| Selection of suitable tillage is an important factor to improve the quality of arable land and crop yield in the mountainous areas of Ningnan.In this study,mainly focusing on the problems of low water and fertilizer utilization rate and yield of traditional tillage in potato production in rain-fed agricultural area of Ningnan,a field trial was conducted in Baisheng village,Xinying Township,Xiji County,from 2020 to 2021 with QingYangYang No.9 as the test variety,and a 2-factor split-zone design experiment of tillage and mulching was set up.The main zone was the tillage method with traditional tillage of 20 cm(CT)and smashing ridge tillagetillage of 30 cm(FL30),45 cm(FL45)and 60cm(FL60);the secondary zone was tillage with no mulch(NM)and black mulch(BM).Randomized group arrangements were made.The experiments were carried out to evaluate the effects of smashing ridge tillage mulching,smashing ridge tillage nitrogen application and smashing ridge tillage after-effects to explore the effects of smashing ridge tillage mulching tillage on soil physicochemical properties,spatial and temporal evolution of mineral nitrogen,water and nitrogen use efficiency,potato growth and yield benefits in Ningnan dry rainfed agricultural area.The main experimental results are as follows.(1)Smashing ridge tillage can break the plough bottom layer and have significant effects on soil physicochemical properties in the 0～60cm soil layer.There is a continuous effect on the soil efficiency after three years of smashing ridge tillage,while there is no significant difference between smashing ridge tillage and traditional tillage after four years.The soil porosity of FL45×BM treatment was significantly higher than that of CTxNM treatment by 6.48%and 7.16%on average in the 0～40cm soil layer;the DR0.25 of FL30×NM treatment was significantly higher than that of CTxNM treatment by 5.86%,4.19%and 6.86%in the 0-60cm soil layer.The soil water content and water storage of FL60×BM was the highest in both years.2a period,the crop water consumption and water use efficiency of FL60×BM treatment were significantly reduced by 11.10%and increased by 65.88%compared with CT treatment.In 2020,the FL60 treatment had the highest content of alkaline N,fast-acting K and organic matter in the 0-80 cm soil layer,with an average increase of 18.8%,27.01%and 25.64%compared with the CT treatment.(20～80cm soil layer)distribution pattern.(2)The content of nitrate and ammonium nitrogen in 0-80 cm increased with the increase of the depth of the smashing ridge tillage,and the smashing ridge tillage could block the nitrate nitrogen in the tillage layer and reduce the leaching loss of nitrate nitrogen,which was beneficial to the uptake and utilization of the crop.The ammonium nitrogen content of potatoes was low at all fertility periods,ranging from 0.40 to 14.05mg·kg-1,and the ammonium nitrogen content of each treatment decreased as the fertility period moved later.There was no significant difference in the accumulation of ammonium nitrogen from flowering to maturity in the 2-year trial,while the decrease in nitrate nitrogen accumulation was smaller in the smashing ridge tillage than in the conventional tillage.(3)In the 2a trial,the FL45×BM treatment increased the height,stem thickness and dry matter of potato plants,and the most significant result was obtained by fitting the logistic equation.Among them,FL60 treatment was the most significant.After three years,the effect on plant height and stem thickness in the early stage of potato fertility was not significant,while after four years,the effect on plant height and stem thickness in the early stage of potato fertility and critical fertility was not significant.(4)During the 2a period,both milling and mulching measures significantly affected potato yield.Among all treatment combinations,FL45×BM and FL60×BM treatments significantly increased the 2year average total potato yield by 47.63%and 33.64%compared with CT×NM treatment,and the analysis of 2-year yield and economic benefits showed that FL45×BM treatment had the best effect on increasing total potato yield and commercial potato rate,and FL45 had the best economic benefits.The nitrogen fertilizer bias productivity,nitrogen fertilizer agronomic efficiency and nitrogen fertilizer utilization efficiency were all significantly higher in smashing ridge tillage than in conventional tillage,while potato yield and nitrogen uptake rate were both improved compared with conventional tillage.There was a sustained efficiency gain in potato yield after three years of smashing ridge tillage,while there was no significant difference after four years of smashing ridge tillage.(5)Potato yield was highly significantly and positively correlated with nitrate-nitrogen,ammoniumnitrogen,alkaline nitrogen and effective phosphorus in 2020.potato yield was positively and significantly correlated with ammonium-nitrogen,nitrogen uptake,nitrate-nitrogen and effective phosphorus in 2021.The composite scores of the principal components of different tillage and mulching treatments showed that the composite scores of mulching treatments were higher than those of non-mulching treatments,with FL45×BM treatment having the highest composite score among the eight treatments,indicating that FL45×BM had the best yield and income benefits.In conclusion,the combination of smashing ridge tillage and mulching can improve the physical structure of soil,thus storing water and moisture,activating nutrients,and promoting the root system to root down,which is beneficial to potato growth and indirectly or directly promotes the improvement of potato yield and water and nitrogen use efficiency,and is an effective measure to improve the quality of soil cultivation,and smashing ridge tillage will have a continuous good effect on soil within three years at a time.Therefore,the 45cm combination of smashing ridge tillage and black film is more conducive to soil water and fertilizer retention on the basis of improving the physical structure of the soil in the tillage layer,while the need to smashing ridge tillage once every three years,so as to maximize the economic benefits in the case of potatoes to obtain better yield increases,providing a practical reference for highyielding and efficient potato cultivation in the dry zone of Ningnan. |
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