Summary
The main aim of this trial was to identify the effect that crop grazing has on ewe condition score (therefore productivity) and crop yield in the Moora-Miling area of WA to determine a whole-farm perspective. This included potential changes to pasture quantity as a result of deferring pasture grazing through the use of grazing crops. The effect that time of sowing has on available Feed on Offer (FOO) of crops early in the season was also investigated.
Climatic conditions over the three years of data varied considerably, causing inconsistent results. Crop grazing was found to be consistently beneficial to the sheep enterprise and of particular value in tighter feed years. In general, the drier the year and less abundant the feed, the greater the benefits of crop grazing to the sheep enterprise. However, in drier years, the crop was less able to compensate for the effects of grazing, resulting in lower yields but overall a modelled net gain for the mixed farm enterprise.
Selective grazing was an issue in one of the years, with one area of the crop heavily grazed. This resulted in weeds out-competing the crop, reducing overall yields. The impact on crop yield outweighed the benefit to sheep, and a modelled net loss was the result.
This reinforced the Grain & Graze guidelines for crop grazing: 1) paddocks should have low weed burdens, and 2) paddocks should be grazed early and with a medium intensity to minimise the risk of selective crop grazing. This was one of the main learnings from the group’s participation. If farmers adhere to these, the risk of reducing crop yield should be minimised.
The final year of the trial produced interesting results. A wet year with an abundance of feed, higher protein and energy levels in the crop enabled the ewes to gain slightly from grazing the barley compared with the pasture. The crop however benefited from being grazed. This was due to the impact of frost, which was avoided in the grazed crop, as grazing deferred flowering and therefore minimized the frost’s impact. This resulted in a much higher modelled net income of $322.50/ha as a result of the crop grazing.
It was only possible to trial the effect of different sowing times in the final year of the trial. The favourable season reduced the effects of crop grazing on the ewes, although, on both farms, the ewes benefitted slightly from crop grazing compared to going straight onto pasture. Crop FOO was higher where the crop was sown earlier.
This project showed that mixed farming systems have a feed source that can be utilised to improve lambing ewes’ condition scores, and therefore lamb survival. Having abundant feed on offer during lambing by deferring pasture during crop grazing can lead to increased lamb survival rates, especially in twins. If managed correctly, crop grazing can lead to overall net profits as the benefits to the sheep outweigh the impacted of crop grazing on yields (when managed appropriately). This will help reduce time and money spent on supplementary feeding, as well as increasing ewe productivity.
Further research is required to validate these results, due to so much weather variation, as well as looking into the impact of crop type and variety, sowing time, climatic impacts and the potential to reduce frost risk.
