The role of indeterminate growth, rooting depth and maturity time in establishing a legume seedbank under drought conditions

Belinda Hackney1, 3, Simon Flinn1, 3, Jeff McCormick2, 3, John Piltz1, 3, Susan Orgill1, 3

1 NSW Department of Primary Industries, PMB, Pine Gully Rd, Wagga Wagga, NSW 2650

2 School of Agriculture and Wine Sciences, Charles Sturt University, Wagga Wagga, NSW 2650

3 Graham Centre for Agricultural Innovation, Charles Sturt University and NSW Department of Primary Industries, Pugsley Place, Wagga Wagga, NSW, 2650


Drought can be catastrophic to pasture establishment resulting in establishment failure and financial loss.  A range of annual legumes with varying characteristics (capacity for extended periods of indeterminate growth, varying rooting depth and differing maturity times) were sown in a replicated trial near Kikoira in central NSW where growing season rainfall was only 44% of the long term average. Biserrula, an indeterminate, deep-rooted legume produced more than 170 kg seed/ha with one-third produced prior to the end of October.  French serradella, another indeterminate, deep-rooted species but of later maturity in our study produced more than 85 kg seed/ha. The early maturing gland clover was the most successful of the shallow-rooted species in producing seed, although its seed yield was significantly less than either biserrula or French serradella. Subterranean clover failed to produce seed and annual medics produced less than 10 kg seed/ha. Trifolium diffusum, a little-known species, produced 120 kg seed/ha and requires further assessment of potential. Overall, species with capacity for extended periods of indeterminate growth, deep root systems and/or early maturity were the most successful in establishing a seed bank under severe drought conditions.

Banded application improves the recovery of phosphorus fertiliser in a temperate pasture sward containing red clover

Jonathan W. McLachlan1, Chris N. Guppy1, Richard J. Flavel1

1University of New England, School of Environmental and Rural Science, Armidale, NSW, 2351,


Phosphorus (P) fertiliser is commonly broadcast onto existing pasture swards for ease and cost of application. However, improvements in P acquisition efficiency may be achieved by banding fertiliser. Micro-swards of red clover (Trifolium pratense L.) were grown in intact sandy loam soil cores with a 33P-labelled fertiliser source. Dissolved P fertiliser was applied either to the surface or at a depth of 30 mm, to either small or large volumes of soil. Growth rates were modest and significant differences were not observed for shoot yield among treatments. However, shoot P content and P recovery were 37% and 35% higher, respectively, when P fertiliser was distributed across a larger soil volume when compared to concentrated points. Similarly, banded treatments increased recovery by 40% compared to surface-applied fertiliser. The results suggested that banded application of a low concentration liquid P fertiliser may improve the recovery of P fertiliser by pasture legumes grown in soil with a low phosphorus buffering index (PBI).

Differences in subsoil P acquisition by two subterranean clover cultivars in a P deficient soil

Jonathan W. McLachlan1,2, Richard J. Flavel1, Chris N. Guppy1, Richard J. Simpson2, Rebecca E. Haling2

1 University of New England, School of Environmental and Rural Science, Armidale, NSW, 2351,

2 CSIRO Agriculture and Food, GPO Box 1700, Canberra, ACT, 2601


Phosphorus (P) is usually concentrated in the uppermost layers of the soil profile under pasture, hence topsoil root allocation is important for maximising P acquisition. However, total root length was recently found to be a marginally better predictor of variation in P uptake among twenty-six genotypes of subterranean clover (Trifolium subterraneum L.) when compared to topsoil root length alone. This result prompted a preliminary assessment of P acquisition by subsoil roots. Micro-swards of two cultivars were grown with a topsoil layer that was either P-deficient or amended with P for improved plant growth, overlying a low-P subsoil that contained 32P-labelled phosphate. Both cultivars produced less shoot dry mass under P constraint, and the cultivar that allocated more root length to the subsoil layer produced a larger shoot dry mass in the P-deficient soil. This cultivar also recovered more 32P-labelled phosphate from the subsoil layer in both P treatments. Therefore, variation exists for subsoil P acquisition and this trait may be important for determining shoot yield in P-deficient soil.

Effect of sowing time on biomass production and partitioning into grain yield of pigeonpea genotypes (Cajanus cajan L.Millsp.)

Mahendraraj Sabampillai 1*, Marisa Collins 2, Yash Chauhan 3, Rao C.N. Rachaputi 1

1 Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, Australia

2 La Trobe University, Melbourne

3 Queensland Department of Agriculture and Fisheries, Kingaroy, Queensland, Australia


The effect of sowing date on growth and partitioning of dry matter into yield of pigeonpea (Cajanus cajan L.Millsp) genotypes were investigated using split design. Six genotypes (Quest, UQPL941, UQPL1001, ICPL86022, CIPL86039 and ICPL14425) were sown in December 2017 and January 2018. The dry matter production and grain yield of the genotypes under different sowing conditions ranged from 12 – 17 t ha-1 and 3.7 – 4.6 t ha-1. The highest harvest index was recorded in January. The genotypes in both sowings performed differently with respect to yield and harvest index. The results showed significant effect of sowing date on dry matter production and partitioning efficiencies of pigeonpea genotypes and an appropriate adjustment in planting time would optimize the genotype performance.


