Key farming decision points to improve water use efficiency and profit on red soils

Take home messages

• Combinations of agronomic decisions, not single factors drive the highest efficiency and profit in grain production.
• The central west of New South Wales has one of the highest grain yield responses to the application of strict summer fallow weed management practices.
• Good crop sequence and fallow management provides the opportunity for early and timely sowing of crops for well-prepared operators to maximise yield and minimise risk, with multiplying effects at the whole-farm scale.  Early crops can be grazed on mixed farms providing further benefits.
• In-crop (post-sowing) management should be about protecting the potential, not fixing problems – monitor well, evaluate the return, and be timely and effective.

Business profit drivers and scope for improvement

Several recent studies of commercial farm businesses emphasise the dramatic changes in the economics and risk of grain farming in recent years as cropping intensity has increased.  As farm size, cropped area and land values increased, so too have debt levels, machinery costs and total interest, so that despite improvements in productivity, farm income to cost ratios have decreased significantly. However, the fact that the top 25% of grain businesses make double the return on capital (8.8%) as compared to the other 75% (4.5%) (ABARES 2015), emphasises the point that “it is not what you do, but how well you do it” that defines the success of most farm businesses.  Numerous recent studies of the key drivers of successful businesses emphasise three important areas – (1) agronomic and technical; (2) business and financial and (3) people and relationships (e.g. Hillicoat et al., 2018) and they make important reading. As a farming systems agronomist, my talk will focus on the agronomic and technical, where a consistent message in studies of successful intensively cropped farms (in addition to sound financial management) is the importance of more frequent monitoring and measurement to assist in management decisions, and timeliness in implementing them.

Recent national studies of “yield gaps” between the water-limited potential of crops and those achieved by farmers suggest there is significant scope for improvement – including in the central west, where wheat and canola crops achieved around 50-60% of water-limited yield potential for the years 1990 to 2015 (Yield Gap Australia website). Field studies investigating the economic performance of a range of different 3-4 year crop sequences and management suggest differences in the average annual gross margin of up to $400/ha between the best and worst sequence and management options, and $150/ha between the best and common district practice.  Thus there appears to be significant scope to improve management for increased profit – but what are the key decisions that can provide the biggest “bang for the buck”, while managing business risk? Here we provide a framework to consider them, and evidence for their impact using examples from the central west, or nearby environments on red soils where possible.

Management levers for high efficiency and profit – at paddock and farm scale

No one technology – be it a new variety, tillage system, new machine, or fertiliser – will alone close existing yield gaps to maximise yield and profit.  Highly efficient systems must combine several pre-crop and in-crop management strategies that only together can capture, store and use water most efficiently (Figure 1). It is convenient to discuss them alone to consider the scale of the response possible – but the key message is that maximum efficiency is only achieved when they act together.

Figure 1. Using water efficiently requires a combination of pre-crop and in-crop management to capture, store and use water to produce grain. No single management factor alone drives efficiency and much of the effort occurs well before seeding (from Kirkegaard and Hunt 2010).

1. Long-term soil management

Long-term management decisions can affect the capacity of the soil to capture, store and supply water to the crop. Some examples include:

Soil structure: Pasture phases, maintaining cover (stubble, cover crops), no-till, controlled traffic (CT) and gypsum on sodic soils all act to maintain stable soil structure for maximum water capture and storage. Many red soils in CNSW are prone to hard-setting and crusting if excessively tilled or left bare.

Weed seed banks: Pasture phases, diverse rotations, hay, herbicide rotations, and inclusion of non-herbicide weed management tactics such as harvest weed seed management, all act to keep weed seed banks at low levels.

Nitrogen (N) fertility: Inclusion of legumes (pasture or pulses), increased N fertiliser and more efficient N use will preserve long-term soil fertility.

Sub-soil constraints: On red soils, soil acidification is inevitable without regular addition of lime, and sub-surface acidity (5-15 cm) due to insufficient incorporation is an emerging issue.

Flexibility may be required to deal with short-term issues (e.g. strategic tillage, stubble reduction, consecutive cereals) but these are of little consequence provided a longer-term strategy of sound soil management is maintained.

2. A suitably diverse crop sequence

System choice: Economic modelling to compare continuous cropping and mixed farms at low rainfall sites in southern Australia including West Wyalong show that while continuously cropped farms and mixed farms may have similar profitability in average seasons, the continuously cropped farm was able to better capitalise in good seasons, but were at greater risk in poor seasons (Analysis by Ed Hunt, Michael Moodie and Mallee Sustainable Farming).  Less diverse, continuously cropped farms (i.e. 100% cereal) had the lowest economic performance in all but the very best of seasons, supporting much of the experimental data related to the benefits of diversity.

