The Effect of Plant Mulches on the Nutritive Value of Red Cabbage and Onion

The effect of three methods of soil mulching: autumn or spring ploughing and leaving mulch as a cover crop on the soil surface without incorporation till the end of cabbage growth on the contents of selected nutrients in red cabbage and onion was investigated. The following plants were used as intercropped mulches: phacelia, vetch, serradella and oat. Mulching effects were compared to a non-mulched control as well as a farmyard manure application at the rate of 40 t·ha^-1. Nutrient content in both vegetable species depended on weather conditions and varied in study years. Accumulation of dry matter in cabbage was favoured by phacelia and oat mulches, irrespective of the date of ploughing. Non-incorporated oat and autumn-incorporated phacelia increased dry matter content in onion. An increase in the protein content in cabbage was observed when following serradella and vetch mulches. The protein content in onion cultivated in the second year following mulching did not change significantly as a result of the influence of examined factors. Among an the mulches taken into study, serradella and oat increased the content of vitamin C in cabbage. Similarly, autumn- or spring-incorporated oat mulch and non-incorporated serradella mulch increased the content of vitamin C in onion.