Why a new alfalfa strain is big news for hard-pressed farmers

A NEW plant with an old name is promising to simplify good soil management and cut back on fertilizer costs for hard-pressed farmers everywhere. It is a recently developed alfalfa variety with nearly twice the nitrogen-fixing capacity of ordinary strains along with one other significant attribute: It can be grown as an annual in the Snowbelt. This makes it far more attractive as a soil-building option for farmers reluctant to tie up land for the four to six years necessary to get similar results with conventional alfalfa.

Tests show that Nitro, as the new strain is named, will yield three hay cuttings in a season and still leave 94 pounds an acre of fixed nitrogen in the soil for succeeding crops. In contrast, the best conventional varieties put back about 59 pounds of nitrogen in a year.

Nitro is the result of a decade-long effort by a University of Minnesota research team, headed by Donald K. Barnes, Gary Heichel, and Craig Sheaffer.

``Minnesota has accomplished by conventional breeding techniques what was once considered possible only through genetic engineering,'' says United States Department of Agriculture spokesman Russell P. Kaniuka.

Potential benefits from the new crop include:

Significant production of home-grown nitrogen fertilizer for the following year's crop. Dr. Heichel sees it as ``a workable alternative for shaving nitrogen bills in these times of low profitability.'' Nitro can be used in rotation with more than grain crops such as corn and wheat, Mr. Kaniuka points out. It would also benefit truck farming's vegetable crops. Meanwhile, Nitro rates high in protein, making it valuable for pelleting or as a straight hay crop.

Control of soil erosion. Worked into erosion-prone, row-crop rotations, Nitro would act as a cover crop, its deep roots anchoring soil against wind, rain, and snow melt for most of the year.

The fact that it is winter-killed makes it ideal for no-till plantings where the new crop is sown in slits that are cut into the old cover. As well as adding nitrogen to the soil, the deep, fibrous root system adds considerable organic matter to the soil.

Agriculture that is less susceptible to rising energy costs. The United States is not self-sufficient in anhydrous ammonia, the principal feedstock for nitrogen fertilizer, so conserving it becomes important.

In 1978, when the Minnesota breeding program was little more than a year old, Heichel estimated that if ``10 percent of the nation's corn crop of 7.5 million acres were grown in rotation with alfalfa, the fertilizer saved would reduce the demand for natural gas by 28 billion cubic feet.... That quantity of natural gas, for example, would heat 440,000 Minnesota homes for one year.''

Now that Nitro has simplified the inclusion of alfalfa in a rotation program, the hope is that a majority of grain farmers might one day opt for this soil- and energy-saving approach.

When researchers began their concentrated effort to breed a super strain of alfalfa, they were looking only for improved nitrogen fixation. An annual hadn't been seriously considered.

But among the thousands of test plants, they noticed a few that tended to continue growing long after the others had begun to go dormant and ``harden off'' for the winter.

By enhancing this trait, the researchers came up with the present strain, which continues growing vigorously until stopped cold by plunging winter temperatures.

This extended growth period allows the plants to fix much greater quantities of nitrogen in the soil. In the process, they do not harden off in preparation for winter and are readily winter-killed in the North, effectively making them an annual.

Meanwhile, added reasons to return to good soil-management systems on US farms are contained in a lengthy article in the March issue of Scientific American. The authors, J.F. Power and R.F. Follett, both veteran soil scientists with the Agricultural Research Service of the US Department of Agriculture, have concluded that mono-cropping (repeated growing of the same crop on the same soil year after year) is losing its economic advantage because of degrading soils and an adverse environmental impact in general.

Nitro seed stocks (available through the Petersen Seed Company, in Savage, Minn. and the Andrews Seed Company of Ontario, Ore.) have been sold out for this year, but the expectation is that seed supplies will be plentiful next year.

The Minnesota scientists believe that they have only just begun. Commercial seed producers are now using Nitro as a genetic baseline to develop further one-year varieties. According to Dr. Barnes, these ``probably better varieties'' will be available in three to five years.