Optimal fractions of phosphorus fertilizer applied in preplanting and in drip fertigation of tomato crop

Abstract:The objective of this work was to establish the optimal fractions of the total amount of phosphorus to be applied in preplanting and in drip fertigation of determinate-growth tomato, as well as to determine the effect of the different forms of nutrient application on their soil spatial distribution. Treatments consisted of five schemes of fertilizer application: 100, 75, 50, 25, and 0% of P total dose divided between the pre-planting (triple superphosphate in band placement) and the fertigation (phosphoric acid). The experiment was carried out in a clayed Oxisol with two P availability classes - 7.5 and 32.9 mg dm-3 (Mehlich-1). The treatments showed no effect on tomato production variables in the soil with high P availability. However, in the soil with smaller availability of the nutrient, P fertigation showed a quadratic effect on fruit yield, net income, and net rate of return. The best results were obtained with half of the P total dose applied by fertigation. The fertigation allowed P movement in the soil up to 30 cm deep, and horizontal movement up to 15 cm.

摘要：本研究旨在明确有限生长型番茄（determinate-growth tomato）播前施肥与滴灌施肥的总磷最优施用量占比，并探究不同养分施用方式对土壤磷素空间分布的影响。试验设置5种肥料施用方案：将总磷施用量按100%、75%、50%、25%和0%的比例分配至播前条施重过磷酸钙（triple superphosphate）与滴灌施肥施用磷酸（phosphoric acid）两个环节。本试验在两种磷素有效性等级的黏质氧化土（clayed Oxisol）中开展，其有效磷含量分别为7.5 mg dm⁻³和32.9 mg dm⁻³（采用梅利奇-1浸提法（Mehlich-1）测定）。在高磷有效性土壤中，各处理对番茄产量相关指标无显著影响；但在低磷有效性土壤中，滴灌施磷对果实产量、净收益及净回报率均表现出二次效应。当总磷施用量的一半通过滴灌方式施用时，可获得最佳试验结果。滴灌施肥可使磷素在土壤中向下移动深度达30 cm，水平移动距离可达15 cm。