Long term Aglime trials
Aglime of Australia has been conducting field trials to measure the effectiveness of its agricultural limesand. This R&D program not only aims to identify the many benefits, but also to detect any problems that may be associated with liming. For this reason the trials are run under normal commercial farming conditions (and range of rotations) used in the wheatbelt.
Like seasons, responses to aglime varies. Of note, was 1998, when all aglime field trials were harvested and all gave significant yield increases from Aglime’s limesand applied up to 14 years previously.
Aglime was originally spread over 10m wide plots at selected rates with three replicates for each rate. The cooperating farmer managed the trial site from the beginning. All operations including sowing, fertilising, spraying, grazing etc were handled in exactly the same way as the rest of the paddock. An independent contractor harvested the trials and sent the yield results to Aglime of Australia for analysis.
Crop yield and soil pH results for the 1998 season are outlined below.
Trial site 1 was sown to wheat in 1998 and yield increased by 0.4 and 0.5 t/ha where Aglime rates of 2.5 and 5.0t/ha respectively were applied 14 years previously in 1985.
Trial site 2 was sown to canola and yields increased by 0.1 and 0.3 t/ha where Aglime rates of 2.5 and 5.0 t/ha respectively had been applied 14 years previously in 1985. Larger yield responses were apparent from visual inspection and it is possible direct heading may have caused loss of seed.
At site 1 in the first summer after liming, the topsoil pH (0-10cm) was around 4.6 in the unlimed plots, and had increased to around 6.0 and 7.0 where 2.5 and 5.0t/ha respectively had been applied.
By January 1999, topsoil pH had declined on all plots due to normal acidification. However, larger falls in topsoil pH were seen on limed plots as some Aglime had moved from the topsoil into the acidic subsoil. The subsoil pH of limed plots are now 4.7 to 5.0, some 0.6 to 0.9 units higher than unlimed plots (Figure 3). It is likely that aluminium toxicity would be limiting crop root growth and yield only in the unlimed plots.
The Konnongorring trial site was sown to barley in 1998 and produced yield increases of around 0.8t/ha from both 2.5 and 5.0t/ha of Aglime’s limesand applied in 1985
This trial was also sampled in both the topsoil (0-10cm) and subsoil (10-20cm). The results were similar to Wongan Hills site 1. The pH of the subsoils on plots that had received Aglime’s limesand 14 years earlier increased substantially above the control levels. These increases in subsoil pH were also evident when this trial was tested previously in 1992.
The Yorkrakine sites (yellow sand and loamy sand) were sown to wheat in 1998. Each site achieved a 0.2t/ha yield increase where 4t/ha of Aglime have been applied 4 years previously in 1995
The trials demonstrate that Aglime of Australia’s limesand:
1. Increases yields on acid soils
2. Lasts for at least 19 years
3. Increases subsoil pH. This undoubtedly contributes to continuing effectiveness
4. Returns large profits to farmers, especially over the long term