While most maize growers in 2018 achieved reasonable yields and good quality forage harvested early in near perfect conditions allowing early establishment of successor crops, in many ways it was far from a vintage season. The wet, cold spring meant many crops were drilled late and were then quickly hit by the spell of hot, dry weather. While this ensured exceptional accumulation of Ontario Heat Units (OHU) fundamental for crops maturity, the drought put many crops under stress.
“The wet spring caused a number of problems,” comments Rick Swait from LG Seeds. “With drilling delayed, a proportion of crops went into poorly prepared seed beds, particularly on heavier land and this affected how well crops got away.
“In addition, a wider issue was that maize is a lazy plant and with high moisture in the soil the root system was under-developed. Then, when the weather improved and vegetative growth accelerated, crops became under drought-stress quicker due to the poor root structure. Later in the season when the summer storms hit the UK, the weaker roots contributed to an increased incidence of lodging.”
Mr Swait says that the early season also caught farmers out at harvest with many crops ready three weeks sooner than usual. Crops that are over mature at harvest and more lignified will have reduced feed value and will consolidate less well in the clamp, increasing the risk of aerobic spoilage when clamps are opened. In addition, the senescing plant will have a higher population of yeast and moulds which not only cause spoilage but can also lead to problems with mycotoxins. Finally, the poorer forage will not promote intakes as high as a crop harvested between 32-35% DM.
The impact of all these challenges was minimised in many cases by appropriate variety choice and careful management. Variety selection has been a key decision for Dorset dairy farmer Richard Davies who farms at Bishops Caundle in the Blackmore Vale, near Sherborne.
Milking 260 cows on a 580 acre farm, Richard is the second generation of the family at the farm and his father Michael is still involved in the business. It was Michael who began production of Dorset Blue Vinney cheese at the farm in 1983 and now 20% of their production is processed on farm, with the balance sold to Barbers on a constituent based contract.
Milk quality is fundamentally important to their business model and the all year round calving herd is averaging 9500 litres at 4.20% fat and 3.4% protein. The closed herd in breed to bulls which are positive for constituents but Richard admits you need the right breeding and feeding to produce high quality milk.
“Our system is based on a TMR ration in the winter and we graze during the summer although high yielders only go out by day,” Richard explains. “The TMR typically contains grass and maize silage, a blend and caustic wheat and we are looking for M+30 from the highs and M+20 from the low yielders. Dairy cake is fed in the parlour.
“We are currently feeding 30% maize and 70% grass and maize is vital for compositional quality, being a great source of starch for glucogenic energy. We have been as high as 50% maize but with predominantly heavy land we need to be prudent about how we grow the crop.”
They are not new to the crop having first grown maize around 40 years ago but struggled with the typical late varieties of that time and getting the crop harvested.
At the peak they were growing 120-140 acres of maize but have reduced this for a number of reasons. In wet autumns they were doing soil damage and had a lot of exposed ground over the winter. Now 70-80 acres of maize is grown in rotation with winter wheat. As maize is the only spring crop grown it needs to be off early to allow wheat to be established, so they are restricted as to the fields that can be used successfully.
“Maize is a fantastic feed but is not cheap to grow. We are looking to produce around 1400 tonnes but quality is key. We want high energy content with digestible starch to promote dry matter intakes. So variety choice is a big decision.”
Over time they have moved to earlier varieties, working closely with Tim Rutter from Pearce Seeds, who says that early varieties with good early vigour are crucial to a successful crop.
“The right variety has a big impact and locality can make a big difference,” Tim comments. “To help farmers make an informed choice, we run local variety screening trials at Sturminster Newton which is an area similar to where Richard farms.
“For several years Richard has grown the LG variety Glory alongside another variety to spread risk but this year we went 100% Glory as it has been performing so well in the field and in the feed trough. With only one maize clamp everything has to be harvested in one go and a single variety reduces any spread of maturity”
Typically the farm is not early drilling with maize usually sown in the first week of May, but this year Richard had to wait until 21st May for a suitable seed bed and soil temperature. A seed rate of 45,000 seeds per acre is used. They had drilled at 42,000/acre in the past as a way to bring maturity forward, but as Glory is early maturing they have increased seed rate again to push total yields. The maize land receives a generous application of slurry along with 100kg/acre of 25:0:16 and 50kg/acre of Maizestart in the seed bed. Maizestart contains trace elements to encourage early growth. Weed control is based on a pre-emergence herbicide which takes the pressure off timing for the post-emergence spray and Tim believes it gives better overall weed control.
“We want to keep the maize as clean as possible so we don’t need to worry about weeds after harvest.”
Harvest is usually in the second week of October but Tim and Richard regularly walked the crop and this year the forager went in on 26th September, some two weeks earlier.
The crop was cut with an 8” stubble to leave as much lignin in the field as possible for better feed value and to reduce soil contamination. The maize was copped at 25mm to increase effective fibre and particle size to drive butterfat. Richard usually expects to get 15 tonnes per acre, but while yield was slightly down this year, quality was excellent and he expects the maize to feed well (see table).
Richard Davies says crop management at harvest is key. “Getting the right chop length while ensure the grain is adequately processed makes a big difference to how the maize feeds alongside the grass.
“Crop management is also vital to reduce any spoilage. The clamp is rolled well and covered with clingfilm and two sheets of plastic. We have used an inoculant in the past.
“Silage is removed using a shear grab and we get across the 11m clamp face in three days.
“By focussing on early maturing varieties combining high vigour with excellent dry matter yields and energy content we can produce the tonnage of high quality feed we need despite the restrictions imposed by the farm and produce the high quality milk which is core to our business,” Richard concludes.
Rick Swait believes there are three important lessons that maize growers should take forward into next year which will be beneficial irrespective of how the season unfolds. The first is to not rush drilling, even if it is delayed by the weather.
“Maize needs a fine tilth and a soil temperature of at least 8°C so take the time to get the seed bed right to give the plant the best chance of getting away quickly and develop a strong root system. This can be helped by selecting a variety with good early vigour.
“The second lesson is to make sure you select a variety which is going to mature in time irrespective of the season. Early harvest can benefit in multiple ways: cutting in good field conditions, having a forage available to feed sooner and reduced mud on the road, plus easier establishment of a successor crop.
“Our OHU map allows you to see the average OHU accumulation for your postcode and so determine the most suitable maturity class for your farm. As early varieties require fewer OHU, they are generally a more reliable option. Make sure you order seed early to ensure you get the variety you want and don’t have to compromise.
“Finally, you are making a quality feed so select a variety which will produce good yields of an energy dense forage, but remember feed value is affected by crop maturity and the crop needs to be harvested at optimum condition. This will vary dependent on the season. There is no set harvest window for maize. It is determined by the farm, the variety and the season so get into the habit of walking crops regularly from late August.”
2018 Maize silage analysis
|Dry matter (%)||35.7|
|Crude protein (%)||6.9|
|D value (%)||74.6|
|Starch degradability (%)||78.5|