Seed is the most vital input on any farm, as without a seed we do not have our desired crop. While there are several factors that will affect seed germination and seedling survival we will focus on in-furrow nutrition impacts on the crop. Early nutrition for the developing seedling is important, however we can be caught up in a “too much of a good thing” situation if we aren’t cognizant of the risks associated with in-furrow nutrition. Key factors to consider when placing fertilizer with your seed are seed bed utilization (SBU), soil texture, soil moisture conditions, and fertilizer source.
A soil test is a great place to start when planning any fertility program. When looking at developing a 4R fertility program (right rate, place, time, source) we look at each nutrient individually and how we manage their application in our program. Mobile nutrients such as Nitrogen and Sulphur are well suited to banded applications such as a fall or spring bands, side-band or mid-row banding operations away from the young seedlings as they will move in soil solution to reach the roots of the crop. Non-mobile nutrients such as phosphate and potassium are best suited to a placement in closer proximity to the seed and at the time of seeding, taking into consideration safe rates in the seedrow.
Phosphate is perhaps the most important nutrient to have in-furrow or close to the seed furrow (sideband) as it is vitally important in energy production in the plant and is relatively immobile in the soil so proximity to the rooting zone is paramount. We often refer to the “pop-up” effect using seed-placed phosphate fertilizer which is important to getting the young crop off to the best start. Our main sources of dry phosphate in Western Canada are either monoammonium phosphate (MAP) or products that use MAP in their primary makeup. MAP has a low salt index and has low toxicity to seedlings compared to other nutrients such as potassium chloride or urea for example. Maximum safe rate guidelines have been established in each province using MAP and based on a set SBU and utilizing good to excellent soil moisture conditions.
Seed bed utilization takes into consideration how wide your opener is divided by your implement’s row spacing, for example a 1” opener on 10” spacing would utilize 10% of your potential seed bed. Wider row spacing with narrow openers will concentrate your seed and seed-placed fertilizer band which can lead to increased potential for stand reduction compared to wider openers with narrow row spacing. Soils with a higher clay content will be able to buffer the “salt-effect” of fertilizers more readily, as well with higher seedbed moisture we will see less negative impact to our germinating seed.
In the end it is hard to say there is a perfect formula as to what is a “safe” in-furrow rate of fertilizer with the seed. Each farming operation will differ in their land characteristics, moisture situation from year to year, and obviously equipment considerations. Growers would be well served to evaluate their stand establishment with their current program and evaluate what impact their current practices are having in their operation. Consulting with your local crop advisor can help in working through the variables in determining your best path forward on your fertility plan.
For more information visit ProvenSeed.ca