Furrow formation and Inter-row Compaction (FFIC) for Improved Wheat Production and Profitability in Water-limited Environments of the Eastern Wheatbelt of WA

Key messages

Peaked, smooth edged, compacted inter-row soil profiles can increase in-row soil water capture if suitable rain events occur.

At Merredin yield increased at all row spacings, of furrow formation sown plots compared with plots sown with standard knife point and press wheels, but was not statistically different at the 5% level.

At a lower yielding Southern Cross site, wider row spacings of 375 mm and greater showed increased yields compared to 220 and 300 mm row spacing, but furrow formation for water harvesting did not increase yields..

Background

Crop production in the Eastern Wheatbelt is water-limited in the majority of years, and grain yields in recent seasons have been lost or severely reduced by lower than normal rainfall.

The work described here is to use crop and soil management approaches to capture short term opportunities to substantially increase water-harvesting, increase production, and increase profitability of wheat-based cropping systems in water-limited environments of the Eastern Wheatbelt. This was achieved through the use of furrow formation and inter-row compaction (FFIC). Small plot and large broad acre trials with wheat in a range of soil types provided data to test hypotheses and provide concept credibility.

Callum Wesley, specialist consultant in this project, has designed and produced a prototype of a wheel, called the Wesley Wheel (Patent Pending). This wheel is engineered to compact the soil in-between the rows of the crop, resulting in the formation of two sloping linear faces either side of the inter-row. The intention of the furrow formation is to improve water harvesting into the crop row and reduce moisture lost through evaporation from the inter-row. From preliminary research done in 2012/13, it appeared that the greater the clay content of the soil, and/or the smaller the soil particles, the greater water harvesting effect the concept will produce.

Aims

To measure the influence of furrow formation of the Wesley wheel against standard knife point and press wheel seeding at Merredin and Southern Cross on water harvesting and subsequent yields.

In addition alternate sown rows were included to test the hypothesis that harvesting some inter-row moisture for would assist late grain filling if a dry finish occurred.

Methods

Treatments:

1. Control 220 mm spacing
2. Control 300 mm spacing Southern Cross, Control 600mm spacing at Merredin
3. Control 375 mm spacing
4. Control 460 mm spacing
5. Furrow formation inter-row compaction (FFIC) 220 mm spacing
6. Furrow formation inter-row compaction (FFIC) 300 mm spacing
7. Furrow formation inter-row compaction (FFIC) 375 mm spacing
8. Furrow formation inter-row compaction (FFIC) 460 mm spacing
9. Furrow formation inter-row compaction alternate sown rows (FFICA) 220 mm spacing
10. Furrow formation inter-row compaction alternate sown rows (FFICA) 300 mm spacing

Experimental Design:

Randomised block with 4 replications.

Merredin Trial details:

Soil type: Red sandy clay loam
Stubble treatment: Fallow in 2013 with only light wheat stubble present. Light harrows dragged across plots on 14 April to reduce stubble length and even out distribution
Forming date: 22 April 2014 on dry soil
Forming method: To reduce soil clod size, five passes were done progressively deeper, steel 50 mm points
Row orientation: 21 degrees west of north
Seed Date: 22 May 2014 and all plots sown north to south
Seed Rate: 60 kg/ha Mace wheat, seed weight 42.0 g/1000, lab germination 95%
Viable seed sown: 135 seeds/m²
Fertiliser: 50 kg/ha Agras (16.1%N, 9.1%P, 14.3%S, 0.5%Ca, 0.06%Zn)
Seeder: Points 50mm wide steel, chamfered “V” Agmaster press wheels set at 4 kg/cm width
Sprays: 21/5/14 – 800 mL/ha glyphosate + 118 g/ha Sakura®, 25/7/14 – 380 g/ha Achieve® + 0.12% BS1000 with 80 L/ha water
Harvester: KEW 1.7m wide (leaving outside rows, left side knife blocked off)
Harvest date: 19 Nov 2014

Southern Cross Trial details

Soil type: Red sandy loam
Stubble treatment: Wheat in 2013 with only light wheat stubble present
Forming date: 23 April 2014 on dry soil
Forming method: To reduce soil clod size, three passes were done progressively deeper, steel 50 mm points
Row orientation: North-South
Seed Date: 14 May 2014 and all plots sown north to south
Seed Rate: 40 kg/ha Mace wheat, seed weight 42.0 g/1000, lab germination 95%
Viable seed sown: 90 seeds/m²
Fertiliser: 70 kg/ha Agras (16.1%N, 9.1%P, 14.3%S, 0.5%Ca, 0.06%Zn) 3 cm below the seed
Seeder: Points 50mm wide steel, chamfered “V” Agmaster press wheels set at 4 kg/cm width
Sprays: 14/5/14 – 1.0 L/ha glyphosate + 118 g/ha Sakura®, 18/7/14 – 25 g/ha Monza® + 1.4% Bonza with 70 L/ha water for barley grass
Harvester: KEW 1.7m wide (leaving outside rows, left side knife blocked off)
Harvest date: 18 Nov 2014

Merredin Trial results

The soil pH was low 4.6 at 0-10 cm, 4.8 at10-20 cm and 5.4 at 20-30 cm deep. The organic carbon was 1.02% at 0-10 cm, 0.75% at 10-20 cm and 0.53% at 20-30 cm. The P was 54 mg/kg at 0-10 cm, 32 at 20-30 cm and 18 at 20-30 cm.

