trials at each location. Grain Se content averaged 0.03 mg/kg in the controls (no Se added), increasing to 0.4-0.5 mg/kg where Se was added at 20 g/ha using the most effective application methods-foliar spray and fertiliser at growth stage 31. Fertiliser at sowing was less effective in raising grain than fertiliser at growth stage 31, particularly for autumn-sown crops. The results suggested that the plant availability of applied can decrease rapidly in the soil and, to be most effective, fertiliser Se should be applied when the crop is beginning to grow rapidly in spring. Grain Se levels for the irrigated site were close to those in the corresponding treatment at the dryland site, even though yield was much greater where irrigation was used. Application of superphosphate (200 kg/ha) or urea (100 kg/ha) did not have a large or consistent effect on grain Se. Cultivar effects on grain Se were either small or not significant. For the most effective application methods (fertiliser at growth stage 31; foliar spray), grain Se increased by c. 0.02 mg/kg for an increase in Se rate of 1 g/ha. [ABSTRACT FROM AUTHOR]

The uptake of selenium (Se) by pasture herbage from four different Se fertiliser materials was determined in a field experiment throughout the course of a whole year. The products tested were: the commercially available Selenium Chip™; Selcote® Ultra; and two new formulations (Ravensdown A and B), manufactured in a way to slow the release of Se in the form of sodium selenate. All four Se fertilisers increased pasture herbage Se concentrations above the level required to meet the nutritional requirements of grazing livestock; however, the size and duration of the responses varied between products. The Ravensdown A product was as effective as Selcote Ultra at maintaining pasture Se concentrations above the critical animal health level for the whole year of the trial. The effects of the other two products, particularly the Selenium Chip, were not so long-lasting. Recoveries of Se in the pasture herbage throughout the year ranged between c. 15 and 17% of the Se originally applied in the fertilisers. [ABSTRACT FROM AUTHOR]

Fertiliser, water and pesticides have enabled agricultural enterprises to improve yields and quality of produce, plus reduce risks to production. Increased awareness of the impacts of agriculture has resulted in attempts to quantify its effects on the environment. This paper examines some of the implications of recently developed environmental performance indicators, comparing the results from Australia and New Zealand with those from other developed countries with an agricultural history. Australia's overall performance is apparently poor (ranking 20th globally), despite a high score in environmental, health, because of the high use of available water. In contrast, New Zealand's performance appears to be high (ranking 1st), but the data used for the indicators are outdated and it is known that environmental hot spots, particularly to do with land use intensification, exist. Difficulties associated with the collection and analysis of the data used for the indicators are discussed, as is the new research that is addressing areas of concern. [ABSTRACT FROM AUTHOR]

