Manure bioassay results.

My 2018 potatoes were slow to emerge and grew with stunted, curled foliage.  They were planted in purchased manure so I suspected aminopyralid contamination.

Certain herbicides can linger even after passing through the digestive tracts of ruminants and can affect sensitive plants like tomatoes.  Time and the biological actions of soil inhabitants will eventually dissipate the harmful effects of these herbicides, but meanwhile I have to plan my garden for 2019.

To assess what will grow in the beds where I spread the manure I conducted a bioassay for seedling germination and leaf curl.  I did not test any sensitive plants like tomatoes since I will be growing those elsewhere.  I tested the seeds of plants that I wanted to grow in these beds.

After 3 weeks under indoor lights, I recorded the final results of how many seeds germinated in the manure versus the control (potting soil and vermicompost) and compared the seedlings for any signs of leaf curl or stunting.

Comparing seedlings.

Long story slightly shorter, I plan to go ahead and plant brassicas, beets, and carrots in the beds since they did not seem to suffer any ill effects.  Whether that carries through to harvest will remain to be seen.  Squash will also be planted out in these beds since they loved the manure last year and I suspect will do fine once again this year.  My potatoes will be planted in buckets and will hopefully produce a decent yield next year.  The other change will be to be much more careful with any products I bring in to supplement the garden soil.  I will be paying more attention to producing my own compost next year too.

Happy garden planning to you.


2 thoughts on “Manure bioassay results.

  1. I put manure in my potato pots as well this spring, and now know it was a mistake. Too much nitrogen caused the plants to produce 3′ plus tall foliage, and few, small potatoes. I won’t be using any manure at all in potato pots this year. Your test was interesting and something I might not have thought about!

    Liked by 1 person

    1. Hi Carolee. How big are your potato pots? I have used 4 gallon pails for one plant. Another fellow uses 10 gallons but puts multiple pieces in. I’m staying away from manure and will fill with a combo of compost and peat with a handful of slow release balanced org. fertilizer. Hopefully yields will be better than last year!


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