Rainfed Farming Systems of North-Eastern Australia

Birch, CJ; Bell, Lindsay W.

doi:10.1007/978-1-4020-9132-2_25

Cited by 1 publication

(1 citation statement)

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“…Since in this study the wheat was sown only three weeks after harvest of the canola the results highlight a potential to capitalise on rapid P release from the decomposing canola root system. Agronomic significance therefore may relate more closely to relay or double cropping systems where successive crops are sown within relatively close timeframes, such as occurs more commonly in north eastern Australia (Birch and Bell 2011), although summer crops have been considered in some southern areas (Wilhelm 2001). However, rapid root P inputs are also highly relevant to the intercropping or pasture cropping systems that have recently been suggested as economically viable and environmentally sound options for cropping regions across Australia (Bengough et al 2001;Craig et al 2013) and would be important in dual-purpose systems where canola is utilised for both grazing and grain (Kirkegaard et al 2008b).…”

Section: Modelling Undertaken Bymentioning

confidence: 99%

Use of 33P to trace in situ the fate of canola below-ground phosphorus, including wheat uptake in two contrasting soils

et al. 2016

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Our understanding of the contribution of crop root residues to phosphorus (P) cycling is mainly derived from studies using excavated roots re-introduced to soil. This study aims to quantify total below-ground P (BGP) of mature canola in situ and to estimate directly the proportion accessed by subsequent wheat. 33P-Labelled phosphoric acid was fed by stem wick to canola (Brassica napus) grown in sand or loam in pots. Shoots were removed from all plants at maturity. Half of the pots were destructively sampled. After a 3-week fallow, wheat was grown for 5 weeks in the remaining undisturbed pots. At canola maturity, 23–36% of the 33P was partitioned in recovered roots and 34–40% in the soil. More 33P was recovered in the loam than the sand. Within the soil, 6–10% of the fed 33P was present in resin P and 3–5% was in hexanol-released P pools. Ratios of shoot P : BGP (8 : 1 in sand and 15 : 1 in loam) were much narrower than those of shoot P : recovered root P (17 : 1 in sand and 39 : 1 in loam). A greater proportion and amount of the mature canola BG33P was recovered by wheat grown in the loam (26%, 2.6 mg/plant) than in the sand (21%, 1.5 mg/plant). The majority of canola BG33P remained in the bulk soil. Input of P below-ground by mature canola and subsequent P benefit to wheat was greater in loam than sand. The P from canola below-ground residues contributed up to 20% of P uptake in wheat during the first 5 weeks of growth. Longer term benefits of P from below-ground residues require investigation.

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