Evaluation of several fertility management systems for an organic commercial processing vegetable rotation

Fertility management and nutrient use efficiency remain key concerns for organically managed vegetable crop production. We evaluated an organically managed processing vegetable rotation under a no-input control, composted poultry manure (CPM), plant based with field pea annual cover crop (PB), integrated plant based with field pea annual cover crop and composted poultry manure (IA) and an integrated plant based with alfalfa perennial cover crop and composted poultry manure (IP) fertility management system in Arlington, WI. Total and U.S. number one potato tuber yields were greater in non-control systems than control systems in 2008 and 2009. Potato biomass varied by year and fertility management system with non-control systems producing greater biomass than the control. Nutrient use efficiency values were reduced by low measures of crop productivity within this study. Snap bean pod yield, biomass, and nitrogen use efficiency values were affected by year or a year by fertility management system interaction, except for agronomic use efficiency and nitrogen recovery efficiency values that were not affected by year or fertility management system. Sweet corn total yield, pre-harvest biomass, and nutrient use efficiency values were affected by year, fertility management system, and a year by fertility management system by year interaction, except for partial factor productivity which was unaffected by fertility management system. Soil NO3-N concentrations in non-fertilized columns were affected by fertility management system, sampling time and a fertility management system by time interaction, while soil NH4-N concentration was affected by sampling date. Seasonal accumulated net nitrogen mineralization was affected by year and seasonal accumulated net nitrification was affected by year and fertility management system. Across 2009 and 2010, within season net nitrogen mineralization patterns within non-fertilized systems were affected by sampling date; while net nitrification rates within the 2009 and 2010 sweet corn growing season were affected by fertility management system, sampling date, and a fertility management system by sampling date interaction. These results indicate that organic growers have flexibility in the fertility management system chosen across crops, so long as total soil PAN is budgeted for the entire rotation cycle and proper budgeting is estimated for each residue incorporated.