RESUMO
The effects of 20%-40% fertilizer reduction and different organic fertilizers on soil microbial biomass, enzyme activity and cotton yield were examined for three consecutive years in Hexi area of Gansu, Northwest China. The results showed that compared with single chemical fertilizer application, the abundance of soil bacteria and actinomycetes were significantly increased while that of fungi were decreased with chemical fertilizer reduction combined with organic fertilizer. The abundance of soil bacteria was maximum under the treatment of chemical fertilizer reduction combined with common organic fertilizer and bio-organic fertilizer (COBF2), which was 84.6%, 57.1% and 43.5% higher than that under single application of chemical fertilizer (CF) in the bud stage, boll stage and boll open stage, while the abundance of actinomycetes was maximum under the chemical fertilizer reduction combined with common bio-organic fertilizer (CBF2), which was 28.2%, 32.7% and 32.2% higher than CF. The abundance of fungi was the lowest in the CBF2 treatment, which was 35.8%, 29.3%and 13.4% lower than CF treatment in three periods. The ratios of bacteria to fungi, actinomycetes to fungi and the activity of soil urease, catalase, sucrase and alkaline phosphatase were increased by the chemical fertilizer reduction combined with organic fertilizer. COBF2 was the most effective way to improve enzyme activity. Fertilizer reduction combined with the application of organic fertilizer increased boll number per individual of cotton plant, promoted cotton growth and dry matter accumulation in the ground to a certain extent. The cotton yield under COBF2 treatment was the highest, which showed an significant increase of 14.2% and 10.9% respectively in seed and lint cotton yield than CF. Our results showed that COBF2, with 60% reduction of chemical fertilizer combined with 1800 kg·hm-2 ordinary organic fertilizer and 600 kg·hm-2 biological organic fertilizer, had the best fertilization effect.
Assuntos
Fertilizantes , Solo , Agricultura , Biomassa , China , Microbiologia do SoloRESUMO
To examine the effects of biodegradable film on preservation of soil temperature, moisture, growth and yield of cotton fields in Hexi area of Gansu, the trials were conducted with four treatments of DA (biodegradable film A with thickness of 0.012 mm), DB (biodegradable film B with thickness of 0.008 mm), common plastic film and unmulching were used to analyze the changes of degradation property, soil temperature, moisture, weeds control, and yield in 2016 and 2017. The results showed that the induction period of DB was three to five days earlier than that of the DA and the degradation rate was higher than DA. The mass loss rate of DA and DB could reach 95.6% and 94.5% respectively under 180 days landfill treatment. The DA showed good performance in water retention, soil warming in seedling stage, with no significant difference with the common plastic film. Due to the high degradation rate, water retention property, and insulation of DB were significantly lower than that of common plastic film. The growth period of cotton prolonged by biodegradable film compared with common plastic film, but with no significant difference of the emergence rate, boll number per plant, boll mass and lint percentage. However, the pre-frost yield and weeds control effects significantly decreased. There was no significant difference of cotton yield of DA compared with common film, but significantly increased by 73.1% and 59.9% compared with unmulching. The cotton yield of DB was significantly decreased by 11.8% and 7.1% compared with common film. In summary, DA played good performance on the preservation of soil temperature, moisture and the yield increasing effect, which could be applied in Hexi agricultural area of Gansu.