Nutrient management on the Lincoln University dairy farm: "nutrient budgeting for efficient production"

Nutrient management plays an important role in any dairy farming system. Soil fertility status and fertiliser inputs are key drivers of pasture and animal production, whilst fertiliser represents a significant annual cost to the farm. At the same time, intensive agricultural systems also face the challenge of minimising or reducing nutrient loss in order to maintain environmental quality. Therefore 'best practice' may involve nutrient management in terms of balancing production, economic, environmental and efficiency goals. With ever increasing regulation and compliance requirements for the New Zealand farmer, best practice nutrient management will play an increasingly important role in achieving long term sustainability of the farming system. This paper gives an overview of the use of nutrient budgeting as a method of effective and efficient on-farm nutrient management. The paper will focus on nutrient management on the Lincoln University Dairy Farm (LUDF), including soil fertility monitoring and targets, the decision making process and the use of the nutrient budget output. Aspects of environmental research on the LUDF will also be discussed, including the quantification of nitrogen (N) losses, and results from research into nitrogen loss mitigation technology (eco-n nitrification inhibitor)

Lime, phosphorus and sulphur response of French serradella (Ornithopus sativus) grown in an acid upland soil

Soil acidity severely restricts legume persistence and growth in grazed upland agriculture in New Zealand. An alternative and potentially acid tolerant forage legume, French serradella (Ornithopus sativus), was examined in a climate controlled experiment. Plants were grown for 48 weeks in an acid (pHH20 4.9) upland soil and shoot yield measured every 8 weeks. Treatments were fully replicated combinations of lime (CaCO3; 0, 2, 4 or 8 t ha-1), phosphorus (P; 0, 50, 150 or 500 mg P L soil-1) plus various controls. Shoot yield varied significantly between lime treatments (P < 0.001), but were not strongly affected by P rate. Importantly, yields on the unlimed control treatments were 85% of maximum yield, suggesting that high yields are potentially achievable on even very acid soils. french serradella grew 16.9 g DM pot-1compared to 5.3 g DM pot-1 for the commonly grown reference species, subterranean clover (Trifolium subterraneum). French serradella showed significant potential as a new pasture legume suitable for acidic upland soils

Potential profit gains from improving pasture productivity on New Zealand South Island high-country farms

Soil acidity combined with low levels of key nutrients on New Zealand hill-country farms are limiting factors for legume establishment/growth. However, legumes are a critical component of these farms as they provide nitrogen and high-quality feed. A farm-systems model was developed to estimate the impact of targeted fertiliser and lime application, combined with sowing clover, on whole-farm productivity and profitability. A base model was developed that incorporated 17 years’ worth of Beef + Lamb NZ survey data for Class 1: South Island Farms. This base model was then used investigate two lime-application/oversowing models where part of the modelled high-country farm was targeted for improvement: (1) Conservative, i.e. 0.6% farm area; and (2) Aggressive, i.e. 2.8% farm area. Three scenarios to utilise the additional pasture grown were then investigated for each model by: (a) increasing ewe numbers; (b) increasing ewe performance (lambing percentage); and (c) increasing liveweight gain of stock. Scenario 2a, generated the highest profitability level (Earnings before Interest Tax and Rent, EBITR $58,870) above the base model but became less financially attractive when the two years required to build the maternal ewe flock were factored in. Scenarios 2c and 1b generated increases in profitability (EBITR) between$33,310 and $41,290 above the base model. Variation in product prices, production levels and time to develop the final farm-management system would also influence the productivity and profitability of the scenarios. Environmental aspects, infrastructure and staff availability would affect the suitability of the development for individual farming businesses

