Nitrate and potassium movement in a sandy loam soil cultivated with fertigated grapevine (Vitis vinifera /L.) in the Brazilian semiarid

Abstract Fertigation can increase the efficiency of fertilizer application and facilitate the nutritional management of a crop. Thus, nitrate and potassium movements in a sandy loam soil were evaluated as function of fertilizer doses during three growing seasons of the grapevine cv. Syrah grafted on Paulsen 1103 rootstock (June to October 2013, February to June 2014, and August to November 2014) in Petrolina, state of Pernambuco, Brazil. Five doses of N (0, 15, 30, 60 and 120 kg ha-1) and five doses of K2O (0, 15, 30, 60 and 120 kg ha-1) were combined in a fractional 52 factorial design, totaling 13 combinations, in a randomized blocks experiment with four replications. The concentrations of nitrate and potassium in the soil solution were determined. Samples were collected by porous cup extractors installed at 0.4 and 0.6 m depths. The movement of these ions was obtained by the product between their concentration in the soil solution and the soil water flux density. The increase in nitrogen fertilization promoted a greater movement of NO3- (62.2 kg ha-1) in the soil. The movement of K+ was also observed in two growing seasons .

摘要 灌溉施肥（Fertigation）可提升肥料施用效率，优化作物营养管理流程。为此，本研究于巴西伯南布哥州佩特罗利纳地区，针对嫁接于Paulsen 1103砧木的西拉（Syrah）葡萄品种，在三个生长季（2013年6月至10月、2014年2月至6月、2014年8月至11月）中，探究了不同氮肥（N）与钾肥施用量对砂壤土中硝态氮与钾离子运移的影响。
试验设置5个氮肥（N）施用量梯度（0、15、30、60、120 kg·ha⁻¹）与5个氧化钾（K₂O）施用量梯度（0、15、30、60、120 kg·ha⁻¹），采用5²部分因子析因设计，共计13种试验组合，并以随机区组设计开展试验，设置4次重复。
通过安装于0.4 m与0.6 m深度的多孔杯提取器采集土壤溶液样品，测定其中硝态氮与钾离子浓度。基于土壤溶液离子浓度与土壤水通量密度的乘积，计算得到两种离子的土壤运移量。
研究结果表明，氮肥施用量提升可显著促进NO₃⁻的土壤运移，最大运移量达62.2 kg·ha⁻¹；同时在两个生长季中均观测到K⁺的土壤运移现象。