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Produk-inligting
April 2018
20
A look at the seven wonders
of grain production
P
rof Fred Below is Professor of Plant Physiology in the
Department Crop Sciences at the University of Illinois. Illi-
nois is right in the centre of the lush maize belt and it is here
that Prof Below specialises in examining factors which limit
crop productivity, particularly in maize and soybeans.
He has developed a teaching approach which he calls ‘intelligence
intensification’, which highlights the most important factors that
contribute to increased yield.
The world record maize yield was achieved this past season in the
USA at 34,1 t/ha. The average yield record was also achieved this
past season at 11,1 t/ha. The yield gap is the difference between
what the average grower gets and what the record yield is. This is
what Prof Below calls ‘the opportunity to increase maize yield with
better crop management’.
A review of yield contest winners has shown that all 18 winners
exceeded 20 t/ha in 2017, while five growers exceeded 25 t/ha
and three others, 30 t/ha. Prof Below says it all starts with two key
factors, namely better plant nutrition and making sure the plant is
never stressed. Other crucial prerequisites for yield improvement,
but not part of the seven yield wonders, are:
Drainage.
Pest and weed control.
Proper soil pH and adequate levels of P and K, based on
soil tests.
The seven wonders of
the maize yield world
The weather
The elements always dictate when you can or can’t plant your crop
and weather also dictates the success after planting.
Nitrogen
We can control N but we don’t have complete control over it. Every
single thing about N is influenced by the weather. There are many
examples of weather-induced N loss. In the USA there are even
climate programmes which predict the availability of N. Too much
rain and you will lose N. N moves downwards in the soil, which
explains the N deficiency after heavy rain.
He then asked if N moves downwards and not sideways and where
the best place to put the N would be. Their trials have shown that
placing the N along the row has been worth about 0,6 ton yield
advantage.
Hybrid/variety selection
All hybrids are not equal. In a trial between 44 commercial hybrids
grown at three different sites in Illinois, there was a 3,8 ton range in
yield at the Harrisburg site; a 5,9 ton difference between yields at
Champaign and at Yorkville there was a range of 7,6 tons between
the highest and lowest performing hybrids.
Prof Below says he is often asked which is the best hybrid:
The best hybrid is the fullest maturity for the region build.
The best hybrid is most often the newest and most expensive
one.
He says producers can’t afford to use the same hybrid four years in
a row and miss out on the benefits of improved genetics.
Previous crop
The previous crop grown in a field significantly impacts the new
crop. In this region crop rotation is predominantly between soybeans
and maize. Trials have proved that if soybean was the previous crop,
it will boost the next maize crop by +1,6 ton; whereas if the previous
crop was maize, it would negatively impact yield by -1,6 tons.
He calls it ‘the continuous maize yield penalty’ saying ‘it always
gets worse with time’. Prof Below credits this to crop residue build-
up over time (
Photo 1
). Residue acts like a sponge to prevent rain
from infiltrating. It ties up nutrients and also releases chemicals,
which interfere with the growth of the crop.
REVIEW
Congress
Special
JENNY MATHEWS,
SA Graan/Grain
contributor
Prof Fred Below