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Improving Soil Biology with Diverse Crop Rotations: Consistency Matters
Soil biology populations change with every crop, partly because different microbes like what different plant roots excrete and deposit. Then there are some biota that simply don’t like certain crops. For example, mycorrhizae don’t colonise canola but do colonise wheat and legumes. Legumes, in symbiosis with rhizobia, add soil N, which microbes also use. There are many other localised changes to the soil environment that crops make that influence soil biology populations to some degree.
Diverse rotations, therefore, keep up a steady supply of different foods for a range of soil biota. Enough experiments have shown that rotations with cereals, legumes and pastures will have more diverse pool of soil organisms than continuous wheat.
As for if the changes are long term, that depends on if you keep the rotation up. It’s a bit like flossing your teeth – it only keeps plaque at bay if you keep flossing. You could have diverse rotations for 20 years, but if you start growing continuous wheat the soil biota will change to reflect populations (including diseases) that like the conditions wheat creates
