Corner of Prices & Coolamon Road, Wagga Wagga. Directions to the site
2016 saw the continuation of the multi-year weeds experiments continue while a new rotation trial examined the value of opportunistic summer fodder crops grown in the rains of late 2015 and early 2016, and whether these summer fodders affected subsequent winter crops in 2016.
The Graham Centre's 15 hectare field site was established in 2010. It is a 'living brochure' showcasing the Centre's research outputs to assist farmers, advisers, natural resource managers and students to develop and maintain robust and sustainable farming systems. The site also allows the Centre to promote agriculture and its important contribution to everyday life to the wider community.
For more information on the Field Site, please contact Dr Gordon Murray.
Wheat was sown in autumn 2016 folowing the forage trial over the 2015-16 summer. This wheat was harvested in December 2016. Results will be available once the yields have been analysed.
Rainfall reliability and lower evaporation rates mean that the South West Slopes and eastern Riverina are winter cropping areas. However, heavy showers and storms occur irregularly in summer and promote rapid growth of perennials such as lucerne and some grasses, as well as summer weeds. Research at the field site is asking the question 'can farmers use these irregular rains for opportunistic forage crops to provide valuable summer grazing and as an alternative control of summer weeds?'
Good rains in November 2015 allowed sowing of a grazing experiment at the Field Site. This trial had three treatments: Japanese millet (cv. Shirohie) as the forage crop; Herbicide to control weeds; and Nil Herbicide. There were with nine replicates per treatment.
Plots were prepared on 10 Nov by slashing and raking to remove winter grass, then sprayed with 2 L/ha of glyphosate to control winter grasses (brome grasses, annual ryegrass), wireweed and a small number of medic plants. The millet plots were sown on 11 Nov into good soil moisture with 10 kg/ha Japanese millet 'Shirohie' seed and 105 kg/ha of Pivot 400 fertilizer, with a later application of 50 kg/ha of urea on 24 November.
Millet plants were counted on 11 January 2016. The number of plants/plot was quite variable and ranged from 62 to 147 plants per m2 (average 97.1 ± 30.9). This variation was attributed to the dry conditions experienced after sowing.
Weeds were counted on 11 and 28 January and 9 February. American witchgrass (Panicum capillare) was the major weed with fleabane (Conyza bonariensis), wireweed, flatweed, Clammy goosefoot and other grasses occurring sporadically. The number of witchgrass plants was higher for the Nil Herbicide treatment compared to Millet treatment at all counts, and did not vary between counts for either treatment. The number of witchgrass plants on the Herbicide treatment was reduced after spraying with glyphosate from that observed on Nil Herbicide to that observed on the Millet treatment (Figure 1). In this experiment millet was equally as successful at suppressing witchgrass as glyphosate (Figure 2).
Figure 1. Effects of millet, herbicide and no herbicide treatments on American witchgrass (plants/m2)
Figure 2. Millet and herbicide treated plots had very few witchgrass plants while they reached high numbers in the nil treatment plots
The millet plots were sampled on three occasions at a height of approximately 5 cm above ground level to determine yield and quality - 28 January, 9 February and 7 March - by cutting four 1 m strips per plot at a height of 5 cm. Following sampling all plots were cut to 5 cm to simulate grazing. Samples were dried at 80°C for 24 hours in a fan forced oven to determine dry matter content and ground for quality analysis. Metabolisable energy (ME: MJ/kg DM) and crude protein (CP) content were determined by Near Infrared Reflectance (NIR) at NSW DPI's Feed Quality Service laboratory. Harvested yield was 1052 kg DM/ha on 28 Jan, 1383 kg DM/ha on 9 Feb and 1043 kg DM/ha on 7 March 2016. Metabolisable Energy content at these three times was 10.9, 12.0 and 9.6 MJ/kg DM and crude protein content was 16.7, 20.0 and 8.3%.
Grazfeed (ver13) predicted that crossbred lambs, 6 months old and weighing 32 kg, would consume 1.43 kg/day and gain 151 g/day for harvest 1, 1.48 kg/day and gain 177g/day, for harvest 2 and 1.25 kg/day and gain 73 g/day for harvest 3. Assuming complete utilisation of the harvested material this would provide grazing for 736, 934 and 834 sheep days for these lambs and a total weight gain of 111 kg/ha, 165 kg/ha and 73 kg/ha for harvests 1, 2 and 3, respectively.
Assuming total growing costs of $203/ha for sowing, seed, and fertiliser; 90% utilisation of the harvested forage by the lambs; and the additional liveweight valued at $2.30/kg then the gross margin return on this exercise was $519.19/ha.
The trial plots were sown with wheat in autumn 2016 to determine whether there are any carryover effects of the summer cropping on the subsequent winter crop.
This work is supported by a grant from Meat and Livestock Australia Limited.