Soybean Nutrition in a Novel Single-Nutrient Source Hydroponic Solution

David L Cole,Rachel L Buck,Savannah R Fahning,Savannah J Kobza,Samuel H Stapley,Bryan G Hopkins,Dicken K A Bonsrah

doi:10.3390/agronomy11030523

David L Cole, Rachel L Buck + Show 5 more

Open Access

https://doi.org/10.3390/agronomy11030523

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Abstract

Hydroponic systems are efficient for studying plant nutrition. It is often desirable to adjust individual nutrients for unique species’ needs and/or to create multiple nutrient deficiencies within the same study. However, this is challenging to do with traditional solutions as nutrients are generally added as dual nutrient salts, such as when varying phosphorus (P) concentration also affects nitrogen concentration; potentially, the chemical form of the nutrient taken up when ammonium phosphate is the source for P. This can create unintended consequences with nutrients other than those intended for adjustment. A new hydroponic system has been created to allow for nutrient deficiencies using single-nutrient sources, including ammonium nitrate; phosphoric, sulfuric, hydrochloric, and boric acids; potassium, calcium, magnesium, zinc, and copper carbonates; manganese acetate; sodium molybdate; iron EDDHA; with HEDTA as an additional chelate. This nutrient solution was compared to a traditional “Hoagland” hydroponic solution to grow soybean (Glycine max (L.) Merr). Additional treatments included alteration of pH in the new solution as well as evaluating varying levels of calcium, magnesium, and manganese. This new solution proved effective, as soybean was grown to maturity and performed as well as the traditional Hoagland solution. Adjusting pH downward with hydrochloric acid resulted in healthy plants, but solution pH was not adequately buffered. Adjusting pH with acetic acid resulted in toxicity. Further work is required to provide better pH buffering and approximately align tissue nutrient concentrations with field-grown soybean.

Highlights

Understanding nutrient deficiency symptoms and plant tissue critical levels aids in achieving proper nutrient management in crops
“ctrl” = Hoagland solution; “H” = Hopkins single-nutrient source (SNS) solution; “HCl” and “AA” indicate that pH was adjusted in-season with hydrochloric or acetic acid, respectively; “-Ca/Mg” = reductions of 21% for Ca and 73% for Mg, as compared to the full strength H solution; “+Mn” = 25% increase in concentration compared to full-strength H solution, adjusted with AA (Table 1)
“ctrl” = Hoagland solution; “H” = Hopkins single-nutrient source (SNS) solution; “HCl” and “AA” indicate that pH was adjusted in-season with hydrochloric or acetic acid, respectively; “-Ca/Mg” = reductions of 21% for Ca and 73% for Mg, as compared to the full-strength H solution; “+Mn” = 25% increase in concentration compared to full strength H solution, adjusted with AA (Table 1)

Summary

Introduction

Understanding nutrient deficiency symptoms and plant tissue critical levels aids in achieving proper nutrient management in crops. Knowledge of these characteristics is increasingly important as a vital aspect of providing the food, fuel, and fiber needed for. The goal of such efforts is to achieve maximum economic yield while conserving natural resources and minimizing nutrient pollution. There are differences in growing plants in hydroponics vs soil, there are ample similarities and correlations. Hydroponic systems potentially enable the induction of every mineral nutrient deficiency in a comparative study in a controlled environment, enabling the efficient study of basic plant nutrition studies [1,4,5]

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