Can systems performance be improved by modifying farming systems? Farming systems research – Billa Billa, Queensland
Author: Andrew Erbacher (DAF Qld), David Lawrence (DAF Qld) | Date: 25 Jul 2018
Take home messages
- Different farming systems comparisons conducted over 3 years at Billa Billa QLD have shown that the baseline system (wheat-barley-wheat) has so far returned the highest gross margin ($2.77) per mm rainfall.
- Increasing or decreasing cropping intensity has returned similar gross margins, but had low returns in 2016/17 summer.
While advances in agronomy and the performance of individual crops have helped grain growers to maintain their profitability, current farming systems are underperforming; with only 30% of the crop sequences in the northern grains region achieving 75% of their water limited yield potential.
Growers are facing challenges from declining soil fertility, increasing herbicide resistance, and increasing soil-borne pathogens in their farming systems. Changes will be needed to meet these challenges and to maintain the productivity and profitability of our farming systems. Consequently, the Queensland Department of Agriculture and Fisheries (QDAF), New South Wales Department of Primary Industries (NSW DPI) and Commonwealth Scientific and Industrial Research Organisation (CSIRO) are conducting an extensive field-based farming systems research program, focused on developing farming systems to better utilise the available rainfall to increase productivity and profitability, with the question;
Can systems performance be improved by modifying farming systems in the northern region?
This research question is being addressed at two levels by the northern farming systems initiative; to look at the systems performance across the whole grains region, and to provide rigorous data on the performance of local farming systems at key locations across the region.
Research began in 2014 with local growers and agronomists identifying the key limitations, consequences and economic drivers of farming systems in the northern region; assessing farming systems and crop sequences that can meet the emerging challenges; and developing the systems with the most potential for use across the northern region.
Experiments were established at seven locations; a large factorial experiment managed by CSIRO at Pampas near Toowoomba, and locally relevant systems being studied at six regional centres by QDAF and NSW DPI (Table 1). Several of these systems are represented at every site to allow major insights across the northern region, while the site specific systems will provide insights for local conditions.
The following report details the systems being studied in Billa Billa (Goondiwindi), how they are implemented locally and the results after the first three years. Data and system performance indicators have been developed to compare performance across sites.
Table 1. Summary of the regional farming systems being studied at each location in the northern farming systems initiative.
Baseline – represents a typical zero tillage farming system
Higher nutrient supply – as for the ‘baseline’ system but with fertilisers for 100% phosphorus replacement and nitrogen targeted at 90% of the yield potential each season
Higher legume - 50% of the crops are sown to legumes
Higher crop diversity – a wider range of crops are introduced to manage nematodes, diseases and herbicide resistance
Higher crop intensity – a lower soil moisture threshold is used to increase the number of crops per decade
Lower crop intensity – crops are only planted when there is a near full profile of soil moisture to ensure individual crops are higher yielding and more profitable
Grass pasture rotations – pasture rotations are used to manage soil fertility. One treatment has no additional nitrogen fertiliser, while the other has 100 kg N/ha/year to boost grass production
Higher soil fertility (higher nutrient supply plus organic matter) - as in the high nutrient system but with compost/manure added
Integrated weed management (incl. tillage) – this system is included at Emerald where crops, sowing rates, row spacings and ‘strategic tillage’ are included to manage weeds and herbicide resistance
Billa Billa - 2015 to now
The Billa Billa site is located 50 km north of Goondiwindi on the Leichhardt Highway. The soil is a grey vertosol. The original belah and brigalow trees were cleared and the paddock used as a long-term pasture before being developed for crops in the late 1990s. The previous paddock management has meant there was 360 kg N/ha available at the beginning of the trial.
The paddock grew chickpeas in 2014, so was quite bare prior to commencing the trial in autumn 2015. All of the systems were planted to wheat in the first season to provide stubble cover, yielding 4.7 t/ha. After harvesting this crop, the higher soil fertility system had 75 t/ha of compost broadcast across it to supply an additional 10 t/ha of carbon to this system, which increased the soil carbon by 27% in the top 30 cm of soil. Deep phosphorus was then applied to all of the cropping systems supplying 70 kg P/ha applied in the form of Granulock® Z. After 2015, rotations in the different systems have been quite diverse (Figure 1).
The baseline system was planted to barley in 2016, wheat in 2017 and is planted to chickpea in 2018 (Figure 1).
The summer of 2015-16 was dry with storm rain contributing to the majority of the profile moisture accumulation. The higher crop intensity system triggered an opportunity to be double cropped to mungbean on 15 January. The next effective rainfall this crop saw was after spraying out, so yielded 0.35 t/ha (Figure 2). This double-cropped mungbean crop was planted with the same starting water as the baseline system, which was held in fallow over summer and planted to barley in 2016. This gave the higher crop intensity system a fallow efficiency advantage of 71% versus 30% in the Baseline system(Figure 5). However, differences in the timeliness of in-crop rain had a major impact on the yield outcomes of the mungbean and barley crops (Figure 2).
Autumn 2016 was also dry, requiring faba bean and field pea to be deep sown in the higher legume and higher crop diversity systems respectively. Baseline, higher nutrient supply and higher soil fertility systems were planted to barley on 1 June (Figure 1), with the season remaining quite wet until November. The faba bean and field pea crops matured in early October, and had a wet harvest with a full profile of water, allowing a double crop opportunity in both of these systems. However, the barley in 2016 (baseline, higher nutrient supply and higher soil fertility systems) lodged and put out late tillers, so was harvested mid-November with weather damaged grain. Grain yields averaged 6.3 t/ha for barley and 3.45 t/ha for faba bean and field pea (Figure 2). The yield per mm of water used (water use efficiency) of the two pulse crops were similar to each other, but lower than the barley grown in the same season (Figure 5).