Litterbag decomposition and nutrient change study of poultry litter

Anika Molesworth, Wendy C. Quayle, John Hornbuckle

Centre for Rural and Regional Futures, Deakin University, Hanwood, NSW 2680, Australia


Quantifying in-situ patterns of poultry litter (PL) mass decomposition and changes over time in NO3-N, NH4-N and Colwell P when applied alone or in combination with urea fertiliser helps farmers to synchronise nutrient additions to the soil with crop requirement. Using a buried litterbag technique in the field, decomposition and nutrient changes followed a two-phase pattern suggesting labile and recalcitrant PL components. Twenty-five days after burial (DAB), PL at 10 cm in loam soil contained64% dry matter (DM), 66% NO3-N, 16% NH4-N, and 69% Colwell P compared with initial concentrations at burial. After 27 DAB, PL in a clay loam had 73% DM, 8% NH4-N and 85% Colwell P remaining compared with initial concentrations, with increases of 6 times in NO3-N. Using an exponential model to estimate PL remaining values from day of burial until final excavation in the loam, it was determined there was 63% DM, 6% NO3-N, 5% NH4-N and 55% Colwell P remaining. After another 43 days buried in the clay loam, there was 63% DM and 2% NH4-N remaining of initial PL values, a 1.2 increase in NO3-N, while Colwell P had returned to starting levels. The rate of PL-N:urea-N had significant effect on NH4-N in phase 2, with greater concentration with higher litter ratio. Since only ~5% of starting PL NH4-N remained at the end of the experimental period on both soil types, the data indicates timely application of PL is required to synchronise any short-term N fertiliser benefit to a developing crop. The free-draining nature of the loam compared with the heavier clay loam are likely to be the main drivers of difference in PL decomposition and nutrient change observed between soil types. The patterns suggest that PL may better fulfil the expectations of a slow release nutrient source in a clay loam than a loam.

Adaptive digital tools for nitrogen management: utilising remote sensing data, modelling and sparse ground truthing

Christine Lion1, Ben Jones1, Anastasiia Volkova1

1FluroSat Pty Ltd, 2-4 Cornwallis Street, Eveleigh, NSW, 2015,,


Remote sensing data can be used in conjunction with crop modelling and data analysis tools to estimate the crop canopy nitrogen status and provide up-to-date information to underpin in-season management decisions. In this study cereal tissue samples were calibrated against indices calculated from satellite imagery and used to generate nitrogen mapping models for wheat and barley at tillering (whole plant) and heading (youngest emerged blade) in South Australia. Crop type was not significant for whole plant samples at tillering (p>0.99) but was for youngest emerged blade at heading (p<0.001). Biomass dilution (related to NDVI/NDRE) was the main component of variation in tissue N% (91% of variance), and (apart from crop type, 75% of variance) the CCCI was the main remote sensing component related to youngest emerged blade N% at heading (17% of variance). The nitrogen maps allowed agronomists to test in some fields rather than all and to use a nitrogen map generated using the remote sensing data as a substitute. In conjunction with tools for management zone creation and nutrient prescription, the nitrogen maps were used to target nutrient application in-season with minimal effort on the agronomist’s behalf.

Management of early sown wheat: Evaluation of G x E x M interactions to increase harvest index and yield of early sown wheat

Kenton Porker1, James Hunt2, Michael Straight3

1 South Australian Research and Development Institute, Hartley Grove, Urrbrae SA 5064

2 Department of Plant, Animal and Soil Sciences, La Trobe University, 5 Ring Rd, Bundoora VIC 3086

3 FAR Australia, 4/97-103 Melbourne St, Mulwala NSW 2647


Early sown slow developing wheats offer increased biomass accumulation, grain number and thus potential grain yield. However, the greater vegetative growth of early sown crops can result in low harvest index (HI).  We evaluated management strategies to improve HI in three early sown winter wheat cultivars using four experiments conducted across south eastern Australia. Strategies included low stand densities (30-50 plants/m²), defoliation, and deferred application of nitrogen fertiliser. We found low stand densities had a small positive effect on HI and grain yield. Defoliation tended to increase HI and but also reduce yield (depending on cultivar) due to reduced biomass which negated much of the increase in HI.  Deferring nitrogen had a variable effect depending on starting soil N and timing of in-season rain to allow crop uptake of top-dressed N.  The management factors studied here have some potential for improvement of HI but responses were variable and with small effect sizes. We conclude that genetic improvement is required to raise HI and yield in early sown wheat.


