Sunday, 28 October 2012

Increased Cereal Seeding Rates

Increasing Seeding Rates in Cereals

When it comes to seeding I often find alot of growers who consistently seed their wheat or durum at 75lbs/ac, or somewhere in that range. This may achieve a decent plant stand, but opens you up to a few factors as I will discuss later. Plant stand density achieved through a seed rate like that is going to depend on several factors such soil temperature, whether the seed is treated, depth etc. What should be happening is growers are sending away their seed for a seed test to get levels of disease as well as their, germ, vigor and thousand kernel weight. What you can do with this information is plug it into this thousand kernel weight formula ((lb/ac) = desired plant population/ft² x 1,000 K wt. (g) ÷ seedling survival rate (in decimal form such as 0.90) ÷ 10.4) and play around with your target plant stand density to get an accurate seeding rate. What I want to talk about today are some of the benefits of targeting an increased plant stand density of something like 28-35plants/ft2 vs targeting 20-24plants/ft2.

The first thing I like about a higher seeding rate is the "insurance" type aspect. With wireworms levels climbing in alot of areas across the prairies and suppression options that need them to feed on 1-2, even 3 seeds before it knocks them out, you can still lose a significant percentage of your stand in some situations. If you target 32 plants per foot square then you can afford to lose a couple plants in a foot squared area, where as if you only have 20 plants to begin with, you are losing yield potential.

The next benefit is increased weed competition. This allows your crop to choke out weeds vs. it being the other way around. A vigorous stand with more plants is going to more efficiently cover that ground and out compete weeds. This is even more helpful if you are held up a few days or more at in crop herbicide timing.
This increased competition is evident within the crop itself as well. More plants forces them to actively scavenge for nutrients and water, and this forces them to grow at a faster rate to capture sunlight. What this means is that you are pushing your crop along at a faster rate, decreasing time to maturity. I had a producer in my area this year do a trial where he seeded at the rate he normally did (85lbs/ac) and then do part where he seeded at about 130lbs/ac. The maturity difference was about 6 days. This could be huge in years with an early frost or years where seeding is pushed back late.

Increased plant stands typically show increased stage uniformity across the field. The reason for this is that when you have a lower stand, you increase tillering. Sometimes tillering is inconsistent and it takes an extra 3 days or so (give or take a day) for extra tillers to develop. If you have areas of the field producing an extra tiller that puts your staging difference at around 3-4 days. Doesnt sound like much, but all of a sudden you are looking at spraying for fusarium head blight and this can significantly affect efficacy because of the off timing in parts of the field.

I just touched on fusarium head blight and another area that increased seeding rates help with quality and length of time susceptible to stresses such as insects or disease. If you have increased tillering (say 1 main stem, 4 tillers) that means you have an increased length of time that your crop is  in anthesis and therefore susceptible to wheat midge, ergot or FHB.  If you only have 2 tillers, then that decreases your length of susceptibility by atleast 5 days or so (compared to 4 tillers).
On top of this you typically get 50% of yield from your main stem, and 25% of yield from each of the next 2 tillers. This adds up to 100% of yield potential. Are you willing to lose quality for zero gain in yield? To put even more emphasis on this, why would you want your crop uptaking more nutrients to put into a 4th tiller when you arent gaining from it? It is a waste of energy for the plant.

There has been wetter years recently and more plants does help in cases of excessive moisture. Under drought conditions is the only time where you may see a negative drawback on higher density levels.

Some may have good luck with low seeding rates (I was in a durum field seeded at 45lbs/ac this year, 6 tillers per plant), but I would highly reccommend giving a high seeding rate a try on atleast one field. I talked about my trial earlier and this grower will be seeding everything heavier in 2013. It is a reletively inexpensive investment per acre and has some real benefits.

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