The use of pig slurry as organic fertilizer in intensive horticulture could be possible after hygienization to avoid contamination of products. This research aimed to evaluate a mixture of a tomato ...waste and rice husk as biofilter media to reduce NH3, N2O, CO2, and CH4 losses from a simple and low-cost solution for slurry hygienization by pH modification. The experiment was made in a system of laboratory scale biofilters connected to jars filled with raw slurry as control and three treatment methods: acidified slurry, alkalinized slurry, and neutralized slurry. The gas concentrations were measured for 35 days, and the composition of slurries and biofilters were determined. The results of this study showed that the mixture of biofiltering media, composed of tomato waste and rice husk, has the potential to retain NH3 and greenhouse gases (GHG) from a simple and low-cost solution for slurry hygienization by pH modification. Compared to the treatment raw slurry biofilter, the treatment neutralized slurry biofilter, subjected to a combined treatment by alkalinization/neutralization, retained 19% NH3, 4% CO2, and 83% CH4 losses and had no impact on N2O and global warming potential. Thus, the use of tomato waste biofilter during alkalinization did not increase the loss of NH3 and reduced GHG compared to raw slurry, avoiding the subsequent neutralization of slurry for environmental reasons, and could be used as an organic fertilizer in horticulture. However, using the combined alkalinization/neutralization treatment will improve the fertilizer value of the slurry by adjusting the pH from 9.5 to 7.5.
Slurry storage is a significant source of NH3 and greenhouse gas (GHG) emissions. The aim of this laboratory study was to assess the effects of different chemical additives and biochars on the ...emissions of NH3, N2O, CO2, and CH4 during the short-term storage of pig slurry. The experiment was performed using Kilner jars filled with raw slurry as control and six treatment additives (5% w/w): acidified slurry, alkalinized slurry, neutralized slurry, agroforestry biochar, cardoon biochar, and elderberry biochar. The gas emissions were measured for 30 days, and the composition of the slurries was determined. During short-term storage, the results of this laboratory study indicated that the NH3 emissions were reduced by 58% by acidification and by 20% by the biochars (Agroforestry, Cardoon, and Elderberry treatments), while neutralization reduced this loss by only 12%. Nitrous oxide emissions were not reduced by the chemical additives (Acidified, Alkalinized, and Neutralized treatments), while this loss was increased by 12% by the biochars. Carbon dioxide, CH4, and global warming potential emissions were not affected by the chemical additives and biochars. Furthermore, the absence of differences between the biochars may be related to their similar composition. Regarding the influence of the studied additives on NH3 losses, it can be concluded that acidification was the best mitigation measure and the biochars were quite similar due to their composition. Furthermore, neutralization had the advantage of sanitizing the slurry, but only had a mild impact on NH3 preservation.
Composting is one of the best organic waste management techniques, with zero waste; however, it generates environmental impacts. The objective of this study was to evaluate the emission of NH3, N2O, ...CO2, and CH4 from the composting of olive, elderberry, and grape agro-food waste. The experiment was carried out using reactors receiving straw as control and three treatments receiving mixtures of straw and olive, elderberry, or grape wastes. The gas emissions were measured for 150 days, and the composition of the mixtures and composts was determined. The results showed NH3 and CH4 emissions were reduced by 48% and 29% by the Olive and Elderberry treatments, while only NH3 loss was reduced by 24% by the Grape treatment. Nitrous oxide, CO2, and GWP emissions were reduced by 46%, 32%, and 34% by the Olive treatment, while these losses were not reduced by the Elderberry or Grape treatments. It can be concluded olive waste can effectively reduce NH3 and GWP, while elderberry and grape wastes are also effective in reducing NH3, but not GWP. Thus, the addition of agro-food waste appears to be a promising mitigation strategy to reduce gaseous losses from the composting process.
