Farm Progress

Winter months an excellent time for western alfalfa growers to test the soil for nutrient deficiencies, and correct levels if needed.

Dennis Hannaford, Crop agronomic support

January 11, 2017

3 Min Read
Winter time is the perfect time of the year to check nutrient levels in alfalfa fields.

While alfalfa is mostly dormant during the winter months, growers should still pay attention to the crop since this is an excellent time to test the soil for nutrient deficiencies – and correct them if needed – in time to promote a healthy environment for new spring growth.

Now is a good time for growers to conduct a soil analysis to ensure the growth of a quality alfalfa crop. This is an important strategy when prices are lower since buyers are looking for – and willing to pay a premium price –the best nutritional feed on the market.

The main nutrients levels to assess in new and existing alfalfa fields include phosphorus and potassium. When asked to run a typical alfalfa analysis, a lab will also check the soil pH, sodium absorption ratio (SAR), and other minerals.

A newly planted field typically has a pre-plant amendment so there isn’t much work to be done unless an analysis wasn’t completed. In this case, it can be done now to discover any deficiencies to determine if a correction is needed.

In existing fields, Netafim suggests that growers start sampling areas where deficiencies are more apparent so that corrective action can be taken now or in the spring.

While growers are struggling to make economic decisions with depressed prices, it’s important not to cut important nutrients from the equation.

Seth Rossow, ranch manager at Bert Wilgenburg Farms near Merced, Calif., understands the tough decisions facing alfalfa growers. Another part of the farming operation is a dairy in Hanford which supplies him with dairy manure alfalfa production.

Rossow composts it to spread on the alfalfa fields. He agrees that soil testing is important to correct nutrient deficiencies. He applies compost in the fall anticipating enough rainfall to incorporate and activate the compost. This winter’s storms hold promise for achieving this goal.

He can also flood the fields if needed which can also reduce gopher pressure that can harm his drip lines.

Dry fertilizers can be applied during the winter months if not applied in the fall. Amendments or manures should be applied to the ground’s surface, followed by watering by rainfall or flood or sprinkler irrigation to incorporate the material deeper into the soil.

Drip irrigation is not a good method as the water stays at a shallower depth. An added benefit of getting a deep wetting via rainfall or flooding the fields is that it helps mitigate salts out of the crop’s rooting zone.

“I do a soil analysis during the winter because alfalfa pulls a lot of potassium out of the ground, so I’m trying to put that back in,” says Rossow.

“Soil naturally has a lot of potassium in it, and compost will help increase the biological activity of soil microorganisms to mineralize and make available potassium in the soil, as well as the potassium that naturally comes from the compost to make sure we have adequate levels.”

He adds that alfalfa also likes a lot of phosphorus which the compost also provides. When prices are better and if nutrient levels are low he adds a foliar application.

“The compost is giving us a lot of what we need so we continue to add that so we don’t lose momentum,” Rossow said.

About the Author(s)

Dennis Hannaford

Crop agronomic support, Netafim USA

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