有机肥部分替代化肥对不同土壤连作棉花根系的影响

Effects of partial organic substitution for chemical fertilizer on the root system of cotton continuous cropping in different soil types

[目的]研究有机肥部分替代化肥对新疆不同连作棉田土壤及棉花根系生长的影响,筛选有机肥部分替代化肥的最佳比例,为新疆连作棉田的科学高效施肥提供参考依据。[方法]在新疆常见的棉田灰漠土和风沙土中种植棉花,采用腐熟的农家鸡粪作为有机肥,设置3个有机肥部分替代化肥处理:T1处理:100%化肥;T2:80%化肥+20%有机肥(有机肥2 250 kg·hm^(-2));T3:60%化肥+40%有机肥(有机肥4 500 kg·hm^(-2))。采用聚氯乙烯管开展试验,研究有机肥部分替代化肥对蕾期和吐絮期棉田土壤理化性质,棉花根系的形态特征、生理特征,以及棉花生物量和产量等的影响。并利用综合隶属函数法对所有指标进行主成分分析和回归分析,综合评价不同比例的有机肥和化肥组合对土壤-棉花系统的整体影响。[结果]有机肥替代化肥的T2处理和T3处理均显著提高灰漠土和风沙土中土壤全氮和有效磷含量。在灰漠土中与T1相比,T2处理的土壤全磷含量在蕾期和吐絮期分别增加14.7%和30.3%、有效磷含量分别增加138.7%和202.6%;T3处理的土壤全氮含量在蕾期增加39.2%、土壤全磷含量在吐絮期增加46.2%。T2处理和T3处理均使灰漠土中棉花根系的总根长、比根长、比根表面积、根系可溶性糖含量、硝酸还原酶活性显著增加,而根系组织密度、地上部生物量显著下降。在风沙土中棉花蕾期,T2处理和T3处理下比根长分别显著增加11.9%和9.6%。在风沙土中棉花吐絮期,与T1相比,T2处理和T3处理下土壤碱解氮含量分别显著增加51.3%和97.9%、总根长分别显著减少26.9%和21.0%;比根长显著减少33.4%和36.5%。对于风沙土中种植的棉花,T2处理下棉花蕾期和吐絮期比根表面积分别显著减少18.8%和19.3%;T3处理显著增加棉花吐絮期根系平均直径(65.3%)和地上部生物量(27.6%)。[结论]有机肥部分替代化肥可以通过改善灰漠土和风沙土土壤理化特征,提高土壤养分含量,促进棉花根系生理活性和优化根系构型,使根系投入更少的生物量以获得更高的养分吸收效益,优化对生物量的分配,最终缓解连作障碍。在灰漠土中,有机肥替代40%化肥处理效果最佳。在风沙土中,有机肥部分替代化肥的影响因有机肥添加比例和生育时期而不同。

[Objective]This study aims to analysis the effects of partial organic substitution for chemical fertilizer on soil and cotton root growth in different continuous cotton fields in Xinjiang,and to reveal the optimal proportion of organic fertilizer dosage,so as to provide reference for the rational application of fertilizers in continuous cotton fields in Xinjiang.[Methods]The cotton were planted in the grey desert soil and aeolian sandy soil,two common soil types of cotton fields in Xinjiang,and decomposed farm chicken manure was used as organic fertilizer,and setting up three fertilizer treatments:T1 treatment,100%chemical fertilizer;T2,80%chemical fertilizer+20%organic fertilizer(2250 kg·hm^(-2) organic fertilizer);T3,60%chemical fertilizer+40%organic fertilizer(4500 kg·hm^(-2) organic fertilizer).The experiments were conducted using polyviny chloride pipes to study the effects of partial organic substitution for chemical fertilizer on the physical and chemical properties of cotton soil at the cotton budding stage and boll-opening stages,the morphological and physiological characteristics of cotton roots,as well as the biomass and yield of cotton.Principal component analysis and regression analysis were conducted on all indicators by using the comprehensive membership function method,to comprehensively evaluate the overall impact of different proportions of organic fertilizer and chemical fertilizer combinations on the soil-cotton system.[Results]Both T2 and T3 treatments significantly increased the total nitrogen content and available phosphorus content in grey desert soil and aeolian sandy soil.For grey desert soil,compared with T1,T2 treatment increased the total phosphorus content of the soil by 14.7%and 30.3%,and increased the available phosphorus content by 138.7%and 202.6%during the budding stage and boll-opening stage,respectively.For grey desert soil,compared with T1,T3 treatment increased the soil total nitrogen content by 39.2%during the budding stage and increased the soil total phosphorus content by 46.2%during the boll-opening stage.In T2 and T3 treatments,the total root length,specific root length,specific surface area,soluble sugar content,and nitrate reductase activity of cotton root were significantly increased,while the root tissue density and aboveground biomass were significantly decreased in gray desert soil.During the cotton budding stage in aeolian sandy soil,the specific root length of cotton were significantly increased by 11.9%and 9.6%under T2 and T3 treatments,respectively.Under T2 and T3 treatments during the cotton boll-opening stage in aeolian sandy soil,the alkaline nitrogen contents in the soil significantly were increased by 51.3%and 97.9%,respectively,while the total root length of cotton were significantly decreased by 26.9%and 21.0%;the specific root length of cotton were significantly decreased by 33.4%and 36.5%.T2 treatment significantly reduced the specific root surface areas by 18.8%and 19.3%during two stages,respectively.T3 treatment significantly increased the average root diameter(65.3%)and aboveground biomass(27.6%)of cotton during the boll-opening stage in aeolian sandy soil.[Conclusion]Partial substitution of chemical fertilizers with organic fertilizers can improve the physical and chemical characteristics of grey desert soil and aeolian sandy soil,increase soil nutrient contents,promote the physiological activity of cotton root,optimize root configuration,and enable cotton root to invest less biomass to obtain higher nutrient absorption benefits,optimize the allocation of biomass,and ultimately alleviate continuous cropping obstacles.In grey desert soil,organic fertilizer replacing 40%chemical fertilizer treatment has the best effect.The effect of partially substituting chemical fertilizers with organic fertilizers in sandy soil varies depending on the proportion of organic fertilizer added and the growth period.