Crop sequences: Crop sequences in central NSW remain cereal-dominated (~80% cereal), and this increased to 93% during the millennium drought (2002-2010) when limited early sowing opportunities and dry springs increased the risk of legume and oilseed break crops.  GRDC-funded research in several projects confirmed that in all areas including CWNSW and other low rainfall sites, crop sequences that were more diverse were as profitable, or more profitable, than continuous cereal rotations – and that diversity in both crops and practices (graze, hay, brown manure) were required to cost-effectively manage paddocks with herbicide resistant weed or disease problems (Crop Sequencing, Farmlink website).  In a range of experiments over the last 5 years, the most profitable crop sequences often made $450/ha more annual average gross margin than the worst, and around $150/ha more than common district sequences (Peoples et al., 2015).  Predicting the longer-term economic benefits is difficult as the weed and disease control benefits of diverse sequences are not captured by farming systems models such as APSIM, which focus on water and N.

Fallow: Long-fallowing is still used to manage production risks associated with cropping in central and south west NSW’s variable climate. Fallows comprised 25-30% of farm area between 2000 and 2010, but with more favourable seasons this has now declined to 5-10%. Fallowing can provide benefits at the whole-farm level by compressing the sowing window allowing more crops to be sown on time, and reduce risk in specific crops by provided stored water and N. In theory, long fallowing and early sowing are complementary practices, as the fallow reduces weeds and diseases which can be difficult to control in early sown crops, and early sowing with slow developing cultivars allows the crop to better use soil water and N that is stored during the fallow. Stored soil water also helps to establish early sown crops when there is minimal autumn rainfall.

3. Summer fallow management – weeds, stubble and stock

Weeds: In a national study on the potential value of summer rainfall (Hunt and Kirkegaard, 2011), the red soils of central west NSW had some of the greatest predicted opportunity to capitalise on summer rainfall to produce grain because:

1. equi-seasonal rainfall means there is significant rain to store in summer;
2. the red loam soils have good water-holding capacity; and
3. dry and variable springs mean the stored water is extremely valuable to fill grain.

Preserving summer fallow rain through strict weed management and retained stubble was predicted to contribute 58% of wheat grain yield (0.5 to 2.0 t/ha) and be profitable in 91% of years. In a subsequent series of experiments in the central west (2010 to 2012, Haskins and McMaster 2010; Kirkegaard et al., 2014), strict summer weed control increased the amount of stored water by 48mm at sowing, and mineral N by 59 kg/ha, increased yield by 1.1 t/ha with a return on investment of $6.45 for every $ spent.  Delayed or missed sprays could halve the percentage return on investment (ROI) by reducing the water and N available to crops, but were always preferable to not spraying at all.

Stubble: Maintaining stubble cover to protect soil structure, increase infiltration and water storage over summer is accepted practice.  The main decision in regard to the need to manage, reduce or remove stubble prior to sowing, is to ensure effective and timely seeding.  At least 3 t/ha of cereal residue (70% cover) is required over summer to capture most of the benefits of stubble in the majority of seasons. Heavier stubble loads can increase the duration of soil water storage in the surface by slowing evaporation, but the benefits for early sowing depend on the timing of rainfall at sowing.  A good policy is to retain stubble whenever you can, but manage it to ensure a timely seeding operation and good weed control.

Livestock: Recent studies on red soils at Condobolin and Temora have shown that light grazing of stubble in summer has little impact on water storage or the yield of subsequent crops, provided sufficient cover (70%, >3 t/ha) is retained on the soil surface.  On the contrary, the yield of some crops increased due to increased soil mineral N after grazing stubble in some seasons.  Consequently whole-farm income is generally unaffected or improved by careful stubble grazing.  Overgrazing is the bad decision – “sheep do damage with their mouths, not their hooves!”

4. Fit crops to the growing season – variety and sowing time management

Good fallow management will increase the opportunities for well-prepared growers to capitalise on early and timely sowing opportunities, as the crops can be sown and established into water stored from the summer fallow rainfall.  The need to sow on time to ensure flowering occurs at the optimum time to maximise yield potential is widely recognised, with at least 5% reduction in yield potential for every week delay past the optimum sowing date.  As autumn rainfall declines and sowing programs increase, the sowing window for common fast-maturing spring varieties is being stretched.  Establishing crops earlier on stored moisture can increase yield at the paddock scale if suitable varieties with appropriate phenology are used (Table 1).  Some recent examples are shown in Tables 1 and 2.

