减氮条件下生物质炭施用对珠三角地区生菜产量、品质及土壤性质的影响

Effects of Biochar Application on Yield,Quality,and Soil Fertility of Lettuce Under Nitrogen Reduction

生物质炭(biochar,BC)施用具有改良土壤、提高作物产量等效应。本文探究了生菜产量、品质和土壤性质等对化肥氮(N)减施和生物质炭施用1年后的响应,以期为珠三角地区露地蔬菜生产中化肥合理减量和生物质炭科学施用提供依据。通过在佛山市三水区开展田间小区试验,观测了常规施氮(N100%)、减氮20%(N80%)、减氮40%(N60%)、减氮40%+生物质炭10 t/hm^(2)(N60%+BC10)和减氮40%+生物质炭20 t/hm^(2)(N60%+BC20)处理下生菜产量、品质、叶片SPAD值及土壤养分等指标的变化。结果表明:①较N100%处理,N60%处理生菜产量显著降低13.5%。减氮40%条件下,配施10~20 t/hm^(2)生物质炭可提高生菜产量9.5%~22.7%,与N100%处理产量相当,说明生物质炭施用对生菜产量具有显著提升效果。②氮肥减量和生物质炭施用对生菜单株鲜重、直径和水分含量等均无显著影响,而对叶片SPAD值在不同生育期有不同影响。减氮条件下施用生物质炭处理生菜的氮和磷吸收量提高,是其增产机理之一。③氮肥减施对生菜硝酸盐含量无显著影响,但降低其总糖含量;而N60%+BC20处理可在减氮条件下不影响生菜总糖含量且显著降低其硝酸酸盐含量34.6%,具有改善生菜品质的效果。④减氮与施用生物质炭均可提高土壤pH,与N100%处理相比,N60%+BC10和N60%+BC20处理的土壤pH显著提高0.48~0.65个单位。而且,减氮条件下施用生物质炭有提高土壤全磷和有机质含量的潜力。可见,N80%或N60%+BC10处理在1年后仍可提高生菜对氮磷的吸收,保证生菜产量的同时改善其品质,并改良菜地土壤。

Biochar(BC)application can improve soil fertility,enhance crop yield and exert other positive effect.In this study,the responses of lettuce yield,quality and soil properties to chemical fertilizer nitrogen(N)reduction and BC application after one year were investigated in order to guide the reduction of chemical fertilizer application and scientific usage of BC in open field vegetable production in the Pearl River Delta region.A field plot experiment was conducted in Sanshui District,Foshan City,China,to investigate the changes in lettuce yield,quality,SPAD value and soil nutrients under five treatments,i.e.,conventional N application(N100%),N reduction of 20%(N80%),N reduction of 40%(N60%),N reduction of 40%+BC of 10 t/hm^(2)(N60%+BC10)and N reduction of 40%+BC of 20 t/hm^(2)(N60%+BC20).Lettuce yield is significantly decreased by 13.5%under N60%treatment compared to N100%treatment.Under the condition of 40%N reduction,the application of 10-20 t/hm^(2)BC improves lettuce yield by 9.5%-22.7%,equal to the yield of N100%treatment,demonstrating that BC application has a significant effect in improving lettuce yield.Nitrogen fertilizer reduction and BC application has inconspicuous effect on lettuce single plant weight,diameter and water content,while there are different effects on leaf SPAD values at different growth stages.The increase of N and P uptake in lettuces treated with BC under N reduction is one of the mechanisms of yield increase.Nitrogen fertilizer reduction does not significantly affect nitrate content,but reduces total polysaccharide content of lettuce.While N60%+BC20 does not affect the total sugar content but significantly reduces nitrate content by 34.6%in lettuces,which have the effect of improving the quality of lettuce.Both N reduction and BC application promote soil pH,with N60%+BC10 and N60%+BC20 treatments significantly increase soil pH by 0.48-0.65 units compared with N100%.Moreover,BC application under reduction of N conditions has the potential to enhance total soil phosphorus and organic matter contents.The application of N80%or N60%+BC10 can still improve the uptake of N and P by lettuce after one year,which ensures the yield of lettuce as well as improves the quality and refines soil of the vegetable field.