Fertility large part of New Mexico research team’s pepper studies

The high point for New Mexico chile pepper production was some 850 million pounds. Over time, that figure has dropped until, in 2007 (the most recent data available), the crop was near 200 million pounds.

That is due toa combination of things, “but much of the drop has to do with imports from Mexico and other countries,” says Robert Flynn, New Mexico State University Extension agronomist. “They can produce peppers cheaper. U.S. import levels have risen from less than 100 million pounds in 1989 to near 600 million pounds in 2000.”

U.S. pepper producers are at a distinct disadvantage from the foreign competition. Foreign farmers “might pay workers as little as $2 per day compared to the U.S. minimum of $50 per day. Worker pay is probably where the cost of production is greatest.”

Still, the pepper industry in New Mexico remains major and researchers are tackling a variety of management questions. “Growing peppers, there are so many things that can go wrong. Yet, so much can go right!”

The pepper research group “is mostly interested in green and red peppers – many operations grow red for both spice and color,” says Flynn. “The red chile has been developed so it can be mechanically harvested. That segment of the industry is what I’m most familiar with.

“The need for specialty crops in the U.S. is increasing. Unfortunately, production is going down with rising labor costs and declining profitability.

From a fertilizer and plant nutrition point of view, Flynn and colleagues’ research projects “center around identifying nutritional needs of peppers that promote higher production with minimal nutrient waste.”

However, that’s only one aspect of the larger pepper team. “Fertility is important for chile. However, total farm management and attention to detail like cover crops, previous disease pressure, scouting for insect damage, weed management and other things are also critical.”

What is an optimum pepper fertilizer regime versus the typical regime?

“We’re still working on the optimum. It must be balanced with saline water supplies, saline soils, insect and disease pressure, crop rotations and other things.”

Most of the team’s work has found that management timing for the application of micronutrients and also major nutrients – nitrogen, phosphorus and potassium – is critical.

“Say we’re shooting for 3,000 pounds per acre of dry red chiles and there is a low level of N, P, and K in the soil. A normal soil test in our area might show a pH of around 7.6. If the soil test showed nutrients were lacking, we’d come back with up to 200 pounds of fertilizer nitrogen per acre and anywhere from 60 to 80 pounds of P2O5 and up to 100 pounds of potash.”

Flynn again points to the importance of timing. As in other crops, there are key growth stages in a chile’s life.

“We’re working to establish critical plant nutrient levels and needs at those times. That way, farmers will be able to tell if they need to focus on supply extra nutrients for optimum yield.

“Even though we might suggest 200 pounds per acre, we wouldn’t want all that going out at the beginning of the season. Getting nutrients out when the plants are in most need is one of our research focuses.”

To aid in that, “we’re tracking farms throughout the Chile Belt. There are roughly 20 farms being studied – ranging from 10 acres to 120 acres in size – for plant nutrition, fertilizer application timing, and tissue analysis. We’re checking nutrient content in leaf tissue and petioles to see if those can be used a predictor of adding supplemental nitrogen or any other needed nutrient. From those plots we see the differences between high-yielding versus moderate and low-yielding fields and see if those relate to fertility.”

One of Flynn’s goals: to help farmers use soil testing to make their seasonal fertilization plans. Does he suggest soil testing be done annually or less frequently?

Peppers are one of the first crops planted in the spring and one of the last crops out in the fall. Ideally, you’d want to soil sample every year. Under saline conditions, it’s best to sample annually. For farms not using organic amendments, depending on what they’re rotating out of, they should sample every other year to every third year depending on the crop. If they’re rotating out of alfalfa, it’s a good idea to go ahead and test – especially for micronutrients, independent of their past fertilizer histories.”

The agronomist also recommends irrigation water be tested.

“That’s to ensure the wells aren’t a source of potential problems. Surface water can also be tested although that’s atypical. But for some farms, surface water can be a source of salinity.”

Peppers tolerate a wide range of soil conditions “although they don’t like high saline levels. That can be managed with proper irrigation management to lessen salinity.”

Is sulfate of potash ever used on the pepper crop?

“Occasionally,” says Flynn. “Potassium sulfate (0-0-50-17S) could be used if sulfate is also needed.

Asked about a typical growing season for peppers in New Mexico, Flynn says producersprefer to get a crop in no later than March 15 – “planted, bedded and capped. That will protect from late-season frosts.”

In order to adequately provide nutrients for the crop’s beginning, soil tests should occur in the winter months.

“In New Mexico – and Arizona, as well – we don’t receive a lot of winter precipitation, so it’s nice to know what the carryover nitrogen content in the soil is. That’s plant available and ready to go unless the crop is under a flood irrigation system.”

Drip irrigation/fertigation is typical for pepper growers on sandier soils.

“That spoon-feeds the plants for most of the season. That’s a bit different of an approach. Yield potential is greater with improved water efficiency and timing of irrigation.

“Soil sampling prior to field operations helps establish a protocol for the starter fertilizers that are usually applied after the first irrigation, used for planting moisture. The application should be made at planting or at the point plants are un-capped or de-capped.”

All the while, a good scouting program from a certified crop advisor or equivalent “is very helpful for disease and insect management which are also very critical for optimum yield.”

Another management tool, winter cover crops – typically wheat – “can help decrease the amount of wind damage the crop can sustain in early spring after the plants have been de-capped. They’ll still pull rows and plant wheat in the furrows and then kill it out after the chile is planted. This practice can provide 12- to 15-inch-tall cover that protects the young chile plants when we have our strong spring winds.”

Another researcher on the team is tasked with studying leaf hoppers. “She has a good method of estimating what pressure that pest could be on a field of chile, what damage might be caused, because of a virus leaf hoppers transmit.”

Interestingly, leaf hopper problems in peppers are tied to rainfall. “Places where the insects overwinter are greater when there is winter moisture. So, growers should pay attention to winter rainfall.”

Back to fertility, Flynn says timing nitrogen applications to correspond with the period of rapid pepper growth is important. “Actually, in the future, we’ll likely have recommendations for growth regulators like there is for cotton. That will help limit plant size and focus on fruit development.”

TAGS: Vegetables
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