scholarly journals Liquid digestate features as fertilizer: carbon fractions, phytotoxicity and microbiological analysis

2020 ◽  
Vol 10 ◽  
Author(s):  
María Rosa Yagüe ◽  
María del Carmen Lobo

The circular economy promotes the use of renewable fuels as an alternative to natural gas. Anaerobic digestion for waste management produces methane, carbon dioxide and a residue-the digestate- which must be recovered. This residue can be separated into two parts, namely the liquid and solid fractions, the former characterized by its large volume, presence of nutrients in mineral forms, and highly variable composition. Here we studied the fertilizing capacity of the liquid fractions obtained from the waste derived from artichoke canning (LF-Ar), orange juice manufacturing (LF-Or) and pig slurry (LF-Sl). To this end, we examined the physical-chemical parameters, carbon fractions, phytotoxicity and presence of pathogens in these fractions. The liquid fraction derived from fruit and vegetables had a low nutrient content compared to that of slurry ( ̴1.0 kg total-N m<sup>-3 </sup><em>vs.</em> 5.6 kg total-N m<sup>-3</sup> respectively). The NH<sub>4</sub><sup>+</sup>-N content of the fractions ranged between 70-93% of total N. Given the permissible dose in non-vulnerable areas, LF-Sl, LF-Ar and LF-Or would provide 0.9-1.0 t of organic matter ha<sup>-1</sup> and 134, 128 and 98 kg of C ha<sup>-1</sup> from the total humic extract, respectively. The proportion of humic acids in the total humic extract was 59%, 51% and 34% respectively. The slurry digestate showed phytotoxicity probably due to high salinity, so it should be diluted based on the needs of the crop. On the basis of our findings, the characterized liquid fractions could be recovered in agricultural soils in line to circular economy principles.</p> <p><strong>&nbsp;</strong>

Author(s):  
Betina Nørgaard Pedersen ◽  
Bent T. Christensen ◽  
Luca Bechini ◽  
Daniele Cavalli ◽  
Jørgen Eriksen ◽  
...  

Abstract The plant availability of manure nitrogen (N) is influenced by manure composition in the year of application whereas some studies indicate that the legacy effect in following years is independent of the composition. The plant availability of N in pig and cattle slurries with variable contents of particulate matter was determined in a 3-year field study. We separated cattle and a pig slurry into liquid and solid fractions by centrifugation. Slurry mixtures with varying proportions of solid and liquid fraction were applied to a loamy sand soil at similar NH4+-N rates in the first year. Yields and N offtake of spring barley and undersown perennial ryegrass were compared to plots receiving mineral N fertilizer. The first year N fertilizer replacement value (NFRV) of total N in slurry mixtures decreased with increasing proportion of solid fraction. The second and third season NFRV averaged 6.5% and 3.8% of total N, respectively, for cattle slurries, and 18% and 7.5% for pig slurries and was not related to the proportion of solid fraction. The estimated net N mineralization of residual organic N increased nearly linearly with growing degree days (GDD) with a rate of 0.0058%/GDD for cattle and 0.0116%/GDD for pig slurries at 2000–5000 GDD after application. In conclusion NFRV of slurry decreased with increasing proportion of solid fraction in the first year. In the second year, NFRV of pig slurry N was significantly higher than that of cattle slurry N and unaffected by proportion between solid and liquid fraction.


2013 ◽  
Vol 44 (2s) ◽  
Author(s):  
Niccolò Pampuro ◽  
Alessio Facello ◽  
Eugenio Cavallo

The excessive amount of pig slurry spread on soil has contributed to nitrate water pollution both in surface and in ground waters, especially in areas classified as vulnerable zones to nitrate in accordance with European Regulation (91/676/CEE). Several techniques have been developed to manage livestock slurries as cheaply and conveniently as possible and to reduce potential risks of environmental pollution. Among these techniques, solid-liquid separation of slurry is a common practice in Italy. The liquid fraction can be used for irrigation and the solid fraction, after aerobic stabilization, produces an organic compost rich in humic substances. However, compost derived from swine solid fraction is a low density material (bulk density less than 500 kg􀀀m–3). This makes it costly to transport composted swine solid fraction from production sites to areas where it could be effectively utilized for value-added applications such as in soil fertilization. Densification is one possible way to enhance the storage and transportation of the compost. This study therefore investigates the effect of pressure (20- 110 MPa) and pressure application time (5-120 s) on the compaction characteristics of compost derived from swine solid fraction. Two different types of material have been used: composted swine solid fraction derived from mechanical separation and compost obtained by mixing the first material with wood chips. Results obtained showed that both the pressure applied and the pressure application time significantly affect the density of the compacted samples; while the specific compression energy is significantly affected only by the pressure. Best predictor equations were developed to predict compact density and the specific compression energy required by the densification process. The specific compression energy values based on the results from this study (6-32 kJ􀀀kg–1) were significantly lower than the specific energy required to manufacture pellets from biomass feedstock (typically 19-90 kJ􀀀kg–1).


