Plant Residues and Newspaper Mulch Effects on Weed Emergence And Collard Performance
Small-scale urban agriculture production has become increasingly prevalent in the United States, due to an increased availability of abandoned property and demand for locally grown products. As with most agriculture production, weed suppression is a major concern for urban growers. Mulch is ideal for managing weeds because it is inexpensive and readily available. A variety of mulches have been found successful in conserving soil moisture, moderating soil temperature, suppressing weeds, and improving crop performance. These include continuous mulches such as black plastic, and particulate mulches, such as residues from cover crops. Disadvantages of black plastic, the industry standard, include impermeability and difficulty of removal and disposal. Alternatively, newspaper end-rolls (the unprinted remains of the newspaper printing process) may be a good alternative to black plastic in that they are permeable and biodegradable. However, newspaper has a high C:N ratio which can reduce soil fertility and crop growth. The primary disadvantage of plant residue is the large quantity necessary for adequate weed suppression, but combining newspaper and plant residues may provide adequate weed suppression with reduced mulch material and a lower C:N ratio. The objective of this research was to compare two continuous (sheet) mulches, newspaper and black plastic, with and without an underlying particulate mulch of killed cover crop. Field studies were conducted in 2011 and 2012 to determine the effects of mulches on soil moisture, soil temperature, weed growth, weed removal cost, and collard (Brassica oleracea L.) performance in a low input production system. Mulch treatments were newspaper alone, black plastic alone, cover crop alone (no overlying sheet mulch), newspaper + cover crop, black plastic + cover crop, and a control (no cover crop or sheet mulch). A 60:40 mix of cowpea [Vigna unguiculata (L.) Walp.] (84 kg ha-1) and buckwheat (Fagopyrum esculentum Moench) (107 kg ha-1) was planted on June 7, 2011 and May 18, 2012, and was used based on the species' rapid growth and low C:N ratio. The cover crop treatments were killed with a tractor-mounted undercutting crimper attachment eight weeks after planting. In the sheet mulch treatments, a single layer of black plastic or two layers of newspaper were rolled over the cover crop residues or bare soil and anchored with soil and/or staples. Collards were transplanted after mulches were established at 24 plants plot-1 (August 5, 2011 and June 29, 2012). In general plots with newspaper sheet had lower soil temperature and higher soil moisture than black plastic. Adding newspaper over cover crop alone improved weed control and reduced hand weeding costs compared to cover crop alone. Plots with newspaper sheets yielded as well as plots with black plastic. The addition of a cover crop had no effect. Newspaper alone or the combination of newspaper + cover crop mulch should be considered for further research because of its positive impact on soil moisture and soil temperature and its potential to suppress weeds and improve crop performance with modifications to cover crop management practices.
Agriculture, mulch, newspaper, cover crops, buckwheat, cowpea, undercutter, collards, soil moisture
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