Can uncharacteristicly wet seasons have an impact on no-till fields?

 

Can uncharacteristicly wet seasons have an impact on no-till fields?

By Egon Zunckel

 

I was uncharacteristically quiet at last year’s conference partly because we had a runaway fire on 150 ha of no-till fields and partly because of what I will attempt to explain in this article.

For years I had been crowing about the fact that I had had no problems with No-till with regard to diseases especially. Read this all the way through as I will conclude that the problem is not as simple as blaming No-till.

At the start of the 2009/2010 season I started planting my maize earlier than usual because of increased hectares to plant without increased planter capacity. We started planting in mid October when it was noticeably cool but we pushed on regardless as we needed to” keep the run rate up”. The maize took about 10 days to emerge and when it did it looked bleak. After a topdressing of Urea, these early planted fields looked ok and we thought that all was fine.

At harvest time we were shocked at the amount of lodged plants as well as poor yield in these early planted fields. The yield improved relative to the planting date with the mid November plantings yielding fairly well.

The first centre pivot field yielded 7 tons/ha with the dry-land corners yielding 8.5 tons/ha, all planted on the same day and same cultivar but reduced plant population and fertilizer. The irrigated maize was planted with 160 N : 40 P : 40 K. Some of our top yields over the previous 2 seasons were achieved with this level of Nitrogen. I heard that all the low N plots in the ARC trials planted at Ant Muirhead’s farm that season also lodged and that the high N plots stood well in spite of similar nematode counts. My soil analysis showed the N as depleted, P and K being acceptable.

Crops on my irrigated fields were rotated as follows: 2 years maize, 1 year soya with winter wheat following the soya and back to maize after the wheat. This rotation has worked well for years with our best maize yields being achieved after wheat.

I am grateful to so many people who rallied around to try and find answers to this problem and here is my summary of what was reported:

With the cooler temperatures at planting and subsequent slow emergence, nematodes took advantage of the situation and penetrated the roots allowing fusarium to enter through the lesions. It is easier for disease to attack a stressed plant. The ultimate cause of the lodging and poor yields was fusarium root rot.

My own observation of the problem is as follows: Cool temperatures at planting and subsequent slow emergence; 2 years of maize residue with traces of wheat residue from 2 years back, allowing a build-up of innoculum in these conditions ; Low N levels; and possibly poor leaf disease control. Numerous trials of root stimulants, tricaderma, bacteria and fungi have proved fruitless, maybe they need time to establish themselves.

I am approaching the problem with caution, Beware “revenge” tillage! I know someone who had every scrap of plant residue burnt off in a fire, tilled, planted an oats cover crop and still had serious lodging in the following maize crop.

I also know of someone who tilled their fields properly this last season and had unbelievable lodging.

On a recent trip to Brazil I discovered that they cover crop most, if not all of their millions of hectares to millet or crotalaria, one of the main reasons being to combat nematodes!

There is talk of possible residual glyphosate build-up in the soil, adding to our problems but I will not open that can of worms now!

I am trying cover crops as a solution to my problem having learnt a lot about their beneficial effect on crops. For 2 seasons we have noticed an improvement in maize and soya yields and health following cabbages.

Last year we planted a strip of canola into maize residue and found an improvement of 300kg/ha in the soya yield this year.

I invite readers to attend our conference this year where the focus will be on ley crops. There will be a visit to my farm to view and discuss cover crops of oats, rye and canola.

God Bless

Egon Zunckel