In 2014, Wedgetail sown 17 April after long fallow out-yielded Suntop (at that time the highest yielding milling cultivar in SW NSW NVT) sown 22 May by 1.4 t/ha. In 2015 Wedgetail sown 15 April after fallow, out-yielded Condo (at that time the highest yielding milling cultivar in SW NSW NVT) by 1.5 t/ha (Hunt et al., 2015) (Table 1). As new, slower-maturing varieties (e.g. Kittyhawk , Longsword ) are developed, more opportunities to capitalise on early sowing will emerge.

Table 1. Yield of early-sown, slow maturing varieties compared with later-sown fast maturing varieties sown after long fallow at Rankin Springs in 2014 and 2015.

For canola in the tough 2017 season at Condobolin, the slower developing variety Wahoo sown early (6 April) after good fallow rainfall (313mm), had double the yield of the faster maturing variety Stingray under both dry conditions (122 mm growing season rainfall) and when rainfall was supplemented with 150 mm irrigation (272 mm growing season rainfall) (Table 2) (Brill et al., 2018).

Table 2. Yield of earlier-sown slower maturing canola variety was superior to later-sown fast variety even in the tough 2017 season at Condobolin at 0.5 to 1.6 t/ha yield levels (see Rohan Brill related paper).

Success with early sowing requires good paddock selection and preparation, and ensuring the right variety is chosen that will flower at the optimum time for the selected sowing time. A recent e-booklet providing Ten Tips to Early-sown Canola is now available.

On mixed farms early-sown crops also provide opportunities for grazing to further increase profit. Best-bet management guidelines are available for grazing crops, but the key decision is the lock-up time. See a GRDC Grains Research Update paper from February 2016 on 'Managing dual purpose crops to optimise profit from grazing and grain yield north'.

Careful timing of livestock removal prior to the elongation of stems (cereals) or buds (canola) and with sufficient biomass to achieve the target grain yield are key to profitable outcomes.  High stock prices compared to grain may favour prolonged grazing.

“Luck is when opportunity meets preparedness.”

5. Managing nitrogen well

Without adequate N, the yield and profit potential established with good sequence, fallow and sowing operation management will not be realised.  Attention to the long-term N fertility has been covered in Item 1 in this paper.  Persistent low protein in cereal crops (<10%) and pre-sowing soil N of < 50 kg/ha in the top 60cm may be signals of N-rundown, and a trigger for legume inclusion or increased N rates.  Nitrogen is a significant input cost and a driver of yield (and quality) in non-legume crops and the general “4R principles” promoted by IPNI (right product, right rate, right time, right place) should be adopted (4R Plant Nutrition Manual).  In most cases the following basic decisions will assist:

• Soil test March-April.
• If < 40 kg N/ha (0-60cm) apply some upfront N, especially if soil water store is good, crops are sown early for grazing, and especially for canola.  Separate seed and fertiliser.
• Most N can be top-dressed at stem elongation according to seasonal conditions and yield targets, at rates to ensure the total mineral N supplied to the crop (soil + fertiliser) is 40 kg/ha per tonne of expected wheat yield; 35 kg/ha/t for barley and 80 kg/ha/t for canola.  Relying on soil mineralisation for N makes sense in the short-term, but will run down soil fertility in the longer-term if legume pastures and crops are not included.

In central west (CW) NSW, seasonal uncertainty means N management is more about farm finances than agronomy.  What are the consequences of not getting a return in the current season? Target crops where the return on investment is most likely – weed-free, sown on time, following a good break.  If you err on the side of too much N, remember canola is less likely to hay-off than wheat and much of the N will remain in the system.

6. Crop protection – in-crop “fine tuning” with weeds and disease

Good long-term soil, crop sequence, fallow management, variety choices and harvest weed-seed management will mean that in-crop management of weeds and diseases often becomes a matter of cost-effectively protecting the yield when necessary with good monitoring and sound economic decisions. One exception is the longer term focus on running down the weed seedbank, which requires monitoring and weed management action to minimise weed survivors every year in every paddock.  The management of most diseases (e.g. rust in cereals, blackleg in canola, Ascochyta in chickpea) involve a series of integrated approaches over time (residue management, variety choice, fungicide programs).  Some decisions (seed dressings) are cheap insurance, while some such as later canopy fungicide sprays require careful assessment of the likely costs and return.  Unlike nitrogen, there is no chance to recoup costs from unnecessary crop protection inputs, as there are no residual benefits beyond the active period.  So prepare well, monitor well, be realistic about your yield potential and response to treatment, and be timely and effective with the application.