The treatment of animal slurry is used to improve management on a farm scale. The aim of this laboratory study was to assess the effects of the addition of the additives biochar, alum and ...clinoptilolite before the mechanical separation of whole pig slurry (WS) on the characteristics and emission of NH3, N2O, CO2 and CH4 from solid (SF) and liquid fractions (LF). The additives were mixed with WS (5% w/w), followed by separation, in a total of 12 treatments with 3 replicates, including the controls and WS with additives. Gaseous emissions were measured for 30 d by a photoacoustic multigas monitor, and initial characteristics of the slurries were assessed. The results indicated that the separation of the WS modified the initial physicochemical characteristics and increased the GWP emissions of the SF and LF, but not the NH3 losses. However, the addition of additives before separation increased the nutrient value and reduced the GWP emissions from the SF and LF. Additionally, just the additive alum was effective in the reduction of E. coli. The additives led to significant reductions in NH3 and N2O emissions, with higher reductions in NH3 losses for alum (51% for NH3) and similar N2O losses for all additives (70% for N2O) observed, whereas the CO2 and CH4 emissions were reduced by biochar (25% for CO2 and 50% for CH4) and alum (33% for CO2 and 30% for CH4) but not by clinoptilolite. Although the additives had a positive effect on slurry management, it can be concluded that the addition of alum before mechanical separation has the potential to be the best mitigation measure because it improves the nutrient content and sanitation and decreases gaseous losses from slurry management.
Biofilters are an effective air pollution control technology to break down gaseous contaminants and produce innocuous end products. This laboratory study aimed to evaluate a biofilter media, mainly ...composed by tomato waste, as packing material to reduce NH3, N2O, CO2 and CH4 losses from stored pig slurry. Three mixtures of packing materials, with and without oxalic acid, were arranged in treatments, namely: mixture of tomato waste, pine bark and agricultural compost; mixture of tomato waste and rice husk; tomato waste only. A control treatment (no biofilter) was also included. The experiments were conducted using a system of laboratory scale biofilters connected to jars filled with pig slurry and under a constant airflow rate. The gas concentrations were measured for 14 days and the physicochemical of the packing materials were assessed. Results showed that biofilter media mixtures had a potential for NH3 retention ranging from 51 to 77% and the addition of oxalic acid to these biofilters increased NH3 retention to 72–79%. Additionally, the biofilter media mixtures with and without oxalic acid showed a potential retention for CH4 (29–69%) but not for N2O, yet with no impact on the global warming potential. It can be concluded that tomato based biofilters had the potential to reduce gaseous emissions from slurry.
The storage of animal manure is a major source of gaseous emissions. The aim of this study was to evaluate the effects of biochar and clinoptilolite on the composition and gaseous emissions during ...the storage of separated liquid fraction of pig slurry. The experiment was carried out using containers with 6 L of pig slurry each. The additives biochar and clinoptilolite were added alone and mixed to the pig slurry at a rate of 2.5% each, in a total of four treatments with three replicates including the control. Gaseous emissions were monitored by a photoacoustic multigas monitor, and slurry samples were collected at 0 and 85 days and their composition assessed. Results showed that the addition of biochar could modify the physicochemical properties of the slurry. The addition of biochar did not reduce the E. coli during the experiment while clinoptilolite decreased its prevalence. The addition of biochar or clinoptilolite reduced significantly the NH3 emission during the storage of slurry, but no advantages were gained with their combination. The addition of biochar significantly reduced the CO2 and CH4 emissions relative to clinoptilolite, however N2O emissions and global warming potential did not differ among the additives. We conclude that the biochar and clinoptilolite are recommended as a mitigation measure to reduce gaseous emissions and preserve the fertiliser value at slurry storage.
•Different legume cover crops as N source for maize crop were evaluated.•N uptake by cover crops was not affected by earlier vs. latter sowing date.•Sowing date of cover crops affected the N uptake ...and dry matter of maize grain.•Balansa clover was the most efficiently cover crop to supply N to maize.•Legume cover crops are recommended as N sources for crop production.
Current environmental concerns, the rising economic and environmental costs of mineral fertilizers and the need to respond to the limitations of N fertilization in organic farming motivate the search for alternative sources of N in maize cropping. Forage legumes used as winter cover crops may improve soil N fertility and offer benefits to the environment. The aim of this study was to examine the effects, in a factorial field experiment, of two sowing dates (SD) and nine different cover crop treatments (balansa clover, crimson clover, gland clover, arrowleaf clover, French serradella, yellow lupin, Italian ryegrass, a cover mixture and a weedy fallow) as a potential alternative N source in an organically managed maize crop. The experiment was conducted at Viseu (Portugal) for three years (2007/2008, 2008/2009 and 2011/12), in the same field. Results showed that maize grain yield was not influenced by cover crop species but was affected by SD and the higher dry matter (DM) aboveground biomass production was observed in early SD (6.1 t ha−1). The cover crops revealed their importance in maize N uptake: yellow lupin of earlier SD had the highest N uptake (83.6 kg N ha−1), but this was not significantly different from balansa clover (83.2 kg N ha−1). Ryegrass was the most efficient in depleting soil mineral N but values were just significantly lower than yellow lupin.
