有机肥替代化肥氮对苹果产量、品质及温室气体排放的影响

【目的】通过连续5年田间试验，研究有机肥替代化肥氮对苹果产量、品质以及果园温室气体排放及增温潜势的影响，以确定适宜的有机替代比例，为果园提质、增效、减排提供理论依据。【方法】田间试验于2016—2021年在河北省邢台市果园进行，供试材料为13年生富士苹果。试验设置4个处理，分别为农民传统施肥(CT)、推荐施肥(OPT)、推荐施肥基础上有机肥替代25%化肥氮(OPT25)、推荐施肥基础上有机肥替代50%化肥氮(OPT50)，测定了历年苹果产量、品质，并在试验第5年监测了果园土壤的温室气体排放。【结果】1)与CT相比，OPT和OPT25处理苹果产量在后3年显著增加(P<0.05);OPT、OPT25和OPT50的苹果产量没有显著差异，产量均以OPT25最高，2021年相对CT处理显著增加28.42%(P<0.05)。2)有机肥替代处理的苹果品质优于传统施肥处理，且随试验年限的增加，较高比例的有机肥处理对苹果品质提升效果更显著；而施加有机肥显著提高了果实Vc含量、糖度与糖酸比，显著降低了果实酸度。3) OPT25处理土壤N₂O累积排放量最低，为2.40 kg...

Effects of substituting chemical nitrogen fertilizer with organic fertilizer on apple yield,quality, and greenhouse gas emissions

  【Objectives】  We studied the effects of consecutive replacement of chemical fertilizer nitrogen with organic fertilizer on apple yield, quality, and the greenhouse gas emission and warming potential of orchard soil in field experiments during five consecutive years, so as to provide a theoretical and technological basis for high quality and environmental friendly apple production.  【Methods】  A field experiment was conducted in the orchard of Xingtai City from 2016 to 2021, using 13-years-old Fuji apple trees as test materials. The four treatments were local farmers’ practice (CT), recommended fertilization (OPT), replacing 25% and 50% of chemical nitrogen fertilizer in OPT with organic fertilizer (OPT25 and OPT50, respectively). Apple yield and quality were measured every year, and the greenhouse gas emissions were monitored in the fifth year.   【Results】  1) Compared with CT, the yield of apple treated with OPT and OPT25 increased significantly in the next three years (P<0.05). Yield produced by OPT, OPT25, and OPT50 treatments were similar, while OPT25 obtained a 28.42% higher yield than CT in 2021. 2) Organic substitution promoted apple quality. With the increasing experimental years, OPT50 conferred more significant effect on quality improvement. Organic fertilizer substitution significantly increased vitamin C, sugar content, and the ratio of sugar to acid, thus significantly reducing the acidity. 3) OPT25 had the lowest cumulative N₂O emission in soil (2.40 kg/hm2), which was 6.98% lower than CT (P<0.05), while OPT50 had the maximum cumulative CO₂ emission from soil (3987.93 kg/hm2), which was 2.16% higher than CT. The orchard soil was a weak CH₄ sink in all the four treatments. Compared with CT, OPT and OPT25 decreased the greenhouse gas emission intensity (GHGI) by 12.65%, 15.16%, with OPT25 having the lowest GHGI (0.071 kg/kg).  【Conclusions】  Organic fertilizer substitution markedly improves the yield and quality of apple fruit, but the effect of high substitution rate (50%) reduces with the experimental years. Organic fertilizer substitution reduces soil N₂O emissions and GHGI, but high substitution rate increases soil CO₂ emissions. It is recommended that 25% of the conventional chemical fertilizer for apple production in this region be replaced with organic fertilizer.