Optimizing Application of Phosphorus and Potassium to Processing Tomatoes under Drip Irrigation
IPNI-2007-CAN-ON28
25 May 2007
Methodology
The experiments will be conducted in a sandy loam soil with relative low soil tests for P and K at GPCRC, Harrow, ON. The treatments will include four fertilizer P rates ranging from 0 to 80 kg P ha-1, four fertilizer K rates ranging from 0 to 600 kg K ha-1, and two water management regimes including natural rainfall and natural rainfall enhanced with drip irrigation to best satisfy crop physiological needs in an optimum manner. The experiment will be arranged in a complete factorial randomized block design, with four reps and a total of 128 plots. All fertilizer P and K will be pre-transplant broadcasted and incorporated. All plots will receive 270 kg N ha-1 fertilizer N. Other plot management will follow the local practices. For the drip irrigation treatments, water will be supplied when needed based on the soil holding capacity, evapotranspiration potential, and the permanent wilting point of the crop.
Soil profile samples (0-10, 10-20, 20-40, 40-70, and 70-100 cm depths) will be taken shortly after harvesting and analysed for P, NO3-N and NH4-N to evaluate the leaching potential of soil P and N as a function of fertiliser P and K rates and water regimes.
Fruits from the central rows of each plot will be harvested at the 80% fruit ripening (or peak ripening) stage and graded into marketable, green, blossom end-rot and cull, and weights recorded. Total and assorted fruit yield will be calculated. Fruit soluble solids, lycopene, and vitamin C will be measured. Fruit and stover will be sampled and analysed for N, P and K contents. Total N, P and K uptake and removals will be calculated in combination with fruit and stover yields.
Impacts of fertilizer P and K on yield, quality, NPK uptake and removal, and potential losses of soil N and P will be analysed and quantified using the SAS program.