In Ireland, the annual recommended lists for the different crops are an essential guide to crop variety selection. These lists, along with variety trial results from seed, merchant and independent companies, help Irish farmers choose their varieties.

Here in Missouri, things are different. Farmers rely heavily on recommendations from seed suppliers and information found online, plus previous experiences, when deciding on corn varieties for the coming season.

This dependence led my host farmer, Kevin Rosenbohm, to take things into his own hands. With over 3.5m acres of corn (maize) grown in the state of Missouri, a state which is over twice the size of Ireland, Kevin decided to tackle this situation on his own farm.

Farm trials

In autumn 2016, Kevin began to plan a corn variety trial.

“We needed to get a handle on what would work on our farm and on a field-to-field basis and not to be dependent on what the sales guys told us,” Kevin said. By spring 2017, he had contacted each of the main seed companies and ended up sowing 67 varieties from 12 different companies in his farm trial. These included food grade waxy corn, feed grade yellow dent corn and white corn.

Kevin was no stranger to variety trials. He had conducted assessments on soya bean varieties for the past 20 years in conjunction with Graham Seed cleaning and Elite Seed, two value-added companies owned by Kevin and his family. This year’s soya bean trials focused on seed treatments and their cost justification.

All the corn varieties he tested were genetically modified – the specific traits included Roundup Ready, Liberty (glufosinate) resistance and BT-corn, which produces its own insecticide. The plots were planted on 24 April. The plot size was 16 rows wide (12m) and 190m long. The entire trial site took over 37 acres.

The yield was taken from the centre eight rows. The four rows on each side provided a buffer zone to prevent cross pollination between varieties. The target seed population was 31,000 to 31,500 seeds/acre. All varieties received the same husbandry treatments.

Monitored

The varieties were monitored by Kevin and seed company agronomists. Interestingly, there was a difference of 81mm in rainfall level from one end of the trial site to the other over the growing season.

The plots were harvested on 28 and 29 September using help from six people. A weigh wagon was positioned at either end to record plot/variety weight. A sample was taken from each variety to record moisture and test weight (specific weight) back at Graham Seed.

Large yield variations were found between varieties. The average yield across the plots was 222 bushel/acre (5.6t/ac), with a gap of just over 105 bushels (2.6t/ac) between the highest and lowest. Kevin acknowledges that this trial needs to be replicated for at least three years to add durability to these results.

His variety choices for 2018 were influenced by the trial results. All his seed for 2018 was ordered in early October to avail of early order discounts. Kevin estimates that these discounts provide a 10% saving on seed costs across all suppliers.

Kevin did not plan to share his one-year results but he changed his mind following multiple requests from neighbours and seed companies. He intends to repeat this trial in 2018 but will possibly drop out some of the lowest-yielding varieties.

“It’s a lot of work,” Kevin said, “and not too many farmers, researchers or private companies have done similar trials on this scale. But I think it’s worthwhile – we’re getting good information. Once we get three or four years’ data we will have identified trends.”