After the wet spring and cancelled Feedbase Focus. The summer fodder crops are well worth a look at, hence our upcoming field walk. See events for details…

You can currently see differences in yield amongst six different varieties of forage Brassicas. That were sown on Dec 1st and are approaching maturity, where leaf color will change indicating they are safe to graze and the risk of photosensitisation in stock has subsided.

There are also two sorghums on trial, SF Flourish a hybrid variety that is currently at least 1 metre high and with leaves the width of my forearm.

Sorghums can contain prussic acid and are only safe to graze when the plants become tall which dilutes the amount of ingested toxin. While this crop is ready for grazing, the other variety, SF Calorific, a sweet sorghum type is currently half the size.

Our dilemma is we either hot wire off the shorter sorghum to exclude it from grazing or delay grazing on all the fodders until it grows taller. We will be grazing with sheep and while height is no issue for cattle, the sheep might then struggle to graze our taller sorghum which could get to 1.5 to 2m high.

Millet is another summer growing cereal on display which is currently about 30cm in height. It has the advantage of being able to regrow following grazing provided we get rainfall. While it has none of the other toxicity issues, all summer fodders can cause nitrate poisoning. So, we plan to introduce stock with full bellies of hay and closely monitor.

The difference in insect damage between the crops is startling. The insect pressure has been high on the brassicas and they contain many holes but the summer cereal grasses are untouched. While we have sprayed once, the white cabbage butterfly and other moth pests have only a two week lifecycle. So, the pressure from them will be relentless. For this reason, we can’t wait to graze the Brassicas and utilise the feed and hopefully eat off some of the caterpillar pests.

One thing we don’t have is black field crickets which are normally a problem in the cracking basalt clays. We can only assume their eggs got washed away in the spring deluge.

Apart from grazing and weed clean up benefits before resowing, the brassicas provide a biofumigant role, where they can get rid of troublesome soil borne diseases. The summer fodder crops might also help dewater the soil profile, which could reduce the effects of winter waterlogging. Having roots that are forced to chase moisture deep in the soil profile, offers benefit by introducing organic matter and improving soil structure at depth in the high clay content soils.

How summer fodder crop fit in our mixed farming systems will be a discussion point at our field walk, along with their management.

Image: Sorghum in the centre with forage Brassica trial to the left and millet strips to the right at Rokewood Jan 30th, 2023.

Source: L Miller, SFS