Agronomy ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2391
Author(s):  
Abba Nabayi ◽  
Christopher Teh Boon Sung ◽  
Ali Tan Kee Zuan ◽  
Tan Ngai Paing ◽  
Nurul Izzati Mat Akhir

The wastewater from washed rice water (WRW) is often recommended as a source of plant nutrients in most Asian countries, even though most current research on WRW lack scientific rigor, particularly on the effects of rice washing intensity, volumetric water-to-rice ratio (W:R), and condition of the WRW before plant application. This research was thus carried out: (1) to determine how various rice washing intensities, fermentation periods (FP), and W:R would affect the nutrient content in WRW, and (2) to isolate, identify, and characterize the bacterial community from fermented WRW. The WRW was prepared at several rice washing intensities (50, 80, and 100 rpm), FP (0, 3, 6, and 9 days), and W:R (1:1, 3:1, and 6:1). The concentrations of all elements (except P, Mg, and Zn) and available N forms increased with increasing FP and W:R. Beneficial N-fixing and P- and K-solubilizing bacteria were additionally detected in WRW, which helped to increase the concentrations of these elements. Monovalent nutrients -N, , and K are soluble in water. Thus, they were easily leached out of the rice grains and why their concentrations increased with W:R. The bacteria population in WRW increased until 3 days of fermentation, then declined, possibly because there was an insufficient C content in WRW to be a source of energy for bacteria to support their prolonged growth. While C levels in WRW declined over time, total N levels increased then decreased after 3 days, where the latter was most possibly due to the denitrification and ammonification process, which had led to the increase in -N and . The optimum FP and W:R for high nutrient concentrations and bacterial population were found to be 3 to 9 days and 3:1 to 6:1, respectively. WRW contained nutrients and beneficial bacterial species to support plant growth.


1979 ◽  
Vol 9 (2) ◽  
pp. 224-230 ◽  
Author(s):  
P. E. Pope

Dry weights and nutrient contents of all aboveground biomass components were estimated for four seed sources of 11-year-old loblolly pine (Pinustaeda L.) grown in plantations of the same spacing on an old-field site of high quality in the hilly region of north-central Arkansas, U.S.A. Soil nutrient content was estimated to a depth of 0.61 m. Stand data averaged over all seeds sources are in agreement with published reports for dry weight and nutrient accumulation for loblolly pine if differences associated with seasonal variation are considered. Seed source significantly affected total dry matter and nutrient accumulations. Estimated total aboveground mean annual accumulation of biomass for the four seed sources ranged from 5.99 × 103 to 11.17 × 103 kg/ha per year. Elemental accumulation (kilograms per hectare per year) ranged from 14.06 to 23.66 for N, 1.54 to 3.45 for P, and 6.96 to 18.43 for K. On the average, trees comprise 84% of the aboveground plant biomass and contain 76% of the N, 77% of the P, and 90%, of the K associated with plant tissue. The significant influence of seed source on these stand values can affect the potential impact of short rotation, total tree harvesting on long-term site productivity. The elemental content of the tree biomass ranged from 7 to 11% of the total N, 20 to 35% of the P, and 14 to 30% of the K in the soil–litter–plant system.


Agronomy ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 208
Author(s):  
Martire Angélica Terrero ◽  
María Ángeles Muñoz ◽  
Ángel Faz ◽  
María Dolores Gómez-López ◽  
Jose A. Acosta

The intensification of pig production is considered a risky activity for the environment when the generated pig slurry is not adequately treated. In addition, intensive agriculture practices where pig slurry is applied to the cropland could cause nitrate leaching, salinization, and soil pollution (heavy metals and pathogens), thus the development of an eco-friendly system for pig slurry treatment is essential to avoid undesirable environmental impacts. The main objective of this study was to assess the efficiency of an integrated purification system (IPS) for treating pig slurry. The system included a pretreatment module (raw pig slurry tank, phase separator, aeration tank, and settlement tank), constructed wetlands (CWs) that included an unplanted cell and a planted cell, and a storage pond (SP). Pig slurry samples from the pretreatment modules, CWs, and SP were collected in triplicate and physic-chemical and microbial analyses were performed. Results showed that the pretreatment modules decreased the total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP) concentrations in the liquid fraction. Higher total nitrogen removal was reported in the planted cell, which decreased from 4.0 g L−1 to 1.9 g L−1 in the inflow and outflow, respectively. Total efficiencies over 85% were found in the planted and unplanted cells for TSS, Kjeldahl nitrogen (KN), chemical oxygen demand (COD), and TP. Microbial parameters were eliminated after the treatment in the planted cell. Therefore, the results indicated that filtration (pretreatment), purification (constructed wetland), and bioremediation (storage pond) constituted an appropriate IPS for treating pig slurry.


