Comparing Fertilizer Treatments on Commercial Tomato Production

Researchers compare liquid and conventional fertilizer treatments on tomato yield.

Flavor is of primary concern for tomato growers. High relative concentrations of sugars and acids result in a more flavorful fruit. Brix levels measure the Total Soluble Solid content, which is mainly sugars. Higher Brix readings indicate good soil fertility. Balanced phosphorus and potassium levels in the soil will ensure more even Brix development in the plant. In addition, higher levels of potassium in the plant also increases the acidity of the fruit. The best, most flavorful, combination in the fruit is a high sugar and high acid content.

Depending on soil type, 90-98% of total soil potassium is unavailable. Feldspars and micas are clays that contain large amounts of potassium, but plants cannot use the nutrient if it is trapped between the layers of those clays. In persistently dry soils, potassium remains unavailable, as there is no water film surrounding the soil particles. Over time, these minerals break down, and the potassium is released. However, this process is too slow to provide crops the amount of potassium needed for optimal yield. Typically, only 1-2% conventional potassium fertilizers applied to the soil is available at one time.

Micronutrient deficiencies can be difficult to recognize because they resemble other problems. For instance, in tomatoes, manganese deficiency produces yellowing, which can look like a sulfur deficiency or even be confused with nitrogen deficiency. Often tissue testing can determine the cause, but it is best to have a good soil test so any problems can be addressed ahead of seeing nutrient deficiency symptoms.

Why are micronutrient deficiencies increasingly being seen in the soil?

  • Increased yields due to various technologies means higher removal of micronutrients from the soil.
  • Some micronutrients are no longer contained in high analysis fertilizers and fertilizer materials.
  • Any type of land preparation which results in the removal of several inches of topsoil can result in a deficiency of certain micronutrients on the cut areas.
  • High phosphorus levels can induce micronutrient deficiencies.

AgroLiquid agronomists work with individual growers to determine the needs of their crops. Balancing crop demands, yield and quality goals, and environmental constraints is paramount to growers and the AgroLiquid team.