Nitrogen And Weed Management For Organic Sweet Corn Production On Loamy Sand

Irrigated vegetable production dominates the landscape of the Central Sands region of Wisconsin, where sandy soil limits nutrient and water retention. Sweet corn (Zea mays L. var. rugosa) was managed organically in 2011 and 2012 growing seasons to evaluate effects of organic N input and weed management with respect to sweet corn yield and soil N content. The first treatment factor was early season manure, including spring-seeded field pea (Pisum sativum L.) incorporated as a green manure cover crop, pelletized poultry manure, and no manure. The second treatment factor was weed management intensity. The last factor was varying N application rate, split applied as feather meal during the growing season. There was a positive yield response to feather meal in both years with yields reaching 18.6 and 21.5 Mg ha(-1) in 2011 and 2012, respectively, with 224 and 112 kg N ha-1 feather meal application, respectively. Early season manure treatments did not clearly affect yields despite 90 kg N ha-1 applied as both manure types in 2012, and lower rates of 33 and 75 kg N ha-1 applied in 2011 as field pea and poultry manure, respectively. These results underscore the well-known potential for rapid nutrient loss on coarse soil and management challenges associated with asynchrony between organic N release and crop uptake. Weed management contributed to an interaction effect on yield, with early tillage potentially controlling weeds in both treatments. This study demonstrated benefits of in-season organic amendment use, though limited potential for early season application on loamy sand.