Efficiency of Recycled Biogas Digestates as Phosphorus Fertilizers for Maize

Abstract

Despite phosphorus resources on Earth being limited, over fertilization in many agricultural situations causes significant resource consumption. Phosphorus-recycling within agricultural production can reduce global dilution into the environment and is thus essential to secure sustainable future supply. This study investigated the fertilization efficacy of phosphorus fertilizers recycled from biogas digestates in maize shoots grown under controlled greenhouse conditions, in two soils, in a pot experiment. Variables investigated were plant-available phosphorus in soil, plant biomass production, and concentration of phosphorus, calcium, and magnesium in shoots. Soils were treated with three different fertilizer fractions, separated from biogas digestates, at equivalent phosphorus concentrations, using different combinations and application techniques, isolated or in combination, and compared to triple superphosphate (TSP) as a reference. One of the fractions (P-Salt) had effects on biomass production and plant phosphorus concentration equivalent to TSP in agricultural surface soil. In the second soil (with less active soil life and nutrient content), equivalence to TSP was achieved with combinations of two recycled fractions (P-Salt and dried solids). The enhancement of the phosphorus fertilizing effect by the solids was synergistic, indicating that the solids had a soil conditioning effect. The results show that biogas digestates are a valuable source for phosphorus recycling of fractions that have equivalent or even superior fertilizing properties compared to TSP.

Microbial Volatile Organic Compound (VOC)-Driven Dissolution and Surface Modification of Phosphorus-Containing Soil Minerals for Plant Nutrition: An Indirect Route for VOC-Based Plant–Microbe Communications

“…The pH was then adjusted to 8.5 with 1 N NaOH, followed by gentle shaking for 16 h at room temperature. After centrifugation (3000 rpm and 5 min), the P in the supernatant was quantified using ICP-OES. , To quantify P in the harvested plants, nitric acid (2–5 mL) was added to the dried plants (from 70 °C for 24 h), followed by heating up to 105 °C for 12 h. After filtration with a 0.2 μm membrane filter, the digested solutions were diluted with distilled water for ICP-OES . The same experiments except for sowing the plants were conducted to quantify the total and available P in the soils treated with three different calcium phosphate powders ( i.e.…”

“…21,22 To quantify P in the harvested plants, nitric acid (2−5 mL) was added to the dried plants (from 70 °C for 24 h), followed by heating up to 105 °C for 12 h. After filtration with a 0.2 μm membrane filter, the digested solutions were diluted with distilled water for ICP-OES. 23 The same experiments except for sowing the plants were conducted to quantify the total and available P in the soils treated with three different calcium phosphate powders (i.e., 3 or 6 mg of HANPs, CPD, or MHA) and MVOCs. Statistical tests were based on the least significant difference (LSD).…”

Sole and Combined Application of Biodigestate, N, P, and K Fertilizers: Impacts on Soil Chemical Properties and Maize Performance

“…Importantly, these positive effects are achieved without causing any harm to the soil [ 11 , 12 ]. Currently, numerous studies are dedicated to exploring the impact of digestates on crop and vegetable yields as well as quality [ 13 , 14 ].…”

Phosphorus availability and speciation in soils amended with upcycled dairy-waste nutrients

“…Manures are typically applied to soils at rates needed to meet plant N requirements, thus exceeding P requirements by up to six times (Carey et al, 2011), which may lead to legacy P accumulation in the soil (McDowell and Sharpley, 2001). Due to the widespread threat from dairies to surface water quality (US EPA, 2013;Femeena et al, 2023), there is a major imperative to develop nutrient recycling technology from dairy waste that will reduce nutrient leaching and improve the dairy bioeconomy, soil health, and nutrient resource sustainability (Adhikari et al, 2005;Van Zanten et al, 2019;Bach et al, 2021;Muscat et al, 2021;De Rosa et al, 2022). Meeting this imperative requires research to develop technology to recover P and N from dairy waste and test its efficacy as a beneficial soil amendment (Kushwaha et al, 2011;Kolev, 2017;Ahmad et al, 2019).…”