Capturing the synergies from the system

Whole-farm multipliers: Do the yield increases at paddock-scale (Tables 1 and 2) in one year translate to the whole farm, and across seasons?   The capacity to start the farm sowing program earlier with slower-maturing crops provides a multiplying effect across the farm in any particular year, as all paddocks move into a better sowing window, and the sowing program is completed earlier. The benefits in specific years for a typical 20-day sowing program can be significant and are generally higher on deeper soils in higher rainfall areas, but diminish on shallow soils, and as you move from southern to northern NSW.  The central west is a transition area, but increases in estimated whole-farm wheat yields for a site such as Condobolin by sowing slower maturing wheat varieties when the opportunity arises on a red soil with 200mm PAWC to 1.6m, is estimated to be 5 to 17% (Flohr et al., 2018).

Legacy effects: But will the higher yielding crops simply “steal” water from following years – how often will the profile re-fill?.  In the last 5 to 10 years, novel early sowing systems involving slower-maturing varieties suited to earlier sowing have been developed.  In CW NSW, wheat varieties such as Wedgetail have provided such options for some time, but newer wheat and canola varieties with appropriate agronomy packages are currently in development.  The most recent experimental and simulation evidence (Hunt et al., 2018; Flohr et al., 2018) suggest that capturing opportunities to sow early when they arise, especially with longer coleoptile, fast maturing winter wheats could provide a further boost to farm productivity by using more of the season and more of the soil.  Sequences with forage legumes or fallow provide stored water and N that can boost subsequent wheat yields (Table 3).  Such varieties, now in development can be sown deep into stored water in March and established on stored summer rain (rather than waiting for an autumn break) and have a stable optimum flowering window due to vernalisation requirement that stabilises flowering irrespective of sowing time.  Table 3 shows the predicted average yield benefit for a 20 day sowing program for these novel wheat types at Condobolin, as compared to existing spring wheat sown late April to mid-May.  The early sowing can especially capitalise on the water and N saved by previous legumes or fallows.

Table 3. The predicted average wheat yield for novel, long-coleoptile wheats sown from 15 March in different rotations, as compared with the current baseline of spring wheat sown from 29 April for a typical 20 day sowing program at Condobolin (from Flohr et al., 2018).

The increased efficiency predicted by these novel systems involving earlier sowing systems are now being tested at paddock and whole-system scale in GRDC funded projects CFF00011 and ULA9174837.

Conclusion

Evidence suggests that with combinations of current, best practice management technologies, focussed on the cost-effective capture, storage and use of rainfall, significant increases in whole-farm productivity, efficiency and profit are possible.  New wheat and canola varieties with flexible sowing windows that maintain optimum flowering times will provide an excellent additional tool to shift whole-farm sowing programs into an earlier and more efficient window in the face of drying autumns and more variable springs.  Success requires a combination of decisions that combine to provide a step-change in farm productivity potential with systems that manage the risk in variable climates.

Acknowledgements

The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC, and the author would like to thank them for their continued support.  We especially thanks staff and technicians at CSIRO, NSWDPI and grower groups (FarmLink Research, CWFS) who assisted with field experiments associated with GRDC projects CSP00111, CSP00174, CSP00186, CFF00011 and ULA9174837.

References and further reading

Brill R et al., (2018) Canola - tactical agronomy still makes a difference in a tough 2017.  GRDC Update Wagga Wagga 2018.

Flohr BM et al., (2018) GxM strategies to stabilise the flowering time of wheat in the south-eastern Australian wheatbelt (in review).

Haskins and McMaster (2012) Summer fallow management in 2010 across central west NSW.

Hillicoat et al, (2018) Profit Drivers Groundcover Supplement Issue 132 Jan-Feb 2018

Hunt JR and Kirkegaard JA (2011) Re-evaluating the contribution of summer fallow rain to wheat yield in southern Australia. Crop and Pasture Science 62, 915-929.

Hunt JR (2016) Increasing yield and reducing risk through early sowing.  Final Technical Report GRDC Project CSP00178.

Kirkegaard JA and Hunt JR (2010) Increasing productivity by matching farming system management and genotype in water-limited environments. J. Exp. Bot. 61, 4129-4143.

Kirkegaard JA et. al., (2014) Improving water productivity in the Australian Grains industry—a nationally coordinated approach. Crop and Pasture Science 65, 583-601.

Peoples et al., (2015) Key outcomes from the crop sequencing project.

Contact details

John Kirkegaard
CSIRO Agriculture and Food
GPO Box 1700, Canberra 2601
Mb: 0458 354 630
Email: john.kirkegaard@csiro.au

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