Nitrogen in soil

Asked June 20, 2020, 12:23 PM EDT

Hello, About 2 month ago I purchased soil. They said it is Top soil plus their own leaf grow. I test planted a few crops, attached is a picture showing two Zucchini planted from seed at the same time one in my old soil and the other in the newly purchased one, both at the same environment. Seeing this I sent a sample of the soil for testing to UNIVERSITY OF CONNECTICUT. Attached is the result. I don't see anything bad in the results so I can only think of nitrogen amount in the new soil is the problem. Please advise.

Montgomery County Maryland

9 Responses

Hi- we can't see the plants clearly. Is there any leaf distortion or stunting in the squash plant in the new soil mix? If not, the small, slow growth could be attributed to low nutrients levels. If the growth does not appear normal you may want to test the new mix by placing some in a small container and planting bean or pea. If germination is very poor and/or plants appear stunted/distorted there could be an herbicide contamination issue.
Jon

I'll do the test and would let you know. Per sil test results that I sent you, soil nutrition is not bad or is it? Attached are 2 more pictures. Please see if these help.

Hi- the photo is a little too fuzzy to pick out the details we need to see. This is the potential problem we are concerned about. It's rare but needs to be ruled out:

The P & K levels are low so a complete fertilizer (contains nitrogen, phosphorus, and potassium) should be used to provide plants with needed nutrients. The soil pH is a bit high.

Just realizing now that you have a topsoil/compost mix in your containers. That could be the root of the problem. the mix is excessively dense to allow for good air or root movement. We recommend that people use 100% lightweight soilless growing media or a blend of soilless media and compost.
Please read this: https://extension.umd.edu/hgic/topics/soil-containers
Jon

Update 7/1/2020
Attached are pictures of 2 French Green Beans sowed on 6/23/2020 in the New soil (above) per your request. Night temperatures never went below 60 and hottest day was 93. Please advise.

Hi- the bean plants appear perfectly healthy so we can rule out herbicide contamination.

Container gardens filled with mineral soil (topsoil containing sand, silt, and clay) grow poorly due to compaction of soil particles in the container which reduces pore space, oxygen, and root growth.
Jon

Good to know the soil doesn't kill the plants. This soil was 5 cubic yards (3 yards of topsoil and 2 yards of leaf compost) that cost me $300, let alone the work needed to move it from driveway to the back yard. Please look at the soil test results and let me know what can I do to fix the problem.
Thanks.


7/3/2020. I am not sure if this helps or not. Attached are picture of another bean that was transplanted in the new soil on 5/3/2020. Other beans transplanted at the same time in old soil are producing and I already harvested some. In Bean-6 picture small furits are visible. In Bean-4 picture you can see one of roots is very Long, Bean-5 shows the end of this long root. Please advise.

Hi- the soil test (topsoil plus compost) shows low phosphorus and potassium levels. If you did not receive specific fertilizer recommendations you could safely add the following to bring up the nutrient levels:
5 lbs. of superphosphate or 11 lbs. of triple superphosphate fertilizer/1,000 sq. ft.
8 lbs. of potassium chloride (muriate of potash) fertilizer/1,000 sq. ft.

Our initial answer included a recommendation for fertilizing containers.
Jon

The bean plants and their roots appear normal. Differences in growth rates could be caused by many different factors.