Confirmation of co-denitrification in grazed grassland

peer-reviewedPasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment. Research has focused on losses to air and water due to the health, economic and environmental impacts of reactive N. Di-nitrogen (N2) emissions are still poorly characterized, both in terms of the processes involved and their magnitude, due to financial and methodological constraints. Relatively few studies have focused on quantifying N2 losses in vivo and fewer still have examined the relative contribution of the different N2 emission processes, particularly in grazed pastures. We used a combination of a high 15N isotopic enrichment of applied N with a high precision of determination of 15N isotopic enrichment by isotope-ratio mass spectrometry to measure N2 emissions in the field. We report that 55.8 g N m−2 (95%, CI 38 to 77 g m−2) was emitted as N2 by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m−2), compared to only 1.1 g N m−2 (0.4 to 2.8 g m−2) from denitrification. This study provides strong evidence for co-denitrification as a major N2 production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems.The authors are grateful for the funding that was provided through the Research Stimulus Fund Program administered by the Department of Agriculture & Food under the National Development Plan 2007–2013 RSF 07536. The first author is grateful for the funding provided by Teagasc through the Walsh Fellowship Scheme

Extractable aluminium in New Zealand Andisols and Inceptisols

It is critical to have a soil test that allows for the measurement of potential toxicity. A laboratory experiment was undertaken to investigate the effects of changing the concentration of salt in the extract and extraction time of the standard CaCl₂ and KCl soil Al tests on the Al concentrations extracted from 13 soils from four New Zealand soil orders. Al extracted by KCl (AlKCl) was 13 times higher than extracted by CaCl₂ (AlCaCl2) across all soils. The effect of changing extract salt concentration and extraction time on Al extracted differed among the four soil orders tested for the two extraction methods. Increasing the concentration of CaCl₂ in the extract increased (P .05) the AlCaCl2 extracted from all soils. An increase in the concentration of KCl in the extract up to 1 M increased AlKCl (P .05) with a further increase in concentration. Extraction time affected AlKCl (P < .001) for Pallic soils, while the interaction of concentration of KCl in the extract and extraction time resulted in differences (P < .001) only for the Pallic soils. These findings suggest that the Al concentrations measured by the two extraction methods are affected by specific soil properties in the topsoil related to soil order. This means that when measuring the Al bioavailability in soils, extreme care must be taken when interpreting soil Al test results

Confirmation of co-denitrification in grazed grassland

Pasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment. Research has focused on losses to air and water due to the health, economic and environmental impacts of reactive N. Di-nitrogen (N₂) emissions are still poorly characterized, both in terms of the processes involved and their magnitude, due to financial and methodological constraints. Relatively few studies have focused on quantifying N₂ losses in vivo and fewer still have examined the relative contribution of the different N₂ emission processes, particularly in grazed pastures. We used a combination of a high ¹⁵N isotopic enrichment of applied N with a high precision of determination of ¹⁵N isotopic enrichment by isotope-ratio mass spectrometry to measure N₂ emissions in the field. We report that 55.8 g N m⁻² (95%, CI 38 to 77 g m⁻²) was emitted as N₂ by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m⁻²), compared to only 1.1 g N m⁻² (0.4 to 2.8 g m⁻²) from denitrification. This study provides strong evidence for co-denitrification as a major N₂ production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems

A Sweet Killer: Mesoporous Polysaccharide Confined Silver Nanoparticles for Antibacterial Applications

Silver nanoparticles (AgNP) confined within porous starch have been prepared in a simple, green and efficient manner, utilising the nanoporous structure of predominantly mesoporous starch (MS) to act as nanoparticle stabiliser, support and reducing surface. MS/AgNP materials present high surface areas (SBET > 150 m2 g−1) and mesopore volumes (Vmeso > 0.45 cm3 g−1). The interaction of the AgNP precursor and forming nanoparticle nuclei with the mesoporous domains of the porous polysaccharide, direct porosity to increasingly narrower and more defined pore size distributions, indicative of a degree of cooperative assembly. Transmission electron microscopy images indicated the presence of spherical AgNP of a size reflective of the porous polysaccharide mesopore diameter (e.g., 5–25 nm), whilst XPS analysis confirmed the metallic Ag0 state. Materials were prepared at relatively low Ag loadings (<0.18 mmol g−1), demonstrating excellent antimicrobial activity in solid and liquid phase testing against Gram negative (E. coli) and positive (S. aureus) model bacteria. The resulting materials are biocompatible and present a useful solid porous carbohydrate-based polymer vehicle to control the AgNP size regime and facilitate transference to a biological environment

Dietary fibre supplementation enhances radiotherapy tumour control and alleviates intestinal radiation toxicity.