There was a mix up with the control 300 mm spacing being accidently sown on alternate rows so effectively was a wide 600mm spacing treatment. This however gave a comparison at 600 mm spacing to the furrow formation on 300mm alternate rows.

Soil moisture was measured after 22.2 mm of rain on 8 Sept with a 6 cm long Time Domain Reflectometer probe pushed in from the soil surface on the 375 mm spacing. The furrow formation increased the in-row soil water from 20.2% on the control to 27.6%, an increase of 7.4% while reducing the soil water in the inter-row from 15.4% in the control to 8.3% in the furrow formation treatment (table 1). While this in-row increase seems small, it greatly increases plant available soil water when the upper and lower soil water limits are considered. The lower limit is believed to be around 10% and the upper around 35%.

Table 1. Soil moisture with treatment at Merredin

* Similar letters after the result are not significantly different at the 95% level of confidence.

Twenty four gypsum blocks were installed on 20 June at 15 and 30 cm deep in the control and furrow formation of 220 and 375mm spacing treatments. EM38 readings were also taken by Ed Barrett-Leonard on 20 May from each of the 48 plots in the vertical and horizontal position.

There was a general trend of lower plant number as row spacing increased, which is generally considered to be caused by inter plant competition. This site was severely affected by crown rot and it was estimated that up to 50% of the heads were empty (Table 2.). Crown rot apparently is worse where early moist sowing is followed by a dry finish, which is what happened in 2014. This could have contributed to the relatively high coefficient of variation of the yields. Crown rot samples were taken for analysis from all plots but the results were not available at the time of printing.

Table 2. Plant density and yield with treatment at Merredin

* Similar letters after the number are not significantly different at the 95% level of confidence.

** Similar letters after the number are not significantly different at the 9.4% level.

Furrow formation was 25% higher yielding (0.26 t/ha) than control at the 460 mm spacing, but only at the 9.4% statistical level. Furrow formation showed some small effects on yield at other spacings. At the 220 mm and 375 mm spacings, the furrow formation was 23% and 4.5% higher but not statistically different.

Site Rainfall Merredin

Southern Cross Trial results

The soil pH was 5.5 at 0-10 cm , 5.8 at 10-20 cm and 5.8 at 20-30 cm . The organic carbon was low at 0.83% at 0-10 cm, 0.80% at 10-20 cm and 0.57% at 20-30 cm. The P was marginal 19 mg/kg at 0-10 cm, low at 12 at 20-30 cm and low at 8 at 20-30 cm.

The seed rate was less than Merredin to allow for lower yield potential. The first treatments sown were the 375 mm spacing (treatments 3 and 7). Seed placement was too shallow as the tines were hanging back with 50 mm wide Super Seeder points, and plant establishment was poor. The remaining treatments were sown with 50 mm steel points that stopped the tines breaking out and allowed better seed placement by the attached boot.

Soil moisture was measured on 23 Sept, after 15.4 mm of rain the day before, with a 6 cm long Time Domain Reflectometer probe pushed in from the soil surface five times per plot. Treatments 2, 4, 6 and 8 were taken early in the day while 1, 5 and 7 were at 1pm and treatment 3 was not measured due to its poor establishment. As these later measurements were lower,drying in the furrow was relatively fast. The furrow formation increased the in-row soil water in the morning by about 2% but showed no difference by 1pm. Inter-row moisture was similar for all treatments for the same time of day (table 3.).

There was a slight trend to lower plant number as row spacing increased, which is generally considered to be caused by inter-plant competition as plants become more packed at the wider rows when seed rate is maintained.

The yield was low given the very dry season and lack of rain events which would have caused limited water harvesting with the furrow formation treatments. Between seeding and the middle of September no rain event was greater than 5.4mm, highlighting the poor season. However, the highest yields were with all treatments with row spacings of 375 mm and wider (table 4.). This may have been due to the soil water carried over from autumn being accessed from the inter-row late in the season. Interestingly, treatment 3 (Control 375 mm spacing) had half the plant number of the other treatments but still yielded as well as other treatments. This fits with the general assumption that 50 plants/m² is needed to achieve a per potential yield of 1.0 t/ha.

Table 3. Soil moisture with treatment at Southern Cross

* Similar letters after the number are not significantly different. Bold values were taken earlier in the day.

Table 4. Plant density and yield with treatment at Southern Cross

* Similar letters after the number are not significantly different at the 95% level of confidence.

Rainfall Southern Cross

Conclusion

At Merredin furrow formation resulted in greater soil moisture measurements after two rain events of 11mm compared to conventional knife points and press wheels.

Merredin yields tended to increase with furrow formation but were not statistically different, which could have been due to the high incidence of crown rot. Crown rot data is still being assessed.

Daily June, July and August rain events at Southern Cross did not exceed 5.4 mm which reduced the potential of water harvesting, and furrow vs control treatment yields were similar. Row spacings of 375 mm and wider showed increased yields compared to 220 and 300 mm row spacing.

The work needs repeating on more soils in different parts of the wheat belt to establish assess how rainfall event amounts, row spacing and total rainfall is important for yield improvement with this syetm. At Merredin this work was the first indication of wide row spacings with FFIC giving increased yields over narrow rows in yields around 1.0t/ha. Previous work, including Southern Cross in 2014, has only showed wide rows being better in dry seasons with yields around 0.5 t/ha.

Acknowledgments

The authors would like to acknowledgement the Department of Agriculture and Food for funding this work and the help of the DAFWA technical officers Cameron Wild, Trevor Bell and Larry Prosser.