Copper (Cu) deficiencies are an important concern of the New Zealand livestock industry, particularly for deer. Cu fertiliser application to pastures has been proven to be effective, providing the particle size is suitable and the pasture has low molybdenum (Mo) concentrations (<1 ppm). A field study was set up to determine the effect of Cu fertiliser application on deer grazing pastures of moderate to high Mo concentrations (2-8 ppm). Mobs of deer (red x elk and red x wapiti weaners) grazed both Cu fertilised and non-fertilised paddocks on farms near Rotorua (pasture Mo 6-8 ppm) and in Southland (pasture Mo 1-2 ppm) over the winter of 2003. An initial application of solid CuSO4 (12-15 kg ha-1) applied in April 2003 failed to elevate pasture Cu above an effective level of 11 ppm due to large particle size (97.8% > 2.0 mm) and slow dissolution. Liquid CuSO4 at 5-6.7 kg ha-1 was sprayed on pasture in June/July, and grazed by the trial animals. This application resulted in a significant increase in serum Cu (P < 0.05) when compared to untreated controls (16.8 versus 9.1 µmol litre-1 after 14 days at Rotorua and 11.6 versus 7.8 µmol litre-1 after 1 day in Southland). At the Rotorua site, deer serum Cu levels in the mobs grazing Cu fertilised pasture were maintained in excess of 15 µmol litre-1 up to the trial completion in October 2003. In contrast at the Southland site, deer serum levels in the Cu fertilised treatment started to decrease by October 2003. The animal liver Cu levels at both sites were increased by grazing the Cu fertiliser amended pasture for both the August (656 versus 158 µmol kg-1 fresh tissue, P < 0.001) and October (362 versus 83 µmol kg-1 fresh tissue, P < 0.01) samplings. The Cu spray application increased pasture Cu concentration for more than 3 months at Rotorua but only 2 months in Southland. Despite the extremely high initial pasture Cu concentrations achieved (>1000 ppm), there were no visible signs of animal health problems with the animals grazing at the time of spraying. However, further research is required to determine the effect of such high pasture Cu concentrations on deer before a suitable level of Cu application to pasture and animal withholding period can be recommended. The results of this study showed that even at herbage Mo levels ranging from 1-3 ppm in Southland and 2-8 ppm near Rotorua, copper sulphate (5-6.7 kg CuSO4 ha-1) sprayed onto pastures in mid winter resulted in the herbage Cu concentration being increased to in excess of 100 ppm for 90 days. With this increase in herbage Cu, the animal Cu intake from grazing these pastures was sufficient to lift or maintain both serum and liver Cu levels in deer for up to 4 months. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine long-term effects of fertiliser and livestock management and micro-topographical variation on soil physical and chemical characteristics and herbage accumulation on a hill site in the southern North Island of New Zealand. Paddocks subjected to high fertility-high stocking rate (HH) and low fertility-low stocking rate (LL) treatments dating back to 1975 were used. Soil samples were taken from three slope categories (0–12 ° low slope, LS; 13–25 ° medium slope, MS; >25° high slope, HS) from HH and LL and a range of soil chemical and physical features were assessed. Herbage accumulation (green matter and dead matter) was measured over 12 months on each microsite. Greater differences in soil and herbage features, such as unsaturated hydraulic conductivity (Kunsat), bulk density (BD), water holding capacity (VSM), soil compressibility (SC), total soil nitrogen (Total-N), Olsen-P and green dry matter accumulation (GDMA), were measured across slope categories than between management treatments, possibly because slope effects on soils would have operated over longer periods of time than the fertiliser-stocking rate contrasts. Increasing slope decreased GDMA on the site, as well as Total-N, Olsen-P, VSM and SC, but increased Kunsat, BD and soil rebound after compression (SR). Slope, VSM, Kunsat, SC, BD and Total-N were the soil variables with largest influence on differentiation between microsites. Olsen-P and SR were less important. Green dry matter accumulation was strongly influenced by slope, soil VSM and Kunsat, and to a lesser extent by soil Total-N and Olsen-P. [ABSTRACT FROM AUTHOR]

• Wood quality attributes of mature radiata pine are described. • Nutrient removal from harvesting practices did not adversely affect wood quality. • In some cases, negative consequences resulted from repeated fertiliser addition. • This knowledge will help forest managers design forest nutrition programmes. With intensification of forest management, there has been increasing focus on the impacts of harvest residue removal on tree growth and long-term site productivity. The intensity of harvest removals, which has a direct impact on the available nutrient pools, influences tree growth and are also likely to impact the quality of wood formed. This study focused on the effects of harvesting residue removal practices (whole tree + forest floor, whole tree and stem only) at the end of the previous rotation and repeated fertiliser addition during the current rotation on selected wood quality attributes. Growth, wood density and standing tree acoustic velocity data were collected from almost 600 radiata pine (Pinus radiata D. Don) trees from long term site productivity trials across New Zealand (Woodhill, Tarawera and Berwick Forests). A sample of 116 trees were felled to obtain detailed wood quality measurements on logs and cross-sectional discs at different heights along the stem. There was little or no effect of different levels of harvesting removal on any of the measures of wood quality. However, repeated fertiliser addition throughout the course of the rotation (up to 3200 kg N ha−1 at Woodhill Forest) did result in adverse impacts on wood density, stiffness, branch size and heartwood content. The degree to which these affect returns to forest growers and end-product performance will depend on the market segment that logs are being sold into. It is recommended that nutritional strategies aimed at increasing forest productivity should incorporate studies to evaluate their potential adverse impacts on wood quality. [ABSTRACT FROM AUTHOR]

