Browsing by Author "Hanly JA"

Now showing 1 - 6 of 6
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    Effects of full inversion tillage during pasture renewal on soil and plant cadmium concentrations: a case study in New Zealand
    (CSIRO Publishing, 5/12/2022) Peng Y; Hanly JA; Jeyakumar P; Calvelo-Pereira R
    Context: Cadmium (Cd) accumulation is a concern in permanent pasture soils, as it can lead to increased Cd uptake by plants. Aims: This study aimed to quantify the effect of full inversion tillage (FIT or ploughing deeper than 30 cm), used during pasture renewal, on the redistribution of Cd within the soil profile and on plant Cd concentration. Methods: Two field trials (Trial 1, Alfisol; Trial 2, Andisol) were established in New Zealand using contrasting tillage practices (FIT; SIT, shallow tillage; and NT, no tillage) to sow turnips as summer forage crops, followed by autumn re-sowing of perennial ryegrass/white clover pasture. Key results: In the Alfisol, no measurable differences (P > 0.05) in soil and plant Cd were detected among the tillage treatments. In the Andisol, FIT decreased (P < 0.05) total (0.25 mg/kg) and extractable soil Cd (0.013 mg/kg) in the 0–5 cm depth, compared to pre-tillage (0.42 and 0.031 mg/kg, respectively). Moreover, at this soil depth, FIT achieved a 52% lower (P = 0.034) extractable soil Cd concentration than the ST treatment. In addition, the subsequent new pasture had lower (P = 0.007) average Cd concentration following FIT compared to ST (0.03 vs 0.05 mg/kg). Conclusions: We demonstrated that the use of FIT during pasture renewal is a potential solution to reduce topsoil Cd concentration. Implications: The FIT is more effective in soil where total soil Cd concentration or its degree of vertical stratification with depth is relatively high.
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    Effects of Sheep Grazing Systems on Water Quality with a Focus on Nitrate Leaching
    (MDPI (Basel, Switzerland), 2022-06-01) Maheswaran S; Cranston LM; Millner JP; Horne DJ; Hanly JA; Kenyon PR; Kemp PD
    This article reviews the literature on nitrate leaching under sheep grazing systems and focuses on identifying future research needs. Urinary nitrogen (N) is an important source of the nitrate leached from pastoral agriculture. Urinary N excretion can be measured or simulated using models and has been well characterised for dairy systems. It is difficult to continuously monitor the urinary N excretion of sheep under field conditions; consequently, measurements of N excretion in sheep urine are limited. Urination events by sheep vary greatly in volume (0.5 L to 6.9 L), concentration (3 to 13.7 g N/L), and frequency (8 to 23 events/day); this variation results in a corresponding variation in N loading rates in urine patches. The amount of nitrate leached under pastures grazed by sheep has typically varied between 1 and 50 kg N/ha/year, but rates as high as 300 kg N/ha/year have been reported. The quantity of nitrate leached under sheep depends on the season, climate, quantity and timing of drainage, the interaction between forage production and stocking rate, fertiliser applied, N fixation by legumes, forage type, and grazing management. The majority of studies examining nitrate leaching under sheep grazing systems are more than 20 years old; so, there is little recent information on nitrate leaching under modern pasture-based sheep production systems. Further research is required to quantify nitrate leaching levels under current sheep farming practices, to understand the impacts of this leaching on water quality, and to help identify effective strategies to reduce the transfer of N from grazed paddocks to receiving water bodies. This additional information will help provide information for decision support tools, including models and management practices, to help sheep farmers minimise their impact on the aquatic environment.
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    NITROGEN LOSSES FROM PLANTAIN: WHAT CAN WE SAY?
    Rodriguez MJ; Kemp PD; Navarrete Quijada S; Hanly JA; Horne DJ; Bishop P
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    Plantain (Plantago lanceolata) nitrogen use and excretion by lactating dairy cows
    Navarrete Quijada S; Kemp PD; Rodriguez MJ; Horne DJ; Hanly JA; Hedley MJ
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    PLANTAIN SWARD: IS IT EFFECTIVE IN REDUCING N2O EMISSIONS IN SPRING AND AUTUMN?
    (11/02/2020) Rodrigues MJ; Kemp PD; Bishop P; Hanly JA; Navarrete Quijada S; Horne DJ
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    The potential of plantain based pastures to reduced nitrogen losses from dairy systems
    Navarrete Quijada S; Rodriguez MJ; Kemp PD; Hedley MJ; Horne DJ; Hanly JA; Currie, LD; Christensen, CL