results from 3 years of testing variable rates of … trials 2012 to 2014...results from 3 years of...

Results from 3 years of testing

variable rates of lime on crops and

pastures

About these notes These trial results have been prepared by Cam Nicholson, Nicon Rural Services for the Woady

Yaloak Catchment Group. They combine results from an earlier investigation into lime through

a Caring for Our Country project to enhance biodiversity and soil conditions in the Woady Yaloak

Catchment along with a second Community Landcare Grant.

Disclaimer The advice provided in these results is intended as a source of information only. The Woady

Yaloak Catchment Group, its employees, contractors or funding partners do not guarantee that

these results are without flaw of any kind or is wholly appropriate for your purposes and

therefore disclaims all liability for any error, loss or other consequence which may arise from

you relying on any information in this publication.

Acknowledgements The Woady Yaloak Catchment Group would like to thank the nine landholders who provided sites for the trials.

John Carr

Troy Missen

Neilson Carr

Daniel Laffan

Rod Kennedy

Col McKenzie

Ken McBeath

George McKenzie

Phil Cunningham. Special thanks to Jim Caldwell for trial management and the support of Simon Falkiner and Southern Farming Systems for crop harvesting. The groups would also like to thank the generous funding from the Australian Government through their Caring for our Country program.

Lime trials

Background

The Woady Yaloak Catchment Group was successful in obtaining a Caring for our Country grant to quantify the benefits of lime to cropping and grazing enterprises in the Woady Yaloak Catchment. Due to the short duration of the grant, a further Community Landcare Grant (2013 to 2014) was obtained to continue measurement on these sites for a further 18 months.

The lime work was prompted by results from previous trials on alternative fertilisers and biological products (2009 - 2011), where a consistent responses was measured to regular light rates of lime applied with one of the biological treatments (worm castings). This occurred on soils where the pH and aluminium levels were questionable in regards to an expected response from liming. While the yield response measured may have been due to the worm castings and not the lime, soil testing at the end of the trial indicated a change in pH but no change in soil fertility.

The trialling was established to investigate two aspects was decided to investigate two aspects:

The yield response to using lower rates of lime

The yield response to lime on soils that are in the ‘grey’ area between a liming and non-liming response.

Trial sites & products Six sites are included in the trialing. These included three crop and three improved pasture sites. Crop yields were measured in 2012, 2013 and 2014. Multiple cuts were taken on the pasture sites across the same three years. A further three ‘native’ grassland sites also received lime, but only at one rate (2.5 t/ha) and did not have dry matter cuts. All sites were soil tested before application of lime (appendix 1) and select treatments were sampled eight months later to measure changes in soil pH and also soil biology. The sites were deliberately chosen to have a pH and soil aluminium level in the ‘grey area’ when having to make a choice between applying or not applying lime. Previous work, and farmer observations have already confirmed that in extreme cases of very high soil acidity lime is highly beneficial. Products (or treatments) were replicated four times at each site. At each site one treatment was assigned no product, except for the crop sites, where traditional fertiliser at sowing was used. This was considered the NIL treatment and all other products have been compared to the response of the NIL treatment. A ‘standard’ fertiliser recommendation for the pasture sites was made for each site based on the soil test results. The rate of lime application and traditional fertiliser are listed (table 1). Kurdeez fine lime (NV 97%) was broadcast applied in April 2012. Traditional fertiliser was broadcast on the three pasture sites at the same time.

Table 1: Rate of lime products and traditional fertiliser applied. Type Location Traditional fertiliser

(applied in 2012, 2013 and 2014)

Treatment in 2012 Traditional

fertiliser 250

kg/ha once off

750 kg/ha

once off

1250 kg/ha

once off

2500 kg/ha

once off

Crop

Rokewood, (J Carr)

70 kg/ha MAP1 At sowing X X X X

Werneth (Missen)

50 kg/ha MAP + zinc, copper, moly

At sowing X X X X

Rokewood (N Carr)

100 kg/ha MAP2 At sowing X X X X

Pasture

Mt Mercer (Laffan)

250 kg/ha SP3 2:1 X X X X X

Pittong (Kennedy)

100 kg/ha SOP X X X X X

Illabarook (McKenzie)

125 kg/ha SOP4 X X X X X

Analysis of results The results for total dry matter have been mathematically analysed to take into account the natural variability across the site and also between replicates of the same treatment at the same site. This enables a dry matter or grain yield figure to be calculated so treatments can be compared. This dry matter figure is referred to as the least significant difference or LSD. If the difference between two treatments is less than the LSD, then even though there may appear to be difference between the numbers, this difference is due to chance or luck. However, if the difference is greater than the LSD, then the difference is not due to chance or luck, it is due to the treatment. If we repeated the trial we would expect the same result to occur 95% of the time. Any product that exceeds the LSD value can claim to have achieved a different result and that difference is repeatable.