• End of rotation results released from the New Zealand LTSP trials. • Forest floor retention at harvest is beneficial to long-term site nutrition. • Whole tree versus stem only harvest had no impact on soil or forest productivity. • Fertiliser addition increased soil carbon and nitrogen stocks where they were low. Forest harvesting practices remove tree biomass and the nutrients that they contain. There is uncertainty around the impact of this nutrient removal on the long-term sustainable production of forests over multiple rotations. To explore the impact of harvest management practices on planted forest sustainability, three long-term trials in Pinus radiata D. Don forests were assessed at the end of their second rotation of 26 to 27 years to determine the impact of harvest residue removal and fertiliser additions on sustainable forest productivity. The harvest residue removal treatments were stem only (SO), whole-tree (WT), and whole-tree plus forest floor (FF) removal with and without urea-nitrogen fertiliser additions (cumulative range across three sites 950 – 3200 kg N ha−1) from early rotation out to mid-rotation (last fertiliser application age range across sites 8 – 22 years). The FF removal treatment reduced soil carbon and nitrogen stocks throughout the subsequent rotation, whereas forest floor carbon and nutrient stocks had recovered from the FF removal treatment by the end of the rotation. Forest productivity was reduced at one site with the FF removal treatment, taking 3 years longer for stems to reach 35 cm diameter at breast height than other residue removal treatments. Between WT and SO harvest residue treatments there were very limited impacts on soil carbon and nutrient stocks, no impact on forest floor mass, carbon and nutrient stocks and the sum of the above ground live biomass, carbon and nutrient stocks or tree productivity. Across all harvest removal treatments fertiliser addition increased soil carbon and nitrogen stocks for sites with low initial soil stocks. The increased soil carbon and nitrogen stocks from fertiliser addition were associated with forest productivity gains with the time to reach 35 cm (diameter at breast height) for one site reduced by 3 – 5 years. Fertiliser addition to sites with FF removal was able to mitigate soil carbon and nitrogen stocks only when very large amounts of fertiliser were added (cumulative amounts of 1150 and 3200 kg N ha−1). The end of rotation results from this long-term study demonstrate the importance of harvest residues and forest floor material at low fertility sites for long-term nutrient sustainability in planted forests. [ABSTRACT FROM AUTHOR]

• Nursery fertiliser and fungicide use can alter multiple seedling properties. • Seedlings raised with various exposure rates were planted and tracked for six years. • Stock exposed to less fungicide in the nursery grew notably better in the forest. • Ectomycorrhizal community status at planting was the likely driver of this gain. • Optimisation of nursery chemical use can produce benefits in the nursery and forest. The fertilisers and fungicides used in tree nurseries to stimulate growth and provide disease protection are an important component of conventional nursery management. However, it has been demonstrated that the ectomycorrhizal (ECM) fungi associating with Pinus radiata D. Don seedlings in the nursery can be significantly affected by increasing exposure to these products, driving reductions in the relative proportion of the ECM species most positively correlated with seedling nutrient uptake. Increasing fungicide exposure was also shown to reduce seedling size. To determine the significance of these effects on post-nursery performance, 2592 P. radiata seedlings were randomly selected from within treatment plots in this nursery chemical exposure trial and established at a site in Kaingaroa Forest, New Zealand. Assessments of the ECM community present on the trees in the plantation determined that after two years there was no longer any effect of the nursery treatments, likely due to the homogenising effect of the site conditions. Over six years the performance of the trees in the plantation was not affected by the extent of fertiliser application during their time in the nursery, but decreased nursery fungicide use had slight positive legacy effects on both tree survival and diameter growth. These gains combined to produce a significant increase in plot level basal area with reduced nursery fungicide use. Further analysis incorporating the effect of thinning on stand dynamics reinforced the potential gains in the forest from reduced fungicide use in the nursery, and the lack of benefit from fertiliser use. Based on the data collected following trial establishment, it was concluded that the observed differences in tree performance were likely driven by the impact of the ECM communities initially associated with the seedlings at planting. While the authors strongly recommend any reductions in P. radiata nursery fungicide use be considered carefully due to ongoing issues with fungal pathogens in these monoculture systems, the potential for improved nursery and plantation performance is significant and should be explored more widely. [ABSTRACT FROM AUTHOR]

Worldwide supply of water and nitrogen (N) are critical to crop yield with multiple interactions that need to be untangled. We used an allometric framework to quantify the dynamic relationships between crop growth, transpiration and N uptake in maize (Zea mays L.) and sorghum (Sorghum bicolor L.) using published data from experiments in France, New Zealand and United States. Our analysis highlighted a two-fold effect of drought on crop growth: a direct effect whereby crop growth is reduced proportionally to the reduction in transpiration, and an indirect effect mediated by a drought-induced crop N deficit, quantified as N nutrition index (NNI), the ratio between actual and critical plant N concentration (the minimum plant N concentration for achieving maximum crop mass). Under drought, sorghum maintained NNI and transpiration efficiency (biomass per unit of transpiration) whereas both NNI and transpiration efficiency declined in drought-stressed maize in comparison to well-watered crops. Nitrogen uptake per unit of transpiration (N/T) is a valuable trait for analyzing the combined effect of water and N deficit on water use efficiency (biomass per unit of evapotranspiration). However, both N/T and crop N concentration decline allometrically with biomass, hence comparisons of genotypes, environments and management practices would be biased unless they are scaled by crop biomass. [ABSTRACT FROM AUTHOR]

