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Preparing For Difficult Growing Conditions


Cold, wet weather with low PAR light and few or shortened growing degree-days made 2019 a disastrous year for agriculture in many parts of the United States. It delayed planting in some areas and prevented planting in others — all resulting in a shortened growing season. Much of the same was predicted for 2020. Developing a plan to mitigate the effects of difficult field conditions is essential for the farmer to survive and crops will need all the help they can get at the very start. So, what do we do to play catch-up and even avoid having to replant?

Get a good start with starter fertilizers

“Pop-Up”/Starter Fertilizers can be game-changers to your ultimate success. Getting your crop off to a healthy, strong start is more important than ever in persistently poor conditions. Conditions such as compaction, crusting, cold soil temperatures, salinity and wet/dry soils are detrimental to most crops.

Achieving good starts with rapid and strong early root development is essential — then followed by in-season monitoring utilizing sap analysis to proactively achieve balanced nutrition. While season-long balanced plant nutrition is needed to minimize plant stress for best yields and quality, phosphorous is the foundation for good roots, early fruiting and uniform maturity.

Utilizing proper adjuvants based on soil type is essential for keeping the phosphorus plant- bioavailable for an extended period of time to keep the rhizosphere active during less than ideal conditions. The solubilities of other elements to form compounds holding or binding phosphorous are directly related to soil pH. The pH range of greatest phosphorus availability is 6.0 to 7.0. At a lower pH (< 6.0), when the soil is very acidic, more iron and aluminum are available to form insoluble phosphate compounds. In strongly alkaline soils (> 7.0), more calcium and magnesium are available forming insoluble phosphate resulting less available phosphorus.

The use of starter fertilizer is a source of debate for many agronomists. Most growers see the benefit of early uniform harvest but are likely to over-fertilize. There are hazards to using fertilizer in close proximity to the seed and this scares-off many advisors from recommending it. Like physicians, advisors’ first concern is to “do no harm.” It is easiest to say, “Just Don’t Do It.”  

But in dire times, the battle for profitability and survival requires stepping out of a traditional “safe” zone.

Starter fertilizer risks and benefits

Due to their close proximity to the roots, starter fertilizers in particular, with high salt indices are to be avoided, as they cause reverse osmotic pressures on the roots resulting in dehydration of the plant — resulting in stress or death. Accordingly, components of starters must be carefully researched and selected.

The risk of seedling injury is higher in sandy soils due to the low CEC of such soils causing more nutrients to remain in solution. The injury risk increases under dry conditions because of higher concentration near the seed for extended periods of time. Salt injury from fertilizers is typically not a problem if fertilizer and plant roots are separated by time, distance or both.

Starter placement for maximum benefit has been shown by research to be most beneficial when germinating seeds’ first roots immediately hit a band of high phosphorous — especially in cold, wet soils. It is safest to place the band of starter fertilizer in-furrow in a 2×2 band (two inches below and two inches on each side of the seed). With this placement, the risk of seedling injury is virtually nonexistent.

Be aware that the benefit of early phosphorous decreases by each additional half-inch away from the seed. Seed treatments are now available for sown crops. Dr. F.L. Fisher of Texas A&M University was one of the first researchers in starter fertilizer in the early 1960s.

Phosphorous by itself is seldom harmful. It is the other plant nutrients in fertilizer, which have high salt that can harm germination and plant growth. Nitrogen, potassium and sulfur have high salt indices and should be kept to a minimum but are beneficial early as are micronutrients such as zinc, iron, manganese, copper and boron in minute amounts.

Use fertilizer sources and rates that minimize the chance for injury. In addition to salt injury, some N compounds (such as UAN, urea, and ammonium thiosulfate) produce free ammonia, which can cause poor germination or seedling death.

The best fertilizers for seed-row application have a low salt index and N compounds that do not produce free ammonia, and potassium phosphate rather than potassium chloride as the K source. Additions of carbon sources such as humic/fulvic acids, amino acids and sugars also help protect the seed and buffer the fertilizers. They also help keep the fertilizer in a bioavailable form for extended periods — especially in cold or alkaline soils.

These carbon sources also feed the soil life thus increasing the microbial activity, which slightly raises the soil temperature, enhancing germination. Areas with potential for heavy surface crusting that may interfere with germination, over-the-top applications of soil inoculants (beneficial soil bacteria) can help alleviate this potential problem.

Additionally, a multiple hormone (auxin, cytokinin, gibberellins, seaweed/kelp) formula can yield dramatic results, especially during prolonged bad weather. Root systems are a plant’s lifeline and the use of plant hormones with starter fertilizers or foliar-applied can give a plant the best chance at success.

The bigger and healthier the root system, the bigger and healthier the plant. It has been proven that the use of these products can:

  • Promote the growth of roots and shoots;
  • Improve early season vigor;
  • Enhance a crop’s ability to produce its own natural growth hormones;
  • Reduce early season stress with increased healing abilities;
  • Increase the overall health of the plant, and
  • Increase both yield and quality.

Again, many consultants avoid using these, as they don’t well understand them and they must be fairly precisely applied.

Application info

Phosphorous can be sprayed directly on the seed but caution is advised, as too much of any good thing can be harmful. Use products that are designed for foliar application and have low salt indices. Only one quart per acre of a high phosphorous formula next to the seed is needed to produce benefits. It is generally recommended that one to three gallons per acre of a high P formula be used that contains a balance of nutrients. This should be mixed with enough water to allow accurate application. Five gallons per acre total solution is minimum but a 10-gallon per row-acre rate would be much better for dilution as well as accuracy of application.

Application equipment must also be functioning properly to deliver uniform rates of starter fertilizer when using in-furrow placement. Fertilizer injury often occurs from problems with application equipment on the planter. A common problem is getting rates too high due to improper settings or calibration, or unequal distribution on liquid systems (some rows receiving more than others) that can lead to over-application and fertilizer salt injury.

Foliar applications while crops are under stress from excess soil moisture and cloudy conditions for extended periods are highly effective. Plants under prolonged anaerobic conditions will be stressed and have retarded development. Supplementing with a balanced phosphorous formula can boost plants while mitigating stress and enhancing development. Guidance from sap analysis at critical stages of plant development is used to formulate the proper foliar program and customize it to specific crop needs. This is essential to playing catch-up in times of duress.

First feeding the soil and then the plants with a balanced diet at their critical stages of growth will accelerate maturity, lower production costs and increase yields and profits.

Noel Garcia is a senior consultant at TPS Lab.

Editor’s Note: This article first appeared in the January 2020 issue of Acres U.S.A. magazine

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