Effect of chemical fertilizer dose on nutrient absorption and utilization of tomato cultured in organic substrate

Tomato was cultured in an organic substrate with two parts vermiculite and one part sheep manure. The effects of different chemical fertilizer application doses on N, P and K absorption and utilization of tomato were investigated under solar greenhouse conditions. Based on the results, N, P and K absorption and yield of tomato were enhanced by proper fertilizer application. The amount of N, P and K absorbed increased with the increasing chemical fertilizer dose. Also the utilization rate of N and K in organic substrate decreased with increasing fertilizer dose. However, the utilization rate of P increased with increasing of fertilizer dose. Furthermore, transformation of slow-releasing nutrients to available nutrient improved by proper fertilizer application. Under the organic cultivation, producing 1 000 kg tomato required 2.540 kg N, 0.751 kg P, 4.347 kg K. The calculation method of optimal chemical fertilizer dose under organic substrate culture was advanced in the study. The calculation formula was: chemical fertilizer dose = (1.5 times fertilizer dose needed for target yield - available nutrient content in organic substrate)/chemical fertilizer nutrient uptake ratio.