Ancon-Agri, 26 Clarence St. Shepparton, Vic 3630 firstname.lastname@example.org
The objectives of this survey and sampling were to quantify the levels of soil compaction in Goulburn valley loams and identify if these levels may have be reducing pasture growth in 2017. The survey also sought to find the extent of soil compaction caused by high stocking rates of cattle on dairy pastures in 2016. Eleven farms across the Goulburn valley were selected to be representative of differing areas in the valley. These farms were selected because they had a paddock(s) which had been severely impacted by large numbers of cattle where pasture had been destroyed and the soil structure damaged. Soil Bulk density (BD) in g/cm3 was measured to indicate the level of soil compaction in the paddocks with severely impacted soil and compared with areas of the same or similar soil type where there had been little or no effect on the soil from cattle. These paddocks were analysed for soil fertility, pH and salinity. The paddocks were identified by soil type and group. Typically the soils tested were loams or sandy loams which were able to withstand high stocking rates. On average these soils had low calcium to magnesium ratios and low levels of sodium. The BD levels were measured at two depths, 0-10 cm (surface soil) and 10-20 cm (root zone). This study found that for 80% of the farms sampled, BD in the 10-20 cm zone was 1.6g/cm3 or greater. According to Taylor and Brar (1991) at this level of BD plant root growth can be severely inhibited because the soil is so tightly compacted. Analysis of the relationships between BD and calcium, sodium, soil type, soil texture and soil organic carbon (SOC) found that the correlation of BD with SOC was reasonably strong while all the other correlations were weak. This meant that where the SOC content was high the BD levels were low. When BD was plotted against SOC for both the compacted and non-compacted soils a difference of around 8% was consistently found which is attributed to the effect of the cattle.
A phone survey was undertaken to sample fifty dairy farmers in the Goulburn valley to investigate the methods used to prevent damage to pasture and remediate the soil from damage caused by cattle. The survey also sort to find the level of understanding on the impact of soil compaction on pasture production. Prevention of soil damage by the cattle was by far the most popular method using feed pads, sacrifice paddocks and non-arable land. Prevention methods were regarded as the best method of moderating lost production from excessively wet conditions. Very little work was done to remediate soil and the farmers’ understanding of the impact of soil compaction was low.