Ammonia Volatilization Reduced by Combined Application of Biogas Slurry and Chemical Fertilizer in Maize–Wheat Rotation System in North China Plain

Abstract

Digestate and biogas slurry (BS) are the byproduct of biogas engineering that could be used for elevating plant growth. However, the consequent emissions of ammonia from BS are considered a severe threat to the atmosphere. Herein, we conducted two consecutive field experiments with wheat–maize rotations to find out the optimum ratio of BS to combine with chemical fertilizer (CF) to reduce ammonia volatilization (AV) while keeping the stable crop yield. In maize season, 226.5 kg N/ha of CF was applied. In wheat season, 226.5 kg N/ha was applied at different ratios (100%, 80%, and 50%) between BS and CF. Our results found that the maximum yield of 6250 kg/ha was produced by CF, and this yield could be obtained through a combined application of 38% BS mixed with CF. Highest AV produced of 16.08 kg/ha by CF. BS treatments significantly reduced the emission from 18% to 32% in comparison to CF. The combined application of BS-CF produced the highest yield due to essential nutrients coming from both BS-CF. Subsequently, it reduced the AV depending on fertilizer type and fertilizer rate. An optimal ratio of 38% BS was recommended to produce the highest yield and lowest ammonia emissions. The application of BS together with different ratios of CF could be an alternative agricultural strategy to obtain desired crop yield and reduce AV in North China Plain (NCP).

Overview on agricultural potentials of biogas slurry (BGS): applications, challenges, and solutions

“…In comparison to traditional compost, BGS is an easily available form of compost [ 17 ] and is also reported to have stronger plant growth-promoting activities than raw slurries due to higher concentrations of ammonical nitrogen [ 54 ]. As compared to CD, BGS have lower C/N content, thus enabling higher fertilization potential, and anaerobic digestion aids mineralization effects, hence increasing the bioavailability of nutrients to the plants [ 16 ], though the susceptibility towards N loss due to VOA can be increased [ 19 ]. Tumuhimbise [ 55 ] recorded higher biofertilizer potential of CM bioslurry as compared to the sun-dried slurry, fresh CM, and NPK treatments on the overall growth of radish in ferralsol soil.…”

“…Such losses were also observed at the time of drying BGS or soon after its application in agriculture fields [ 14 ]. BGS have pH values usually in the alkaline range [ 11 , 14 , 15 ], and as per the reports, the higher pH (>7) promotes N loss through VOA [ 16 ].…”

“…However, such losses can be minimized with the use of nitrogen-rich organic substrates during composting of BGS. High air temperature can also increase the N loss through ammonia emissions [ 16 ]. Studies mentioned that the available nitrogen in BGS is comparatively less efficient than mineral fertilizers due to such N losses [ 17 ].…”

Key Factors in Measuring Ammonia Emissions with Dynamic Flux Chamber in Barns

“…The dynamic flux chamber was fabricated directly with reference to previous studies and the EPA method [25,26]. The size is 40.64 cm in inner diameter and 17.78 cm in height and is fabricated as an integrated type.…”

“…EPA method [25,26]. The size is 40.64 cm in inner diameter and 17.78 cm in height and is fabricated as an integrated type.…”