Wednesday, June 8, 2011

The second fallow

Despite all the wet weather, the nitrate comes bouncing back after the wheat harvest. Over 32 days the nitrate jumps from 23 to 109 kg N per ha. In other words the soil organic matter is mineralising at a rate that supplies 19 kg N per ha per week, even faster than we saw after the sweetcorn crop a year ago.

My gardens have had regular applications of compost over the years, which of course is a good thing. But you can’t turn the microbes off, and so in warm wet soil they are having a field day. The implication of this is that the soluble nitrate must now be managed by very careful irrigation. Even a bed managed ‘organically’ can be swimming in nutrients in a highly soluble form.

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