2013 ◽  
Vol 295-298 ◽  
pp. 2544-2548
Author(s):  
Jiu Jin Xiao ◽  
Hong Xing Ma ◽  
Chuang Tai Lu

It is generally accepted that to overuse fertilize can led to cause fertilize resource waste, increase agriculture production cost, reducing the quality of agricultural products, and cause agricultural non-point source pollution. Determining soil nutrient distribution is critical to identify sites which are at risk of N, P and K nutrition loading. In order to know the soil nutrition spatial distribution and to determine agricultural rational fertilization, a total of 98 soil samples from the plow layer (0-20 cm) were collected in low mountain-hilly region of Sichuan Province, China. Spatial variability and distribution of soil organic matter (SOM), total N (TN), available nitrogen (AN), available phosphorus (AP) and available potassium (AK) in agricultural soils were studied using geographic information system (GIS) software. And the analytical hierarchy process (AHP) was used to determine the weight of indexes by using quantitative analysis.


Author(s):  
Zhiyang Lie ◽  
Zhuomin Wang ◽  
Li Xue

With one-year-old Tephrosia candida trees as experimental material, influence of stand density on soil nutrient content and enzyme activity was studied. The results showed that density had little influenced on pH value in 2, 4 and 8 trees m2 stands. The contents of soil organic matter, effective nitrogen and effective phosphorus significantly increased in 2 trees m2 stands. The contents of soil organic matter and effective nitrogen significantly increased, whereas total N, total P, total K, effective N, effective P and effective K significantly decreased in 4 trees/m2 stand. Soil organic matter and nutrients except for total P significantly decreased in 8 trees m2 stand. Among the three density stands, the activities of urease, catalase and phosphatase were the lowest in 8 trees m2 stand.


1997 ◽  
Vol 129 (2) ◽  
pp. 187-191 ◽  
Author(s):  
J. A. HOUNTIN ◽  
D. COUILLARD ◽  
A. KARAM

Excessive applications of liquid pig manure (LPM) could result in nutrient accumulation in the soil, thereby increasing the potential for plant nutrient losses through movement in groundwater. The objective of this work was to measure the concentrations of total carbon (Ct), total nitrogen (Nt), total phosphorus (Pt) and Mehlich-3 extractable-P (PM3) with depth in a Le Bras silty loam soil growing maize (Zea maize L.) under reduced tillage conditions. The soil was fertilized annually with various rates of LPM (0, 30, 60, 90 and 120 m3/ha) in four completely randomized blocks since 1979. In autumn 1992, twenty soil plots were sampled in increments of 20 cm to a depth of 1·0 m and analysed for total C, total N, total P and Mehlich-3 extractable-P. LPM application rate (R), soil depth (D) and the interaction R × D had highly significant (P<0·001) linear effects on Ct, Nt, Pt and PM3 concentrations throughout the 100-cm depth profiles. At all depths, Ct, Nt, Pt and PM3 contents increased with increasing rates of LPM application. The zone of maximum accumulation of Ct, Nt, Pt and PM3 concentrations occurred at the first 0–40 cm depth. A significant relationship was found between soil organic matter and Nt, Pt and PM3. Differences in N and P concentrations between manure rates are due to manure and maize. The increase in PM3 was generally greater for soil samples with high Pt content. Results from this study indicate that long-term application of a high rate of LPM leads to greater total C, N and P concentrations in the soil profile.


2013 ◽  
Vol 72 (2) ◽  
pp. 237-256 ◽  
Author(s):  
Marcin W. Woch ◽  
Magdalena Radwańska ◽  
Anna M. Stefanowicz

Abstract - The aim of the present study was to investigate the composition of spontaneous plant cover and the physicochemical properties of the substratum of spoil heaps of the Siersza hard coal mine in Trzebinia (southern Poland) abandoned in 2001. Floristic and soil analyses were performed in 2011. The substratum was very diverse in terms of texture (sand: 55-92 %, clay: 6-38 %), nutrient content (total C: 1.3-41.0 %, total N: 0.05-0.49 %, total Ca: 0.5-7.3 %) and pH (3.7-8.7). Moreover, total thallium concentration in the substratum was high, ranging from 6.0 to 14.6 mg kg-1. Plant cover varied from 50 to 95 %. The number of plant species per 4m2 varied from 6 to 29 and correlated negatively with total carbon content (r = -0.85, p < 0.01), and positively with sand content in the substratum (r = 66, p < 0.05). The highest number of species per area unit was observed on a humus substratum, where initial soil has developed on the part of carboniferous waste rock spoil under 20-30 year old trees, and the lowest on carbon shale with coal and culm. Among 197 plant species, most belong to Asteraceae, Fabaceae, Poaceae and Rosaceae families. Hemicryptophytes (49%) and terophytes (18%) predominated. The investigated area was primarily colonized by native species spread by the wind. However, invasive alien species also had a significant share (8%) in the plant cover.


Sign in / Sign up

Export Citation Format

Share Document