Nicole Robinson

This case study explores the transformative role of a student-staff partnership (SSP) in redesigning assessment and learning experiences for the core master’s-level course, Global Challenges in Agriculture (AGRC7047). At the heart of this initiative was a diverse team of student and staff partners who co-developed new learning materials and assessment structures to better engage a heterogeneous cohort. A key outcome of this collaboration was the design and implementation of a reflexive ePortfolio assessment. This innovation emerged from the SSP’s commitment to inclusivity, pedagogical alignment, and global citizenship education. Rather than positioning the ePortfolio as the central course, this paper foregrounds the SSP process: how students and staff worked as co-creators, how diverse disciplinary and cultural perspectives enriched the project, and how this model can inform broader efforts to co-create curriculum in agricultural sciences and beyond. By documenting the application of SSP within agricultural sciences, an area where partnership-based pedagogical research remains limited, this study contributes new insights into how co-creation can reshape teaching practices in applied and interdisciplinary STEM-adjacent fields. The findings offer valuable insights into how SSPs can lead to sustainable pedagogical innovation and shift disciplinary cultures toward more reflective and student-centred practices.

The circular nutrient economy repurposes organic (formerly alive, containing organic carbon) and inorganic (mineral) recycled materials as fertilisers and soil ameliorants, and halving nitrogen (N) waste is a global goal. Our focus was unavoidable food waste and garden waste (FOGO food organics garden organics) as suitable feedstock for compost and use for cropping. We hypothesised that to realise benefits of compost, organic and organo-mineral fertilisers (OF/OMF) must be optimised for target crops and biophysical environments. We explored compost and organic recyclates (dried bacterial biomass PPB, chicken litter manure) as N sources for vegetable, fruit and grain crops in controlled experiments with single or combinations of contrasting N release and carbon-to-N ratios of 20, 13.5 (compost), 13.5 (poultry manure), 6.1 (PPB) and 0.5 (mineral N). With standardised N input (0.5–1 g N/pot and plant), compost as the sole N source resulted in less yield than all other N sources, while suitable mixtures of organic recyclates with/without added mineral N matched the yield of crops grown with mineral N. Adding 5% compost to sand growth substrate modulated crop growth and phenology, increased tillering and panicle production, or accelerated fruit ripening. This confirmed effects beyond nutrient supply, likely crop-growth modulating substances are present. Exploring effects of crop species, N source and water supply confirmed statistically significant interactions on yield, biomass and N use efficiency (NUE). This means a robust strategy for optimising OF/OMF is testing target crops with compost and recyclates to identify crop-specific responses. We recommend that applying such strategy allows manufacturers targeting N-efficient OF/OMF to service the expanding market for recyclate-based organo-mineral fertilisers and soil ameliorants for the circular N economy.

Enhanced efficiency fertilizers (EEFs) can reduce nitrogen (N) losses in temperate agriculture but are less effective in the tropics. We aimed to design a new EEF and evaluate their performance in simple‐to‐complex tests with tropical soils and crops. We melt‐extruded urea at different loadings into biodegradable polymer matrix composites using biodegradable polyhydroxyalkanoate (PHA) or polybutylene adipate‐co‐terephthalate (PBAT) polymers with urea distributed throughout the pellet. These contrast with commercially coated EEF that have a polymer‐coated urea core. We hypothesized that matrix fertilizers would have an intermediate N release rate compared to fast release from urea or slow release from coated EEF. Nitrogen release rates in water and sand–soil columns confirmed that the matrix fertilizer formulations had a more progressive N release than a coated EEF. A more complex picture emerged from testing sorghum [Sorghum bicolor (L.) Moench] grown to maturity in large soil pots, as the different formulations resulted in minor differences in plant N accumulation and grain production. This confirms the need to consider soil interactions, microbial processes, crop physiology, and phenology for evaluating fertilizer performance. Promisingly, crop δ¹⁵N signatures emerged as an integrated measure of efficacy, tracking likely N conversions and losses. The three complementary evaluations combine the advantages of standardized high‐throughput screening and more resource‐intensive and realistic testing in a plant‐soil system. We conclude that melt‐blended biodegradable polymer matrix fertilizers show promise as EEF because they can be designed toward more abiotically or more microbially driven N release by selecting biopolymer type and N loading rate.

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Societal Impact Statement: Restoring degraded tropical lands is important for biodiversity protection and human livelihoods. Newly planted tree seedlings are often challenged by drought brought about by climate change. Here, we explored how nitrogen sources used for plant growth affected the water use of tropical tree seedlings under water limitation. We found that the application of the amino acid arginine reduced water use in the studied seedlings under water limitation, compared with the conventional ammonium nitrate fertiliser. Alternative sources of nitrogen should be considered for tree seedling production in nurseries as this could enhance drought resilience traits and improve the survival of seedlings in restoration plantings.Summary: Restoration via tree planting is impacted by climate change‐induced water scarcity. Nitrogen (N) supply modulates the morphology and physiology of plants and impacts water use. We compared the responses of rainforest tree seedlings Acacia mangium and Alphitonia petriei grown with inorganic N (Osmocote™, ammonium nitrate) or organic N (Argrow™, liquid arginine), hypothesising that organic N confers drought resilience by increasing water use efficiency (WUE). Seedlings were grown in a glasshouse for 12 weeks with organic or inorganic N in well‐watered conditions, and then half the seedlings were subjected to water limitation for a further 4 weeks. A. mangium grew equally well on all N sources, but water limitation reduced biomass production. In contrast, N sources but not water regimes influenced biomass production in A. petriei. Under water limitation, arginine‐supplied A. petriei had higher WUE and more depleted leaf δ¹³C than inorganic N‐supplied plants. Our results suggest that organic N in the form of arginine can regulate stomatal conductance in A. petriei to convey drought resilience in seedlings. The generality of these findings should be explored to evaluate if organic N is a feasible source for generating drought‐resilient seedlings for restoration plantings.

