Acidification of animal slurry is recommended in order to reduce NH3 emissions, but relatively little is known about the effect of such treatment on C and N dynamics during acidification, storage, and after soil application. A laboratory study was performed, and the CO2 emissions from a high–dry matter slurry (HDM), a low–dry matter slurry (LDM), and the same respective acidified slurries (AHDM and ALDM) were followed during a storage period and after soil incorporation. The N‐mineralization and nitrification processes, as well as microbial‐biomass activity were also estimated in soil receiving both the acidified and nonacidified materials. We observed a strong CO2 emission during the acidification process, and acidification led to a small increase in CO2 emissions (≈ 11%) during storage of AHDM relative to HDM. No effect of LDM acidification on CO2 emissions during storage was observed. About 30% of C released during storage of AHDM was inorganic C, and for ALDM the C release was exclusively inorganic. Soil application of AHDM and ALDM led to a decrease in soil respiration, nitrification, and microbial‐biomass‐C values, relative to soil application of HDM and LDM, respectively. Furthermore, it was shown that this effect was more pronounced in ALDM‐ than AHDM‐treated soil. Considering both steps (storage and soil application), acidification led to a significant decrease of C losses and lower C losses were observed from LDM slurries than from HDM slurries.
Solideliquid separation of slurry is used to obtain a solid (SF) and liquid fraction (LF), both used as organic fertilisers. Previous works showed that the separation technique used influences the composition of the resulting SF but no data are available relative to the LF. Four commonly used separation processes were considered e centrifugation, sieving, enhanced settling by the addition of cationic polyacrylamide (PAM-), and sediment settling as well as a recent sequential process e sieving followed by PAM addition to the resulting LF. The resulting LFs and SFs were comprehensively characterised and the amount of N potentially available for plants after incorporation to soil was also evaluated. Except for slurry that was only sieved which was very similar in composition to whole slurry (WS), the SFs and LFs had, respectively, higher and lower, concentrations of nutrients and organic matter (OM) than the WS. The ratio of ammoniacal to total N in the LFs varied from 0.33 to 0.92 whereas the values in the SFs varied between 0.16 and 0.31. The N:P:K ratio was also significantly influenced by the separation technique. Less than 10% of the total N applied in the WS, SFs or LFs was found to be potentially available for plants and, in some LFs, N immobilisation occurred after soil application. Since separation technique strongly influences nutrient distribution between LF and SF, as well as N speciation, the choice of the technique has to consider the final use of the resulting fractions as well as acquisition and operating costs.
The current data article presents a set of fluxes of ammonia (NH 3), nitrous oxide (N 2 O), methane (CH 4), and carbon dioxide (CO 2) measured from two different soils under a Mediterranean doublecropping system (oat in autumn/winter followed by maize in spring/summer). The two soils were fertilized using four different treatments: (i) Injection of raw cattle slurry (100 mm depth), (ii) application of raw cattle slurry followed by soil incorporation (20 mm depth), (iii) band application of acidified (pH ¼5.5) cattle slurry followed by soil incorporation (20 mm depth), and (iv) band application of acidified (pH ¼ 5.5) cattle slurry without soil incorporation. A non-amended soil was also considered as control treatment. The data presented here were obtained over a three years experiment between 2012 and 2015. Fluxes were measured in a period between slurry applications to soil (before plant seeding) till crop harvest. The data presented here are supporting the research article "Band application of acidified slurry as an Contents lists available at ScienceDirect
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