Non-toxic approaches to enhance radiotherapy outcomes are beneficial, particularly in ageing populations. Based on preclinical findings showing that high-fibre diets sensitised bladder tumours to irradiation by modifying the gut microbiota, along with clinical evidence of prebiotics enhancing anti-cancer immunity, we hypothesised that dietary fibre and its gut microbiota modification can radiosensitise tumours via secretion of metabolites and/or immunomodulation. We investigated the efficacy of high-fibre diets combined with irradiation in immunoproficient C57BL/6 mice bearing bladder cancer flank allografts. Psyllium plus inulin significantly decreased tumour size and delayed tumour growth following irradiation compared to 0.2% cellulose and raised intratumoural CD8+ cells. Post-irradiation, tumour control positively correlated with Lachnospiraceae family abundance. Psyllium plus resistant starch radiosensitised the tumours, positively correlating with Bacteroides genus abundance and increased caecal isoferulic acid levels, associated with a favourable response in terms of tumour control. Psyllium plus inulin mitigated the acute radiation injury caused by 14 Gy. Psyllium plus inulin increased caecal acetate, butyrate and propionate levels, and psyllium alone and psyllium plus resistant starch increased acetate levels. Human gut microbiota profiles at the phylum level were generally more like mouse 0.2% cellulose profiles than high fibre profiles. These supplements may be useful in combination with radiotherapy in patients with pelvic malignancy

Dietary fibre supplementation enhances radiotherapy tumour control and alleviates intestinal radiation toxicity

Background: Non-toxic approaches to enhance radiotherapy outcomes are beneficial, particularly in ageing populations. Based on preclinical findings showing that high-fibre diets sensitised bladder tumours to irradiation by modifying the gut microbiota, along with clinical evidence of prebiotics enhancing anti-cancer immunity, we hypothesised that dietary fibre and its gut microbiota modification can radiosensitise tumours via secretion of metabolites and/or immunomodulation. We investigated the efficacy of high-fibre diets combined with irradiation in immunoproficient C57BL/6 mice bearing bladder cancer flank allografts. Result: Psyllium plus inulin significantly decreased tumour size and delayed tumour growth following irradiation compared to 0.2% cellulose and raised intratumoural CD8+ cells. Post-irradiation, tumour control positively correlated with Lachnospiraceae family abundance. Psyllium plus resistant starch radiosensitised the tumours, positively correlating with Bacteroides genus abundance and increased caecal isoferulic acid levels, associated with a favourable response in terms of tumour control. Psyllium plus inulin mitigated the acute radiation injury caused by 14 Gy. Psyllium plus inulin increased caecal acetate, butyrate and propionate levels, and psyllium alone and psyllium plus resistant starch increased acetate levels. Human gut microbiota profiles at the phylum level were generally more like mouse 0.2% cellulose profiles than high fibre profiles. Conclusion: These supplements may be useful in combination with radiotherapy in patients with pelvic malignancy. C3P3Z-i-BEWcsPG8U_9P4fVideo Abstrac

Dietary fibre supplementation enhances radiotherapy tumour control and alleviates intestinal radiation toxicity

Acknowledgements We thank Professor William Kim (University of North Carolina, Chapel Hill) for his generous gift of the UPPL1591 cell line. We thank Dr. Mark Hill (Department of Oncology, University of Oxford) for assistance with irradiation procedures, and Dr. Jia-Yu Ke and Dr. Vijay Indukuri (Research Diets, Inc.) for formulation of the mouse diets. We thank Dr. Graham Horgan (James Hutton Research Institute, Aberdeen) for statistical advice. We thank Grampian Biorepository at Aberdeen Royal Infirmary for providing the faecal samples from cancer patients.Peer reviewe