The time td must be less than ti for the supply of fertigation to be equal in both treatments and to not overlap.
The values of EC, pH, and LF in fertigation drainage are frequently used parameters for the practical control of soilless systems (e.g., Gorbe and Calatayud, 2010; Hayward and Long, 1943; Urrestarazu et al., 2008b).
No information is available on the effect of the time of application of a fertigation volume given to a crop compared with the standard time of a fertigation based on the elements used in each fertigation installation, i.e., the emission duration to deliver the AV volume. This would not change the delivered volume but would affect the time that the roots are subject to a lower matric potential for a given time and, thus, the energy required for water absorption.
Of note, the improvement of the spatial distribution of fertigation in the cultivation unit in turn improves the production (Morales and Urrestarazu, 2013). This increase in production is due to better utilization of the substrate unit volume causing improved availability of water and nutrients (Robinson, 1994), which results in increased root growth. By occupying a greater volume, the roots can access better physicochemical conditions that are distributed unevenly, depending on the fertigation method (De Rijk and Schrevens, 1998; Sonneveld and Voogt, 1990).
The aim of the present study was to evaluate the effect of time on the application of a fertigation volume on the parameters of fertigation, water consumption, emission of pollutants, root distribution, and production of a pepper and tomato crop in a soilless culture system.
Abbreviations and concepts used:
AV = Volume (mL) delivered in each fertigation.
A = Volume consumed (mL·m−2) by the crop that corresponds to 10% of the readily available water consumed by the crop and must be replaced in cultivation units.
LF = Proposed leaching fraction. Generally varies between 0.1 and 0.5.
n = Number of fertigation applications.
f = Frequency of fertigation applications. Number of fertigation applications per unit time.
t = Time (in minutes) that a required applied volume (AV) lasts for a given system.
ti = Time (in minutes) elapsed between the start of two consecutive irrigations.
td = Time added to t (minutes) by interposing a device that reduces the flow (four times) the system issues; it is placed between the drip emitter and the cultivation unit.
EC = Electrical conductivity of the nutrient solution.
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