Distribution of Phosphorus Forms Depends on Compost Source Material

Marge Lanno,Maidu Silm,Mait Kriipsalu,Merrit Shanskiy,Anu Kisand

doi:10.3390/resources10100102

Marge Lanno, Maidu Silm + Show 3 more

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https://doi.org/10.3390/resources10100102

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Abstract

Composting is a sustainable method for recovering nutrients from various organic wastes, including food waste. Every input waste has different nutrient contents, in turn, suggesting that every compost has different fertilizer and/or soil improvement values. The phosphorus (P) concentration and relative distribution of P forms is related to the original organic material. The relative distribution of P forms determines how readily plants can absorb P from the compost-amended soil. The aim of this study was to investigate the content and relative share of P forms in composts made from fish waste, sewage sludge, green waste, and horse manure. Six forms of P (labile; bound to reducible metals; bound to non-reducible metals; bound to easily degradable organic material; and bound to calcium) were determined using sequential extraction method. The results indicated that fish waste compost had relatively high proportion of labile P, suggesting good biological availability. In comparison, sewage sludge compost contained the highest overall P concentration per dry weight unit, while labile P constituted only 6% of summary of P forms. The results indicate that the evaluation of composts as alternative P sources in agriculture should rely on the relative distribution of P forms in the compost in addition to the typically recognized value of the total P.

Highlights

With the growing human population, the need for more sustainable agriculture and food production is increasingly essential
Experimental composts were prepared from fish waste (FW1-FW3), horse manure (HM), green waste from municipal areas (GW), and sewage sludge (SS) from the regional municipal Wastewater Treatment Plant (WWTP) (Table 1)
Green waste (GW) compost is low in P content, and a relatively low percent of it is in labile-P form

Summary

Introduction

With the growing human population, the need for more sustainable agriculture and food production is increasingly essential. As the population grows, the need for fertilizers increases. To ensure the higher crop yield, nitrogen (N) and phosphorus (P) fertilizers are widely used [1]. P is added to the soil with chemical fertilizers. As phosphorite is mined from Earth’s crust, our natural P resources become increasingly limited [2,3]. Indiscriminate application of chemical fertilizers can exhaust the soil in the long term [4,5]. To avoid increased P concentrations in streams and lakes, it is important that P added with fertilizers is assimilated by plants [2,4,6]

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