Evaluation of Nitrogen Supply Rate Measured by in situ Placement of Plant Root Simulator™ Probes as a Predictor of Nitrogen Supply from Soil and Organic Amendments in Potato Crop

Nitrogen (N) supply from organic sources to the potato (Solanum tuberosum L.) crop is difficult to predict and to synchronize with crop demand. In this study, Plant Root Simulator (TM) (PRS (TM)) probes were evaluated as a tool for prediction of N supply from two rates (300 vs. 600 kg N ha(-1)) of either a hog manure-sawdust compost (HMC) or a pelletized dehydrated poultry manure (NW) in Atlantic Canada. The cumulative PRS mineral N supply rate (PRS-N) measured for the period of 31 days after planting (DAP), soil mineral N at 10 DAP and soil NO(3)-N at 31 DAP were closely related to plant N uptake (PNU) (r = 0.77, 0.71 and 0.73, respectively; P < 0.001) and PNU plus soil mineral N to 30 cm depth at tuber harvest (PNU + SMN(h)) (r = 0.77, 0.81 and 0.74, respectively; P < 0.001). The supply of N from organic sources to a potato crop can be predicted by PRS-N early in the growing season.