The increase in water contamination and eutrophyzation has advised the regulation of depuration of residual waters as well as the reduction of nitrate emission by the agricultural production. As a consequence, nitrogen application needs to be regulated according to the requirements of each crop and to the supplies from the soil, the water for irrigation and the atmospheric precipitations.
Nitrogen is an essential element absorbed in great amounts by plants able to produce high yields. Almond is able to accumulate great amounts of nitrogen in the fruits, where N may reach 0.73% of the fresh weight. Among the fruit components, the kernels reach 61.08% of the total N exports, the endocarp 14.31 %, and the mesocarp 24.61%.
The high yields obtained in irrigated almond orchards, reaching 1500 kg of kernel/ha, represent more than 120 kg of nitrogen per hectare and year. In the ensemble of the cultivars studied, the most efficient cultivars are those with the higher kernel percentage (over the total fruit weight and not over the in‑shell weight) and the lower mesocarp percentage.