Potato Tuber Yield, Tuber Size Distribution, and Quality as Impacted by Preceding Green Manure Cover Crops

Abstract

Sustainable potato production systems are needed to maintain higher tuber yield and quality. Studies were conducted from 2005 to 2008 on commercial potato farms to evaluate the effect of preceding green manure cover crops on potato tuber yield, tuber size distribution, and quality. Sorghum sudan (Sorghum sudanensis var super sweet), Sorghum sudan (Sorghum sudanensis var sordan 79), mustard (Brassica spp.), and canola (Brassica napus) were planted prior to the 2006 and 2007 potato crop. Another treatment included sordan 79 planted but the above ground biomass removed for hay before incorporating the stubble and roots into the soil. A wet fallow plot where no cover crops were planted was included as a control. Additional green manure cover crops planted prior to the 2008 potato crop included barley (Hordeum vulgare L.), barley plus applied compost, sunflower (Helianthus annus), peas (Pisum sativum), and annual rye grass (Lolium spp.). Results from these studies suggest that green manure cover crops can increase potato tuber yield by increasing tuber size, and can improve tuber quality by reducing tuber external defects such as knobs, growth cracks, and misshapes. The positive impact of sorghum sudan suggest that it is possible to harvest the above ground biomass for hay and still obtain high tuber yield and quality when the remaining stubble and roots are plowed into the soil prior to planting potatoes.