Combining Biophysical and Price Simulations to Assess the Economics of Long-Term Crop Rotations

Biophysical simulation models (e.g. APSIM) using historical rainfall data are increasingly being used to provide yield and other data on crop rotations in various regions of Australia. However, to analyse the economics of these rotations it is desirable to incorporate the other main driver of profitability, price variation. Because the context was that APSIM was being used to simulate an existing trial site being monitored by a farmer group Gross Margin output was considered most appropriate. Long-run rotational gross margins were calculated for the various rotations with yields (and other physical outputs) derived from APSIM simulations over a period of 100+ years and prices simulated in @Risk based on subjective triangular price distributions elicited from farmers in the group. Rotations included chickpeas, cotton, lucerne, sorghum, wheat and different lengths of fallow. Output presented to the farmers included mean annual gross margins and distributions of gross margins presented as probability distributions, cumulative probability distributions and box and whisker plots. Cotton rotations were the most profitable but had greater declines in soil fertility and greater drainage out of the root zone.Crop Production/Industries,

Combining biophysical and price simulations to assess the economics of long-term crop rotations

Long-run rotational gross margins were calculated with yields derived from biophysical simulations in APSIM over a period of 100+ years and prices simulated in @Risk based on subjective triangular price distributions elicited from the Jimbour Plains farmer group. Rotations included chickpeas, cotton, lucerne, sorghum, wheat and different lengths of fallow. Output presented to the farmers included mean annual GMs and distributions of GMs with box and whisker plots found to be suitable. Mean-standard deviation and first and second-degree stochastic dominance efficiency measures were also calculated. Including lucerne in the rotations improved some sustainability indicators but reduced profitability.Crop Production/Industries, Farm Management,

Reduced Fecundity in Free-Ranging Norway Rats After Baiting With a Liquid Fertility Control Bait

Norway rats (Rattus norvegicus) cause extensive crop loss, infrastructure damage, and are vectors for zoonotic diseases. Due to reduced efficacy, environmental and animal welfare concerns related to traditional pest management tools, such as rodenticides, it is imperative to find new methods for controlling commensal rodents. Fertility control is emerging as a safe, humane, and effective method of long-term population management. Vinylcyclohexene diepoxide (VCD) and triptolide are 2 compounds that are known to target and inhibit ovarian function. Furthermore, triptolide debilitates spermatogenesis and sperm motility. We prepared liquid bait containing no active ingredients (control) or containing VCD (0.098%) and triptolide (0.0012%, treatment) and offered ad libitum for 56 days to male and female Norway rats placed in open, indoor arenas and allowed to breed for 4 rounds (a total of 138 days). The first 3 breeding rounds of treatment-matched matings produced fewer pups in the treatment rats compared to control rats (P \u3c 0.001). In the fourth breeding round, control rats were cross-bred with treatment rats. There were no differences in pup numbers between these cross-breeding groups, but the litter sizes in both groups were smaller than those seen in the control female/control male matings. In addition to reduced pup numbers, treatment males and females exhibited decreased reproductive organ weights without any effect on adrenal, kidney, spleen, and liver weights compared to control rats. Use of a liquid contraceptive bait containing VCD and triptolide may be a suitable alternative to the traditional pest management tools used to control wild rat pest populations

Benchmarking to improve long-term carrying capacity estimates for extensive grazing properties in Queensland

Safe carrying capacity information can assist producers in making stocking rate decisions to ensure minimal decline in land condition over the long-term. FORAGE, a modelling framework which uses the GRASP pasture growth model, spatial data, remote sensing and climate data, provides long-term carrying capacities for individual paddocks and land types for grazing properties in Queensland. Applying the framework across Queensland’s diverse grazing lands and capturing the large range of land types and climates is challenging. To overcome this challenge, we will collate on-ground data and expert-knowledge for reference properties to help validate the modelling framework and ensure the best-available safe carrying capacity information is provided