Help understanding how to apply fertilizers after getting soil test results

Asked March 21, 2017, 10:06 PM EDT

Hi, I am a beginner gardener who eliminated invasives from my yard a year and a half ago and am now ready to plant this Spring. Following the advice on your website, I got my soil tested for three areas of my property (results are attached). Looking at the results, it seems that I clearly need to add some nutrients to "front" area that I tested, but as a beginner, I want to make sure I understand how to add these nutrients. For the 25 lbs of lime/1,000 square feet that it is recommending, from my online research so far, I think I need to purchase a bag of "pelletized limestone" (I also see an option for "fast acting" lime on the garden store website - which is better?) and then rent a "drop spreader" or "rotary spreader" to add this to the entire area. Are these easy for an amateur to use? Next, the recommendation tells me I should add P205, which I think is Phosphorus. I searched for Phosphorus on my local garden store website, but nothing came up, so I did a web search and I see one gardening site saying I can add Bone Meal instead, but that seems to contain nitrogen, phosphorus, and calcium in a 6-12-0 ratio. That does not seem to match the ratio called for in the recommendations, so what should I do? For the K2O (which is think is potassium), I don't see a fertilizer which only contains potassium either. I am feeling perplexed about what I actually need to purchase to follow these recommendations. If I simply need to settle for a mix, what would the ratio be that I should look for given my results? Also, am I correct that these other amendments (the ones not lime) are simply mixed into the top couple of inches around the plants I put in? Finally, for the other two areas of my property, which I am also attaching results for, I was happy to see that all of the readings were medium to optimal. Do you think it is really necessary to add any amendments? I will be planting Pennsylvania sedge on the area called "hill" and shade-tolerant native perennials on the area called "left". The "left" area has a very high level of compost matter, and I suspect that a previous homeowner left woodchips from a cut tree all over that area. But the soil seems to have good nutrients. Do you think the plants would do ok if I left the "left" and "hill" areas alone?

Montgomery County Maryland

4 Responses

Thank you for your question.
Pelletized lime is fine to use as is agricultural limestone. The pelletized lime is a little easier to distribute evenly. Some type of spreader would be helpful but you can broadcast by hand if spreader is not available.

The soil test lab assumes you will spread the recommended amount of fertilizer over the entire area. Yes, it's best to mix dry fertilizers into the top few inches of soil.

Nutrient levels are adequate for the "hill" and "left" samples so that no fertilizer is necessary. The organic matter levels are quite high and nutrients will be slowly released from that soil organic matter, especially once soil temps rise. A soluble fertilizer mixed with water and applied around new plants will get them off to a quick start.

The "front" sample will receive the 25 lbs. of lime. Selecting fertilizers, in your case a source of phosphorous and potassium, can be very confusing. The simplest and least expensive solution would be to apply 50 lbs. of 5-10-10 fertilizer per 1,000 square ft. That would give you 5 lbs. of potash plus 5 lbs. of phosphate and 2.5 lbs. of nitrogen.

You could also buy the phosphate and potash separately. You'd need 6.5 lbs. of super triple-phosphate (0-45-0) and 8.3 lbs. of muriate of potash (0-0-60) per 1,000 square ft.

In either case you could cut the amount by as much as half if you want to apply fertilizer only to the holes where plants are going. JT

Further clarification on fertilizer application based on soil test recommendations

Thank you - your response is so helpful and I'm extremely grateful for your assistance. For the lime application to the "front" sample area, that is helpful to know that it can be broadcast by hand. Do I understand correctly that "broadcast" simplly means that it should be sprinkled evenly over the soil, not worked in? If I broadcast by hand, does this mean I can simply use gloves to pick up handfuls of the lime to sprinkle it around the application area as evenly as I can until the recommended amount is used up? I also want to check the measurements. The recommendation calls for 25 lbs of lime per 1,000 square feet. My area is about 30 feet by 20 feet, which is only 600 square feet. So, I think that means I should be spreading 15 lbs of fertilizer over the area, not 25. Is that correct? Also, can I apply all of the lime called for now, or do I need to do it over the course of a longer period of time? With the other fertilizers for the "front" area, I think it will be best to apply only to the holes where the plants are going. I see a 10 lb. bag of 5-10-10 (N-P-K) at my local garden store. It is called "tomato and vegetable food" but the description says "all purpose" so is that ok? How many lbs would I need to purchase for using in holes for 40-50 plants that I will add to this "front" area? Also, some are going in this week as bare roots, and some will be plugs planted in a couple of months. Is there anything I need to do differently when mixing in the fertilizer for bare root vs. the plugs? Again, thanks so much for your help. As a beginner, I would feel lost without this MD Extension Ask and Expert Service!

If the area is bare, it would be okay to work the lime into the soil. Otherwise, you can broadcast over the soil. Rain and earthworms will work it in. You can broadcast by hand and you can use gloves.
Your calculations are correct and you can apply the lime now.
The all purpose fertilizer is ok. Follow the directions on the bag for application.
Otherwise, sprinkle 1/2 cup of fertilizer around the plants. There is no difference between bare root versus plugs.