Off to a Good Start?

During the days following planting, optimum soil temperature, good seedbed preparation, viable seed, proper planting depth and spacing, and favorable weather conditions lead to excellent crop establishment. Wait! Did you think about ensuring proper nutrition? Sometimes, we believe a simple pre-plant application of a little N, P, and K is sufficient. But is it?

In that little package we call “seed” is found all the stored energy and nutrition needed for germination. It’s enough nutrition to send a small bundle of roots into the soil, expand the cotyledons, and develop a couple of small true leaves. After that, the plant is expected to capture sunlight utilizing its chlorophyll, as well as obtain nutrients and water from the soil. It must be self-sufficient because the stored energy and nutrition in the seed has already been expended.

At this very young stage of growth, the plant has a limited root system. It faces significant risk and stress from:

• Variable spring weather conditions
• Competition from pests such as plant-parasitic nematodes
• Root and shoot diseases
• Insects and weeds
• Impacts from early season herbicide applications and/or cultivations that may physically damage roots and shoots or alter metabolism for short periods of time

Pop-up or starter fertilizers are beneficial at providing a nutritional boost at this critical stage. One of the key nutrients at this growth stage is phosphorus. Phosphorus’ role in plant nutrition includes photosynthesis, respiration, energy transfer, cell division and enlargement, transfer of sugars and starches, and nutrient movement. Phosphorus is also an essential component of DNA and RNA which tells the plant how to grow.

Plant uptake of phosphorus occurs primarily in the orthophosphate forms of HPO42- or H2PO4-. Many crops respond favorably to available phosphorus early in the season, and a continuous supply of phosphorus is important throughout the entire life cycle of the crop. Since phosphorus moves in the soil solution primarily by the process of diffusion, cool soil temperatures and often wet or saturated conditions experienced in the spring slow the rate of diffusion. This can sometimes result in temporary phosphorus deficiencies, leading to slower plant growth. Soil phosphorus is subject to precipitation by iron (Fe) and aluminum (Al) in acidic soils, and principally by calcium (Ca) in calcareous soils, also rendering it less available for plant uptake. It’s necessary to ensure adequate phosphorus in the right form and in the area near the young, developing roots early in the season to get the crop off to a good start.

- Michael Larkin, NW Division Agronomist