Pasture options for production in low rainfall environments

Lucerne is the major perennial legume component of improved pastures in low rainfall environments due to its ability to respond to moisture and grow high quality feed. Well managed lucerne has metabolisable energy (ME) levels that range from 9.5-11 MJME/kgDM and protein levels that range from 18-24% of drymatter (DM)  . Lucerne develops a long taproot which (if unimpeded) allows the plant to access moisture deep in the soil profile and persist through dry times. In spring, summer and autumn, established lucerne responds well to rain which has been very noticeable in the recent dry conditions. Lucerne stands have looked almost dead throughout the dry autumn and winter but, after receiving late spring rain, plants are putting up green shoots within days. Lucerne varieties vary in winter activity; semi-winter active (5), winter active (6-7) and highly winter active (8 -10). Winter activity comes at the cost of persistence, but in a cropping rotation of 3-5 years winter activity is desirable.

Doug McDonald has a mixed farm just out of Barellen NSW (460mm average rainfall), he prefers to grow a highly winter active lucerne, Titan 9, on his property instead of older varieties such as Aurora (6). “It was amazing the growth Titan 9 gave in June and July, and we hammered it,” said McDonald. See Figure 1.

Some temperate grasses have the ability to go dormant over summer, this means the plants are not actively growing in hot dry conditions allowing them to persist for many years. Mediterranean tall fescues, such as Flecha, develop a deep fibrous root system and are well suited to heavy soils. Fescues can withstand water logging better than lucerne. They are most productive in spring and need to be managed well to stop them from going reproductive and less palatable to livestock. Another species with summer dormancy is Hispanic type cocksfoot, such as Uplands. Cocksfoot is more suited to lighter soils and has some acid tolerance. A benefit of using grasses in a mix with legumes is that it creates a more varied diet and reduces animal health issues associated with legumes such as bloat and red gut.

A farmer near Hillston NSW, with less than 350mm annual rainfall, is running a mixed enterprise using a perennial grass and legume mix in the pasture phase of his cropping rotation (see Figure 2). “We have found that the AusWest Seeds pasture mix of medics, clovers and Uplands cocksfoot, for winter grazing, and lucerne for summer feed, works really well in providing year-round, high quality feed for our livestock. The strong legume base in the mix provides a great nitrogen source for the grass and consequently good bulk. This appears to be quickly building our organic matter levels and setting the nutrition for the cropping program very well.”