Deep-drainage control and yield: the trade-off between trees and crops in agroforestry systems in the medium to low rainfall areas of Australia

Oliver, Yvette; Lefroy, EC; Stirzaker, Richard; Davies, C.L.

doi:10.1071/ar04213

Cited by 21 publications

(17 citation statements)

References 33 publications

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“…These findings, along with some of the economic implications, are discussed below. The average extent of tree-crop competition adjacent to unharvested mallees (11.3 m, or 2.6 H) was within the range reported for mallees (Sudmeyer and Flugge 2005;Sudmeyer and Daniels 2010) and for various exotic and native tree species in southern Australia (Bird et al 2002;Sudmeyer et al 2002a;Woodall and Ward 2002;Unkovich et al 2003;Oliver et al 2005 Huth et al 2010) and temperate areas elsewhere in the world (e.g. Brandle et al 2009).…”

Section: Discussionmentioning

confidence: 74%

“…an area next to the belt where yield was effectively zero (the zeroyield distance) and the remaining area where yield was equivalent to open values. This approach has been taken with crop yield or drainage below the root-zone in several other studies (Lefroy et al 2001;Knight et al2002;Ellis et al 2005;Oliver et al 2005;Robinson et al 2006;Crosbie et al 2008). The zero-yield distance was calculated using Eqn 1:…”

Section: Crop and Pasture Growthmentioning

confidence: 99%

“…Australian research has shown that competition for water is the primary cause of reduced agricultural yields in the competition zone and that the economic impacts of competition are generally not offset by the productivity benefits of wind-speed reductions and associated micrometeorological changes (George-Jaeggli et al 1998;Jones and Sudmeyer 2002;Sudmeyer et al 2002aSudmeyer et al , 2002bUnkovich et al 2003;Oliver et al 2005;Sudmeyer and Flugge 2005;Bennell and Verbyla 2008;Huth et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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The extent and cost of mallee - crop competition in unharvested carbon sequestration and harvested mallee biomass agroforestry systems

Sudmeyer

Daniels²,

Jones³

et al. 2012

Crop Pasture Sci.

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Abstract. Mallee-based agroforestry has potential to provide farmers with new income sources derived from biofuels, biofeedstocks, and carbon sequestration. Although mallees are planted on >12 700 ha across the south-west of Western Australia, very little commercial harvesting of mallee has occurred to date. The development of biomass processing industries is constrained by lack of robust information regarding the productivity of integrated mallee and agricultural systems. This study addresses this constraint by quantifying the productivity and economics of agricultural crops and pastures growing in the competition zone adjacent to mallee belts at 15 sites across the Western Australian wheatbelt. The sites covered a range of climate and edaphic conditions, three mallee species (Eucalyptus polybractea R Baker, E. loxophleba ssp. lissophloia LAS Johnson and KD Hill, or E. kochii ssp. plenissima (CA Gardner) Brooker), various crop and pasture rotations, and various mallee harvest-management treatments.Mallee-crop competition was negatively correlated with rainfall and positively correlated with mallee age and size, and greater for crops than pasture. Consequently, extent and magnitude of competition were highly variable across sites and years. On average, mallee-crop competition extended 11.3 m from unharvested belts and reduced crop and pasture yields by 36% within 2-20 m of the mallee belts relative to open paddock yields. This is similar to what has been reported for taller tree species. Harvesting mallees reduced competition such that crop and pasture yield was reduced by 22 or 27% relative to open paddock yields for mallees harvested at 3-or 6+-year intervals, respectively.The economic cost of mallee-crop competition on agricultural enterprises was also highly variable between sites, and between years within individual sites. Averaged across all site-years, the opportunity cost of competition was equivalent to forgoing agricultural production for 14.4 m on each side of unharvested mallee belts, or 9-10 m on each side of harvested belts.Farmers with mallee agroforestry systems will need to manage the economic impacts of competition by reducing agricultural input costs in the competition zone, timing crop-grazing rotations with mallee harvests, ensuring that the width of alleys is at least 25 times the height of the mature trees, and possibly root-pruning mallees in unharvested or long harvest interval systems.This research has shown that mallee-crop competition presents a significant cost to farmers and must be considered when designing mallee agroforestry systems. The findings have relevance for the development of appropriate biomass and carbon sequestration pricing benchmarks for mallee plantings.

