2016 No-till Corn on Gravity Irrigation

With the new species we tried in our grazing project last fall we felt we could improve our cover crop results. Our first cover crop efforts focused on low-carbon species and the sudan grass demonstrated the potential benefits for weed suppression by keeping the soil covered better.

So when the 2016 pea crop was harvested we slipped in on the old beds and planted our new mixture of sudan grass, forage brassica, forage radish, and red clover in late July. Then we recorrugated and put the water to it. I think the clover was planted too deep (1" or more with the sudan) and was unable to establish itself.



After 2 irrigations we could see our stand had some unusual spots in it. In places the sudan grass was completely absent in the mix and others the brassicas were missing. The only real explanation I can generate regards the initial irrigation. Some rows were very difficult to run to the end of the field and so got extremely wet; I think the sudan grass flooded out leaving only the brassica species.



Where there was not so much water, the sudan grass did well and choked out the broadleafs, I think.

By early October the sudan grass was 4-5' tall and at the end of it's growing season. In an effort to size the residue and aid in decomposition we decided to shred the sudan grass. Removing the top growth also gave the brassicas a chance to grow in the late fall and into next spring.



The shredder really did a nice job of chopping the residue to prevent problems in the spring plugging up corrugators or cultivators. With all that bio-matter on the surface we expected the winter and spring moisture to really help decompose it prior to irrigation time.



Despite the impressive appearance of the standing crop, it really condensed down with the shredder. The resulting mat was around 3/4" thick when green. After it dried the cover shrank further.



The areas where the sudan grass didn't perform well never did recover.



The radishes and brassica did well to compensate for the missing sudan grass and covered the ground well.

Our sudan grass cover was mostly decomposed by early April. All that remained now was to terminate the remaining species, clean up the corrugates, and plant the corn.



We had sprayed our cover crop about 3 days before we arrived with the corrugator. Our logic was to get the chemical on the plants before any dirt was on the leaves to absorb it. It was fairly obvious where the different species performed better in our cover crop mix. We never did see any real population of the red clover.



Our neighbor let us rent his disk corrugator since we didn't have anything quite like it in our lineup. It was a machine he cobbled together but really performed well in this situation. There wasn't much residue in the corrugates so we just moved enough dirt to reshape the furrows.



We only allowed the front points to run about 3/4" deep so as not to disturb any more than necessary. Then the disks just tossed the loose dirt up on the beds and we had nice clean furrows again.

Planting went very smoothly on this field now that we have a couple years' experience behind us.

The irrigation water ran quite well on the 1/4 mile rows. Cleaning the furrows with that disk corrugator was a key element in our irrigation success.

Terminating the forage brassica and forage radish after their winter cycle was very challenging (a phenomenon noted in a previous cover crop). If I remember correctly we used glyphosate (Round Up) and 2,4-D as our termination herbicides but they were not able to kill those bigger brassicas. It certainly slowed them down but the plants were starting to bolt and reproduce and would not be stopped. We had to use a post-emergence application of glyphosate and dicamba to finally eliminate them.