OVERSEER® nutrient budgets - moving towards on-farm resource accounting

Wheeler, D. M.; Ledgard, Stewart; Klein, Cecile A. M. de; Monaghan, Rachel; Carey, Peter; McDowell, R. W.; Johns, Kimberly

doi:10.33584/jnzg.2003.65.2484

Cited by 67 publications

(23 citation statements)

References 3 publications

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“…The amounts of leached DOC, DON and mineral N were calculated from the concentrations of these elements measured, times the volume of leachate collected during the experimental period. The 20‐year mean annual rainfall data for each of the sampling sites (see footnote in Table 1 for data source) was used in the OVERSEER ® model—Version 2 (Wheeler et al , 2003) to estimate an annual drainage factor of water that would percolate through the soil profile beyond the rooting depths of the pasture plants. This is a simplistic model where annual drainage is calculated by subtracting annual evaporation losses from the annual total rainfall.…”

Section: Methodsmentioning

confidence: 99%

Dissolved organic matter leaching in some contrasting New Zealand pasture soils

Ghani

Müller

Dodd

et al. 2010

European J Soil Science

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Leaching of dissolved organic matter (DOM) from pastoral soils is increasingly seen as an important but poorly understood process. This paper examined the relationship between soil chemical properties, microbial activity and the losses of dissolved organic carbon (DOC) and nitrogen (DON) through leaching from six pasture soils. These soils differed in carbon (C) (4.6-14.9%) and nitrogen (N) (0.4-1.4%) contents and in the amount of organic C and N that had accumulated or been lost in the preceding 20+ years (i.e. −5131 to +1624 kg C ha −1 year −1 and −263 to +220 kg N ha −1 year −1 , respectively). The paper also examined whether between-soil-type differences in DOC and DON leaching was a major explanatory factor in the observed range of soil organic matter (SOM) changes in these soils. Between 280 and 1690 kg C ha −1 year −1 and 28-117 kg N ha −1 year −1 leached as DOC and DON, respectively, from the six soils in a lysimeter study, with losses being greater from two poorly drained gley soils. Losses of C and N of this magnitude, while at the upper end relative to published data, could not fully explain the losses at Rawerawe, Bruntwood and Lepperton sites reported by Schipper et al. (2007). The study highlights the leaching of DOM as a significant pathway of loss of C and N in pasture soils that is often ignored or given little attention in predictive models and nutrient budgeting. Leaching losses of DOC and DON alone, or in combination with slightly increased respiration losses of SOM given a 0.2 • C increase in the mean annual soil temperature, do not fully explain long-term changes in the SOM observed at these sites. When soils examined in the present study were separated on the basis of drainage class, the losses of DOC by leaching were correlated with both total and hot-water extractable C (HWC), the latter being a measure of the labile SOM fraction. Basal microbial CO 2 respiration rates, which varied between 1 and 3.5 μg CO 2 -C g −1 soil hour −1 in surface soils (0-75-mm depth), was also linked to HWC and the quantities of C lost as DOC. Adoption of the HWC method as an approach that could be used as a proxy for the direct measurement of the soil organic C lost by leaching as DOC or respired needs to be examined further with a greater number of soils. In comparison, a poor relationship was found between the hot-water extractable N (HWN) and loss of DON by leaching, despite HWN previously being shown to be a measure of the mineralizable pool of N in soils, possibly reflecting the greater competition for N than C in these soils.

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Section: Methodsmentioning

confidence: 99%

Dissolved organic matter leaching in some contrasting New Zealand pasture soils

Ghani

Müller

Dodd

et al. 2010

European J Soil Science

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“…), while the leaching ( n ) values are typically derived from nutrient‐cycling models, such as OVERSEER (Wheeler et al . ).…”

Section: Calibration Of Nzfarmmentioning

confidence: 97%

Methodological limitations in the evaluation of policies to reduce nitrate leaching from New Zealand agriculture

Doole

Marsh

2013

Aus J Agri & Res Econ

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The land-use optimisation framework, NZFARM, has been promoted as a tool that can be used to assess the economic and environmental impacts of policy on regional land use. This paper outlines how methodological limitations presently restrict its capacity to provide meaningful insight into the relative value of alternative land-use configurations. The model is calibrated using positive mathematical programming, which has been shown in the literature to result in models that yield arbitrary output outside of the calibrated baseline. There is a high likelihood that this is the case, as no validation appears to have been carried out. Significant model development will be required before NZFARM outputs can be used with any confidence to inform future policy development. We conclude with suggestions on how NZFARM and models of its kind can be further developed to improve their capacity for meaningful simulation.

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“…Across our entire sample of sites, application rates varied from 0–96 kg N per ha per year. On-farm N fixation rates were estimated from OVERSEER version 5.4 farm nutrient-budget model [ 64 , 65 ] based on estimated parameters for topography, climate, geomorphology, pasture type and land management practices at each site. Estimated N fixation rates varied from 37–151 kg N per ha per year.…”

Section: Methodsmentioning

confidence: 99%

Agricultural Intensification Exacerbates Spillover Effects on Soil Biogeochemistry in Adjacent Forest Remnants

et al. 2015

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Land-use intensification is a central element in proposed strategies to address global food security. One rationale for accepting the negative consequences of land-use intensification for farmland biodiversity is that it could ‘spare’ further expansion of agriculture into remaining natural habitats. However, in many regions of the world the only natural habitats that can be spared are fragments within landscapes dominated by agriculture. Therefore, land-sparing arguments hinge on land-use intensification having low spillover effects into adjacent protected areas, otherwise net conservation gains will diminish with increasing intensification. We test, for the first time, whether the degree of spillover from farmland into adjacent natural habitats scales in magnitude with increasing land-use intensity. We identified a continuous land-use intensity gradient across pastoral farming systems in New Zealand (based on 13 components of farmer input and soil biogeochemistry variables), and measured cumulative off-site spillover effects of fertilisers and livestock on soil biogeochemistry in 21 adjacent forest remnants. Ten of 11 measured soil properties differed significantly between remnants and intact-forest reference sites, for both fenced and unfenced remnants, at both edge and interior. For seven variables, the magnitude of effects scaled significantly with magnitude of surrounding land-use intensity, through complex interactions with fencing and edge effects. In particular, total C, total N, δ15N, total P and heavy-metal contaminants of phosphate fertilizers (Cd and U) increased significantly within remnants in response to increasing land-use intensity, and these effects were exacerbated in unfenced relative to fenced remnants. This suggests movement of livestock into surrounding natural habitats is a significant component of agricultural spillover, but pervasive changes in soil biogeochemistry still occur through nutrient spillover channels alone, even in fenced remnants set aside for conservation. These results have important implications for the viability of land-sparing as a strategy for balancing landscape-level conservation and production goals in agricultural landscapes.

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OVERSEER® nutrient budgets - moving towards on-farm resource accounting

Cited by 67 publications

References 3 publications

Dissolved organic matter leaching in some contrasting New Zealand pasture soils

Dissolved organic matter leaching in some contrasting New Zealand pasture soils

Methodological limitations in the evaluation of policies to reduce nitrate leaching from New Zealand agriculture

Agricultural Intensification Exacerbates Spillover Effects on Soil Biogeochemistry in Adjacent Forest Remnants

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