Advance Time to Determine Injection and Flushing Times in Drip Fertigation

Drip fertigation has shown unquestionable benefits in recent decades compared to traditional farming fertilization practices. However, a fertilizer dissolved in the irrigation water must be evenly distributed in the fertigated area. Irrigation system and fertigation system characteristics and operational management potentially affect the uniformity of fertilizer and water distribution. Advance time (AT), which is an intrinsic and determinable characteristic of the irrigation system, has not been assessed as a useful technical criterion for managing the uniformity of fertilizer distribution in drip fertigation. The objective of this study was to assess the use of advance time as a technical criterion for determining the duration of injection time and flushing time that provides a satisfactory uniformity of spatial distribution of the fertilizer in drip fertigation. Therefore, the distribution uniformity of potassium chloride (KCl) fertilizer and water was evaluated at six injection times equivalent to 25, 50, 75, 100, 150, 200% AT, and two flushing times equivalent to 100 and 200% AT through Christiansen’s uniformity coefficient (CU) and distribution uniformity (DU). The used drip irrigation system had 10 drip strips with 12.5 m length, a flow rate of 1.40 L h−1 per dripper, and AT of 12.5 min. The injection solution was prepared with 40 g L−1 of KCl. The results indicate that the distribution uniformity of KCl improved significantly with increasing injection time. The injection time of 200% AT promoted the greatest uniformity of distribution of KCl with CU of 0.977 and DU of 0.962. The flushing time of 100% AT was sufficient to rinse the irrigation system and promoted a satisfactory spatial distribution uniformity with a CU of 0.983. In both tests, the uniformity of irrigation water distribution was satisfactory, with CU of 0.988 and DU of 0.982 (average). Advance time is an intrinsic characteristic of the irrigation system that is useful in determining the duration of injection time and flushing time in a more technical way for drip fertigation with satisfactory spatial distribution uniformity of the fertilizer.