1 Also applied 5 l/ha Beaulieu R.U.M liquid fertiliser (a nitrogen source) in 2012 2 Also applied 1250 kg/ha gypsum and 6 l/ha Beaulieu R.U.M liquid fertiliser (a nitrogen source) in 2012 3 SP = super potash 4 SOP = sulphate of potash

Results Crops Carr, J (Rokewood) Key starting soil data (March 2012).

P K S pH (CaCl2) Al (%)

16.8 157 14.9 4.8 3.0

Fertiliser: None above standard practice that was applied to the entire trial at sowing each year. Crop yields

Canola yield from NIL treatment in 2012 = 1.72 t/ha

Wheat yield from NIL treatment in 2013 = 5.99 t/ha


Results The application of lime resulted in a large increase in canola yields above the NIL treatment in 2012 (LSDp=0.05 = 0.25 t/ha), but no significant response for wheat in 2013 and 2014 (figure 1).

Figure 1: Crop yields compared to the NIL (no lime) treatments from 2012 to 2014 (J Carr, Rokewood). This results is in line with expectations as canola is sensitive to even moderately low levels of soil aluminium (>2%), whereas wheat is more tolerant (>8%). The starting soil aluminium level was 3%, so a yield response in canola but not wheat confirms current triggers for liming.

The economic return from liming was positive after three years, with the cost recovered after the first crop (because of the high value of canola). Details of the economic analysis are provided (appendix 2), with the following net return (table 2). Table 2: Net economic return from liming compared to the NIL treatment after three years (J Carr, Rokewood).

Treatment Income above

NIL ($/ha) Cost above NIL ($/ha)

Net return ($/ha)

Lime @ 250 kg/ha $ 82 $ 21 $ 61

Lime @ 750 kg/ha $ 75 $ 41 $ 35

Lime @ 1250 kg/ha $ 205 $ 61 $ 145

Lime @ 2500 kg/ha $ 269 $ 111 $ 159

Missen (Werneth) Key starting soil data (March 2012).


28.4 270 30.0 4.7 2.3

Fertiliser: None above standard practice that was applied to the entire trial at sowing. Crop yields

Canola yield from NIL treatment in 2012 = 2.41 t/ha


Bean yield from NIL treatment in 2014 = 3.24 t/ha

Results The application of lime resulted in minimal yield response (figure 2). The soil aluminium at the start of the trial was on the threshold level for a sensitive crop like canola, but under the levels expected to affect wheat and faba beans. The results may indicate some response in the canola crop but not in the subsequent crops (variability in yield compared to the NIL treatment of 2% in the wheat in 2013 and 4% in the faba beans in 2014). After 3 years the common rate of 2.5 t/ha showed no significant yield response, however lime applied at half the rate (1.25 t/ha) resulted in small yield increases in all three years. These yield increases were not significant compared to the NIL treatment.

Figure 2: Crop yields compared to the NIL (no lime) treatments from 2012 to 2014 (T Missen, Werneth). The economic return from liming was roughly break even or positive after three years except for the highest rate of lime applied (table 3). This result is confusing because lime applied at 2.5 t/ha resulted in a negative return after 3 years, mainly because the yield response especially in

the high value canola and faba bean crops was minimal. Yet a positive yield response was measured when the liming rate was halved, leading to a return of $127/ha. Table 3: Net economic return from liming compared to the NIL treatment after three years (T Missen, Werneth).

Treatment Income above

NIL ($/ha) Cost above NIL ($/ha)

Net return ($/ha)

Lime @ 250 kg/ha -$ 3 $ 21 -$ 24

Lime @ 750 kg/ha $ 91 $ 41 $ 51

Lime @ 1250 kg/ha $ 188 $ 61 $ 127

Lime @ 2500 kg/ha -$ 70 $ 111 -$ 181

Carr, N (Rokewood) Key starting soil data (March 2012).


