General Comments (November 2014)

Another dry late winter/early spring has presented many challenges to both crop and livestock managers. Low rainfall, relatively heavy frosts on 19 and 20 September 2014, plus warmer than average maximum temperatures combined with colder than average minimum temperatures during this spring, have all combined to reduce crop and pasture production potential this year.

Analysis of some clients’ rainfall records covering the last 30 to 50 years, confirms a huge variation in annual rainfall from one year to the next, plus a shift in rainfall distribution throughout the year, during this period.

Traditional Growing Season Rainfall (GSR) for the period April to October is declining, while rainfall outside of this period is increasing. February rainfall in particular is trending up, while October rainfall is trending down. April/May rainfall is also declining.

These trends have implications for both crops and pastures, helping explain why shorter season crop types and varieties, which generally have a higher harvest index due to lower dry matter at anthesis, are yielding better than crops of traditional maturity.

The traditional winter growing season is being squeezed both ends, which has far greater implications for annual crops and pastures, than it does for perennial species. Conservation of moisture outside the growing season by either fallowing or controlling weeds in stubbles, is having a significant positive influence on crop yields. This conserved moisture is helping crop establishment and root development in dry autumns, with the challenge being not to deplete the moisture profile with highly vegetative crops, but leaving some in reserve to assist with grain fill during the spring.

A trade-off exists between having crops flowering and grain filling earlier to beat moisture and heat stress, and having crops frosted. However it appears that crops have a much greater ability to compensate for early frost damage, than they do from late frost damage. Crops which are more mature with solid grain are more tolerant of later frosts than those with watery or milky immature grain, due to the viscosity of the grain contents.

Consideration should be given to sowing shorter season subterranean clover varieties in conjunction with perennial pasture species, to ensure clover seed set.