Evaluation over four seasons of a paper mulch used for weed control in vegetables

A paper mulch, derived from recycled fibres and formed into sheets for application using a purpose-built machine, was evaluated in vegetables from 1994 to 1997. In the first of three experiments, paper was used to suppress weeds in lettuce and calabrese crops that were grown in the same locations on silt and pear soils for three or four successive years, respectively. In the final year, two sequential crops of lettuce were planted in the same location on each soil type. The paper mulch was rotovated and ploughed into the soil at the end of cropping in each year. The paper mulch was compared with a black polythene mulch and a standard herbicide regime. The paper and plastic mulches suppressed weeds for the duration of cropping, a maximum of sixteen weeks. Both paper and plastic mulches gave similar or higher mean head weights than herbicides for both crops, except in 1996, when plastic gave a heavier mean head weight than both paper and herbicide. Soil samples with incorporated paper mulch residue (up to 5 tonnes/ha applied over four years) gave levels of heavy metals and organic micropollutants similar to soil in hand-weeded plots. In a second experiment, paper mulch increased soil moisture levels in nonirrigated courgettes but not in irrigated celery compared to non-covered soil. In a third experiment, the effects of the paper mulch on soil temperatures at 0-10 cm were observed on courgettes and celery sown on sand and peat soils. Soil temperatures beneath the paper mulch were lower than both the non-mulched and black polythene-covered plots.