Abstract

The main source of nitrogen for most cultivated plants is nitrate. Agriculture has overused this nutrient, resulting in serious environmental problems in various parts of the world. The common practice in open intensive horticultural fields with clay-loam soils with a high water retention capacity (e.g., high percentage of clay) is to irrigate two to four times per week. Technically and logistically, this is much easier than one or more irrigation events per day. However, the loss of nutrients and water below the root zone may occur, with the consequent loss of efficiency. In this work, two cultivation cycles in an open-field endive crop were carried out under plastic soil mulching. We compared three fertigation strategies based on different frequencies of fertigation events; low fertigation frequency (LF, two to three fertigation events per week that simulates common farmer practice), medium fertigation frequency (MF, one fertigation event per day), and high fertigation frequency (HF, three fertigation events per day). The three fertigation strategies applied equal water and fertilizers doses per week. The high fertigation frequency increased volumetric water content in the upper soil profile, while the low fertigation frequency in the lower soil profile. The results demonstrated that HF fertigation increases shoot fresh weight (harvest yield) by increasing shoot water content, but did not improve shoot nutrient uptake or nitrogen nutritional status. The important finding, from the environment point of view, is that high and medium fertigation frequencies decreased nitrate concentration in the root influence zone, where it may be prone to leaching due to heavy rain events.

中文翻译：

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施肥频率是集约化露天农业硝酸盐管理的有用工具

摘要

大多数栽培植物的氮的主要来源是硝酸盐。农业过度使用了这种营养素，导致世界各地出现严重的环境问题。在具有高保水能力（例如，高粘土百分比）的粘壤土的开放式集约化园艺田中，通常的做法是每周灌溉两到四次。从技术和后勤角度来说，这比每天进行一次或多次灌溉活动要容易得多。然而，根区以下的养分和水分可能会流失，从而导致效率损失。在这项工作中，在塑料土壤覆盖下对露地菊苣作物进行了两个栽培周期。我们根据不同频率的灌溉施肥事件比较了三种灌溉施肥策略；低灌溉施肥频率（LF，每周 2 至 3 次灌溉施肥事件，模拟普通农民的做法）、中等灌溉施肥频率（MF，每天 1 次灌溉施肥事件）和高灌溉施肥频率（HF，每天 3 次灌溉施肥事件）。三种灌溉施肥策略每周施用相同剂量的水和肥料。高施肥频率增加了上部土壤剖面的体积含水量，而低施肥频率则增加了下部土壤剖面的体积含水量。结果表明，高频灌溉施肥通过增加枝条含水量来增加枝条鲜重（收获产量），但没有改善枝条养分吸收或氮营养状况。从环境角度来看，重要的发现是，高和中度灌溉施肥频率降低了根部影响区的硝酸盐浓度，该区域可能容易因大雨事件而发生淋滤。