Impacts of different pig slurry application methods on soil quality indicators in a maizesoybean cropping sequence in the Subhumid Pampas of Argentina

Purpose In Argentina, pig slurry (PS) is spread in surface with N losses in ammonia form. Different methods to decrease these emissions are available, but there is poor information about their impacts on the soilplant system. The objective of this study was to compare the effects of different PS application methods on the soil quality in a maizesoybean cropping sequence. Methods PS application methods were evaluated: acidified (AS), incorporated (IS), surface (SS), mineral fertilization (MF) and control (C). The experimental design was arranged in a randomized block with three replicates. Chemical parameters and microbiological parameters were determined. Also, grain yields and N uptake were measured. Results IS caused increases in anaerobic nitrogen and basal respiration of soil on soybean. Treatments with PS and/or FM showed lower values in pH than C in both crops, and higher electrical conductivity only in maize. SS treatment showed higher Pe on soybean, indicating a maintenance of the P levels with respect to those in MF and C. The concentration of NO3 increased with MF in both crops. In maize, MF presented similar concentrations to AS and SS. IS increased grain yields of maize by 16 %, whereas SS and AS increased yields of soybean by 112% and 79%, respectively, compared to C. Conclusions The different PS application methods had similar effects on most of the indicators of soil quality. In maize, IS and AS were more efficient in retaining N within the soilplant system, whereas, in soybean, the SS led to higher yields.