Effective grazing management in Australia’s semi-arid rangelands requires monitoring landscape conditions and identifying sustainable and productive practice through understanding the interactions of environmental factors and management of soil health. Challenges include extreme rainfall variability, intensifying drought, and inherently nutrient-poor soils. We investigated the impacts of grazing strategies on landscape function—specifically soil health—as the foundation for productive pastures, integrating the heterogenous nature of grass tussocks and the interspaces that naturally exist in between them. At Wambiana—a long-term research site in north-eastern Australia—we studied two soil types, two stocking rates (high, moderate), and resting land from grazing during wet seasons (rotational spelling). Rotational spelling had the highest biocrust (living soil cover), in interspaces and under grass tussocks. Biocrusts were dominated by cyanobacteria that binds soil particles, reduces erosion, sequesters carbon, fixes nitrogen, and improves soil fertility. Rotational spelling with a moderate stocking rate emerged as best practice at these sites, with adjustment of stocking rates in line with rainfall and soil type recommended. In drought-prone environments, monitoring the presence and integrity of biocrusts connects landscape function and soil health. Biocrusts that protect and enrich the soil will support long-term ecosystem integrity and economic profitability of cattle production in rangelands.

Nutrient-rich organic wastes and soil ameliorants can benefit crop performance and soil health but can also prevent crop nutrient sufficiency or increase greenhouse gas emissions. We hypothesised that nitrogen (N)-rich agricultural waste (poultry litter) amended with sorbents (bentonite clay or biochar) or compost (high C/N ratio) attenuates the concentration of inorganic nitrogen (N) in soil and reduces emissions of nitrous oxide (N₂O). We tested this hypothesis with a field experiment conducted on a commercial sugarcane farm, using in vitro incubations. Treatments received 160 kg N ha⁻¹, either from mineral fertiliser or poultry litter, with additional N (2–60 kg N ha⁻¹) supplied by the sorbents and compost. Crop yield was similar in all N treatments, indicating N sufficiency, with the poultry litter + biochar treatment statistically matching the yield of the no-N control. Confirming our hypothesis, mineral N fertiliser resulted in the highest concentrations of soil inorganic N, followed by poultry litter and the amended poultry formulations. Reflecting the soil inorganic N concentrations, the average N₂O emission factors ranked as per the following: mineral fertiliser 8.02% > poultry litter 6.77% > poultry litter + compost 6.75% > poultry litter + bentonite 5.5% > poultry litter + biochar 3.4%. All emission factors exceeded the IPCC Tier 1 default for managed soils (1%) and the Australian Government default for sugarcane soil (1.25%). Our findings reinforce concerns that current default emissions factors underestimate N₂O emissions. The laboratory incubations broadly matched the field N₂O emissions, indicating that in vitro testing is a cost-effective first step to guide the blending of organic wastes in a way that ensures N sufficiency for crops but minimises N losses. We conclude that suitable sorbent-waste formulations that attenuate N release will advance N efficiency and the circular nutrient economy.

Organic forms of nitrogen (ON) represent potential N sources for crops and an alternative to inorganic N (IN, ammonium nitrate). Sugarcane soils receive organic harvest residues (~40–100 kg ON ha–1), but it is unknown whether ON is a direct N source for crops. We investigated whether sugarcane can use organic monomers in the form of amino acids and whether the use of amino acids as a N source results in distinct metabolic or morphological change when compared with use of inorganic N (IN). Plantlets cultivated in sterile culture and young plants grown in non-sterile soil culture were supplied with IN, ON (five amino acids present in sugarcane soils), or combined IN and ON. All treatments resulted in similar biomass and N content indicating that sugarcane has a well developed capacity to use ON and confirms findings in other species. ON-supplied plants in axenic culture had increased total branch root length per unit primary root axis which has not been reported previously. In both experimental systems, ON supplied plants had increased asparagine concentrations suggesting altered N metabolism. Root of ON-supplied soil-grown plants had significantly reduced nitrate concentrations. We interpret the shift from nitrate to asparagine as indicative of N form use other than or in addition to nitrate by sugarcane. N metabolite profiling could advance knowledge of crop N sources and this will aid in development of N efficient cropping systems with a reduced N pollution footprint.

While importance of amino acids as a nitrogen source for plants is increasingly recognised, other organic N sources including small peptides have received less attention. We assessed the capacity of functionally different species, annual and nonmycorrhizal Arabidopsis thaliana (L.) Heynh. (Brassicaceae) and perennial Lobelia anceps L.f. (Campanulaceae), to acquire, metabolise and use small peptides as a N source independent of symbionts. Plants were grown axenically on media supplemented with small peptides (2–4 amino acids), amino acids or inorganic N. In A. thaliana, peptides of up to four amino acid residues sustained growth and supported up to 74% of the maximum biomass accumulation achieved with inorganic N. Peptides also supported growth of L. anceps, but to a lesser extent. Using metabolite analysis, a proportion of the peptides supplied in the medium were detected intact in root and shoot tissue together with their metabolic products. Nitrogen source preferences, growth responses and shoot–root biomass allocation were species-specific and suggest caution in the use of Arabidopsis as the sole plant model. In particular, glycine peptides of increasing length induced effects ranging from complete inhibition to marked stimulation of root growth. This study contributes to emerging evidence that plants can acquire and metabolise organic N beyond amino acids.