16.1 172 20.2 4.8 2.4

Fertiliser: None above standard practice that was applied to the entire trial at sowing. Crop yields

Wheat crop harvested by mistake – no data collected

Bean dry matter in NIL treatment when cut for hay in 2013 = 6.13 t/ha

Canola yield in Nil treatment in 2014 = 1.81 t/ha

Results A mishap at harvest resulted in the loss of trial data in 2012. In 2013 severe problems with herbicide resistant annual ryegrass led to a decision to cut the site for hay (which enabled the ryegrass seed to be collected). Hay yields were measured instead of crop yields. The site was sown to canola in 2014. There was no difference in hay yield in 2013 or canola in 2014 due to the application of lime (figure 3). The variability in measured results was higher than expected for trials of this type (CoVar 12% in 2013, 15% in 2014) so the data need to be interpreted with some caution. Nevertheless it does suggest there is no dramatic change in yield due to liming.

Figure 3: Crop yields compared to the NIL (no lime) treatments from 2012 to 2014 (N Carr, Rokewood). Faba beans are moderately tolerant to low pH and aluminium and given the starting pH of 4.8 it would be expected no yield response would be measured. The yield response for canola was also inconclusive, with no response at all lime rates except for the 1.25 t/ha rate, although this was not significantly different from the NIL.

The small negative yield response to lime in most cases, combined with the up-front costs of lime application, has resulted in a negative return to the investment in lime (table 4). These results only include two years of yield data. Table 4: Net economic return from liming compared to the NIL treatment after three years (N Carr, Rokewood).

Treatment Income ($/ha)

Cost ($/ha)

Net return ($/ha)

Lime @ 250 kg/ha -$ 136 $ 21 -$ 157

Lime @ 750 kg/ha -$ 38 $ 41 -$ 79

Lime @ 1250 kg/ha $ 9 $ 61 -$ 51

Lime @ 2500 kg/ha -$ 12 $ 111 -$ 122

Improved pastures Three pasture sites had the same lime treatments applied. The sites were located on three different soil types and contained different perennial grasses. Also unlike the cropping sites, the lower soil fertility levels measured through baseline soil testing may have an influence on the dry matter response to liming (table 5). Therefore at each site a fertiliser treatment was included, with the rate and type of fertiliser based on soil testing and achieving target nutrient levels. Table 5: Soil and pasture type and key fertility and pH measures for pasture trials.

Location Soil type Pasture type P K S pH (CaCl2) Al (%)

Mt Mercer (Laffan)

Basalt Tall fescue / sub clover

11.2 95 13.6 4.8 1.7

Pittong (Kennedy)

Granite Ryegrass / sub

clover 32.5 66 11.5 5.2 0.6


Sedimentary Cocksfoot / sub clover

18.8 36 14.3 4.9 1.5

The result for the three sites have been combined to compare the difference in dry matter production over three years (2012 to 2014) compared to the NIL treatment. The most striking result is the response to fertiliser at two of the three sites. There was significantly more dry matter produced and a different pasture composition at the Pittong site with the application of 100 kg/ha/yr of sulphate of potash than the NIL treatment or any lime treatment (image 1 & 2).

Image 1 & 2: Pasture response to 100 kg/ha/yr of sulphate of potash fertiliser (left) compared to the NIL treatment (right) The Colwell potassium from the soil test was 66 mg/kg , which is well below the target nutrient level and therefore it is not surprising a response was recorded. Interestingly the fertiliser response increased each year, with no difference compared to the NIL in 2012, a yield difference due to fertiliser of 6% in 2013 (not significant) but a significant response in 2014 (89% compared to the NIL treatment).

