The quiet cost of rice after wheat after rice
Two crops a year keeps land busy and families fed. It also draws down the organic matter that holds a soil together — slowly enough that nobody notices until yields stop responding to fertiliser.
Soil Science
The rice–wheat rotation is the backbone of the Terai. It is also unusually hard on soil. Rice wants standing water and a puddled, compacted layer that holds it; wheat wants the opposite — loose, well-drained, well-aerated ground. Every year the same field is asked to be both, and the switching costs are paid quietly, in structure.
Organic matter is what buffers that. It is the difference between a soil that holds water through a dry fortnight and one that cracks; between nutrients that stay put and nutrients that leach past the roots after the first heavy rain. It is built slowly, from roots and residue, and it is lost quickly — to burning, to removal for fodder, to continuous tillage with nothing returned.
The remedies are unglamorous and well established. Leave residue on the field instead of burning it. Put a legume in the rotation and let it fix nitrogen for free. Reduce tillage where the soil will tolerate it. None of these produce a visible result in one season, which is precisely why they are hard to advocate and easy to defer.
That is the argument for measuring. A soil test costs less than a bag of urea and tells a farmer which of these problems is actually theirs. Without one, fertiliser is a guess — and the usual response to a disappointing harvest is to guess higher next year.