Effects Of Different Manures On Carbon And Nitrogen,Grain Growth In Coal Mining Reclaimed Soil

Soil reclamation in coal mining subsidence area is an important way to effectively increase the cultivated area.After engineering reclamation,the subsoil layer covers topsoil layer in coal subsidence reclaimed soil,thereby resulting in the destruction of the original soil structure,lack of nutrients,low nitrogen availability and serious problem of "carbon deficiency".In order to effectively fertility soil,improve soil organic carbon content and nitrogen availability in coal mining subsidence area,this experiment took the reclaimed soil from coal mining subsidence area in Xiaoyi City,Shanxi Province as the object.The three consecutive years of field experiments was used to study effects of organic fertilizers(chicken manure,pig manure,cattle manure)and chemical fertilizer on maize growth,carbon and nitrogen nutrient and related enzyme activity,thus providing scientific theoretical basis for fertilizing quickly reclaimed soil in coal mining subsidence area or similar low yield soil.The main research results are as follows:(1)Effects of applying different organic fertilizers on the maize yield,nitrogen absorption and utilization in reclaimed soil.The results showed: compared with no fertilizer treatment,maize grain yield of each fertilizer treatments significantly increased by 27.67%-154.61% for three consecutive years.In the first year,the maize grain yield of chemical fertilizer treatment was 13.88 t hm-2,and the maize grain yield of chemical fertilizer treatment was significantly higher than that of pig manure treatment and cattle manure,but there was no significant difference between chemical fertilizer treatment and chicken manure treatment.In the second year and third year,there was no significant difference among fertilizer treatments.Compared with the first year and second year,the maize grain yield of the third year decreased,because of reduction in precipitation at maize growth period of this year.In the first year and second year,there was no significant difference in plant nitrogen uptake among fertilizer treatments.In the third year,compared with chemical fertilizer treatment,plant nitrogen uptake of chicken manure treatment and cattle manure treatment significantly increased by 30.56% and 25.40% respectively,but the difference of both treatments was no significant,meanwhile there was no significant difference between pig manure treatment and chemical fertilizer treatment.As the reclaimed years increased,maize nitrogen absorption efficiency of different fertilizer treatments showed increased trend.In the first year and second year,there was no significant difference in nitrogen absorption efficiency among fertilizer treatments;in the third year,chicken manure treatment and cattle manure treatment significantly higher than chemical fertilizer treatment,but there was no significant difference between pig manure treatment and chemical fertilizer treatment.Maize nitrogen harvest index decreased with reclaimed years increasing.In three consecutive years,there was no significant difference in Maize nitrogen harvest index between organic fertilizer treatments and chemical fertilizer treatment mainly.(2)Effects of applying different organic fertilizers on nitrogen nutrients in reclaimed soil.The results showed: Compared with the CK,the contents of total nitrogen and available nitrogen in each fertilization treatment were significantly increased in the surface(0-20cm)soil for three consecutive years.The effect of different organic fertilizer treatments on improving the contents of total nitrogen and available nitrogen in the surface(0-20cm)soil was better than that in the chemical fertilizer treatment,but there was no significant difference among the organic fertilizer treatments.For three consecutive years,mineral nitrogen content of fertilizer treatments in 0-60 cm soil layer was increased with soil layer depth and then decreased,and mineral nitrogen content of 0-20 cm soil layer was higher than that of 20-40 cm soil layer and 40-60 cm soil layer.Mineral nitrogen content in 0-60 cm soil layer varied with three kinds of organic fertilizer treatments,with a sequence of pig manure ≥ chicken manure ≥ cattle manure.Compared with chicken manure treatment and cattle manure treatment,pig manure treatment could significantly increase mineral nitrogen of surface(0-20cm)soil layer.But chicken manure treatment could significantly increase mineral nitrogen of deep(40-60cm)soil layer.Different fertilizer treatments significantly increased soil soluble organic nitrogen content,and soluble organic nitrogen content increased with reclaimed years increasing.In the first year and second year,there was no significant difference in soluble organic nitrogen content among fertilizer treatments;in the third year,the soluble organic nitrogen content of pig manure treatment was highest,which was significantly increased by 171.74% and 75.23% respectively,compared with chicken manure treatment and cattle manure treatment.By the person double-tail correlation analysis,it was found that soil soluble organic nitrogen was significantly correlated with the soil total nitrogen and nitrate nitrogen,and the soil soluble organic nitrogen content only accounted for 0.05%-0.67% of the soil total nitrogen content.(3)Effects of applying different organic fertilizers on soil organic carbon in reclaimed soil.The results showed: In the first year of fertilization and the second year of fertilization,organic fertilizers and chemical fertilizer had little effect on soil total organic carbon,and there was no significant difference on soil total organic carbon content between different treatments;in the third year of fertilization,compared with chemical fertilize,soil total organic carbon content of chicken manure treatment and cattle manure treatment increased by 73.27% and 83.39% respectively,but there was no significant difference on soil total organic carbon content among pig manure,chemical fertilizer and blank treatment.As the fertilization years increased,there was no significant difference on inert organic carbon content between different treatment in the same year,but the effects of different fertilizer treatment on soil active organic carbon and chronic organic carbon were different.In the first year of fertilization,compared with chemical fertilizer treatment,cattle manure treatment significantly increased soil active organic carbon content,different organic fertilizer all significantly increased soil chronic organic carbon content,but there was no significant difference between organic treatments;in the second of fertilization,compared with chemical fertilizer,chicken manure and pig manure treatment significantly increased soil active organic carbon,increased by69.81% and 100% respectively,and cattle manure treatment significantly soil chronic organic carbon content,increased by 78.62%;in the third of fertilization,the soil active organic carbon content of different organic fertilizer treatment all significantly higher than that in chemical fertilizer treatment.(4)Effects of applying different organic fertilizers on carbon and nitrogen related enzyme activities in reclaimed soil.For three consecutive years,the fertilizer treatments significantly increased soil urease,phosphatase,invertase activity,and soil urease,phosphatase,invertase activity all increased with reclaimed years increasing.In the third year,compared with chicken manure treatment and cattle manure treatment,pig manure treatment significantly increased soil phosphatase activity.Compared with pig manure treatment,cattle manure treatment significantly increased soil invertase activity,but there was no significant difference between cattle manure treatment and chicken manure treatment.Meanwhile there was no significant difference in soil urease activity among different organic fertilizer treatments.