A similar positive yield response was recorded at Mt Mercer from the fertiliser application, with increases compared to the NIL treatment of 4% in 2012, 17% in 2013 and 7% in 2014. Combined, the total yield difference over the three years was significantly higher than the NIL treatment. Like the Pittong site the baseline Colwell K level of 95 mg/kg and Olsen P of 11.2 mg/kg was lower than desirable and a response would be expected with the addition of 250 kg/ha of super potash each year. The surprising result was at Illabarook, on a heavily weathered sedimentary soil with very low nutrient retention characteristics. The Colwell K was very low (36 mg/kg) and a rapid response to fertiliser would be expected. However this was not the case. Despite the addition of 125 kg/ha of sulphate of potash each year for three years, there was no significant dry matter response to applied fertiliser. Visual observation would suggest that the composition of the pasture is changing, with more sub clover in the fertilised treatment than the NIL treatment. Differences may be recorded in subsequent years. There was no significant yield response at any site over the three years from liming (figure 4). The low soil fertility may be limiting the lime response, however the soil aluminium levels measured in the baseline testing are low and are very unlikely to affect pasture growth, especially given the tolerance of the species in the pasture.

Figure 4: Difference in dry matter compared to NIL treatment at 3 improved pasture sites (2012 to 2014).

Soil pH All lime was surface applied in the autumn of 2012. Subsequent soil testing on two liming rates and the NIL treatment in November 2012 clearly shows the change in pH (table 6). Additional measurements down the soil profile also indicate the depth lime has moved from the surface into the soil (figures 5 & 6).

Table 6: Change in soil pH (0 -10 cm) with the application of different rates of lime.

Type Location Rate of lime applied

Nil Lime @ 250 kg/ha

Lime @ 2500 kg/ha

Crop

Rokewood (Carr, J)

4.7 4.9 5.4

Werneth (Missen, T)

4.7 4.8 5.2

Rokewood (Carr, N)

4.8 4.9 5.4

Pasture

Mt Mercer (Laffan)

4.8 4.8 5.3

Pittong (Kennedy)

4.85 5.1 5.1


4.9 5.1 5.8

0

2

4

6

8

10

4.0 4.5 5.0 5.5 6.0 6.5

Soil

de

pth

(cm

)

J Carr - Soil pH (CaCl2)

Nil - Nov 2012 250 kg/ha 2500 kg/ha

0

2

4

6

8

10

4.0 4.5 5.0 5.5 6.0 6.5

Soil

de

pth

(cm

)

D Laffan - Soil pH (CaCl2)

Nil - Nov 2012 250 kg/ha 2500 kg/ha

Figures 5 & 6: Changes in soil pH down the soil profile (examples for only one crop - Carr and one pasture - Laffan) are shown.

5 Baseline soil testing in February 2012 indicated a pH of 5.2 but this may be incorrect.

Native pastures There are three sites in this grouping. One site is a dominant kangaroo, wallaby and spear grass area (rarely grazed and never had fertiliser, Olsen P 2.9 mg/kg). The second site contains native species but also some exotic weeds such as dandelion and sweet vernal (Olsen P 4.9 mg/kg). It is grazed mainly by kangaroos and may have occasionally received fertiliser (current owner unsure). The third site is constantly grazed, has some native grass, mainly wallaby grass and occasionally receives fertiliser (Olsen P 7.3 mg/kg). No dry matter cuts were taken on the native grassland sites. These sites were included just to gain an understanding on the level of soil acidity and if liming would change the botanical composition of the pasture. There was no observable change in pasture composition of the native species at any of the sites when measured in November 2014. These sites will be monitored in subsequent years to see if any changes occur over time. Soil pH A surprising result was the soil acidity under the native grassland sites. These sites recorded lower pH and higher aluminium than the crop or pasture site (table 7). Table 7: pH and aluminium at the native grassland sites

Site pH (CaCl2) Aluminium (% of cations)

Dominant kangaroo, wallaby and spear grass

4.7 6.4%

Mix of native and exotic species

4.4 18.5 %

Mainly exotic species with some wallaby grass

4.5 3.2 %

Combined results from six crop and pasture sites

4.9 (range 4.7 to 5.2)

1.9% (range 1.6% to 3.0%)

Discussion The sites used in these trials were deliberately chosen to examine the ‘grey’ line around where a response to liming would be expected. The pH range was between 4.7 and 5.2, with a corresponding aluminium (Exch AL%) of 1.6% to 3.0 %. At these pH and aluminium levels it is debatable if any yield response to lime should be measured except for highly sensitive crops. Results show a yield response to lime only for canola at two of the three sites where it was sown. Canola is known to be intolerant to soil aluminium, even at low levels and these results confirm that conclusion. As rates of lime were increased, the yield difference compared to the NIL treatment was greater, except at 2.5 t/ha, the traditional liming rate (figure 7).

