Key points

• Nitrogen (N) test strips are the most common test strips and these help growers decide on N top-up rates during the season
• For phosphorus (P) and other nutrients only applied at sowing, test strips can help gauge the rates needed for future crops
• Run the strips across different parts of the paddock which are representative of production zones used for pre-season soil testing
• Assess the strip’s performance within each zone throughout the season, especially at the start of stem elongation
• Look for clear visual differences in growth between strips and consider taking plant tissue samples to quantify nutrient uptake
• If the crop responds to a high rate of N or sulfur (S) fertiliser (i.e. it is significantly better in the high rate compared to the grower rate), topping up that nutrient may boost crop performance. If plants in the high rate or half rate test strips are no better than the grower rate, fertiliser rate adjustment may be warranted, or another other factor may be limiting growth
• Harvest the strips separately and compare the yields to assess responsiveness and profitability
• Comparison of crop performance between treatments can help guide local critical soil test values and targets for future seasons

Application rates can be estimated using the pre-season soil testing results from within paddock zones. Test strips can then verify the effectiveness of these rates and whether in-season applications of nitrogen are warranted.