Lupin: A crop that doesn’t like water
July 29, 2013
Lupine: a crop that doesn't like water.
What's this all about?
Let me explain.
Is lupine a crop?
It's not a crop.
It's a weed — and a toxic one.
At least that's what I thought until I visited Australia.
The University of Wyoming in 1993 approved and funded my travel down under to study annual medic and ley farming. This led to the release of the first winter annual medic "Laramie," suitable for ley farming on the central high plains.
The concept behind ley farming is the rotation between annual pasture and cereal grain production.
I discovered that lupin spelled without "e" is a major high protein — 35 percent approximate — grain crop used primarily as stock feed.
Australia was producing 1.27 million metric tons of grain lupin annually at the time of my visit.
I was excited because, like soybean, lupin produces a large seed in pods that are on a high, rigid stalk, making it easy to harvest. Unlike soybean, it was growing on millions of acres of land with limited rainfall similar to what we deal with on the central high plains.
Obtain Seed for Trials
I gathered some seed from an Australian scientist for testing.
I made sure I got domesticated varieties, ones in which the genes for low seed alkaloid content — 0.010 percent approximate — had been incorporated along with the trait for a "softer seed coat." These wonders of plant breeding had made lupin a "crop."
The seed had made lupin a "crop."
The seed was now easy on livestock and easy to establish in the field.
Trials were conducted at the former University of Wyoming Torrington Research and Extension Center.
Because seed was limited, initial trials were under sprinkler irrigation where I believed I could maximize seed yield and increase my limited seed supply.
Results were disappointing.
The plants would start out looking okay but, more often than not, they would turn yellow and die before producing any seed.
Lupin is a legume, and, like most legumes, they require a specific bacterium to nodulate and fix nitrogen.
Maybe this was the problem.
Were the plants running out of nitrogen?
I had been careful to inoculate seed with the proper commercial rhizobium bacteria before planting.
So, what else might explain the problem?
I knew that the lupins I had tested might not perform well in our high pH calcareous soils.
Perhaps the poor plant performance was due to the bicarbonate in the soil out-competing iron and magnesium in terms of root uptake resulting in nutrient deficiency.
End of story — except for two things.
I became aware of a breeding program headed up by Bevan Buirchell of the University of Western Australia in Perth focusing on developing lupins for calcareous soils.
I contacted him, and he sent me some domesticated experimental lines for testing. The second thing was that I decided to try lupins on a dry land site as well as an irrigated site. Thanks to Dan Smith at the Sheridan Research and Extension Center, a dry land trial was conducted in 2004.
Sheridan results encouraging
The irrigated trial at Torrington is not worth talking about, but the dryland trial at Sheridan produced some encouraging results.
The plants on the right in the photo were of the greatest interest. They were very dark green and healthy, but the season ended before they produced seed, and the seed supply I held was all but exhausted.
Until recently, I have been concentrating on other crops, other research activities, and other duties; however, my passion has been crop variety development.
Therefore, once again I am pondering the lupin question.
Why did they do so well at Sheridan and flop in Torrington?
An Answer to the Puzzle
After reading more on the subject, I think I have come up with a possible answer.
I learned that lupins do not like water — at least not too much water.
A group of Australian scientists headed by J.D. Brand at the University of Adelaide found that "lupin genotypes were able to recover from chlorotic symptoms at 80-percent moisture in calcareous soil."
They survived much better than in soil at 100 percent and 120 percent field moisture capacity.
Apparently, as soil moisture drops, less bicarbonate is available to interfere with root nutrient uptake.
Had I been testing them under the wrong soil moisture conditions?
Is the lupin a potential crop in replacement of fallow in our wheat/fallow rotations?
I want to know so am gearing up to look again at lupin.
This year, I hope to increase the limited seed of lines I received from Buirchell in 2004, and, with the help of my colleagues at the James C. Hageman Sustainable Agriculture Research and Extension Center, establish a field trial on a dryland site containing four modern lupin varieties I hope to get from Australia.
If this trial pans out, developing this legume into a viable crop for the central high plains will take some time.
I have become an emeritus faculty of the university, but I still plan to work toward the release of an adapted lupin variety because I believe the benefit of potentially having an easily harvestable, high-protein dryland grain crop that can be used by the livestock industry is worth it. ❖
James Krall is a retired professor at the University of Wyoming's Department of Plant Sciences.
James C. Hageman is a specialist at the UW Sustainable Agriculture Research and Extension Center.
This article appeared in the most recent edition of "Reflections," published annually by the UW Agricultural Experiment Station and now available electronically.