Enhancing rock phosphate integration rate for fast bio-transformation of cow-dung waste-paper mixtures to organic fertilizer

Abstract

Rock phosphate (RP) addition in cow-dung waste-paper mixtures at rates above 2% P has been reported to increase the rate of bio-transformation and humification of organic waste mixtures during vermicomposting to produce organic fertilizer for organic farming. However, the optimization of RP for vermicomposting was not established. The objective of this study was to determine the optimal amount of RP integration rates for effective bio-transformation of cow-dung waste-paper mixtures. Arrays of RP integration degrees (0, 0.5, 1, 1.5, 2, and 4% P as RP) were thoroughly mixed with cow- dung waste-paper mixtures to achieve an optimized C:N ratio of 30 and allowed to vermidegrade following the introduction of earthworms at a stocking mass of 12.5 g-worms kg−1. The bio-transformation of the waste mixtures was examined by measuring C:N ratios and humification index (HI) and per cent ash and volatile solids. Application of 1% P as RP resulted in fast bio-transformation and maturation of cow-dung waste-paper mixtures. A scanning electron microscopy (SEM) was used to evaluate the morphological properties of the different vermicomposts affected by rates of RP showing the degree of degradation of initial compacted aggregates of cellulose and protein fibres in the mixtures at maturity. A germination test was used to further determine phytotoxicity of the final composts and microbial biomass assessment. The final vermicompost (organic fertilizer) had a C:N ratio of 7, MBC of 900 mg kg−1 and HI of 27.1%. The RP incorporation rate of 1% P of RP investigated is therefore, recommended for efficient vermidegradation and humification of cow-dung waste-paper mixtures. However, higher rates of RP incorporation should be considered where greater P enrichment of the final vermicompost (organic fertilizer) is desired.

Enhancing organic waste decomposition with addition of phosphorus and calcium through different sources

“…Thus, SEM images in this study were similar to that of (Lim et al 2015(Lim et al , 2016, and it reveals that increase in the decomposition of the mixtures significantly depends on time. The wider contrasts in the degree of decomposition observed from various treatments at 14th and 28th days agreed with the time of most extreme microbial action (Unuofin et al 2016). < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001…”

“…Rock phosphate (RP), Triple superphosphate (TSP), Phosphoric acid (PHA) and calcium chloride (CaCl 2 ) were the treatments used. The P-source treatments were inoculated into the waste mixtures at 1%, P since this gave the ideal rate of RP application that brought about speediest decomposition of the waste mixtures (Unuofin et al 2016). Calcium chloride was also applied to the mixtures at the level of Ca supplied by RP when applied at 1% P. A control (with earthworm yet no P sources) was included.…”

“…In another study, (Mishra 1992) got an exceedingly humus-like manure when they composted vegetable wastes with 25% Mussoorie RP. Unuofin et al (2016) explored the effectiveness of adding RP at rates less than 2% P to cow dung-waste paper mixtures. The result revealed that, an improved decomposition and humification of the mixtures could be realized even at 0.5% P rate of RP application, even though faster decomposition as well as maturation was achieved at 1% P. Although, 1% P application rate of rock phosphate is what is vital to produce mature vermicompost; however, application greater than 1% P was desirable for vermicompost-enriched P fertilizer.…”

Toxicity of paper mill pelletized waste using germination and biomass production as bioindicators

“…Seed GI is a direct indicator of residue or compost toxicity (Phoungthong et al, 2016) because it directly establishes if the residues can inhibit plant growth when used as soil amendment or as a direct means of growth. A GI greater than 80%, observed for all the treatments in the present study, indicated that pellets mixed with a degraded Alfisol would have phytotoxin or heavy metal levels that do not affect plant growth (Unuofin et al, 2016); instead, evaluated indices increased as indicated by the radish seed germination tests. Agricultural application of pellets of ash and sludge may be limited by their phytotoxic effect during seedling establishment, which was assessed using the Germination Index (GI).…”

“…Phytotoxicity was determined by GI as suggested by Tiquia and Tam (1998), allowing the evaluation of the low or minor toxicity that affects root growth, as well as the high or major toxicity (Nafez et al, 2015;Unuofin et al, 2016), to determine the effect on radish seed germination, as expressed in equation 1:…”