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Water beading on compost

Sat, 18 Apr 2020 02:32:30 GMT

Last year one of the loads of compost we bought seemed to now allow water to penetrate easily. The water would bead up and run off. It made watering a challenge. I remember hearing someone talk about this in a podcast but I can't remember who, or the details. I am curious about what causes it and what the solution might be, just in case we run into the problem again.

Wed, 22 Apr 2020 00:37:54 GMT

I have had a similar issue before, the water would penetrate but the compost would not moisten. Very frustrating. Once it broke down more it seemed to hold the moisture better. I'm thinking that it just wasn't decomposed enough.

Wed, 22 Apr 2020 10:32:48 GMT

My understanding is that if the compost is too woody (oe what I call "mulchy") then the space between is too great for microbes to build the aggregates required to hold moisture. As they slowly break it down, they are more able to lock those pieces of organic matter together and create a greater water holding capacity (think of it a bit like sand). We've run into this a lot when seeding. If it's not broken down enough seeds won't germinate. Adding a little peat can help or seed a little deeper than usual (ie 1/2 inch instead of 1/4 inch for carrots). You can also rake a little of the top layer off if it's just mulch, seed, then rake it back over top.

Wed, 06 May 2020 20:51:56 GMT

It happens to us too. Very slow and frequent watering with very fine microsprinklers over the composted beds did the trick for us. We could observe the change of this hydrofobic behaviour in the compost piles themselves in parts that were not covered, frequent rains would eventually manage to soak the particles and make them hidrophilic. This reminds me of how some microfilament kitchen cloths work, they need to be soaked then wrung to achieve good water absorption, otherwise they just push water around when dry.

Mon, 11 May 2020 14:58:22 GMT

super helpful everyone, thank you. I was worried it may be more of an issue but as long as we can adjust our watering schedule to penetrate better, and seed a little deeper I think we should be good. So far this year's compost deliveries haven't had this problem but glad to understand it a little better.