Nutritional, Physiological, and Morphological Effects on Almond Trees Grown by Fertigation with the Nitrification Inhibitor 3, 4-DimethylpyrazoleSuccinic Acid

Abstract

Nitrogen fertilization is key to improve crop yield. However, due to the harmful environmental effects of fertilizers, farmers and governments are searching agronomic practices that provide nutrients to the crops with minimal environmental impact, as for example the use of nitrification inhibitors. These compounds act on ammonium reducing its oxidation to nitrate, and soil´s nitrogen remains longer in the form of ammonium helping prevent nitrate lixiviation. The objective of the experiment was to evaluate the effect of a new nitrification inhibitor (DMPSA) in almond trees. We studied the effect of three solutions on vegetative growth, nutrition, and physiology on Alvijor almond plants irrigated with one of three possible study solutions i) 3:1 nitrate:ammonium rate solution ii) 1:1 nitrate:ammonium rate solution, or iii) 1:1 nitrate:ammonium rate solution plus a nitrification inhibitor (3,4-dimethylpyrazolesuccinic acid). Plants were grown in a greenhouse in calcareous and alkaline soil from the Spanish Levante area. Macro and micronutrients were determined from drainage samples collected throughout the experiment. At the end of the experiment, gaseous exchange and chlorophyll fluorescence parameters were measured and plants harvested to analyse morphological characteristics (leaf, stem and root fresh and dry weight, aerial part rate, and trunk diameter) and N, P, K, Ca, and Mg content in the leaves. We found higher levels of ammonium and lower nitrates in the roots and higher vegetative growth with the irrigation solution containing the nitrification inhibitor in comparison with treatment solutions 1:1 and 3:1. The drainage showed that NI reduces the level of nitrates in the leachate, limiting its discharge to the subsoil. In conclusion, the nutrient solution with the nitrification inhibitor has a positive impact on Alvijor almond plants and the environment.