PurposeTo investigate the effects of biogas slurry partial replacement of chemical fertilizer on the accumulation of nutrients and heavy metals in crops and soil under the annual wheat-maize rotation mode in Shajiang black soil area.
MethodsField trials were conducted with blank control (CK), conventional fertilization (CF), biogas slurry+conventional fertilization reduction of 40% (BRF) and slow controlled release fertilizer (20% reduction of CF, CRF), and the accumulation of nutrients and heavy metals in crops and soil were measured when wheat and maize were sown and harvested.
ResultsIn annual wheat-maize rotation, BRF and CRF treatments increased soil alkali-hydrolytic nitrogen and organic matter contents in 0-60 cm soil layer but had little effect on soil total nitrogen; CRF treatment increased soil available phosphorus content, but the soil available phosphorus content under BRF treatment was significantly lower than other fertilization treatments. In maize season, the soil available potassium content under CRF treatment was higher than other fertilization treatments; in wheat season, the available potassium content at soil layer >20-60 cm under BRF treatment was significantly higher than that in other fertilization treatments. The contents of Cu and Zn in the soil treated in wheat-maize seasons gradually decreased with the increase of soil layer, the contents of Cu, Zn and As in the soil treated with BRF treatment did not exceed the national secondary standard of soil environmental quality, and the contents of Cu, Zn and As in the grain of wheat-maize seasons did not exceed the National Food Hygiene Standard.
ConclusionUnder the annual wheat-maize rotation, biogas slurry+conventional fertilization reduction of 40% should not increase the heavy metal content of crops and soil, biogas slurry+conventional fertilization reduction of 40% and slow controlled release fertilizer can increase the soil fertility level.
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