Gypsum treatment

You will be analyzing and writing an
Introduction, Methods, Results and Discussion for a pasture establishment experiment using
protocol described below.
The soils of northern Australia are often hostile for plant germination and establishment. For
example, many soils are low in available P and organic matter, while some also have high levels of
exchangeable sodium meaning that they are prone to surface crusting. Under these conditions, it is
likely that desirable species, particularly surface-sown legumes, will establish slowly and will
eventually be outcompeted by species that are more competitive under those conditions (e.g. native
grasses or weeds). Furthermore, many extensive grazing systems are low input so these problems
are often not ameliorated before planting. An understanding of how amendments can be used at
planting would be highly informative for potentially improving the legume content of these
extensive pasture systems. The objective of this experiment is to determine the benefit of starter
fertiliser and/or gypsum on the germination of Desmanthus genotypes. The experiment aims to
replicate a ‘normal’ sowing technique, by applying the gypsum before planting followed by a
wetting/drying cycle and applying the starter fertiliser and seed together.
The experimental design is as follows:
• Three soils – collected from Cungelella (Brigalow), Armraynald (Gulf Country) and Gregory
Downs (Gulf Country), QLD.
• Two gypsum rates – 0 or 1 t/ha.
• Two starter fertiliser (MAP) treatments – 0 or 12 kg P/ha.
• Four genotypes – JCU 2 Desmanthus, JCU 4 Desmanthus, JCU 7 Desmanthus, and JCU 9
Desmanthus.
• Four replicates.
• 192 pots in total.
Small PVC pots will be filled with ~1.3 kg (oven-dry equivalent) of three alkaline clay soils. Gypsum
will be applied to the surface of the + gypsum treatment, followed by a wetting/drying cycle (i.e. the
pots will be watered to 80% field capacity then dried). Following this, the starter fertiliser and
Desmanthus seed will be placed on the soil surface. 25 seeds will be planted per pot (after
accounting for seed viability). Pots will be watered every second day after planting. Pots will be
monitored for plant germination (% of the number of seeds sown) daily for two weeks before the
pots are thinned to 5 plants. Plant height and NDVI will then be recorded weekly after 2 weeks
growth (this will indicate varietal and treatment differences in plant vigour). After 5-6 weeks growth,
plants will be harvested to determine shoot yield, shoot P concentration and total shoot P uptake.
The submission will require you to write a small 4 page paper outlining what you found. This will
require you to be complete, but succinct. A template example of a report is provided on Moodle
and it is wise to simply cut-and-paste your information into that format. 20% of the marks will be
deducted for failure to use the template format. You will be required to use references (4-6
minimum) to explain what happened.