Differences in the economics of the systems to date have largely been driven by the high yields of the 2016 winter crops (Figure 3). The high starting available nitrogen levels at this site has allowed the baseline, higher nutrient supply and higher soil fertility systems to grow 11 t/ha of cereal grain over the first two years, without the expense of nitrogen fertiliser. As such, these three systems have been the most profitable, with the only difference being a higher starter P fertiliser rate in the two higher nutrient systems.
The higher legume and higher crop diversity systems were both planted to pulses in winter 2016 that yielded similarly to each other, but the value of faba bean vs field pea meant the faba bean income and $/mm was similar to the much higher yielding barley, whereas the field pea was quite a bit lower (Figure 3 & 4). The pulse crops in 2016 appear to have fixed nitrogen despite the high starting N. They have similar nitrogen removed in the grain to the barley crops but have an extra 50 kg N/ha left in the soil profile post-harvest. Add to this, the early maturity date of the pulses left an extra 150 mm plant available water, which provided an opportunity double crop. However the dry summer that followed provided poor returns on that double-crop.
The lower intensity and higher intensity systems were planted to sorghum on 15 October, with 200 mm and 120 mm plant available water (PAW) respectively. With only 80 mm in-crop rainfall, these crops were low yielding at 1.5 t/ha and 0.8 t/ha (Figure 2). These yields both lined up with the APSIM predicted yield for the driest 10% of years, for their starting plant available water.
Apart from the 2015 wheat crop that is common to all systems, this sorghum crop was the only crop grown in the low crop intensity system from November 2015 to May 2018, whereas the higher crop intensity system grew three crops to achieve similar cumulative gross margins, with a fourth (sorghum) crop putting the higher crop intensity system slightly ahead. The major commonality in these two systems, that is different to the other systems, is all the crops grown after the initial wheat crop have had received below average in-crop rainfall. Two of these crops were grown in the driest 5 % of seasons for Goondiwindi. As a result the higher crop intensity and lower crop intensity systems are providing the lowest economic returns to date.
After 2016 winter crop was harvested with a full profile of water, the higher legume and higher crop diversity systems were planted to mungbean and sorghum respectively at the next planting opportunity, which wasn’t until December (Figure 1). With no effective rainfall before flowering, the mungbean yielded 0.15 t/ha, whereas the sorghum held on to take advantage of autumn rain for a yield of 1.5 t/ha, harvested in July.
The three systems that grew barley in 2016 were all planted to wheat in May 2017. The higher crop intensity system was also double-cropped to wheat at the same time. This crop received 25 mm rainfall prior to maturity, but received a further 83 mm before it could be harvested. The fallowed systems (baseline, higher nutrient supply and higher soil fertility) yielded 1.7 t/ha on average and the double cropped wheat (higher crop intensity) yielded 1.4 t/ha. These systems had similar crop water use efficiencies (WUE) of 12.5 kg/mm on average (Figure 5). The difference in yield is reflecting differences in starting plant available water.
The mungbean grown in the higher legume system had only dried the top 30 cm of soil, so was one rainfall event off being planted to wheat. With the dry winter this did not eventuate, but 80 mm of rain in October allowed it to be planted to spring sorghum with a good profile of plant available water. This sorghum was looking good with 200 mm of in-crop rain, but a dry January capped the yield at 2.9 t/ha with 40% screenings.
The wet spring in 2017 allowed the higher intensity system to be double-cropped again to sorghum. This crop had a dry start, but 150 mm in February and March allowed it to tiller again for a yield of 2.4 t/ha, harvested in May.
Six systems have been planted to winter crops in 2018 (Figure 1). Higher crop diversity has been planted to canola and lower crop intensity to wheat, both after long fallows. Baseline, higher nutrient supply and higher soil fertility were planted to chickpeas after a short fallow and higher legume double-cropped to chickpeas. This leaves only higher crop intensity in fallow, having received no rain from sorghum harvest to the end of June 2018.
Figure 1. Crops grown at the Billa Billa farming systems trial, presented on a time scale. The coloured sections are planting to harvest of each crop, and the grey bars are fallow periods.
Figure 2. Cumulative grain yields of the seven grain systems at the Billa Billa farming systems trial
Figure 3. Cumulative cash-flow from the seven grain systems at the Billa Billa farming systems trial. This shows the actual production costs and incomes (based on 10 year average commodity prices), over time for each of the systems.
Figure 4. Gross margin per mm of rainfall for each crop grown, including the preceding fallow period, and total for each system (up to the harvest of the last crop). The coloured bars represent the crops depicted in Figure 2.
Figure 5. Crop water use efficiency and fallow efficiency, overlaid onto the crop durations represented in Figure 2. The value in the coloured bars is the kg of grain produced per mm of plant available water used + in-crop rainfall. The value in the grey bars is the proportion of rainfall available at planting of the next crop.
Table 2. Grain pricing used in calculations based on median prices over the past ten years, less $40/t cartage costs,
for selected crops
This trial is part of a collaboration between the Grains Research Development Corporation (GRDC) Queensland Department of Agriculture and Fisheries (DAF), New South Wales Department of Primary Industries (NSW DPI) and Commonwealth Science and Innovation Research Organisation (CSIRO). DAQ00192.
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