Impact of Different Green Manures on the Content of S-Alk(en)yl-l-cysteine Sulfoxides and l-Ascorbic Acid in Leek (Allium porrum)

This field study investigated the impact of various fertilization strategies with red clover (Trifolium pratense L.) green manure on the levels of S-alk(en)yl-l-cysteine sulfoxides (ACSO) and l-ascorbic acid in leek. Two of the 12 treatments were controls, one without fertilizers and the other with a commercial mineral fertilizer. The remaining 10 treatments were different forms and quantities of green manure prepared from red clover. One treatment consisted of direct incorporation into soil of the preceding red clover crop. The other 9 treatments comprised three types of red clover green manure [anaerobically digested red clover biomass (biodigestate), composted red clover, fresh red clover as mulch] applied at three different doses. Yield was increased only at the highest dose of compost and the highest dose of mulch. High doses of green manure decreased dry matter content in leek. The fertilizer treatments increased the nitrogen uptake and the nitrogen content of leek. Sulfur uptake and sulfur levels w...