Mustard Seed Meal is the defatted meal left after pressing oil from mustard seed (Brassica and Sinapis species), and it works on two fronts. As it breaks down in moist soil, naturally occurring glucosinolates are hydrolysed into isothiocyanates — the same pungent compounds behind mustard's bite — which act as a natural biofumigant, suppressing plant-parasitic nematodes and soilborne fungi without synthetic chemicals. At the same time it's a high-protein, nitrogen-rich meal that feeds the following crop as it mineralises.
This makes mustard seed meal a genuine dual-purpose input: a pre-plant soil cleanse and a nitrogen feed in one. It suits growers managing disease or nematode pressure in beds, no-till plots or reused living soil, and slots neatly into a reset between cycles. Because its biofumigant action doesn't discriminate between good and bad, it's worked into bare soil ahead of planting rather than around living roots.
