Determining injection strategies of phosphorus‐coupled nitrogen fertigation based on clogging control of drip emitters with saline water application^*

Abstract

The beneficial effect of fertigation with acidic fertilizers to protect emitters from chemical and biological clogging might be inhibited by improper fertigation modes. An on-site drip irrigation experiment was conducted to investigate the injection strategies of phosphorus (P)-coupled nitrogen (N) fertigation and water salinity on clogging of emitters with plain channel and labyrinth structures. The results demonstrated that the H + in acidic P fertilizer solutions inhibited the precipitation of carbonate and phosphate simultaneously. However, a weak acidic P fertilizer could no longer protect the emitters from clogging effectively under saline water with an electrical conductivity (EC) exceeding 2 dS m À1 because the phosphate sediments accounted for more than 80% of the total clogging substances. A strategy of applying a weak acidic phosphate fertilizer following N fertigation performs better in reducing emitter clogging than fertigation using N and phosphate fertilizers together. The target pH values were obtained as 6.0, 4.0, and 3.0 for protecting emitters from clogging for drip irrigation systems applying irrigation water with an EC of 0.5, 2.0, and 4.0 dS m À1 , respectively. An optimal fertigation mode for emitter clogging control should consider water quality, type and pH value of fertilizer, and emitter type comprehensively. K E Y W O R D S acid phosphate fertilizers, electrical conductivity, micro-irrigation Résumé L'effet bénéfique de la fertigation avec des engrais acides pour protéger les émetteurs du colmatage chimique et biologique pourrait être inhibé par des modes de fertigation inappropriés. Une expérience d'irrigation goutte à goutte in-situ a été menée pour étudier les stratégies d'injection de fertigation à l'azote (N) couplé au phosphore (P) et la salinité de l'eau en cas de colmatage des émetteurs avec des structures en canal plat et en labyrinthe. Les résultats ont démontré que le H + dans les solutions d'engrais P acides inhibait la * Détermination des stratégies d'injection de fertigation à l'azote couplé au phosphore basées sur le contrôle du colmatage des émetteurs goutte à goutte avec application d'eau saline

Effects of saline water with different concentrations of calcium and magnesium ions on emitter clogging in drip irrigation integrated water–fertilizer system

“…The salinity of brackish water mainly affects the mineral ingredients and the content of clogging substances in the emitters (Muhammad, Zhou, et al, 2021). The combination of brackish water and fertilizer makes the emitter clogging mechanism even more sophisticated (Ma et al, 2020; Wang et al, 2021), particularly if the fertilizer contains Ca 2+ , Mg 2+ , Mn 2+ , PO 4 3− and SO 4 2− (Shinde et al, 2012). Previous studies revealed that the use of monopotassium phosphate (Ma et al, 2020; Wang et al, 2021) and ammonium polyphosphate (Xiao et al, 2020) in saline water exacerbates clogging.…”

“…The combination of brackish water and fertilizer makes the emitter clogging mechanism even more sophisticated (Ma et al, 2020; Wang et al, 2021), particularly if the fertilizer contains Ca 2+ , Mg 2+ , Mn 2+ , PO 4 3− and SO 4 2− (Shinde et al, 2012). Previous studies revealed that the use of monopotassium phosphate (Ma et al, 2020; Wang et al, 2021) and ammonium polyphosphate (Xiao et al, 2020) in saline water exacerbates clogging. When the saline water conductivity is greater than 4 dS/m, coupled drip irrigation with nitrogen and phosphorus fertilizers leads to rapid clogging of the emitter (Wang, Yang, & Li, 2020).…”

Biochemical Fulvic Acid Modification for Phosphate Crystal Inhibition in Water and Fertilizer Integration

“…The clogging has seriously restricted the promotion of water and fertilizer integration. Research shows that chemical clogging could be relieved by enhancing the acidity of irrigation water or using acidified fertilizers [ 17 , 18 ]. Due to its strong acidizing effect, hydrochloric or nitric acid has also been considered as an effective additive for eliminating the phenomena [ 19 , 20 ].…”