Figure 7: Yield response in canola to liming at different rates compared to the NIL treatment. The more favourable yield response to liming at the John Carr’s site may be due to slightly higher starting aluminium levels compared to the other two sites (3.0% Exch AL% compared to 2.3% and 2.2%). The reason for the lack of response at two of the three sites to liming at 2500 kg/ha is unclear. This requires further investigation to determine if this is simply experimental variability or that at higher rates the pH change is so great as to unbalance other biological or nutrient levels. Understanding the fertiliser influence is critical when interpreting the lime response. It is likely that at two of the three pasture sites (Mt Mercer and Pittong), that the low soil potassium would be masking any possible effect of the lime treatments. Correcting the soil fertility imbalance may result in a different response to liming. The fertiliser influence also confirms that liming is not a substitute to fertiliser if low soil fertility is present. The yield responses at the six sites has helped to clarify where the ‘grey’ line is in for the application of lime. It confirms highly sensitive crops like canola will benefit from liming at pH levels around 4.8 and with soil aluminium around 2.0% (exch Al%).

line with expectations as canola is sensitive to even moderately low levels of soil aluminium (>2%), whereas wheat is more tolerant (>8%). The starting soil aluminium level was 3%, so a yield response in canola but not wheat confirms current triggers for liming.

Appendix 1: Baseline soil test data

Laboratory Identification: FS 126034 - 126036

ANALYSIS UNITS

Cro

p

(CA

RR

, J)

Cro

p

(CA

RR

, N

)

Cro

p

(MIS

SE

N,

T)

Pastu

re

(LA

FF

AN

)

Pastu

re

(McK

EN

ZIE

, C

)

Pastu

re

(KE

NN

ED

Y)

Phosphorus (Olsen) mg/kg 16.8 16.1 28.4 11.2 18.8 32.5

Phosphorus (Colwell) mg/kg 46.0 47.0 80.0 28.0 51.0 79.0

Phosphorus Buffering Index PBI 60.0 81.0 87.0 132.0 59.0 50.0

Potassium (Colwell) mg/kg 157.0 172.0 270.0 95.0 36.0 66.0

Sulphur (KCL40) mg/kg 14.9 20.2 30.0 13.6 14.3 11.5

pH (1:5 water) 5.4 5.5 5.3 5.7 5.7 6.0

pH (CaCl2) 4.8 4.8 4.7 4.8 4.9 5.2

Salinity (EC) (1:5 water) dS/m 0.17 0.23 0.28 0.11 0.07 0.12

Soil Texture Loam Clay loam Clay loam Clay loam Loam Loam

Organic Carbon % 2.04 2.42 2.39 3.32 2.04 2.20

Labile Carbon mg/kg 520 590 579 790 510 520

Nitrate mg/kg 42.0 32.0 64.0 2.0 6.0 30.0

Ammonium mg/kg 4.0 4.0 6.0 14.0 5.0 4.0

Calcium (Exch) meq/100 g 4.37 4.98 5.30 7.64 3.88 5.55

Magnesium (Exch) meq/100 g 0.89 1.59 1.48 2.86 0.54 0.71

Sodium (Exch) meq/100 g 0.17 0.74 0.51 0.41 0.12 0.18

Potassium (Exch) meq/100 g 0.40 0.41 0.69 0.25 0.09 0.17

Aluminium (Exch) meq/100 g 0.18 0.19 0.19 0.19 0.07 0.04

Calculations

Sum of cations (CEC) meq/100 g 6.01 7.91 8.17 11.35 4.70 6.65

Calcium/Magnesium ratio 4.9 3.1 3.6 2.7 7.2 7.8

Sodium % of cations (ESP) 2.8% 9.4% 6.2% 3.6% 2.6% 2.7%

Aluminium % of cations 3.0% 2.4% 2.3% 1.7% 1.5% 0.6%

Appendix 2: Costs and returns used in partial economic analysis

Costs Price Unit

Lime $ 18.00 $/t

Transport $ 22.00 $/t

Spreading $ 10.50 $/ha

Income Price Unit

Canola $ 563.00 $/t

White wheat $ 280.00 $/t

Red wheat $ 240.00 $/t

Beans $ 510.00 $/t

Beans (hay) $ 260.00 $/t

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