This page is a summary of what I consider to be the best bets for maize agronomy in Southern Victoria. I will update this page as info becomes available
- Choose a paddock with the ability to retain moisture. Clay soils are going to yield significantly higher than sands.
- Do not plant unless there is at least 1 meter depth of stored moisture. A clean no-till fallow of 6-9 months should achieve this in most years. Double cropping may be possible in a wet spring, if harvest has occured early enough.
- Maintain soil cover. Standing wheat stubble will act as a mulch, retaining moisture while the crop becomes established. Avoid grazing the fallow, trampling of stubble will lead to faster breakdown significantly reducing ground cover later on.
- A summer crop will reduce winter weeds with knockdown herbicides used in the spring prior to planting. Selecting a paddock with winter weed problems will be worthwhile for the whole cropping program. Aim to have good summer weed control in the summer prior to growing a summer crop
- A range of hybrids from 87 - 112 day CRM have been trialled. Yields have been lower for hybrids less than 100 day. Longer season hybrids (109-112 day) may yield higher in good seasons, although they may 'fall over' in a dry summer.
- Best bets so far would be Pioneer 36B08 (103 day) and HSR Maximus (102 day). Pacific Seeds Hycorn 533 (109 day) has also performed well although it is no longer available.
- Aim to plant from early October. The absolute minimum soil temperature is 10 degrees. It is preferrable to plant at 12 degrees or more. It may be possible to plant in September, however this will be less likely with no till planting. Early planting is preferred as it will help to avoid flowering in the hotter parts of the year. Another benefit is that harvest can start earlier and reduce drying expenses. Rainfall patterns favour early planting with November being our wettest month and then getting progressively drier each month to February, after which rain picks up again.
- Avoid flowering in late January and Early February. At the moment flowering dates for different hybrids in Southern Victoria have not been recorded.
- Stagger flowering dates. Either sow 2-3 different Hybrids, or stagger planting dates. This will help to spread the risk of adverse climatic conditions.
- How late can we plant? In 2009 we planted a range of hybrids from 87 day to 109 day CRM. The planting date was December 9. The later hybrids performed the best, most likely due to timely March rain. With yields approaching 6t/ha it seems that this date is not too late.
- A rough rule of thumb is to allow 8000 plants for every 1t of target yield. Eg: 5t/ha x 8000 plants/t = 40,000 plants/ha. Quicker (<100 day) hybrids will require more plants and Slower (>110 day) hybrids less.
- Lower populations will be more reliable. One of the barriers to dryland maize production is the cost of seed. Planting lower populations will not only save money but will also reduce the risk of a failed crop. A population of 30 - 40,000 plants/ha is suggested until we've had more experience, especially in drier summers.
- Higher populations are necessary for higher yields. Maize does not have the ability to tiller like other cereals. If a plant is producing two cobs, then you are suffering lost yield through low populations. Yields are maximised with one full size cob. On the other hand, you are losing yield if the plants are producing a lot of small cobs.
- Maize is generally planted on 30" (75cm) row spacing. For dryland production it may be worthwhile considering wider rows (1m) and/or skip row planting. Skip row planting is where every third row is left unplanted. This will save moisture for later in the season and provide a type of drought insurance. Yields will be sacrificed in a good year, but crop failures will be less likely.
- No till planting is essential for dryland summer crop production. Zero-till (Disc seeder) is preferred due to lower soil/residue disturbance and more accurate seed depth.
- Cultivation will severely reduce yields due to moisture loss prior to and after planting.
- Precision planting is considered essential for maize. A yield advantage of at least 17% is expected for precision planting compared to an airseeder. However if a no-till precision planter is not available then it would be better to use an airseeder than to cultivate.
- 10Kg/ha of N is considered the maximum safe rate to apply with the seed on 30" rows.
Prof. Fred Below from the University of Illinois has developed a list of the top seven factors in producing a high yielding corn crop. He calls this list "The Seven Wonders of the Corn Yield World". The list below includes how many bushels each factor contributes to a 260 bu/acre (16t/ha) corn crop. The seven factors come after you've got the basics right which Fred calls "4 basic prerequisites"
Four Prerequisites
- Good weed & pest control
- Proper soil pH
- Adequate phosphorus
- Adequate potassium
- 70 Bu - Weather; includes planting date as this is determined by the weather
- 70 Bu - Nitrogen
- 50 Bu - Hybrid Selection
- 25 Bu - Previous Crop
- 20 Bu - Plant Population
- 15 Bu - Tillage; meaning correct tillage which may or may not be no-till
- 10 Bu - Chemicals; mainly fungicides