• Soil water repellency (SWR) can enhance phosphorus (P) losses in runoff. • SWR-induced runoff lost up to 8 kg P ha−1 within 21 days of superphosphate being applied. • Losses from lower water solubility products were less than a quarter of superphosphate. • Lower water-soluble P fertilisers could decrease P losses in areas where SWR-induced runoff is unavoidable. Phosphorus (P) losses via surface runoff can be large. Soil water repellency (SWR) occurs in warm and dry conditions. If SWR coincides with P fertiliser applications, the risk of P loss by surface runoff may increase. Losses during hotter months can be particularly detrimental to surface water quality because warmer waters help algal growth. We hypothesized that, compared to highly water-soluble superphosphate, the application of P as a low water-soluble fertiliser would decrease P losses caused by SWR-induced surface runoff. A three-year trial was conducted on a grazed dairy pasture soil in the central North Island of New Zealand. The soil was classified as moderate to severely SWR by water droplet penetration time and molarity of ethanol tests. Phosphorus (40 kg P ha−1) was applied in autumn as superphosphate, serpentine super and as a new fertiliser product similar to di-calcic phosphate. These fertilisers had water solubilities of 85, 34 and 12 g P kg−1 fertiliser, respectively. Yields of P lost were <1 kg P ha−1 for the first year, but in the third year >8 kg P ha−1 was lost from the superphosphate treatment due to SWR-induced surface runoff within 21 days after fertiliser application. In contrast, P losses in the third year from lower water-soluble P fertilisers, serpentine super and the new product, were 2.2 and 1.6 kg P ha−1, respectively. The use of a low water-soluble P fertiliser is therefore recommended to prevent P losses in areas where SWR-induced surface runoff is likely and unavoidable. [ABSTRACT FROM AUTHOR]

Compared to discharge into waterways, land application of treated municipal effluent (TME) can reduce the need for both inorganic fertilizers and irrigation. However, TME irrigation may result in the accumulation of phosphorus (P) or trace elements in soil, and increased salinity and sodicity, which could damage soil structure and reduce infiltration. TME irrigation can also result in groundwater contamination through nitrate leaching or surface water contamination through runoff. This study aimed to evaluate the effects of increasing TME irrigation rates on quantity and quality of leachate and pasture growth in a lysimeter experiment using a Fluvial Recent soil and a Fragic Pallic soil. Pasture growth in the lysimeters was up to 2.5-fold higher in the TME treatments compared to the non-irrigated treatments. There were no signs of toxicity or accumulation of B, Al, Cd, Cu, Fe, Mn, As, and Zn. TME significantly increased the concentration of P and Na in the pasture. Nitrogen leaching from the lysimeters was negligible (< 1 kg/ha -1 equiv.) in all treatments, but mineral N accumulated in the soil profile of the highest application rate (1672 mm/yr). Although more P was added than removed in pasture, the rate of accumulation indicated that over a 50-year period, P will still be within the current New Zealand thresholds for grazed pastures. Sodium accumulated in the soil columns in all the TME treatments. The rate of accumulation was not proportional to the TME application rate, indicating that Na was moving down through the soil profile and leaching. Results indicate a low to moderate risk of sodicity in soil or toxicity in plants caused by Na.

New Zealand agriculture is composed predominantly of pastoral grazing systems; however, forage crops have been increasingly used to supplement the diet of grazing animals. Excreta from grazing animals has been identified as a main contributor of NO emissions. Some forage crops, such as brassicas ( spp.), contain secondary metabolites that have been identified to inhibit soil N cycling processes, and nitrification in particular. Our objective was to determine if secondary metabolites released from brassica tissues inhibited nitrification and reduced NO emissions when incorporated into soil, which was amended with a large amount of urea N (such as derived from urine patches deposited during grazing). Three brassica tissues (kale [ L.], turnip [ L.] bulb, and turnip leaf and stem) and ryegrass ( L.) tissue were incorporated into soil with and without urea solution, and NO, NO, and NH were measured during a 52-d incubation. All brassica tissues reduced urea-derived NO emissions relative to ryegrass tissues when incorporated into soil. According to the mineral N and microbial community data, this reduction, however, could not be attributed to inhibition of nitrification. Although there was less NO from urea in the brassica treatments, total NO emissions increased after incorporation of all tissue residues into soil, so this tradeoff must be explored if brassica tissues are to be considered as a tool for NO reduction., (Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.)