Dairy farmer increases maize yields by upping seed rates

Dave Stewart grows 101ha of maize to feed his 600-cow herd at Ferny Lees Farm, Tiverton near Tarporley.

Maize silage is fed year-round to the herd and Mr Stewart has been keen to embrace new growing techniques to optimise the crop’s performance and help him hit his annual target feed requirement of about 5,000t overall.

Since moving to the farm four years ago, he is now consistently yielding more than 49.4t/ha (20t/acre) freshweight from a variety of soil types ranging from medium loams to light clay.

See also: Step-by-step guide to planting maize

The yield improvement is being maintained by adopting a strict approach to the timings of spring land work, meticulous seed-bed preparation and using a seed rate to achieve about 111,150 plants/ha (45,000 plants/acre).

Seed-bed preparation

“In the past, before we knew better, our seed-bed preparation wasn’t good. We only used power harrows with the best of intentions, and because we rolled after we had drilled we were doing more harm than good.

“We were actually doing very little to create the type of seed-bed the crop needed and were ending up with really wet patches across the fields.

“The power harrows produced a pan that the maize seedlings just couldn’t get through and we paid the price with lower yields,” recalls Mr Stewart.

Maize consultant Ian Grandfield of Green Gem Agriculture, Malpas, Cheshire, stepped in to advise with a precise plan of crop establishment guidelines.

It began with a total rethink on the farm’s seed-bed cultivation techniques and applying the results of several years of trial work on seed rates.

“Creating a seed-bed of the correct consistency – as well as sowing at the right time – is absolutely critical to get the best results from maize.

It’s something a lot of dairy farmers growing maize could improve on,” says Mr Grandfield.

He describes using solely power harrows for spring maize cultivations as being a “fundamental error” in trying to create the ideal seed-bed.

Using more appropriate machinery was one of the first changes made in the new cultivation methods introduced at Ferny Lees Farm.

“We were starting to get the message that rolling wasn’t doing anything to help us produce the correct seed-bed for maize so we looked at alternatives.

“We needed to create a more ‘fluffy’ type of seed-bed so switched to the spring-tine crumbler,” says Mr Stewart.

“We needed the soil to be light and airy so I could kick my foot through it. That’s what proves to me we have achieved the sort of consistency of soil in the bed the maize seeds need to get the best start,” he adds.

Whenever possible, some of the farm’s maize fields will be turned over in the autumn with the aim of opening up the soil with a single pass of a heavy-duty cultivator immediately after the crop has been harvested.

“It helps to stop any run-off from the field and prevents water collecting. Once there’s water standing in these fields it can take a long time to drain away.”

Keeping any “traffic” off maize fields until the land is dry enough to start proper cultivations is paramount,” says Mr Grandfield.

“The aim must be to produce the best possible ground conditions for drilling and not be tempted to start until the weather allows that.”

Ian Granfield (left) and David Stewart.

Once conditions are dry enough for slurry to be applied, the land is ploughed. No pre-emergence weed killer is used but a post-emergence treatment is applied to young weeds – although to specify that this takes place at the four-leaf stage is considered too precise.

“Once we start to plough we like to push on as fast as we can and usually have everything drilled within 10 days,” says Mr Stewart.

“We don’t want to go too deep – shallow enough to do the job and yet invert everything that’s on top to bring up good-quality soil. Anything deeper than ploughing to more than 20cm will bring up poorer soil that’s too cold.

“We do try to subsoil each year if we can but it depends on the season and the timings. We like to start sowing maize by 15 April if conditions allow, but would be happy to leave it until the last week of April, but not into May.”

A key element of the changes made to improve maize establishment has been the way the land is “worked” after being ploughed.

“We look at each field individually and on this land may have to go through once with the power harrows but then follow that with the crumbler to create the correct seed-bed conditions.

“Once we’re happy with the seed-bed we don’t waste any time getting the crop drilled.”

Liquid ammonium sulphate provides the N source and is applied with the ploughing. The target is to achieve 370kg of N/ha (150kg of N/acre); any of that amount not reached with slurry applications is topped up with ammonium sulphate.

“The liquid ammonium sulphate is slow release so it feeds the plant all the way through the growing season and is there when the plants have a really big demand in July,” says Mr Grandfield.

“While a yield of 15t or 16t/acre can be achieved without giving the crop any additional nitrogen, an appropriate application can add another 5-6t/acre to the yield.”

Seed rates

But dairy farmers with high phosphate soils should not assume there’s enough available to meet the needs of young maize plants.

“Phosphate can be slow to become available to developing maize seedlings unless ground temperatures are rising. A starter fertiliser will avoid the challenges young plants face in a cold spring.”

Seed rates have also come under review at Ferny Lees Farm. The new seed rate is 123,500 seeds/ha (50,000 seeds/acre) to achieve about 111,150 plants/ha (45,000 plants/acre).

“The 50,000 rate is the optimum level to optimise yield and starch levels. Sowing maize early enough to achieve optimum establishment, but not so early that germination will be adversely affected by cold, wet ground conditions, is the big challenge for dairy farmers,” says Ian Grandfield.

Several years of trials looking at seed-rate impact on cob production have been undertaken on Cheshire farms by Mr Grandfield, who says farmers should aim to get 45,000 plants/acre or 11 plants/sq m.

His trial work results continue to show that 45,000 plants gave the best total yield of plant and cob while maintaining a high cob:plant ratio.