Speaker
Description
1.Introduction
The future scarcity of phosphoric rock stocks is forcing to nutrient recycling at a societal scale by producing the so-called bio-based fertilizers (BBFs), allowing phosphorus (P) recovery and reuse in crop production. However, BBFs present a huge variability because they are produced from a wide range of agro-industrial by-products and different nutrient recovery techniques (e.g. composting, digestate, incineration, P-precipitation). P fertilization considerably affects not only P nutrition and crop yields, but also certain micronutrients bioavailability, such as Zinc (Zn) or Iron (Fe). These elements are essential for crops and, in addition, necessary in human diets. Low dietary intake in human diets produces many health problems, known as "hidden hunger". P fertilization also affects root architecture traits, influencing accessibility to soil nutrients and, consequently, crop performance and quality.
2.Materials, methods
In order to study how different P-BBFs affect crop micronutrient uptake and soil exploration (root architecture), a rainfed field experiment was conducted using 11 different BBFs to evaluate the effect on root development, micronutrient availability to crop, and grain biofortification in durum wheat (Triticum durum), particularly sensitive to Zn deficiency in calcareous soils. The molar ratio of P to micronutrients was also studied since it determines the digestibility of these micronutrients. The effect of BBFs was compared with commercial mineral P fertilizer (superphosphate) applied at the same rate.
3.Results and discussion
Limited yields were produced due to thermal stress and water scarcity during the trial. Despite not all BBFs performed equally, most BBFs increased Fe and Cu concentration while no significant differences were observed in Zn or Mn concentration in wheat grain. The molar ratio in wheat grain was also significantly affected by the P source, in particular the P: Fe ratio. This ratio was not affected by commercial mineral P supply but BBFs affected differently ranging from an increase of P Fe ratio with a variation of 24% to -50% when compared with non-fertilized control. BBFs obtained from sewage sludge ashes and poultry manure fertilizer presented the best performance in increasing micronutrient uptake and biofortification of Fe, Cu, Mn, and Zn. However, some organic BBFs with low P concentration (such as olive husk compost, or vermicompost) produced a negative effect on Fe concentration, probably due to sorption processes to organic matter that reduced its bioavailability under water deficiency. Higher root biomass was found in the BBF treatments that presented higher biofortification (sewage sludge ashes and poultry manure fertilizer), presenting up to a 22% increment of root biomass compared to non-fertilized control. A higher specific length express of roots was found in organic BBF treatments such as olive husk compost or plant digestates In this case, a lower nutrient bioavailability of organic BBFs would have produced an increase in root exploration of soil, which could make plants more resilient under water and nutrient scarcity conditions. Present results evidence the ability of BBFs to increase grain yield quality and modification of root development and morphology. However, variability among BBFs should be considered.
Funding: This work was funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 818309 (LEX4BIO). The results reported in this paper reflect only the authors’ views, and the European Commission is not responsible for any use that may be made of the information it contains.
| Keywords | Bio-based fertilizer; micronutrients; biofortification; root architecture; circular economy |
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