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Section: Discussionmentioning

confidence: 74%

Section: Crop and Pasture Growthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The extent and cost of mallee - crop competition in unharvested carbon sequestration and harvested mallee biomass agroforestry systems

Sudmeyer

Daniels²,

Jones³

et al. 2012

Crop Pasture Sci.

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“…Upscaling volumetric tree water use to areal transpiration requires that the mixed zone be eliminated and the tree/pasture system be reduced to a binary state. Reduction of this complex system to a binary state has been done previously for investigations of tree-crop interactions in a no-yield zone (Stirzaker et al 2002;Oliver et al 2005) and a no-recharge zone (Ellis et al 2005).…”

Section: Mathematical Formulationmentioning

confidence: 99%

The upscaling of transpiration from individual trees to areal transpiration in tree belts

Crosbie

Wilson²,

Hughes³

et al. 2007

Plant Soil

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Sap flow measurements have long been used to measure transpiration in individual trees and there exist some well established methods for upscaling individual tree volumetric transpiration to areal transpiration in plantation and forest plots. However, where edge effects are significant, such as in tree belts, the area the volumetric transpiration is to be projected upon is unknown. This paper provides a methodology for estimating the area that a tree belt hydrologically occupies by using either measurements of tree root density or soil moisture distribution. An application of the proposed methodology shows that simply assuming that the area of the tree belt is the crown projected area could lead to an overestimation of the areal transpiration of 100%.

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“…The economic potential of perennial alley systems may also be enhanced if they can be developed as greenhouse sinks and sources of biofuel (Harper et al, 2007;Bartle et al, 2007). Research to date has focused on understanding the hydrological functioning of hillslope alley systems (Ellis et al, 2006;Oliver et al, 2005;White et al, 2002;Wildy and Pate, 2002) and the water requirements for successful production in dryland environments (Cooper et al, 2005).…”

Section: S L Noorduijn Et Al: Water Table Response To Alley Farmingmentioning

confidence: 99%

Relative impacts of key drivers on the response of the water table to a major alley farming experiment

Noorduijn

Smettem

Vogwill³

et al. 2009

Hydrol. Earth Syst. Sci.

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Abstract. Widespread clearing of native vegetation in Southwest Western Australia has led to land degradation associated with rising groundwater, secondary salinisation and waterlogging. Re-establishing deep-rooted perennial vegetation across parts of the landscape is one technique for managing land degradation. Alley farming is an agroforestry practice where multiple perennial tree belts are planted in alternation with traditional agricultural crops. To identify the best configuration (belt width versus alley width) for controlling rising groundwater levels and providing viable economic returns, a large scale experiment was established in 1995. The experiment contains seven different alley farming designs, each with transects of piezometers running across tree belts into adjacent alleys to monitor changes in the groundwater level. Two control piezometers were also installed in an adjacent paddock. Groundwater at the site is shallow (<3 m) and of poor quality (pH 3-5, Ec 2.1-45.9 mS cm −1 ) so root water uptake from the saturated zone is limited.Simple hydrograph analysis could not separate treatment effects on the water table response. Subsequent statistical analysis revealed that 20-30% of the variability in the water table data over the 12 year study period was attributable to the alley farming experiment. To futher investigate the effect of the experiment on groundwater response, additional hydrograph analysis was conducted to compare the trends in the control piezometers in relation to those located within the belts. A difference of 0.9 m was observed between the mean groundwater levels in the control piezometers and the mean Correspondence to: A. Ghadouani (anas.ghadouani@uwa.edu.au) levels in the perennial belt piezometers. For a mean specific yield of 0.03 m 3 m −3 (standard deviation of 0.03 m 3 m −3 ) this equates to an additional average annual water use of 27 mm yr −1 (standard deviation of 33 mm yr −1 ) by the perennial agroforestry system. It is concluded that declining annual rainfall is the principal control on hydrograph response at the site, whilst perennial biomass development has a lesser impact on water table depth.

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Deep-drainage control and yield: the trade-off between trees and crops in agroforestry systems in the medium to low rainfall areas of Australia

Cited by 21 publications

References 33 publications

The extent and cost of mallee - crop competition in unharvested carbon sequestration and harvested mallee biomass agroforestry systems

The extent and cost of mallee - crop competition in unharvested carbon sequestration and harvested mallee biomass agroforestry systems

The upscaling of transpiration from individual trees to areal transpiration in tree belts

Relative impacts of key drivers on the response of the water table to a major alley farming experiment

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