Use of Pre-sidedress Nitrate Test and SPAD Meter to Evaluate Nitrogen Needs of Peppers
Hot cherry peppers were grown after incorporation of the following three winter cover crop regimes in Summer 1994—hairy vetch (Vicia villosa) plus winter rye (Secale cereale), hairy vetch alone, and no cover crop. For each main effect there were three N rates applied to peppers in three applications over the course of the season: 0, 85, and 170 kg·ha–1. The pepper yield was significantly higher with hairy vetch plus rye than rye alone or no cover crop. There was also no significant yield increase with the addition of N fertilizer to the peppers grown with hairy vetch. Soil nitrate–N levels taken just prior to N sidedress were significantly higher in plots that had hairy vetch plus rye compared to other treatments. There was also a significant linear relationship of the soil nitrate–N levels among the three N rates. Based on the results of this study, sidedressing peppers would be recommended when soil nitrate levels are above the 25 ppm that is the current threshold for other crops. SPAD readings were taken several times during the season. There was a high correlation of SPAD readings to pepper yield very early and very late in the season. The correlation of SPAD readings to pepper yield was poorest when taken at the time of N sidedress.