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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Citrus and Other Subtropical Products Research » Research » Publications at this Location » Publication #334338
Title: Irrigation water acidification to neutralize alkalinity for nursery crop production: Substrate pH, electrical conductivity, nutrient concentrations and Plant Nutrition and Growth

Author
item Albano, Joseph
item Altland, James
item MERHAUT, DON - University Of California
item WILSON, SANDRA - University Of Florida
item WILSON, CHRIS - University Of Florida

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2017
Publication Date: 10/1/2017
Citation: Albano, J.P., Altland, J.E., Merhaut, D.J., Wilson, S.B., Wilson, P.C. 2017. Irrigation water acidification to neutralize alkalinity for nursery crop production: Substrate pH, electrical conductivity, nutrient concentrations, and Plant Nutrition and Growth. HortScience. 52(10):1401-1405. https://doi.org/10.21273/hortsci11439-17.
DOI: https://doi.org/10.21273/HORTSCI11439-17

Interpretive Summary: Leachate/runoff chemistry (i.e. water that runs out the bottom of a pot during irrigation) from plant production operations is important for both environmental and economic reasons. Environmental concerns focus on how runoff water chemistry affects eutrophication of receiving waterbodies (i.e. the nutrient status of water systems that receive runoff water) while economic concerns focus on the efficient use of fertilizer inputs during crop production (i.e. the waste of fertilizer by running out the bottom of the pot during an irrigation). Production factors that can affect leachate/runoff chemistry includes fertilizer type, potting mix composition, plant type, climatic conditions, and irrigation water quantity and quality. This study focuses on water quality dealing with irrigation water alkalinity (or lime) and its remediation by acidification (i.e. lime reduction in irrigation water). A commercial nursery with a high alkalinity irrigation water source was identified in Fort Pierce, Florida. Plant material, substrate, and water for irrigation, were all acquired from this nursery to conduct a 52-week study. Potting mix was amended with controlled- and slow-release fertilizers by the manufacturer with a supplemental application of controlled-release fertilizer (CRF) applied to substrate surface on day 58 of the study. Treatments consisted of irrigation water acidified with sulfuric acid to neutralize 0% (control), 40%, or 80% [NOA (neutralization of alkalinity)] of calcium carbonates. Leachate/runoff pH and electrical conductivity (EC) levels were statistically significant for NOA treatment with pH/EC (millisiemens per centimeter) for the 0%, 40%, and 80% NOA treatments 7.48/1.42, 6.77/1.90, and 5.31/2.20, respectively. Nutrient levels for calcium, copper, iron, potassium, magnesium, manganese, phosphorous, and zinc were all statistically significant for NOA treatment with increasing level of acidification corresponding to increase nutrient leaching/runoff. These data demonstrate how acidifying irrigation water to neutralize alkalinity, alters leachate/runoff chemistry/nutrients with both environmental and economic consequences, i.e. greater nutrient leaching and more acidic runoff with increasing levels of irrigation water acidification and duration of application.

Technical Abstract: Leachate/runoff chemistry (i.e. pH, EC, and nutrients) from nursery and floriculture operations is important for both environmental and economic reasons. Environmental concerns focus on how runoff water chemistry affects eutrophication of receiving waterbodies while economic concerns focus on the efficient use of fertilizer inputs during crop production. Production factors that can affect leachate/runoff chemistry includes fertilizer type, substrate composition, plant type, climatic conditions, and irrigation water quantity and quality. This study focuses on water quality dealing with irrigation water alkalinity and its remediation by acidification. A commercial nursery with a high alkalinity irrigation water source was identified in Fort Pierce, FL. Plant material, substrate, and water for irrigation, were all acquired from this nursery to conduct a 52-week study. Substrate was amended with controlled- and slow-release fertilizers by the manufacturer with a supplemental application of controlled-release fertilizer (CRF) applied to substrate surface on day 58 of the study. Treatments consisted of irrigation water acidified with sulfuric acid (H2SO4) to neutralize 0% (control), 40%, or 80% [NOA (neutralization of alkalinity)] of calcium carbonates (CaCO3) yielding a CaCO3 (miliequivalent per liter)/pH levels of 5.2/7.37, 3.1/6.37, and 1.0/4.79, respectively. Leachate/runoff pH and electrical conductivity (EC) levels were significant (P = 0.001) for NOA treatment with pH/EC (millisiemens per centimeter) for the 0%, 40%, and 80% NOA treatments 7.48/1.42, 6.77/1.90, and 5.31/2.20, respectively. Nutrient levels for calcium, copper, iron, potassium, magnesium, manganese, phosphorous, and zinc were all significant (P = 0.001) for NOA treatment with increasing level of acidification corresponding to increase nutrient leaching/runoff. These data demonstrate how acidifying irrigation water to neutralize alkalinity, alters leachate/runoff chemistry/nutrients with both environmental and economic consequences, i.e. greater nutrient leaching and more acidic runoff with increasing levels of irrigation water acidification and duration of application.