Lupin was the least efficient, leaving more mineral N in the soil than the others cover crops, immediately before the period when the risk of leaching is high. It was concluded that, under the edaphoclimatic conditions tested, most of the tested cover crops were efficient in supplying N to maize, and balansa clover had the best performance.
The soil incorporation of green manures is a practice that can be used in sustainable agriculture and in organic farming, where nitrogen (N) sources are limited. The aim of this study was to evaluate ...balansa clover (Trifolium michelianum Savi), yellow lupine (Lupinus luteus L.) and ryegrass (Lolium multiflorum Lam.) as potential alternative N sources. A total of nine treatments were considered in this study: control, aerial of balansa clover, roots of balansa clover, aerial of yellow lupine, roots of yellow lupine, aerial of ryegrass, roots of ryegrass, mixture aerial + roots of yellow lupine and mixture aerial + roots of ryegrass. A laboratory incubation experiment was conducted under controlled conditions during 196 days and carbon and N mineralisation were followed. Results showed that green manures are appropriate N sources for Mediterranean farming. No significant differences in terms of N mineralisation were observed between aerial or roots biomass of the green manures. Besides, 37-55% of total N applied was mineralised in treatments amended with balansa clover or yellow lupine, whereas 13-21% of total N applied was mineralised in ryegrass. It can be concluded that the most efficient green manure for supplying mineral N to the succeeding crop was yellow lupine.
Background:
Tannery industry produces high amounts of nutrient rich sludges that can be used as organic fertilizers.
Objective:
The aim of this study was to evaluate the fertilizing potential of ...composted tannery sludge.
Methods:
A pot experiment was carried out with ryegrass (
Lolium perenne
L.) to test two different composts: 2.0 kg dry matter (DM) tannery fatty sludge + 1.5 kg DM sheep manure + 1.5 kg DM wheat straw (Compost 1) and 2.0 kg DM tannery sludge + 1.5 kg DM sheep manure + 1.5 kg DM wheat straw (Compost 2). Five treatments, with three replicates each, were assigned: Control (C); Compost 1 at 6 t (C1-6) and 12 t (C1-12) DM ha
-1
; Compost 2 at 6 t (C2-6) and 12 t (C2-12) DM ha
-1
. Each treatment was applied in a pot and mixed with 5 kg of sieved soil (<2 mm).
Results:
Results showed that production of DM ranged between 1.2 t DM ha
-1
for C1-6 and 2.4 t DM ha
-1
for C2-12. The highest B, Na and N levels in ryegrass was observed in C2-12, with 175 mg kg
-1
DM, 9 g kg
-1
DM and 30 g kg
-1
DM, respectively. At the end of the experiment no differences were observed between treatments for C, N, P
2
O
5
, and K
2
O levels. Differences were observed at Zn level ranged between 101 mg kg
-1
DM for C1-6 and 71 mg kg
-1
DM for C2-12.
Conclusion:
The C2-12 treatment was the best because induces higher DM production and nutrients in ryegrass and without dangerous concentration of heavy metals in soil. Composted waste from the tannery industry is a good source of nutrients for agriculture.
Background:
Understanding soil nitrogen (N) dynamics is essential to find alternative N sources and improve N use efficiency in agriculture.
Objective:
The aim of this study was to assess N ...mineralization rates from residues of winter cover crops, during maize crop season, under Mediterranean conditions.
Methods:
A field experiment was carried out from May to September in central Portugal, with four replications, two sowing dates of cover crops (15/10/2011 and 29/11/2011) and three cover crops residues (balansa clover, ryegrass and yellow lupine) that were incorporated in the soil. Plots were cropped with local maize and net N mineralization was measured during the crop cycle, using soil cylinders placed inside micro-perforated polyethylene bags.
Results and Discussion:
Early sowing of the cover crops residues increased the NH
4
+
and NO
3
-
contents in the soil. Yellow lupine residue had the highest rate of daily N mineralization (0.71 mg N kg
-1
day
-1
). For all treatments, the highest mineralization rate was found in the last incubation period, ranging between 0.78 mg N kg
-1
day
-1
and 1.84 mg N kg
-1
day
-1
, both for balansa clover, from the second and the first sowing date, respectively.
Conclusion:
The present study suggests that, under Mediterranean field conditions, cover crops residue of Italian ryegrass, balansa clover and yellow lupin can be used as a nitrogen source namely for sustainable maize crops.
PDF
