Efficiency of Phosphorus Fertilizers Derived from Recycled Biogas Digestate as Applied to Maize and Ryegrass in Soils with Different pH

Abstract

Three phosphorus (P) fertilizer fractions recycled from biogas digestates were tested alone and in combination for their efficiency in two agricultural surface soils with different pH: a silty sandy loam and a clay loam. The experiments were carried out in pots under greenhouse conditions, using mineral triple superphosphate (TSP) as a reference. Maize was cultivated for 50 days, followed by ryegrass cultivation for an additional 84 days in the same soil, without additional fertilization. The variables investigated were above-ground plant biomass production, plant phosphorus concentration and content, and plant available phosphorus concentration in soil. The dry matter (DM) yield of maize was increased by the organic P fertilizers equal to or more than TSP in both soils. In the neutral soil, biomass was almost doubled compared to TSP when using one of the fractions (Struvite containing P-Salt) alone or in combination with dried solid fractions. P concentration in maize cultivated in the neutral soil was not significantly different between the P fertilization treatments. However, associated with biomass increase, the total P content in maize plants was equal to or higher than that with TSP. In the acidic soil, P concentration and total P content in maize plants, as well as the calcium-acetate-lactate extractable P (CAL-P) concentration in soil, were equal to or even higher than TSP. Ryegrass DM yield was unaffected by all P fertilizers, independent of the soil, although P concentration and total P content increased in the acidic soil with all fertilizers. Our results show that recycled P fertilizers from biogas digestates are effective P fertilizer alternatives to mineral TSP for maize cultivation under acidic and neutral soil conditions. The lack of growth effects in ryegrass indicates that recycled P fertilizers do not require changes in weed control. On the other hand, P extraction by ryegrass in overfertilized acidic soils as an option for soil remediation also works in soils fertilized with biogas digestate fractions.

Phosphorus retention and agronomic efficiency of refined manure-based digestate—A review

“…In a crop rotation involving forage maize, potatoes (Solanum tuberosum L.), fodder beet (Beta vulgaris L.), and oats (Avena sativa L.), Vanden Nest et al (2015) found that application of solid phase digestate based on a mixture of organic waste, energy crops, and animal slurry increased soil calcium chloride-extractable phosphorus (P-CaCl 2 ) concentration and phosphorus leaching but not soil ammonium lactate-extractable phosphorus (P-AL) concentration, hot water-extractable phosphorus, or crop yield or quality compared with application of equal, higher, or lower doses of TSP to a soil with initially high phosphorus status. Bach et al (2022) found similar or higher maize biomass and biomass phosphorus content in treatments that received phosphorus as struvite, calcium phosphate, and magnesium phosphate precipitated from cow manure and maize silage-based digestate in combination with dried solid phase of the same types of digestate, than in treatments that received phosphorus as TSP on two soils with low phosphorus status. Ehmann et al (2019) found that steam dried solid digestate from pig manure resulted in higher sunflower (Helianthus annuus L.) shoot and flower biomass than a mixture and calcium phosphates and struvite precipitated from the same digestate type.…”

Evaluation of selected organic fertilizers on conditioning soil health of smallholder households in Karagwe, Northwestern Tanzania

“…A study conducted in Karagwe found that low soil pH, ranging between 3.8 and 4.2 in agricultural fields, is one of the factors that limit agricultural yield [ 8 ]. According to a study by Bach et al [ 55 ], recycling materials from BS can solve low pH issues in soil when applied to acidic soils.…”

Effect of Arbuscular Mycorrhizal Fungi on Nitrogen and Phosphorus Uptake Efficiency and Crop Productivity of Two-Rowed Barley under Different Crop Production Systems

“…Farming practices generally adversely affect the AM relationship, and agricultural soil is depleted of AMF, especially in terms of the number of species [5,7]. Intensive agricultural production, for example, has resulted in the use of phosphorus (P) fertilizers that far exceed crop requirements, resulting in in the accumulation of overall and, in some instances, readily accessible P in the soil [8,9]. Consequently, crops have a reduced dependence on AM association and present lower root colonization and densities of settled propagules [10].…”