免耕或深松结合秸秆覆盖提升土壤碳氮水含量和马铃薯产量的协同效应

Synergistic effect of no-tillage or sub-soiling tillage with straw mulching increasing soil carbon,nitrogen and water storage and potato yield

【目的】研究不同耕作方式结合秸秆覆盖措施对土壤有机碳、全氮、水含量及马铃薯产量的影响,以探明耕作结合秸秆覆盖措施的增产机理,为宁南旱作节水农业发展提供技术和理论参考。【方法】于2014—2016年开展田间定位试验,设置6个处理:免耕+秸秆覆盖(NS)、免耕+不覆盖(NN)、深松+秸秆覆盖(SS)、深松+不覆盖(SN)、传统耕作+秸秆覆盖(CS)、传统耕作+不覆盖(CN)。在2016年马铃薯收获期取样测定了0—40 cm土层土壤有机碳与全氮含量,播种、现蕾、块茎形成和块茎膨大期测定了0—200 cm土层土壤蓄水量,苗期、现蕾、块茎形成、块茎膨大以及收获期测定了地上部生物量,成熟期调查了产量。【结果】同一耕作措施下,覆盖秸秆较不覆盖能显著提高0—40 cm土层土壤碳、氮含量,提高马铃薯播种期、现蕾期、块茎形成期和块茎膨大期0—200 cm土层土壤蓄水量。以CN处理为对照,0—20 cm土层土壤碳、氮含量的提高幅度以SS处理最高,增幅分别为29.9%和24.7%,20—40 cm土层则以NS处理最高,增幅分别为52.4%和27.4%(P<0.05);播种期土壤蓄水量2014年(干旱年)以NS处理最高,2015年(平水年)和2016年(干旱年)以SS处理最高,增幅依次为6.4%、11.4%和29.6%;马铃薯关键生育期平均土壤蓄水量的增幅在2014和2016年以SS处理最高,分别为21.6%和26.0%,2015年以NS处理最高,增幅为17.2%。根据马铃薯生物量累积动态变化的Logistic模型计算,3年均以SS处理进入快速增长起始期最早,最大累积速率在2014年以NS处理最高,2015和2016年以SS处理最高。相比CN,马铃薯产量2014年以NS处理最佳,增幅为51.8%,2015和2016年均以SS处理最佳,增幅分别为36.7%和87.5%。降水年型、耕作方式和秸秆覆盖对土壤蓄水量、马铃薯地上部生物量以及产量的影响均达到极显著水平,秸秆覆盖对土壤碳、氮含量的影响也达到极显著水平(P<0.01)。马铃薯产量与土壤碳含量呈显著正相关,与土壤全氮、蓄水量和生物量呈极显著正相关,土壤有机碳、氮含量和蓄水量之间也呈极显著正相关。【结论】不同耕作措施配合秸秆覆盖可进一步提高土壤碳、氮含量和0—200 cm土层蓄水量,保证马铃薯稳产高产。在秸秆覆盖条件下,连续深松能够显著提升0—20 cm土层土壤碳、氮含量,提早马铃薯的生物量快速累积期,并在干旱年份延长快速增长持续期和提高最大累积速率;免耕在第一年提高马铃薯产量的效果最佳,但连续免耕的增产效果不如连续深松甚至传统耕作。因此,综合考虑土壤碳氮水与作物产量的协同效应,建议免耕、深松配合秸秆覆盖措施在宁南山区马铃薯栽培中进行推广应用。

【Objective】We studied the effects of tillage methods combined with straw mulching on soil carbon,nitrogen and water storage to provide technical and theoretical support for water-saving potato production in southern Ningxia.【Methods】A field experiment was conducted from 2014 to 2016 in Guyuan City,Ningxia.There were six treatments,including no-tillage with and without straw mulching(NS,NN),sub-soiling tillage with and without straw mulching(SS,SN),and traditional tillage with and without straw mulching(CS,CN).The organic carbon and total nitrogen(TN)in 0-20 cm and 20-40 cm soil layer were determined at maturing stage of potato in 2016.Soil samples were collected at 0-200 cm deep every 20 cm to determine the water storage before sowing and the key growth stages of potato.The potato plants were sampled at whole growing stages to investigate aboveground biomass(AB),while potato yield was investigated at harvest.【Results】Compared with no straw mulching in the three tillage methods,straw mulching(P<0.05)increased soil total C and N content and water storage.SS treatment had higher soil C and N than CN(29.9%and 24.7%)in the 0-20 cm layer;NS recorded the highest soil C and N in the 20-40 cm layer.Before sowing potatoes,the highest soil water storage in 2014 and 2015 was recorded in NS and SS,respectively.SS(P<0.05)increased the potato's mean soil water storage at key growth stages by 21.6%and 26.0%in 2014 and 2016,respectively.Similarly,NS increased mean soil water storage by 17.2%in 2015.According to the logistic growth equation simulation,the potato's rapid growth stage was the earliest in SS treatment.The maximum accumulation rate of potato biomass was higher in NS in 2014 and SS in 2015 and 2016.NS treatment recorded the highest potato yield in 2014,with an increase of 51.8%over CN.Similarly,SS had the highest yield in 2015 and 2016,increased by 36.7%and 87.5%over CN.Annual precipitation,tillage method,and straw mulching were highly significant on soil water storage,potato aboveground biomass and yield.Straw mulching(P<0.05)affected soil C and N contents.Potato yield was(P<0.05)positively correlated with soil C,and potato yield had a significantly positive relationship with soil N,water storage and potato biomass.We found a(P<0.05)correlation among soil C,N,and water storage.【Conclusions】Combining the three tillage methods with straw mulching increases the soil carbon and nitrogen contents in the 0-40 cm layer and water storage in the 0-200 cm layer throughout the potato growing period,promoting the accumulation of aboveground biomass and potato yield.Applying straw mulching to the subsoiling increases soil C and N in the 0-20 cm layer,rapidly enhances the growth stages and fosters optimum biomass accumulation in dry years.No-tillage with straw mulching treatment had the highest yield in the first year but was lower than the range recorded under subsoiling with straw mulching and conventional tillage with straw mulching.Therefore,comprehensively considering the synergistic effect of soil carbon,nitrogen,water storage and crop yield,the application of straw mulching to no-tillage and sub-soiling are recommended for the potato production in southern Ningxia.