Demetrio Gonzalez1, Patricia Almendros1, Ana Obrador1, Jose M Alvarez1. 1. Departamento de Química y Tecnología de Alimentos, ETSI Agronómica Alimentaria y de Biosistemas, Centro de Estudios e Investigación para la Gestión de Riesgos Agrarios y Medioambientales (CEIGRAM), Universidad Politécnica de Madrid (UPM), Avda Puerta de Hierro 2-4, 28040 Madrid, Spain.
Abstract
BACKGROUND: Intensive cropping systems have caused widespread Zn deficiency, low nutritional quality of cereals and environmental problems. The aim of the microplot field experiment reported in this paper was to assess the option of using Zn in conjunction with urea fertilization in order to reduce N rate and to maintain the yield level and grain quality but minimizing environmental risks. Barley (Hordeum vulgare L.) was cultivated in a calcareous soil under semi-realistic conditions. Combinations of four Zn levels, applied by spraying aqueous solutions of ZnSO4 , and three N levels, applied by spreading granular urea, were tested. RESULTS: Zn and N showed a synergistic effect, increasing yield and Zn content in all plant parts and protein content in grain. A low Zn dosage of 5 kg ha-1 was sufficient to significantly increase the amount of bioavailable Zn in soil and significantly raise its concentration in plant material and also the protein content in grain. The remobilization of Zn from leaf tissue to grain was dependent on the availability of Zn and was only crucial when its bioavailability was low. CONCLUSIONS: A Zn dosage of 5 kg ha-1 enhanced the agronomic efficiency of N by 15.5 kg grain kg-1 N. The Zn applied to the soil permitted a reduction in the rate of N with only a small decrease in barley grain yield and nutritional value. However, due to the interannual variability in rainfall, which is characteristic of Mediterranean climates, further studies will be necessary to confirm and extend these results.
BACKGROUND: Intensive cropping systems have caused widespread Zn deficiency, low nutritional quality of cereals and environmental problems. The aim of the microplot field experiment reported in this paper was to assess the option of using Zn in conjunction with urea fertilization in order to reduce N rate and to maintain the yield level and grain quality but minimizing environmental risks. Barley (Hordeum vulgare L.) was cultivated in a calcareous soil under semi-realistic conditions. Combinations of four Zn levels, applied by spraying aqueous solutions of ZnSO4 , and three N levels, applied by spreading granular urea, were tested. RESULTS:Zn and N showed a synergistic effect, increasing yield and Zn content in all plant parts and protein content in grain. A low Zn dosage of 5 kg ha-1 was sufficient to significantly increase the amount of bioavailable Zn in soil and significantly raise its concentration in plant material and also the protein content in grain. The remobilization of Zn from leaf tissue to grain was dependent on the availability of Zn and was only crucial when its bioavailability was low. CONCLUSIONS: A Zn dosage of 5 kg ha-1 enhanced the agronomic efficiency of N by 15.5 kg grain kg-1 N. The Zn applied to the soil permitted a reduction in the rate of N with only a small decrease in barley grain yield and nutritional value. However, due to the interannual variability in rainfall, which is characteristic of Mediterranean climates, further studies will be necessary to confirm and extend these results.