2018 ASHS Annual Conference

Polyethylene (PE) and biodegradable mulches are commonly used for many vegetable crops, but use is relatively new for sweet corn and interest is increasing especially due to decreased days to harvest and water conservation attributes. Biodegradable mulch that can provide crop production benefits and completely biodegrade in the soil after tillage incorporation would serve as a sustainable alternative to PE mulch. We carried out a field experiment in 2017 to compare five potentially biodegradable plastic mulches (BioAgri, Organix, clear Organix, Experimental, and Naturecycle), a cellulose mulch [WeedGuardPlus (100% biodegradable)], PE mulch (non-biodegradable), and a bare ground treatment for their effect on sweet corn (Zea mays cv. Xtra Tender 2171) growth, yield and quality at Mount Vernon, WA, where average air temperature during the growing season was 16.3 °C (range 11 °C to 23 °C). All mulches were black except clear Organix and brown WeedGuardPlus. Weed pressure was minimal throughout the growing season in all mulch treatments except clear Organix. While most mulches remained sufficiently intact until the end of the growing season, clear Organix split, starting shortly after laying, and fresh weight of weeds at 3 weeks after seeding was 39 % more compared to the bare ground treatment. Plant height at 90 days after seeding was lowest for plants grown on bare ground (103 cm), intermediate for clear Organix and WeedGuardPlus (average 118 cm) and greatest for all black plastic treatments (average 139 cm). Days to 50 % tasseling and 50 % silking were delayed for bare ground and WeedGuardPlus by 9 and 13 days, respectively, compared to all other treatments. Marketable ear yield was higher with PE, Organix, and Experimental (average 10.8 t^.ha^-1), intermediate with BioAgri and Naturecycle (average 9.5 t^.ha^-1), and lower with bare ground, WeedGuardPlus and clear Organix (average 6.6 t^.ha^-1). There was no difference among treatments in total soluble solids of kernels (average 15.4 °Brix), but ear length and diameter were 8% smaller on average for ears grown on bare ground, WeedGuardPlus, and clear Organix compared to other mulch treatments. The length of the unfilled ear tip was greater for bare ground (2.95 cm) compared to all other treatments (average 1.2 cm). These results indicate that yield and quality of sweet corn grown with black biodegradable plastic mulches can be comparable with PE mulch, but that crops grown with clear and paper biodegradable mulches may need different management practices than with PE mulch.