Importance of different plant traits for dual-purpose cereal dry matter production and grain recovery in southern NSW

Mehrshad Barary1, Peter Matthews2

1NSW Department of Primary Industries, Wagga Wagga, NSW, 2650,

2NSW Department of Primary Industries, Orange, NSW, 2800


With growers` increased focus on dual-purpose (DP) cereal varieties and the development of new DP varieties, a set of experiments investigating the grazing and grain recovery of DP cereals were run at Wagga Wagga in 2016 and 2017. The experiments were designed in a randomised complete block with one or two factors. With two factors e.g. variety and sowing time, the experiments were arranged in split-plot or factorial (depending on the second factor). Sixty three different wheat, barley and triticale genotypes were tested over the two years, with a core subset of 24 genotypes studied in detail. Various measurements and plant traits such as plant population, plant growth stage, dry matter production, morphological attributes, grain yield and quality were recorded. The study found that there were differences between both crop type and genotypes and how they accumulated dry matter and then recovered from grazing to produce grain. The key variables and traits were plant population, tillers number and leaf dry weight for dry matter production before anthesis and total dry matter, fertile tiller number and stem dry weight at anthesis for grain yield.

Does root growth slow during fast stem and ear growth in wheat?

Xiaoxi Li1, Michael Weiss1, Richard Richards1

1 CSIRO Agriculture and Food, GPO Box 1700, Canberra, ACT 2601, Australia 


Differential carbon allocation between the shoots and the roots has a potential impact on crop yield as well as water and nutrient use. A pot experiment in 2-m long tubes was established to monitor the shoot and root growth at different stages in wheat until anthesis, and to obtain detailed root distribution data at different soil depths. Two Australian cultivars, Suntop and Westonia, and two Indian cultivars, C306 and HI1500 were compared. After root washing, the seminal roots were sectioned along the root axis into 20-cm segments to measure morphological traits and dry weight. Preliminary results showed that from fully emerged flag leaf to heading, root biomass did not increase while the shoot growth was rapid in all four cultivars. Subsequently, from heading to anthesis, the roots of the two Indian cultivars grew more rapidly than the two Australian ones. The Indian cultivars tended to have smaller root systems than the Australian cultivars. However, the Indian cultivar HI1500 tended to grow more roots at depth (below 1 m) by anthesis, compared with other cultivars. These preliminary results highlight that the carbon allocation to roots declined markedly during the fast stem and ear growth, but variation among cultivars existed in root growth at depth at later growth stages. The study provides information on competition for carbon between roots and shoots which may be useful in modelling. Genetic variation in root growth may be useful for accessing deep soil water during grain-filling and may result in greater yields, especially under terminal drought conditions.

Increasing grain protein with delayed applications of fertiliser nitrogen

Jeremy Curry1, Blakely Paynter2, Stacey Hansch2, Andrew van Burgel3

1 Department of Primary Industries and Regional Development, Melijinup Road, Esperance, WA, 6450

2 Department of Primary Industries and Regional Development, 75 York Road, Northam, WA, 6401

3 Department of Primary Industries and Regional Development, 444 Albany Hwy, Albany, WA, 6330


Low grain protein can cause downgrading of barley from Malt1 (GIWA Malt1 protein window is 9.5-12.8%). With increasing productivity and decreasing nitrogen (N) supply available from the soil (primarily due to lack of legumes in the crop rotation), growers need to increase their fertiliser N applications to produce adequate protein levels. In addition to increasing N rate, growers can improve their fertiliser effectiveness by changing the timing of N application. In this study, shifting N from seeding and mid-tillering to the stem elongation period consistently increased grain protein, although was often associated with increased screenings and for some treatments reduced grain yield. Most delayed N strategies (except N timings 2 and 4) provided a protein increase of 0.5-1.0% relative to the strategy of ⅓ N at seeding, mid tillering and stem elongation (N timing 1 – current practice control) in at least three of the four sites. Only two delayed N strategies, N timing 2 and 3, did not affect grain yield at any site. Compared to N timing 1 moving the ⅓ N from mid-tillering to stem elongation (N timing 2) increased grain protein at only two sites whereas applying the bulk of the N at stem elongation (N timing 3) increased grain protein at all four sites. Both strategies, however, increased screenings (at two and three sites respectively), though did not negatively impact on hectolitre weight or grain brightness. The grain protein increase of the other delayed N strategies may often have been larger than N timings 2 and 3 but came at a risk of higher screenings, lower hectolitre weight or lower grain yield (site specific). The best of the other strategies evaluated was N timing 10 (⅓ N at seeding, stem elongation and flag leaf emergence), which increased protein at three sites, had no impact on screenings or hectolitre weight at any site, although did reduce yield and brightness at one site.



The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

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